I
This book was created and written by Professor Boyd at Miramar Plaza Towers, overlooking the Panama Canal, the Pacific Ocean and the city of Panama. Project Director: Andres Caballero, Ph.D Production Manager: Kayra Mejia Page Design and Typesetting: Kayra Mejia Laura Duran Art Design: Eduardo Chandeck Spanish Translation: Cristela F. Aleman, M.D. Medical Illustrations: Stephen F. Gordon, B.A. Trina Fennell, M.S. Samuel Boyd, M.D. Sales Manager: Tomas Martinez Marketing Manager: Eric Pinzon Customer Service Manager: Miroslava Bonilla International Communications: Joyce Ortega
ISBN Nº 9962-613-03-5 ©Copyright, English Edition, 2001. Highlights of Ophthalmology Int'l P.O. Box 6-3299, El Dorado City of Knowledge Clayton, Bldg. 207 Panama, Rep. of Panama Tel: (507)-317-0160 FAX: (507)-317-0155 E-mail:
[email protected] All rights reserved and protected by Copyright. No part of this publication may be reproduced, stored in retrieval system or transmitted in any form by any means, photocopying, mechanical, recording or otherwise, nor the illustrations copied, modified or utilized for projection without the prior, written permission of the copyright owner. Printed:
Bogota, Colombia South America
OUTLINE OF MAJOR SUBJECTS
Chapter 1:
Surgical Anatomy of the Human Lens
Chapter 2:
Indications and Preoperative Evaluation
Chapter 3:
IOL Power Calculation In Standard and Complex Cases - Preparing for Surgery
Chapter 4:
Preventing Infection and Inflammation
Chapter 5:
Proceeding with the Operation
Chapter 6:
Phacoemulsification - Why So Important?
Chapter 7:
Preparing for the Transition
Chapter 8:
Instrumentation and Emulsification Systems
Chapter 9:
Mastering Phacoemulsification The Advanced, Late Breaking Techniques
Chapter 10: Focusing Phaco Techniques on the Hardness of the Nucleus Chapter 11:
Complications of Phacoemulsification Intraoperative - Postoperative
Chapter 12: Cataract Surgery in Complex Cases Chapter 13: Manual Extracapsular Techniques of Choice Planned ECCE - Small Incision ECCE Chapter 14: The New Cataract Surgery Developments
II
ACKNOWLEDGMENTS
All the text in this Volume has been written by the author. I am very much indebted to the Master Consultants and to all Guest Experts who are listed in this Front Section of the ATLAS. They are all highly recognized, prestigious authorities in their fields and provided me with most valuable information, perspectives and insights. The production of this ATLAS is a major enterprise. In addition to our dedicated staff at HIGHLIGHTS, three of my most valuable collaborators have been vital to its success: Robert C. Drews, M. D., as Co-Editor of the English Edition; Cristela Ferrari de Aleman, M.D., an expert in phacoemulsification who advised me in all the technical stages of the step-by-step small incision surgical procedures and Samuel Boyd, M.D., for his strong support, valuable advice derived from his expertise in all the vitreoretinal techniques related to cataract surgery. Among my closest collaborators in HIGHLIGHTS, Andres Caballero, Ph.D., the Project Director and Kayra Mejia, my editorial right hand Production Manager of many years have gone the extra mile to accomplish a very difficult task in production of this work. To each person mentioned in this page, on behalf of the thousands of readers of HIGHLIGHTS, I express my profound recognition and gratitude.
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D EDICATION This 25th Volume of the Atlas and Textbooks of HIGHLIGHTS is dedicated to my colleagues in 106 nations worldwide who faithfully read the HIGHLIGHTS in seven major languages. May "THE ART AND THE SCIENCE OF CATARACT SURGERY" contribute to your further understanding of what is best for your patients. May it also help you to master the "state of the art" techniques in your continuous quest for the right answers. May it provide you with insights in your efforts to rehabilitate vision to millions of people who are still blind from cataract, a curable disease. "The Art and the Science of Cataract Surgery" is also dedicated to the countless ophthalmic surgeons who, through combined efforts with leaders and scientists in industry, have made of modern cataract surgery the safest and most effective major operation in the field of medicine. And, by all means, to the great innovators each of whom developed a new era for cataract surgery in their time. Symbolically, IGNACIO BARRAQUER, M.D., whose innovation of intracapsular extraction by mechanized suction in 1917 resulted in the first practical and efficient method to remove a cataract without vitreous loss. To JOAQUIN BARRAQUER, M.D., for his pioneering work in rendering ophthalmic surgery under the microscope a feasible and practical new method leading to the era of microsurgery. To CHARLES KELMAN, M.D., who, by providing us with phacoemulsification, started the new era of small incision surgery. And to HAROLD RIDLEY, M.D., the symbol of intraocular lens implantation. The recognition to the great innovators is for their ingenuity and for their courage. All innovators stimulate opposition. They all encountered strong opposition but they overcame it through their courage and results.
BENJAMIN F. BOYD, M.D., F.A.C.S.
IV
AUTHOR AND EDITOR-IN-CHIEF
BENJAMIN F. BOYD, M.D., D.Sc. (Hon), F.A.C.S. Doctor Honoris Causa Immediate Past President, Academia Ophthalmologica Internationalis Honorary Life Member, International Council of Ophthalmology Recipient of the Duke-Elder International Gold Medal Award (International Council of Ophthalmology), the Barraquer Gold Medal (Barcelona), the First Benjamin F. Boyd Humanitarian Award and Gold Medal for the Americas (Pan American), the Leslie Dana Gold Medal and the National Society for Prevention of Blindness Gold Medal (United States), Moacyr Alvaro Gold Medal (Brazil), the Jorge Malbran Gold Medal (Argentina), the Favaloro Gold Medal (Italy). Recipient of The Great Cross Vasco Nuñez de Balboa Panama's Highest National Award. Founder and Chief Consultant, Ophthalmology Center of Clinica Boyd, Panama, R.P.; Editor-in-Chief, Highlights of Ophthalmology's ten Editions (Brazilian, Chinese, English, German, Indian, Italian, Japanese, Middle East and Spanish); Author, Highlights of Ophthalmology's Atlas and Textbooks (25 Volumes); Diplomate, American Board of Ophthalmology; Past-President (1985-1987) and Executive Director ((1960-1985) Pan American Association of Ophthalmology; Fellow, American Academy of Ophthalmology; Fellow, American College of Surgeons; Guest of Honor, American Medical Association, 1965; Guest of Honor, American Academy of Ophthalmology, 1978 and Barraquer Institute in Barcelona, 1982 and 1988; Doctor Honoris Causa of Five Universities; Recipient of the Great Cross of Christopher Columbus, Dominican Republic's highest award, for "Contributions to Humanity"; Founding Professor of Ophthalmology, University of Panama School of Medicine (1953-1974); Former Dean and Chief, Department of Surgery, University of Panama School of Medicine (1969-1970); O'Brien Visiting Professor of Ophthalmology, Tulane University School of Medicine, New Orleans, 1983; Honorary Professor of Ophthalmology at Four Universities; Past-President, Academy of Medicine and Surgery of Panama; Honor Member, Ophthalmological Societies of Argentina, Bolivia, Brazil, Canada, Colombia, Costa Rica, Chile, Dominican Republic, Guatemala, Mexico, Paraguay, Peru; Recipient of the Andres Bello Silver Medal from the University of Chile for "Extraordinary Contributions to World Medical Literature."
V
MASTER CONSULTANTS JOAQUIN BARRAQUER, M.D., F.A.C.S., Director and Chief Surgeon, Barraquer Ophthalmology Center; Barcelona, Spain. Professor of Ophthalmology, Autonomous University of Barcelona, Spain. Chair, Academia Ophthalmologica Internationalis. MICHAEL BLUMENTHAL, M.D., Director, Ein Tal Eye Center, Israel. Professor of Ophthalmology, Sidney A. Fox Chair in Ophthalmology, Tel Aviv University. Past President, European Society of Cataract and Refractive Surgery. EDGARDO CARREÑO, M.D., Assistant Professor of Ophthalmology, University of Chile; Director, Carreño Eye Center, Santiago, Chile. VIRGILIO CENTURION, M.D., Chief of the Institute for Eye Diseases, Sao Paulo, Brazil. JACK DODICK, M.D., Chief, Department of Ophthalmology, Manhattan Eye and Ear Hospital, New York. Clinical Professor of Ophthalmology, Columbia University College of Physicians and Surgeons, New York. CRISTELA FERRARI ALEMAN, M.D., Associate Director, Cornea and Anterior Segment, Boyd Ophthalmology Center. Clinical Professor, University of Panama School of Medicine, Panama, Rep. of Panama. I. HOWARD FINE, M.D., Clinical Associate Professor of Ophthalmology, Oregon Health Sciences University. Founding Partner, Oregon Eye Surgery Center. HOWARD V. GIMBEL, M.D., MPH, FRCSC, Professor and Chairman, Department of Ophthalmology, Loma Linda University, California; Clinical Assistant Professor, Department of Surgery, University of Calgary, Alberta, Canada; Clinical Professor, Department of Ophthalmology, University of California, San Francisco, California; Founder and Director, Gimbel Eye Centre in Calgary, Albert, Canada. RICHARD LINDSTROM, M.D., Medical Director, Phillips Eye Center for Teaching and Research. Clinical Professor,, University of Minnesota, Minneapolis. MAURICE LUNTZ, M.D., Chief of Glaucoma Service, Manhattan Eye and Ear Hospital, New York. Clinical Professor of Ophthalmology, Mt. Sinai School of Medicine, New York. OKIHIRO NISHI, M.D., Director of Jinshikai Medical Foundation, Nishi Eye Hospital, Osaka, Japan. MIGUEL A. PADILHA, M.D., Professor and Chairman, Department of Ophthalmology, School of Medical Sciences of Volta Redonda, Rio de Janeiro. Professor, Graduate Course of the Brazilian Society of Ophthalmology and Director, Central Department of Ophthalmology, Brazilian College of Surgeons. Former President, Brazilian Society of Cataract and Intraocular Implants.
VI
CO-EDITOR ENGLISH EDITION
Robert C. Drews, M.D., F.A.C.S., F.R.C.Ophth. Professor Emeritus of Clinical Ophthalmology, Washington University School of Medicine, St. Louis, Missouri. President Elect of the American Ophthalmological Society Gold Medal of Pan-American Association of Ophthalmology; Rayner Medal, United Kingdom Intraocular Implant Society; Binkhorst Medal, American Intraocular Implant Society; Gold Medallion of the National Academy of Science of Argentina; The Montgomery Medal, Irish Ophthalmological Society; Gold Medal of the University of Rome; Gold Medal of the Missouri Ophthalmological Society. Former Chief of Surgery, Bethesda General Hospital, St. Louis, Missouri, and Former Chief of the Section of Ophthalmology, Bethesda General Hospital, St. Louis and St. Luke's Hospital, St. Louis, Missouri. Past Chairman of the Council of the American Ophthalmological Society, Former member of the American Board of Ophthalmology, and of the Board of Trustees, Washington University in St. Louis. Past President of the Pan American Association of Ophthalmology, International Ophthalmic Microsurgery Study Group, International Intraocular Implant Club, American Intra-Ocular Implant Society, Southern Medical Association, Section on Ophthalmology, Missouri Ophthalmological Society, Missouri Association of Ophthalmology, St. Louis Ophthalmological Society, St. Louis Society for the Blind, Past Vice President, American Academy of Ophthalmology. Named Lectures: the Luedde Memorial Lecturer, St. Louis University School of Medicine; Rayner Lecture, United Kingdom Intraocular Implant Society; Binkhorst Lecture, American Intraocular Implant Society; C. Dwight Townes Memorial Lecture, Louisville Kentucky; The Montgomery Lecture, Dublin, Irish Ophthalmological Society; Boberg-Ans Lecture, Copenhagen, Denmark, ESCRS; G. Victor Simpson Lecture, Washington DC; Gradle Lecture, PAAO; Joseph P. Bryan Glaucoma Lecture, Durham, North Carolina.
VII
GUEST EXPERTS
EVERARDO BAROJAS, M.D., Dean, Prevention of Blindness and Rehabilitation of Sight Society, Mexico, D.F. PROF. RUBENS BELFORT JR., M.D., Professor and Chairman, Department of Ophthalmology, Federal University of São Paulo (Escola Paulista de MedicinaHospital São Paulo), Brazil; Chair, Academia Ophthalmologica Internationalis. RAFAEL CORTEZ, M.D., Director, Ophthalmic Surgery Center (CECOF), Caracas, Venezuela. FRANCISCO GUTIERREZ C., M.D., Ph.D, Anterior Segment Surgery and Pediatric Ophthalmologist Specialist, Department of Ophthalmology, Hospital General de Segovia, Spain. Former Fellow of Ramon Castroviejo, M.D. FRANCISCO MARTINEZ CASTRO, M.D., Associate Professor of Ophthalmology, Autonomous University of Mexico. Consultant in Uveitis, Institute of Ophthalmology "Conde de Valenciana" and Seguro Social Medical Center, Mexico, D.F. JUAN MURUBE, M.D., Professor of Ophthalmology, University of Alcala and Chairman, Department of Ophthalmology, Hospital Ramon y Cajal, Madrid, Spain. DAVID McINTYRE, M.D., Head, McIntyre Clinic and Surgical Center, Bellevue, Washington. CARLOS NICOLI, M.D., Associate Professor of Ophthalmology, University of Buenos Aires, Argentina. Director, "Oftalmos" Institute. FELIX SABATES, M.D., Professor and Chairman, Department of Ophthalmology, University of Missouri, Kansas City School of Medicine, Missouri. JUAN VERDAGUER, M.D., Academic Director, Los Andes Ophthalmological Foundation, Santiago, Chile; Professor of Ophthalmology, University of Chile; Professor of Ophthalmology, University of Los Andes; Past President, Pan American Association of Ophthalmology. LIHTEH WU, M.D., Associate Surgeon in Vitreoretinal Diseases, Instituto de Cirugia Ocular, San Jose, Costa Rica. Consultant in Vitreoretinal Diseases, Department of Ophthalmology, Hospital Nacional de Niños, San Jose, Costa Rica.
VIII
CONTENTS FOCUSING AND OVERVIEW OF WHAT IS BEST Tackling the Challenges Role of Small Incision Manual Extracapsulars IOL's of Choice The Best Phaco Techniques
CHAPTER 1 SURGICAL ANATOMY OF THE HUMAN LENS CLINICAL APPLICATIONS Behaviour of Different Cataracts Anatomical Characteristics of Different Types of Cataract How Cataracts Respond Differently Incidence and Pathogenesis
5 7 7 8
CHAPTER 2 INDICATIONS FOR SURGERY PREOPERATIVE EVALUATION INDICATIONS Role of Quality of Life The Role of Visual Acuity Contrast Sensitivity and Glare Disability Contrast Sensitivity Characteristics Relation of Glare to Type of Cataract Evaluation of Macular Function PREOPERATIVE GUIDELINES IN COMPLEX CASES How to Proceed in Patients with Retinal Disease The Importance of Pre-Op Fundus Exam Cataract Surgery in Diabetic Patients Evaluating Diabetics Prior to Cataract Surgery Importance of Maintaining the Integrity of the Lens Capsule Significant Increase in Complications Following Cataract Surgery Appropriate Laser Treatment Main Options in Management of Co-existing Diabetic Retinopathy and Cataract Cataract Surgery and Age-Related Macular Degeneration RETINAL BREAKS AND RETINAL DEGENERATIONS PRIOR TO CATARACT SURGERY Cataract Surgery in Patients with Uveitis Method of Choice Diagnosing the Type of Uveitis in the Pre-Operative Phase Preoperative Management The Intraocular Lens Cataract Surgery in Adult Strabismus Patients Preoperative Judgment
11 11 11 12 13 14 15 21 21 21 21 21 24 24 25 27 28 28 31 32 32 32 33 33 33
IX
CHAPTER 3 PREPARING FOR SURGERY Making Patients Confident Patients Encounter with the Physician Ingredients of a Strong Relationship Evaluating the Patient's Cataract Approaching the Day of Surgery Patient's Expectations
37 37 37 38 38 39 39
IOL POWER CALCULATION IN STANDARD AND COMPLEX CASES
39
Postop Refractive Errors No Longer Admissible The Challenge of the Complex Cases The Most Commonly Used Formulas Main Causes of Errors Targeting Post-Op Refraction Monocular Correction Binocular Correction Good Vision in the Non-Operated Eye When Cataracts in Both Eyes IOL POWER CALCULATION IN COMPLEX CASES Specific Methods to Use in Complex Cases Practical Method for Choosing Formulas in Complex Cases High Hyperopia The Use of Piggyback Lenses in Very High Hyperopia High Myopia DETERMINING IOL POWER IN PATIENTS WITH PREVIOUS REFRACTIVE SURGERY Methods Most Often Used The Clinical History Method The Trial Hard Contact Lens Method Example as Provided by Holladay The Corneal Topography Method THE IMPORTANCE OF DETECTING IRREGULAR ASTIGMATISM IOL POWER CALCULATION IN PEDIATRIC CATARACTS Different Alternatives Alternatives of Choice IOL POWER CALCULATION FOLLOWING VITRECTOMY
40 43 44 44 45 45 46 46 46 47 47 47 47 48 49 49 52 52 53 53 54 54 54 55 55 57
CHAPTER 4 PREVENTING INFECTION AND INFLAMMATION Use of Antiseptics, Antibiotics and Antiinflammatory Agents Effective Preoperative Antibiotic Treatments Regimens Recommended Gills Formulas to Prevent Infection 1) For High Volume Cataract Surgery 2) Non-Complex, Effective and Safe Alternative for Prevention of Infection
X
63 63 64 64 64 65
CHAPTER 5 PROCEEDING WITH THE OPERATION PREPARATION, SEDATION AND ANESTHESIA Preparation of Patient Sedation Pupillary Dilation ANESTHESIA Topical Selection of Anesthetic Method Unassisted Topical Anesthesia The Anesthetic Procedure of Choice Technique for Irrigation of Lidocaine in AC Injection of Viscoelastic What Can be Done with the Combined Anesthesia Side Effects of the Combined Anesthesia How to Manage Patients Who Feel Pain and Discomfort PHOTOTOXICITY IN CATARACT SURGERY
71 71 71 72 72 72 72 74 75 75 75 75 75 75 75
CHAPTER 6 PHACOEMULSIFICATION - WHY SO IMPORTANT? COMPARING PLANNED EXTRACAPSULAR WITH PHACO EXTRACAPSULAR ADVANTAGES OF THE PHACO TECHNIQUE MAIN TECHNICAL DIFFERENCES ASSOCIATED WITH PHACO LIMITATIONS OF PHACOEMULSIFICATION
83 83 84 86
CHAPTER 7 PREPARING FOR THE TRANSITION GENERAL OVERVIEW AND STEP BY STEP CONSIDERATIONS Equipment - Dependent and Phase-Dependent Technique Mental Attitude UNDERSTANDING THE PHACO MACHINE Becoming Familiar with the Equipment Two Hands, Two Feet and Special Sounds Main Elements of Phaco Machines - Their Action on Fluid Dynamics COMPARISON OF SURGICAL TECHNIQUES FOR TRANSITION VS EXPERIENCED SURGEONS Techniques Which Are the Same for the Transition and for Advanced Surgeons Techniques that Vary According to the Skill of the Surgeon
93 93 93 94 94 95 95 96 96 96
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SURGICAL TECHNIQUE IN THE TRANSITION Anesthesia The Incision How to Make a Safe Transition from Large to Small Incision Role of Conjunctival Flap Anterior Capsulorhexis Hydrodissection THE MECHANISM OF THE PHACO MACHINE Getting Ready to Use Phaco During Transition Optimal Use of the Phaco Machine The Rationale Behind It - Main Functions Parameters of the Phaco Machine How to Program the Machine for Optimal Use Fluid Dynamics During Phaco Fluidics and Physics of Phacoemulsification Importance of and Understanding the Surge Phenomenon Lessening Intraoperative Complications from the Surge NUCLEUS REMOVAL - APPLICATION OF PHACO FRACTURE AND EMULSIFICATION The Divide and Conquer Technique Emulsification of the Nuclear Fragments FINAL STEPS Aspiration of the Epinucleus Aspiration of the Cortex Intraocular Lens Implantation Removal of Viscoelastic Closure of the Wound What to Do if Necessary to Convert Testing the Wound for Leakage Immediate Postoperative Management
97 97 97 97 101 102 104 106 106 106 106 112 114 114 116 119 121 121 123 123 124 126 126 126 126 128 128 129 130 131 131
CHAPTER 8 INSTRUMENTATION AND EMULSIFICATION SYSTEMS INSTRUMENTATION Eye Speculum Fixation Ring Knives and Blades Hydrodissection Cannula Cystotomes or Capsulorhexis Forceps Nuclear Manipulators or Choppers (Second Instrument) Forceps and Cartridge Injector Systems for Insertion of Foldable Intraocular Lenses THE PHACO PROBES AND TIPS Phaco Tips Surgical Principles Behind the Different Phaco Tips PHACOEMULSIFICATION SYSTEMS The Alcon Legacy The Allergan Sovereign The Bausch & Lomb - Storz Millennium
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137 137 137 137 140 141 142 144 147 148 149 150 150 150 150
The Pulse and Burst Modes Differences Between Them Clinical Applications of the Pulse Mode Clinical Applications of the Burst Mode Its Role in Transition to Chopping Advances with the Sovereign Phaco System
151 151 152 154 154 154
CHAPTER 9 MASTERING PHACOEMULSIFICATION The Advanced, Late Breaking Techniques General Considerations Trauma-Free Phacoemulsification Faster Operations Do They Sacrifice Patient Care? Readiness and Know-How to Become Efficient THE ADVANCED, LATE-BREAKING TECHNIQUES Anesthesia Fixation of the Globe THE INCISIONS The Primary Incision Essential Requirements for a Self-Sealing Corneal Incision Position of the Clear Cornea Tunnel Incision Reservations About the Clear Corneal Incision Advantages to the Temporal Approach Importance of the Length of the Tunnel Placing and Making the Primary Incision Surgeon's Position Controversy Over the Strength and Safety of the Wound Testing the Wound for Leakage Closing a Leaking Wound Without Sutures THE ANCILLARY INCISION ANTERIOR CAPSULORHEXIS Key Role Technique for Performing a First Class CCC Size of the Capsulorhexis STAINING THE ANTERIOR CAPSULE IN WHITE CATARACTS HYDRODISSECTION - HYDRODELAMINATION Technique of Hydrodissection Hydrodelamination
159 159 160 160 160 160 160 161 161 161 162 162 164 164 166 166 167 167 167 167 169 169 169 170 170 172 175 175 175
MANAGEMENT OF THE NUCLEUS
176
General Considerations Concepts Fundamental to All Techniques The Essential Principles THE ENDOCAPSULAR TECHNIQUES THE HIGH ULTRASOUND ENERGY AND LOW VACUUM GROUP THE GROOVING AND CRACKING METHODS
176 176 177 177 177 177
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The Divide and Conquer Four Quadrant Nucleofractis Technique Principles of the Divide and Conquer Techniques The Role of D & C Techniques in Cataracts of Different Nucleus Consistency Present Role of Original Four Quadrant Divide and Conquer THE LOW ULTRASOUND ENERGY AND HIGH VACUUM GROUP THE CHOPPING TECHNIQUES Main Instruments Used Surgical Principles of the Original Phaco Chop Chopping Techniques Presented in this Volume THE STOP AND CHOP TECHNIQUE Surgical Principles Absolute Requirements to Perform the Stop and Chop Importance of the Phaco Chopper Highlights of the Stop and Chop Technique FUNDAMENTAL DIFFERENCES BETWEEN CHOPPING AND DIVIDE AND CONQUER (D & C) TECHNIQUES THE CRATER PROCEDURES The Crater Divide and Conquer (Mackool) The Crater Phaco Chop for Dense, Hard Nuclei THE NUCLEAR PRE-SLICE OR NULL PHACO CHOP TECHNIQUE Disassembling the Nucleus How Is the Null-Phaco Chop Done Potential Complications Contributions of this Technique THE CHOO-CHOO CHOP AND FLIP PHACOEMULSIFICATION TECHNIQUE Origin of the Name “Choo-Choo” Comparison With Other Techniques Fine's Parameters THE TRANSITION TO CHOPPING TECHNIQUES REMOVAL OF RESIDUAL CORTEX AND EPINUCLEUS INTRAOCULAR LENS IMPLANTATION The Increased Interest in Foldable IOL's The Most Frequently Used IOL's MONOFOCAL FOLDABLE LENSES THE FOLDABLE ACRYLIC IOL'S THE FOLDABLE MONOFOCAL SILICONE IOL's OTHER MONOFOCAL LENSES The Hydrogel, Foldable Monofocal IOL The Foldable Toric Lens Bitoric Lens But Not Foldable THE FOLDABLE MULTIFOCAL IOL The Array Multifocal Silicone Lens How Does the Array Foldable Multifocal Lens Work? Quality of Vision with Array Multifocal Patient Selection and Results
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177 180 180 181 181 183 183 184 184 184 184 188 188 189 190 191 191 191 194 194 194 198 198 198 199 202 202 204 205 207 207 207 208 208 209 210 210 210 210 211 211 212 212 212
Specific Guidelines for Implanting the Array Lens Special Circumstances for Array Implantation Need for Spectacle Wear PostOp Halos at Night and Glare SURGICAL PRINCIPLES AND GUIDELINES FOR IOL IMPLANTATION PREFERRED METHODS OF IOL IMPLANTATION Use of Forceps vs Injectors Advantages and Disadvantages New Trends for Folding and Insertion of IOL's Guidelines for Insertion of Different Types of Lenses Surgical Technique with Array Lens Carreño's Technique of Acrylic IOL Implantation Through a 2.75 mm Incision Dodick's AcrySof's Implantation Technique Implantation Technique for Silicone Foldable IOL's Using Cartridge-Injector System TESTING THE WOUND FOR LEAKAGE
213 213 214 214 214 214 214 214 214 218 218 218 220 222 223
CHAPTER 10 FOCUSING PHACO TECHNIQUES ON THE HARDNESS OF THE NUCLEUS MULTIPLICITY OF TECHNIQUES The Essential Criteria for Success DIFFERENT NUCLEUS CONSISTENCY TECHNIQUES OF CHOICE Representative Experts LINDSTROM'S PROCEDURES OF CHOICE Advantages of the Supracapsular Disadvantages of the Supracapsular Contraindications of Supracapsular HIGHLIGHTS OF THE SUPRACAPSULAR IRIS PLANE TECHNIQUE CENTURION'S TECHNIQUES RELATED TO NUCLEUS CONSISTENCY CARREÑO'S NUCLEAR EMULSIFICATION TECHNIQUE OF CHOICE (PHACO SUB 3) Adjusting the Equipment Parameters to Remove Cataracts of Various Nuclear Density Three Sets of Values Programmed Into Memory Technique of Choice and Consistency of Cataract NISHI'S TECHNIQUES OF CHOICE FOR NUCLEI OF DIFFERENT CONSISTENCIES
229 229 229 230 230 231 232 232 233 234 237 237 237 238 245
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CHAPTER 11 COMPLICATIONS OF PHACOEMULSIFICATION INTRAOPERATIVE COMPLICATIONS General Considerations Main Intraoperative Complications Incidence Facing the Challenges COMPLICATIONS WITH THE INCISION COMPLICATIONS RELATED TO ANTERIOR CAPSULORHEXIS COMPLICATIONS WITH HYDRODISSECTION COMPLICATIONS DURING NUCLEUS REMOVAL COMPLICATIONS DURING REMOVAL OF THE CORTEX COMPLICATIONS DURING FOLDABLE IOL's IMPLANTATION COMPLICATIONS WITH POSTERIOR CAPSULE RUPTURE Pars Plana Vitrectomy for Dislocated Nucleus
XVI
249-268 249 249 249 250 250 254 258 259 260 260 262 266
POSTOPERATIVE COMPLICATIONS
269-290
MEDICAL Cystoid Macular Edema Diabetes and Cystoid Macular Edema PHOTIC MACULOPATHY AMINOGLYCOSIDE TOXICITY POSTERIOR CAPSULE OPACIFICATION Overview Role of IOL in PCO Role of Continuous Curvilinear Capsulorhexis in PCO Main Factors that Reduce PCO PERFORMING THE POSTERIOR CAPSULOTOMY Size of Capsulotomy Posterior Capsulotomy Laser Procedure Complications Following Nd:YAG Posterior Capsulotomy POSTOPERATIVE ASTIGMATISM IN CATARACT PATIENTS MANAGEMENT Procedure of Choice Highlights of AK Procedure EXPLANTATION OF FOLDABLE IOL'S RETAINING THE BENEFIT OF THE SMALL INCISION RETINAL DETACHMENT POSTOPERATIVE ENDOPHTHALMITIS INTRAOCULAR LENS DISLOCATION
269 269 273 273 275 277 277 277 278 278 279 279 279 281 281 281 282 283 284 284 286 286 288
CHAPTER 12 CATARACT SURGERY IN COMPLEX CASES Aims of this Chapter Broadening of Indications Complex Cases Already Discussed in Previous Chapters FOCUSING ON THE MAIN COMPLEX CASES THE DIFFERENT TYPES OF VISCOELASTICS Their Specific Roles Cohesive and Dispersive Viscoelastics The Cohesive VES - Specific Properties The Dispersive VES- Specific Properties PHACOEMULSIFICATION AFTER PREVIOUS REFRACTIVE SURGERY PHACOEMULSIFICATION IN HIGH MYOPIA CHALLENGES OF PHACOEMULSIFICATION IN HYPEROPIA REFRACTIVE CATARACT SURGERY Why and When Do Refractive Cataract Surgery TECHNIQUE FOR REFRACTIVE CATARACT SURGERY
295 295 296 296 296 296 296 296 297 298
CATARACT AND GLAUCOMA
302
Overview - Alternative Approaches COMBINED CATARACT SURGERY AND TRABECULECTOMY Indications Evolution of the Incision for Combined Cataract Extraction and Trabeculectomy A. Extracapsular Cataract Extraction with Trabeculectomy B. Phacoemulsification with Trabeculectomy Intraocular Lens Implants Preoperative Preparation SURGICAL TECHNIQUES STEP BY STEP ECCE and Trabeculectomy With Single, Unbroken Tunnel Incision Phacoemulsification With Trabeculectomy Antimetabolites in Combined Procedures Results of Combined Cataract Surgery and Trabeculectomy PHACOEMULSIFICATION IN DISEASED CORNEAS PHACOEMULSIFICATION AND IOL IMPLANTATION IN THE PRESENCE OF OPAQUE CORNEA Overview Padilha’s Timing and Technique Specific Recommendations PHACOEMULSIFICATION, IOL IMPLANTATION AND FUCHS’ DYSTROPHY Preoperative Evaluation Special Precautions During Phacoemulsification
298 299 299 299 300
302 303 303 303 304 308 308 308 310 310 315 318 320 322 322 322 322 324 325 325 325
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PHACOEMULSIFICATION IN SMALL PUPILS Pharmacological Mydriasis Mechanical Dilatation with Viscoelastics Mechanical Strategies TRAUMATIC CATARACTS Overview Assessment of the Injured Eye Highlights of Examination Diagnostic Imaging Combined Injuries of Anterior and Posterior Segment Traumatic Cataracts in the Presence of Anterior Segment Penetrating Wounds MANAGEMENT OF TRAUMATIC CATARACT HIGHLIGHTS OF SURGICAL TECHNIQUE The Incision Anterior Capsulorhexis Lens Removal Role of Intracapsular Tension Ring in Traumatic Cataracts Removal of Cortex Selection of IOL IOL Implantation Selection of Viscoelastic in Traumatic Cataracts Phacoemulsification Advantages in Traumatic Cataract PHACOEMULSIFICATION IN SUBLUXATED CATARACTS Strategic Management MANAGEMENT DEPENDING ON SIZE OF ZONULAR DIALYSIS Special Precautions with Subluxated Cataracts Increasing the Safety of Posterior Lens Implantation in Extensive Zonular Disinsertion Fixation of the Anterior Capsule to the Ciliary Sulcus CATARACT SURGERY IN CHILDHOOD Previous Controversies Now Resolved 1) Age and Timing for Surgery Bilateral Cataracts Unilateral Cataracts Preoperative Evaluation History Examination The Special Case of Lamellar Cataracts Rubella Cataracts The Need for Close Monitoring Preoperative Considerations The Decision to Implant IOL’s in Children with Cataract Surgery Surgical Technique The Posterior Approach to Cataract Extraction in Children CATARACT SURGERY IN UVEITIS
XVIII
328 328 328 328 333 333 333 333 333 334 334 334 334 334 334 334 335 336 339 339 339 340 340 340 340 342 344 345 347 347 347 347 347 348 348 349 350 350 350 350 351 351 355 355
CHAPTER 13 THE PRESENT ROLE OF MANUAL EXTRACAPSULARS Overview PERFORMING A FLAWLESS PLANNED EXTRACAPSULAR CATARACT EXTRACTION (with an 8 mm Incision and Posterior Chamber IOL Implantation) General Anesthesia Local Anesthesia Technique for Extracapsular Cataract Extraction with an 8 mm Incision (ECCE) THE MANUAL, SMALL INCISION EXTRACAPSULARS THE MINI-NUC TECHNIQUE SURGICAL TECHNIQUE Anesthesia, Paracentesis, ACM Capsulorhexis Conjunctiva Sclerocorneal Pocket Primary Incision and Tunnel Hydrodissection and Nucleus Dislocation Nucleus Expression Using Glide and High IOP Epinucleus and Cortex Extraction IOL Implantation Pupil Enlarged by Increased IOP Advantages of the Continuous Flow of BSS during Manual ECCE Complications THE SMALL INCISION PHACO SECTION MANUAL EXTRACAPSULAR TECHNIQUE
359 361
361 362 364
375 375 376 376 377 377 378 378 381 383 384 386 387 387 389
Overview Evolution of Technique Indications PHACO SECTION MOST IMPORTANT FEATURES Capsulorhexis Completing the Tunnel Incision Anterior Chamber Maintainer Aspiration of the Anterior Cortex and Epinucleus Phacosection Transition from Extracapsular Extraction to Phacosection
389 389 389 389 390 390 391 392 393 395
THE SMALL INCISION MANUAL PHACOFRAGMENTATION
400
Benefits of (MPF) Experiences with Other Phaco Fragmentation Techniques Why Use Gutierrez' Technique? Surgical Technique Complications
400 400 400 402 405
XIX
CHAPTER 14 THE NEW CATARACT SURGERY DEVELOPMENTS Overview DODICK’S PHOTOLYSIS SYSTEM THE CATAREX SYSTEM Aziz PhacoTmesis Water Jet Technology
XX
409 409 411 411 411
Fo c u s i n g a n d O v e r v i ew o f W h a t i s B e s t
FOCUSING AND OVERVIEW OF WHAT IS BEST Modern cataract surgery is definitely related to lens removal through small, short, valve like incisions and implantation of foldable intraocular lenses implanted through these short incisions.
Tackling the Challenges In this Volume we present what is best for our patients and how to tackle the challenges with vigor. We present the new developments in preoperative evaluation, the expansion of the indications as the outcomes have improved, the new, sometimes complex problems brought by refractive and vitreoretinal surgery in calculating IOL power. And we illustrate the steps that remain rather constant and which apply either to the surgeon in the process of transition or the experienced small incision surgeon, vs the methods that do change and require the skill of an experienced surgeon. We also present the anesthetic methods of choice, the understanding of the phaco machine, how it works and what the rationale is behind its optimal use. How to undergo the safe and successful transition from planned extracapsular to phaco. The incisions of choice for most surgeons, the methods that enhance the performance of capsulorhexis in complex cases, the modern techniques of hydrodissection, hydrodelineation and cortex removal that have stood the test of time and the advantages and disadvantages of the different methods of nucleus removal in phacoemulsification.
Role of Small Incision Manual Extracapsular Although we provide special emphasis on how to master phacoemulsification and foldable IOL implantation, including an indepth analysis of how to prevent and manage intraoperative and postoperative complications, we also present to you the small incision manual extracapsular techniques of proven and lasting value. For those surgeons who are prevented by practical considerations, or who simply prefer to not take the significant step of entering into small incision surgery, the chapter on how to perform a flawless planned extracapsular with 8 mm incision and its merits is superbly as presented by one of the world's master surgeons.
IOL's of Choice In modern cataract surgery it is essential to discuss the IOL's of choice and their merits. Selecting the correct lens implant (size of optic, chemical material, foldable vs non-foldable, mono vs multifocal) may play a more important role in the final patient's final visual outcome and satisfaction than the specific technique used for phacoemulsification of the nucleus.
The Best Phaco Technique The best phacoemulsification technique to use is based on the relation of the type
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of cataract to a specific method of nucleus removal for that specific stage of cataract. The divide and conquer in four quadrants continues to be the procedure of choice for the beginner in the transition period or for the surgeon who does not have a large volume of cataract surgery. The technique for nucleus removal with one hand continues to be fundamental for each phaco surgeon to learn. We will also present the phaco sub-3, phaco chop, phaco pre-chop, choo-choo chop and flip and the phaco burst, all of which are techniques for the more advanced or experienced surgeons. Each has its merits, effectiveness and limitations.
The Complex Cases Small incision cataract surgery has significantly changed the approach and management of the complex cases. It is the most important contribution made in years to a successful and safe combined glaucoma-cataract
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operation, to management of traumatic cataracts and cataract surgery in patients with corneal dystrophies. Pediatric cataracts have not been resolved with the improved management options and almost risk-free capabilities of the magnitude that we have available in adult patients. This, in part, may be related to the fact that the postoperative care depends more on the parents than on the surgeon. The previously highly controversial point of implanting intraocular lenses in children has shifted to a positive decision on the part of most surgeons who now agree to implant IOL's in children when the selection of cases has been done prudently. Let us now proceed to discuss each one of the highlights of modern cataract surgery. The field is exciting and a source of great satisfaction to the surgeon who does it well and with full dedication to the benefit of his or her patients.
C h a p t e r 1: S u r g i c a l A n a t o m y o f t h e H u m a n L e n s
SURGICAL ANATOMY OF THE HUMAN LENS Clinical Applications - Behaviour of Different Cataracts Understanding the three-dimensionality and concentric anatomy of the lens as originally conceived by Henry Clayman, M.D. for HIGHLIGHTS is fundamental for having a clear picture of some of the main steps in performing phaco. I refer to the dissection of the different structures of the nucleus with fluid, that is, hydrodissection of the anterior and posterior capsule from the cortex, separation of the nucleus and epinucleus with fluid and the different tissue reactions to the forces presented during phacoemulsification of the nucleus. The normal crystalline lens is an avascular structure. As pointed out by Howard Gimbel, M.D., lens fibers are surrounded by the lens capsule which is the basement membrane of the lens epithelial cells (Fig. 1). Lens epithelial cells are located just inside the capsule and exist as a single layer. The epithelial cells can differentiate into lens fibers, and this process occurs in an area just posterior to the lens equator. As new lens fibers are formed, the central fibers are compacted, forming the nucleus of the lens. The surrounding densely packed fibers form the cortex (Fig. 1). Due to the anatomical arrangement of cells and fibers, the Y sutures are formed within the lens nucleus. For a surgeon not experienced in small incision extracapsular techniques, there may be difficulties recognizing the hidden anatomy of the morbid cataract. It may be difficult to
distinguish what is really anterior capsule, what is cortex and where the posterior capsule is. When removing the cortex, we must keep in mind that its substance is three dimensional (Fig. 1). As described in this figure, the nucleus is the pit of the avocado. The pit in the avocado does not drop out because it is held in by adhesions between the flesh of the avocado and the pit. Figure 1 also shows that the cortex (C) adheres to the epinucleus and the nucleus. In order to remove the nucleus by whatever technique you prefer, these nuclear-cortical adhesions have to be broken and out comes the nucleus, whether by phacoemulsification or by planned extracapsular. The residual cortex, which is the flesh of the avocado, is wrapped around, three dimensionally, inside the skin of the avocado, which is the capsule (Fig. 1). When aspirating the cortex, it is prudent not to attack the cortex right on but to get a free edge, which you may attract to the aspiration port, and peel from its capsule support. In Fig. 1 you may see a conceptual cross section of the anterior globe, with all the structures of the human lens involved in the maneuvers hereby described. The capsule is like the skin of an avocado, both anterior (A) and posterior (P). The flesh of the avocado is comparable to the cortex (Fig. C). The pit of the avocado is comparable to the lens epinucleus and nucleus (Fig. E-N). In (1) the cortex (C), epinucleus (E) and nucleus (N) are shown removed from the capsule. (2) Shows the cortex (C) removed from the nucleus and epinucleus (E and N). The nuclear-cortical
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Figure 1: Three-Dimensionality of the Lens - Clinical Applications Figure 1 presents a conceptual cross section of the anterior globe and the three dimensional nature of the lens anatomy, with all the structures of the human lens involved in the surgical maneuvers. Think of the lens as if it were an avocado. The capsule is like the skin of an avocado, both anterior (A) and posterior (P). The flesh of the avocado is comparable to the cortex (Fig. C). The pit of the avocado is comparable to the lens epinucleus and nucleus (Fig. E-N). The pit in the avocado does not drop out because it is held in by adhesions between the flesh of the avocado and the pit. The cortex (C) adheres to the epinucleus (E) and the nucleus (N). The residual cortex, which is the flesh of the avocado, is wrapped around, three dimensionally, inside the skin of the avocado, which is the capsule (Fig. AP). When aspirating the cortex, it is prudent not to attack the cortex directly but to get a free edge, which you may attract to the aspiration port, and peel it from its capsule support. In (1) the cortex (C), epinucleus (E) and nucleus (N) are shown removed from the capsule. (2) Shows the cortex (C) removed from the nucleus and epinucleus (E and N). The nuclear-cortical adhesions have to be broken down before the nucleus can come out (2 and 3). In (E) the epinucleus is shown as an entity distinct from the nuclear core. This figure allows us to better understand the anatomical basis for the formation of grooves across the nucleus skillfully utilized by the surgeon in the technique of phacoemulsification.
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adhesions have to be broken down before the nucleus can come out (2 and 3). In (E) the epinucleus is shown as an, entity distinct from the nuclear core. This figure allows us to better understand the anatomical basis for the formation of grooves across the nucleus skillfully utilized by the surgeon in the technique of phacoemulsification.
Anatomical Characteristics of Different Types of Cataract The lens in cross section is made up of a concentric series of elliptical rings. Each one of these rings represents growth of the lens and the laying down of additional lens material from the epithelial cells located on the underside of the anterior capsule. In soft to medium density cataracts, the concentric lamellae of cataract tissue are not densely packed, so much of the space inside the cataract is taken up by
moisture. Medium to firm-density cataracts have concentric lamellae of tissue that are densely packed together, packed so tight that there is no room for moisture between lamellae.
How Cataracts Respond Differently Paul Koch, M.D. emphasizes that each one of these different types of cataracts responds differently, so surgical forces need to be applied differently. In breaking the nucleus the surgeon needs to individualize the operation to take advantage of the natural tendencies of each type of cataract. Soft to medium density cataracts are malleable and compliant. We can hold them in the capsular bag and squeeze them from between neighboring pieces. Medium to firm density cataracts are more like rocks. They have rigid form and are much more demanding of the surgeon's skill. If we
Figure 2: Dense, Nuclear Brunescent Cataract In dense, nuclear brunescent cataracts, as shown in Fig. 2, there is less water content, the capsule is dehydrated and there is a significant increase in the density and opacity of the nucleus (C). These nuclei are more like rocks, and are the hardest to manage with phacoemulsification in the transitional stage or by surgeons inexperienced in phaco. Difficulties during surgery may arise that can be characteristic in this type of cataract such as difficulty in identifying the capsulorhexis or with the hydrodissection.
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rub them against the capsule, the capsule can break. If we pull them up into the anterior chamber, the capsulotomy may split. If they touch the corneal endothelium, they abrade it. Understanding this surgical anatomy of the lens and its clinical applications helps significantly in recognizing that each type of cataract acts differently and that our approach should vary depending on the individual patient (Fig. 2).
INCIDENCE AND PATHOGENESIS It is widely known that cataracts constitute the major source of curable blindness worldwide. Not only do they seriously affect large segments of the population in developing or less economically fortunate regions but also the peri-urban areas of large and developed cities which are equipped with highly trained ophthalmologists and the latest technology. For psychological or social reasons difficult to understand, many blind or almost blind persons living in these peri-urban "belts" do not seek medical advice and treatment when easily available. This is one of the mysteries of people whose quality of life is significantly limited by partial or complete opacification of the crystalline lens. Figure 2 shows a brunescent, advanced, hard cataract which becomes sometimes very difficult to treat by phaco, even in skillful hands. Many patients allow their cataracts to become this much advanced even if they live near medical facilities that may provide proper care at a much more advantageous time. As pointed out by Howard Gimbel, M.D., there are a variety of causes and types of cataracts. By definition, all cataracts share the common feature of opacification of some portion of the crystalline lens which, if within the to cataract formation. 8
BIBLIOGRAPHY Assia, EI., Legler, UFC., Apple, DJ.: The capsular bag after short and long term fixation of intraocular lenses. Ophthalmology, 1995; 102:1151-7. Boyd, BF.: Cataract/IOL Surgery. World Atlas Series of Ophthalmic Surgery, published by HIGHLIGHTS, Vol. II, 1996; 5:5-13. Boyd, BF.: Cataract/IOL Surgery. World Atlas Series of Ophthalmic Surgery, published by HIGHLIGHTS,Vol. II, 1996; 5:34-38. Boyd, BF.: New developments for small incision cataract surgery. Highlights of Ophthalm. Journal, Volume 27, Nº 4, 1999;45-46. Gimbel, HV., Anderson Penno, EE: Cataracts: Pathogenesis and treatment. Canadian Journal of Clinical Medicine, September 1998. Koch, PS.: Simplifying Phacoemulsification, 5th ed., published by Slack; 1997; 7:85-86. Lens and Cataract, Basic and Clinical Science Course, Section 11. American Academy of Ophthalmology, 1998-99.
Chapter 2: I n d i c a t i o n s a n d P re o p e r a t i v e Ev a l u a t i o n
INDICATIONS AND PREOPERATIVE EVALUATION INDICATIONS To date there is no established medical treatment for the prevention or treatment of cataract formation and thus the treatment of cataracts remains surgical. Contrary to the commonly held belief that cataracts must reach a certain degree of density or become "ripe" prior to considering cataract surgery, today the crystalline lens can be removed at virtually any stage. In fact, refractive lensectomy in which the clear crystalline lens is removed may be used to surgically eliminate or significantly reduce the need for glasses in patients with very high myopia or hyperopia. In the latter condition, this may be achieved by implanting several piggyback lenses within the capsular bag following clear lensectomy.
Role of Quality of Life Cataract/IOL surgery improves quality of life better than any other medical procedure known to mankind. Cataract surgery is indicated when the patient's quality of life is being affected by visual impairment, when there is a diminution in vision if the patient is exposed to light or at night, and when the preoperative evaluation indicates that the potential for restoration of sight is good. How much a patient's quality of life is impaired from a cataract is relative, varying with the patient's occupation and age. The key factor is not to wait until a nuclear cataract becomes hard. With time, the lens fiber density becomes a hard nuclear brunescent cataract (Fig. 2) . With most modern phacoemulsification techniques it may be-
come increasingly difficult to perform surgery if the lens becomes extremely dense or brunescent. Waiting too long may require that the surgeon operate on dense nuclear cataracts, which increases the risk of posterior capsule tears, whether we perform planned extracapsular or a phacoemulsification. This complication may lead to other rather serious problems such as dislocated nucleus, retinal detachment, macular edema, bullous keratopathy and inflammation.
The Role of Visual Acuity There are very few strict criteria for recommending cataract surgery. In the United States, however, many professional review organizations have indicated that the reduction of Snellen distance acuity to 20/40 or worse as a result of cataract is sufficient indication in and of itself for cataract surgery. This is generally the minimum standard for driving. In some of the advanced, developed countries, being unable to obtain a driver's license may seriously affect a person's life because he/she may be disqualified to drive to the market or shop to purchase food and other materials essential to daily existence. However, in many cases surgery may be indicated without reduction of visual acuity to the level of 20/40 if the patient has difficulty performing activities of daily living. Because patients have varying occupational and recreational needs, some patients may need cataract surgery prior to having their vision reduced to 20/40 by standard tests. In addition, near vision in some cases may be
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compromised more than distance acuity particularly in the case of central posterior subcapsular cataracts. The trend toward early removal of cataract offers the advantage of operating on a younger age group, many of whom are still productive members of society. Their need for early return to their usual lifestyle is extremely important. The older population, often living alone, also benefits from early visual recovery. These high expectations and needs require that the ophthalmic surgeon perform superior surgery to obtain excellent postoperative visual acuity and early visual rehabilitation. As emphasized by Gimbel, symptoms of cataracts include complaints of a yellowing of vision, glare, halos, decreased night vision, and generally blurred vision in adults. Nuclear sclerosis which is a typical form of age-related cataracts may also induce a myopic shift and patients may give a history of having changed their glasses several times within a short period of time. In children cataracts may present as leukocoria and may result in strabismus and/or amblyopia if not treated promptly.
Contrast Sensitivity and Glare Disability In evaluating a patient with cataract and in the process of deciding when that person requires cataract/IOL surgery, it is fundamental to keep always in mind that standard Snellen acuity measurements do not give any information with regard to symptoms of disabling glare. As a matter of fact, very good visual acuity with the Snellen chart in the physician's examining room may lead the ophthalmologist to making the wrong decision and recommendations unless he or she takes other factors into consideration. In later years, we have become
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increasingly aware that diminished contrast sensitivity which interferes with sharp vision under different color backgrounds or target luminance, is an essential element of sight and a highly limiting factor in the presence of cataract. This is perceived by the patient for example when he or she is unable to read a computer screen at the airport if the background is light blue and the print is light yellow even though visual acuity in the physician's refracting lane was 20/30 or 20/25. The same for disabling glare. These are two additional very important issues in determining when the cataract should be removed. For many years this judgment has been based on Snellen visual acuity. But a patient can score quite well on Snellen acuity while suffering in real life. Posterior subcapsular cataracts are notorious for interfering with reading, even when distance vision is good, and may induce a great deal of glare. Snellen acuity may be 20/20 or 20/25, but against oncoming headlights while driving at night, for instance, the glare may diminish the functional vision to 20/100 or even 20/200. People with nuclear sclerosis, the most common form of cataract, tend to be bothered by decreased contrast sensitivity rather than glare. Although glare disability and contrast sensitivity are distinctly different, the terms often are erroneously interchanged. The testing characteristics of each, however, may overlap, and a reduction in one function often leads to a diminution in the other, further adding to the confusion of their differences. As clarified by Samuel Masket, M.D., glare disability is a light-induced visual symptom. Contrast sensitivity testing is a means of vision analysis, analogous to a markedly expanded form of Snellen acuity evaluation at varied amounts of target luminance.
Chapter 2: I n d i c a t i o n s a n d P re o p e r a t i v e Ev a l u a t i o n
Contrast Sensitivity Characteristics Like audiometry, which measures the sensitivity of the hearing apparatus to stimuli at different audio frequencies, contrast sensitivity analysis determines the ability of the visual system to perceive objects of differing contrasts as well as sizes.
A patient who has a reduction in contrast sensitivity might perceive the small, highly contrasted targets on a Snellen test line but be incapable of identifying larger objects at reduced contrast. There are alterations in the visual system that can cause visual loss that are not detected by the determination of Snellen visual acuity but may be evaluated by testing of contrast sensitivity function. This is unlike
Figure 3 B (below right): Contrast Sensitivity Recording Chart The contrast sensitivity recording chart provides four (4) rows of wave gratings. At the recommended test distance of 8 ft (2.5 meters), these gratings test the spatial frequencies of 3, 6, 12 and 18 cycles/degree. This chart provides a full contrast sensitivity curve. The functional acuity is determined by the lowest level of contrast sensitivity (gray band) that can be detected by the patient. The functional acuity score is shown in a bracket next to the contrast sensitivity score.
Figure 3 A (above left): Importance of Testing for Contrast Sensitivity The Contrast Sensitivity Test is used clinically to evaluate cataracts, glaucoma, diabetic eye disease, contact lens performance and refractive surgery. In the presence of cataract the clouding of the lens causes light scatter on the retina. This reduces image contrast and causes dimness of vision. One of the more difficult problems in evaluating how a cataract is affecting the patient's visual function is that many cataract patients preserve good visual acuity as tested in the refracting lane (Snellen chart) but complain about their visual disability. The true “real-world” vision of cataract patients can be established as a functional acuity score using contrast sensitivity and glare testing.
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disabling glare, which determines the effect of extraneous light on visual performance. Contrast sensitivity evaluation is a measurement of the resolving power of the eye at varied contrasts between image and background (Fig. 3 A-B). A number of useful contrast and glare sensitivity testing methods have been devised (Fig. 3 A-B). They are accessible and inexpensive. Unfortunately, standardization of these techniques has not yet been achieved. It is essential that the clinician be fully aware of these two factors that may impinge on the patient's real vision or quality of vision, in addition to the Snellen acuity test.
Relation of Glare to Type of Cataract Neumann et al. have determined that nuclear cataract is more likely to be associated with nighttime glare disability, while cortical cataract formation is associated with daylight glare, and posterior subcapsular cataracts may induce glare disability associated with bright, direct sunlight or bright central light sources. Cortical cataracts seem more likely to cause glare symptoms than nuclear cataracts. Masket points out that frequently, patients with dense central posterior subcapsular cataracts frequently retain excellent distance Snellen acuity as measured in the refracting lane, yet they perform poorly on any of the available glare testing devices. Such patients
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may have severely lower visual function during daylight driving although they do well with the Snellen acuity chart. In essence, the Snellen chart evaluates quantity of vision. Contrast sensitivity tests evaluate quantity and quality of vision. The equipment to perform the test is accessible and inexpensive. It is basically a chart about 0.3 meters in size and it costs about US$200.00
Preoperative Considerations In addition to determining visual acuity by the Snellen chart, contrast sensitivity and glare disability testing as outllined, all patients with cataracts should have a thorough history taken including any systemic or ocular medications being used and any systemic disease for which they receive treatment. A family history is also included. The ophthalmologic examination should include intraocular pressure (IOP) measurements, keratometry, pupil exam, routine motility testing, and dilated slit-lamp and funduscopic examinations including indirect ophthalmoscopy to examine the central and peripheral retina. Ancillary testing such as visual fields, topography, specular microscopy for endothelial cell counts, and fluorescein angiography should be considered in selected cases. There are many causes for decreased vision and ,especially in older patients, these causes may exist concurrently. Age-related macular degeneration is possibly the most important and difficult to detect because of the existing opacity of the cataract.
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Evaluation of Macular Function The main preoperative tests to determine central visual acuity are: 1) the Potential Visual Acuity Meter (PAM) and 2) the Super Pinhole. They permit evaluation of the macular function in patients in whom examination of the macula is difficult due to media opacities. They are more useful when they are integrated into the total evaluation of the patient. One of the major problems that all of us confront as clinical ophthalmologists is that of patients with cataracts who correct to 20/100 or 20/200 and on whom we are planning to operate but cannot see the fundus, particularly the macula. This is aggravated when the patient has a few old small corneal opacities. The ever-present question is: what is the visual prognosis if we operate, either by a cataract extraction or combined with a corneal transplant? What can we anticipate for the patient or his/her family about future, postoperative vision even if we do not have any significant operative or postoperative complications? Ultrasonography and clinical tests will give us only a partial and limited answer. Since we cannot see the state of the macula or papilla, we are limited as to the prognosis. Sometimes we have the pleasant surprise of obtaining more vision postoperatively than we predicted; in other cases, we face the unpleasant reality of finding macular degeneration or other lesions in the macula or optic nerve that result in poor central vision in spite of a beautifully performed operation.
Any well trained ophthalmologist can diagnose major lesions of the optic nerve or retina preoperatively. The major problem is with the subtle lesions that nevertheless limit the patient's capacity to read or distinguish clear images at distance postoperatively. One of the most important tests for evaluating macular function in the presence of a lens opacity dense enough to make our clinical examination of the macula unreliable is the Guyton-Minkowski Potential Visual Acuity Meter (PAM). The Super Pinhole developed by David McIntyre, M.D., is another highly practical and useful method to evaluate macular function. The Laser Interference-Fringe Method has also been previoulsy used but it is less practical. Most clinical ophthalmologists prefer the PAM test or the Super Pinhole.
The PAM The Potential Acuity Meter (PAM) is an instrument which attaches to a slit lamp. It serves as a virtual pinhole by projecting a regular Snellen visual acuity chart through a very tiny aerial pinhole aperture about onetenth of a millimeter (0.1 mm) in diameter. The light carrying the image of the visual acuity chart narrows to a fine 0.1 mm beam and is directed through clearer areas in cataracts (or corneal disease), allowing the patient to read the visual acuity chart as if the cataract or corneal disease were not there (Figs. 4 and 5A and B). The PAM is taken from its stand and placed directly onto the slit lamp in the same
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Figure 4 : Concept of the Guyton-Minkowski Potential Acuity Meter With Cataractous Lens (PAM) The beam (arrow) of the projected Snellen chart is shown passing through a cataract (C) and forming the image of the chart on the retina (R). The beam of light can only strike the retina when the beam is able to pass through the lens, between opacities. With the chart successfully projected onto the retina, the patient can respond and we can determine the potential visual acuity as if the cataract were not there. The PAM serves as a superpinhole by projecting the regular Snellen chart along a tiny beam 0.1 mm in diameter.
manner as the detachable type of Goldmann tonometer. The examination takes from two to five minutes per eye, depending on the density of the cataract. As pointed out by Guyton, for the PAM to work adequately, there must be some small hole in the cataract for the light beam to pass through. You may find such a hole even in cataracts which have media clouding of up to 20/200 and better. When you find it, then you
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can avoid the light scattering produced by the opacities. It is this light scattering which washes out the retinal image and decreases vision behind cataracts. By projecting the image of the visual acuity chart through one tiny area, we avoid that scattering effect, and the patient can see the chart (Figs. 6 A-B and 7 A-B). How is the instrument operated by the clinician or an assistant? The device is mounted on a slit lamp so that the operator can see
Chapter 2: I n d i c a t i o n s a n d P re o p e r a t i v e Ev a l u a t i o n
Figure 5 A (above left): Concept of the Potential Acuity Meter (PAM) in Cases of Corneal Opacities and Cataract In Fig. 5-A the tiny beam of light (arrow) of the projected Snellen chart is shown striking a corneal opacity and failing to penetrate the cornea.
Figure 5 B (below right): Concept of the Potential Acuity Meter (PAM) in Cases of Corneal Opacities and Cataract In Fig.5-B, by moving the beam to a point between the corneal opacities, the projected Snellen chart can pass on through the cornea and onto the retina (arrow) so that the patient can see it and we can determine the visual acuity. The test as shown in Figs. 4-A and 4-B is particularly important if we are considering a combined cataract extraction and penetrating keratoplasty.
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exactly where the light beam is passing. The light beam is directed to various parts of the pupil (Fig. 4, 6-A, 6-B, 7-A, 7-B). It can be focused in between lens opacities. It is easy to see when the beam is going in because it practically disappears (Fig. 6-B). When it hits an opacity, you can see the opacity light up (Fig. 6-7). When you move the beam with the slit lamp control to lucent, non-opaque areas, you see the beam pierce through (Figs. 6-B and 7-B). It is valuable to observe this because if you know you are getting the beam through and the patient still reads poorly, you can be fairly confident that there will be a poor result after surgery. If you are not sure whether the beam is penetrating and the patient reads poorly, results of surgery will be uncertain. So, the slit lamp monitoring of the light beam is important.
It is sometimes difficult to find a small hole in a cataract with density greater then 20/200, although holes have been found in counting-fingers cataracts. If you obtain good vision behind any cataract, you have the information you need. As to the visual prognosis behind very dense cataracts, if you cannot obtain a good reading, you still do not know quite where you are. The instrument is best operated in a darkened room because it is easier to see the light beam. The best results are obtained with a dilated pupil because you have a better chance of finding an appropriate hole in the cataract. Ninety percent of patients whose best correctable vision is 20/200 and better preoperatively, achieve the predicted vision or within two lines
Figure 6-A: How the PAM Works - Slit Lamp View In Fig. 6-A the ophthalmologist directs the small beam of light through different parts of the dilated pupil in a patient with lens opacities. One can see here that the beam of light (arrow) is hitting a lens opacity. This light is strongly scattered by the opacity, lighting up the opacity, leaving little or no light remaining to penetrate on through to the retina.
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Figure 6-B: How the PAM Works - Slit Lamp View In Fig. 6-B the beam (arrow) is successfully penetrating the lens at a point where no lens opacities are present, and the beam disappears into the vitreous cavity (V). As the light beam broadens out, passing into the vitreous, it is no longer visible to the doctor. The examiner thus can be certain that the light beam of the projected Snellen chart is getting in to the retina. With the beam successfully projecting the Snellen chart image on the retina, the patient can respond accordingly so that the examiner can determine the potential visual acuity irrespective of the lenticular opacities.
than the predicted vision after surgery. When the preoperative visual acuity is worse than 20/ 200, only about 60% achieve vision within three lines of the vision predicted by the PAM. The vision obtained after surgery is generally equal to, or better than the vision predicted with the Potential Acuity Meter. False positives occur in 10-15% of cases. When the test is done in cases of cystoid macular edema, the instrument occasionally indicates better
potential vision than the patient can achieve with best refractive correction postoperatively. No single test of visual function, however, is sufficient to mandate surgery. Instead, it is the visual needs of the patient in combination with careful estimation of the potential for the return of visual function after surgery that finally serves as the basis for the ophthalmologist to decide whether surgery is indicated and useful.
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Figure 7 A: How the PAM Works Cross Section View Figures 7 A and 7 B demonstrate in cross-section the views shown in Figs. 6 A-B. In (A), the light beam (arrow) can be seen striking a lens opacity (C) and thus does not penetrate the lens. The patient in this case cannot see the projected Snellen chart.
Figure 7 B: How the PAM Works Cross Section View In Fig. 7-B the light beam is directed to another part of the pupil where it is focused between lens opacities so that the projected Snellen chart passes to the posterior pole. Hence the patient will see the chart and respond so that we can determine the effective potential visual acuity.
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PREOPERATIVE GUIDELINES FOR CATARACT SURGERY IN COMPLEX CASES HOW TO PROCEED IN PATIENTS WITH RETINAL DISEASE The Importance of Pre-Op Fundus Exam Thorough peripheral retinal examination should be done before cataract extraction. We are all proud to be first class clinical ophthalmologists and not think of cataract surgery only as a mechanical, technical procedure. As patients live longer, they are apt to have more preoperative diseases sometimes difficult to diagnose unless we are on the alert for them. Because the patient with an even moderate degree of cataract has reduced clarity of vision, it is easily possible that recent abnormalities may not have been observed or reported by the patient. This is particularly the case with retinal diseases.
CATARACT SURGERY IN DIABETIC PATIENTS Because of the increasing importance of diabetic retinopathy, both in incidence and severity, we provide special emphasis to this disease in considering cataract surgery in complex cases. Cataract and retinovascular complications often co-exist in diabetic patients. The combination can present problems in determining the cause of decreased vision. Cataract surgery can also result in rapid progression of diabetic retinopathy that may need treatment with photocoagulation (Figs. 8 and 9)..
Diabetic patients are very predisposed to developing cataracts. This is especially true of younger diabetic patients, who are also highly predisposed to developing diabetic retinopathy (diabetes Type I). In a series of diabetic retinopathy and maculopathy patients 15 years after laser treatment, only 22% of the eyes maintained clear lenses (Figs. 10 and 11). Cataracts will often form following vitrectomy surgery for diabetic retinopathy. Rarely retinopathy can cause cataracts. An example would be prolonged vitreous cavity hemorrhage that results in a partial opacification of the lens. (Very high risk proliferative diabetic retinopathy - Fig. 12)
Evaluating Diabetics Prior to Cataract Surgery Clinically significant macular edema (CSME) and less obvious macular changes in non-proliferative retinopathy may be the cause of decreased vision in addition to the cataract (Fig. 13). It is important to listen to the patient's history when evaluating the cause of visual deterioration. This can be helpful in deciding how much of the visual loss may be due to cataract as opposed to visual damage caused by retinovascular conditions. A good fundus examination through a dilated pupil is essential. In diabetic patients as in all patients, cataract should be removed when a patient's visual function does not meet his/her visual needs and the visual loss is consistent with the cataract. It is very rare that
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Figure 8 : Scatter Photocoagulation to Ischemic Retinal Area Invaded by Vessels in Diabetic Retinopathy Cataract extraction does not cause retinopathy to develop when it was not present before cataract removal, but it definitely may worsen pre-existent retinopathy, particularly if there is a proliferative retinopathy already present. This figure shows an ischemic area of the retina being treated with scatter photocoagulation. Please observe the large nets of vessels. (Photo courtesy of Prof. Rosario Brancato, M.D., from Milan, Italy, reproduced from "Practical Guide to Laser Photocoagulation", Italian Edition by Brancato, Coscas and Lumbroso, published by SIFI).
Figure 9: Significant Regression of Retinal Neovascularization Following Scatter Photocoagulation You may observe that the large nets of vessels shown in Fig. 8 have regressed following treatment with scatter photocoagulation of the proliferative neovascularization existing before cataract surgery. You may observe the laser burns. If the fundus is adequately visible in spite of the cataract, it is preferable to perform photocoagulation before doing cataract surgery. (Photo courtesy of Prof. Rosario Brancato, M.D., from Milan, Italy, reproduced from "Practical Guide to Laser Photocoagulation", Italian Edition by Brancato, Coscas and Lumbroso, published by SIFI).
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Figure 10 (above right): Focal Photocoagulation for Diabetic Maculopathy Previous to Cataract Surgery The laser applications are directed to the microvascular alterations responsible for chronic, leaking fluid which gives rise to macular edema. (Photo courtesy of Prof. Rosario Brancato, M.D., from Milan, Italy, reproduced from "Monografie della Societa Oftalmologica Italiana", Italian Edition by Brancato and Bandello, published by ESAM).
Figure 11 (below left): Grid Treatment with Photocoagulation for Diabetic Maculopathy Ophthalmoscopic appearance after grid pattern treatment of the macula in which diffuse rather than focal leakage is identified on the fluorescein angiogram. Only 22% of these eyes maintain clear lenses 15 years after laser treatment, particularly younger diabetics. (Photo courtesy of Prof. Rosario Brancato, M.D., from Milan, Italy, reproduced from "Monografie della Societa Oftalmologica Italiana", Italian Edition by Brancato and Bandello, published by ESAM).
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cataracts need to be removed so that treatment of the diabetic retinopathy can be performed. Occasionally, cataracts need to be removed when performing vitrectomy. It is important that we consider various diabetic factors in planning cataract surgery because the retinopathy can influence the result. We may see increased bleeding and fibrin formation, especially in the younger patients with active retinopathy and compromised retinal perfusion.
Importance of Maintaining the Integrity of the Lens Capsule Cataract surgery may not only result in rapid progression of diabetic retinopathy, but it may also complicate its management and treatment. Rapid deterioration often occurs
when the lens capsule and zonular integrity are sacrificed by the cataract surgery such as with rupture of the posterior capsule. Retained lens material may produce increased inflammation, which may further accelerate this process. While it is important to maintain an intact posterior lens capsule, it is equally important to have an easily dilatable pupil and a clear capsule to allow a good fundus view through which laser treatment can be performed.
Significant Increase in Complications Following Cataract Surgery The progression of retinopathy following cataract surgery may take several forms. We may see a patient with non-proliferative retinopathy rapidly develop macular edema (CSME) (Figs. 10, 11 and 13). Macular edema
Figure 12: Severe, Advanced Proliferative Diabetic Retinopathy, Very High-Risk - A Prolongued Vitreous Cavity Hemorrhage May Result in Partial Opacification of Lens Artistic rendition of severe, advanced, proliferative, very high risk diabetic retinopathy. (A) Shows a fundus view of a severe case of proliferative diabetic retinopathy. There are preretinal hemorrhages (H) in several locations. Note the extensive active fibrovascular proliferation causing a traction detachment (D) nasally due to traction from the fibrovascular tissue (A) on the retina. There is also active fibrovascular proliferation along the retinal vessel arcade (V) with detachment of the macular area. Note the active fibrovascular stalk (S) which obscures the optic nerve. (B) Shows the same eye with the surgeon's view as seen through the pupil, and accompanying cross section view of the tissue pathology. Note hemorrhage (H), traction (arrows) of the posterior hyaloid (C), traction detachment of the retina (D), and active fibrovascular stalk (S) on the optic nerve.
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Figure 13: Diabetic Macular Edema (A) Shows the fundus view of diabetic macular edema. Notice thickening of the macular area (F). From the oblique cross section (B), an area of the retina and choroid is magnified in (C) to show its relationship to the clinical ophthalmoscopic fundus view above. In (C), there is pooling of fluid (D) within the inner layers of the retina. This fluid is trapped between the ganglion cell layer (G) and the outer plexiform layer (P). Notice there is almost complete loss of the intermediary neurons (N) in this area.
may progress from being diffuse to being cystic. Rafael Cortez, M.D., has observed that diabetic patients with proliferative retinopathy (Fig. 12), or non-proliferative retinopathy (Fig. 13) or even without retinopathy, have a higher risk of developing a vitreous hemorrhage, rubeosis of the iris and neovascular glaucoma postoperatively. This risk is particularly high in those patients with proliferative retinopathy (Fig. 12).
Appropriate Laser Treatment Most diabetic retinopathy complications can be prevented by appropriate laser treatment before cataract surgery. Eyes with nonproliferative retinopathy that have clinically
significant macular edema (Figs. 13 and 14) should receive focal or grid laser treatment (Figs. 10, 11 and 14) to seal the leakage which is detectable through fluorescein angiography. Eyes with severe, non-proliferative (pre-proliferative) diabetic retinopathy (Fig. 15) and proliferative retinopathy (Fig. 16) should receive panretinal laser photocoagulation (Fig. 17) before cataract surgery. This treatment will reduce additional proliferation and deterioration. Even with a cataract, laser treatment can usually be performed with good pupillary dilatation. Krypton red wavelengths are often successful in penetrating somewhat dense nuclear sclerotic lenses (Fig. 14). Retrobulbar anesthesia may be necessary.
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Figure 14 (above right): Prevention of Diabetic Retinopathy Complications by Laser Treatment before Cataract Surgery Most diabetic retinopathy complications can be prevented by appropriate laser treatment before cataract surgery. Eyes with non-proliferative retinopathy that have retinal thickening from edema near the macula should receive focal treatment of the macular aneurysms to erase fluorescein leakage. As shown in this figure, even with a cataract, krypton red wavelengths are often successful in penetrating fairly dense nuclear sclerotic lenses. Laser treatment must be performed with good pupillary dilatation.
Figure 15 (center): Severe Non-Proliferative Diabetic Retinopathy (Pre-Proliferative). This photo shows a characteristic severe, nonproliferative diabetic retinopathy, previously known as pre-proliferative. Please observe prominent soft exudates, dot blot hemorrhages, venous beading, and microaneurysms. (Photo courtesy of Lawrence A. Yannuzzi, M.D., selected from his extensive retinal images collection with the collaboration of KongChan Tang, M.D.)
Figure 16 (below right): Proliferative Diabetic Retinopathy This photo shows the next stage in severity of the disease. Please observe a large subretinal hemorrhage surrounding soft cotton exudates at the lower temporal arcade. There are also multiple intraretinal hemorrhages with neovascularization elsewhere (NVE), which is defined as a proliferative retinopathy anywhere in the retina which is greater than 1 disc diameter from the optic disc margin. The macula is not shown. (Photo courtesy of Samuel Boyd, M.D., Clinica Boyd, Panama).
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Figure 17 (above right): Panretinal Laser Photocoagulation Before Cataract Surgery In treating diabetic retinopathy, panretinal photocoagulation covers all of the periphery and mid-periphery of the retina from the ora serrata to the vascular arcades, sparing only the posterior pole. (Photo courtesy of Prof. Rosario Brancato, M.D., from Milan, Italy, reproduced from "Practical Guide to Laser Photocoagulation", Italian Edition by Brancato, Coscas and Lumbroso, published by SIFI.
Main Options in Management of Co-existing Diabetic Retinopathy and Cataract The first and most successful is to defer the cataract surgery until laser treatment can be performed. If there is extensive vitreous hemorrhage or traction retinal detachment, you
may need to combine the cataract removal with a vitrectomy (Fig. 18). Intraocular lenses do not present a problem when a patient is going to have a vitrectomy. The visual results of pseudophakic eyes with diabetic retinopathy complications that have vitrectomy surgery are essentially identical to those of phakic eyes.
Figure 18: Need to Combine Cataract Removal with Vitrectomy (Vitreous Hemorrhage and Traction Retinal Detachment) The first indication for vitrectomy in the case of proliferative diabetic retinopathy is the presence of vitreous hemorrhage (H). This is conditional, however, depending on several factors such as status of retinopathy, visual loss, adequacy of previous photocoagulation, frequency of hemorrhage, vision in the fellow eye, advancing iris neovascularization, response to vitreous surgery in fellow eye, and systemic factors. In general, surgery for retinopathy is more likely to be indicated with hemorrhage in the presence of active fibrovascular proliferation or traction retinal detachment. This is the second indication for vitrectomy, namely a traction retinal detachment, but only when the macula (M) is detached as shown. Note contraction (arrows) of posterior hyaloid (P) causing a non-rhematogenous retinal detachment (D) due to traction from the fibrovascular tissue (A) on the retina.
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CATARACT SURGERY AND AGE-RELATED MACULAR DEGENERATION
RETINAL BREAKS AND RETINAL DEGENERATIONS PRIOR TO CATARACT SURGERY
Felix Sabates, M.D., has best outlined the precautions we must take when considering extracapsular extraction or phacoemulsification in eyes with already present age-related macular degeneration already present. These principles are: 1) It is important to study the macular area in detail prior to cataract surgery to detect the presence of age-related macular degeneration. 2) If cataract surgery is performed in the presence of age-related macular degeneration, special care should be taken to reduce the possibility of inflammation even if it would require immediate use of antiinflammatory drugs. 3) Cystoid macular edema should be aggressively treated, with careful follow-up emphasized. 4) Cataract surgery should not be performed on the patient with active "wet" macular degeneration (Fig. 19) until it has been brought to a dry stage (Fig. 20). If there is bleeding from a neovascular membrane, cataract surgery should be postponed until at least six (6) months after the blood has completely reabsorbed and there has been no recurrence of the bleeding has been present. 5) In patients with macular scars (Fig. 20) and opaque cataracts, surgical removal of the opacified lens with intraocular lens implantation may be of benefit in recovering some degree of pericentral or peripheral vision. The smaller the macular scar, the better the prognosis. No cataract surgery should be performed unless the cataract is opaque enough so that when it is removed, the patient will probably perceive the benefit of the operation.
The preoperative treatment of these retinal lesions has traditionally come into consideration as a possible means of preventing retinal detachments after cataract extraction, especially in myopes. I refer only to those peripheral retinal degenerations which can be clinically defined and identified, and which have statistically been linked with retinal detachment following posterior vitreous detachments. This, therefore, excludes senile retinoschisis, which has a higher prevalence in the general population than among patients with a retinal detachment. What needs to be clarified is the effect of cataract surgery on the risk retinal breaks and degenerations present and what recommendations should be given in regard to their management prior to cataract surgery. This requires therapeutic proof that prophylactic treatment significantly lowers this risk below that which the natural course of untreated lesions would present. There is an increasing tendency to support the concept that retinal detachments generally are associated with recent, not old, retinal breaks. At the present time the picture is not clear. We lack solid reports supporting the prophylactic treatment of preexisting retinal breaks prior to cataract surgery. What happens to an eye with lattice degeneration when cataract extraction is performed? Again, we face a lack of valid reports in the literature to support preventive treatment prior to cataract surgery. About 90% of eyes with lattice degeneration do not detach after small incision cataract extraction even when
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Figure 19 (above right): Anatomy and Pathology of Exudative, ("Wet") Macular Degeneration with Extrafoveal Neovascularization Cataract surgery should not be performed in these cases. Wait until it has been brought to dry stage as shown in Fig. 20. Fundus view (A) shows an example of exudative "wet" macular degeneration with an extrafoveal neovascular membrane (N) and limited subretinal hemorrhage (H) just at the margin of the paramacular retinal vessels surrounding the fovea (F). From the oblique cross section (B), an area is magnified in (C) to show the direct relationship between clinical ophthalmoscopic fundus view above and its corresponding cellular pathology. Pathology reveals that the retina is slightly elevated over a neovascular membrane (N). Note vessels emanating from the choriocapillaris (J), into the neovascular membrane (N) and into the sub-RPE and subretinal spaces, passing through small breaks (T) in the retinal pigment epithelial cell layer (E). There is some atrophy of photoreceptors in this area (P). Subretinal blood (H) is seen to either side of the neovascular membrane. Large choroidal vessels (K).
Figure 20 (below left)): Anatomy and Pathology of Non-Exudative, Geographic ("Dry") Macular Degeneration In these patients, surgical removal of the opacified lens with IOL implantation may be of benefit in recovering some degree of peripheral vision. Fundus view (A) shows an example of non-exudative, geographic atrophic "dry" macular degeneration where atrophy of the retinal pigment epithelium predominates. The smaller the macular scar, the better the prognosis for cataract surgery. Notice the clinical signs of drusen (D) which can appear as discrete subretinal bodies, confluent masses or hard glinting lesions, usually yellowish in color. Darker intraretinal pigment (I) may or may not be present. Retinal pigment epithelium atrophy (E) is identified by prominence of the underlying choroidal vessels. From the oblique cross section (B), an area is magnified in (C) to show the direct relationship between the clinical ophthalmoscopic fundus view above and its corresponding cellular pathology. Pathology includes subretinal drusen (D) and atrophy of the RPE (E). Compare the disorganized RPE cell layer at (E) on the right to the more normal configuration at (N) on the left. Most importantly, though not clinically visible, there is definite loss of photoreceptors (P) in the area of degeneration (compare with normal photoreceptor layer on the left). Other anatomy: inner limiting membrane (L), choriocapillaris (J) and large choroidal vessels (K).
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YAG laser capsulotomy is later performed. Those that do develop a retinal detachment frequently do not detach from retinal breaks adjacent to or within the lattice lesions, but from unrelated areas which previously looked clinically normal. This has now been observed by numerous investigators. Sabates thinks that each case must be individualized. If a patient has a history of retinal detachment in one eye and lattice degeneration with retinal holes in the other eye, he performs cryosurgery or laser surgery and closes those holes in the second eye. Usually cryosurgery is required because the cataract
may preclude the use of laser. The type of tear present and other factors including the location of the tear and the existence of high myopia would influence the ophthalmologist's judgment in deciding when to treat. Fig. 21 shows the typical retinal tear that he treats, sealed with cryotherapy. Since seven to eight percent of the population has lattice degeneration, it is obvious that not all patients with lattice degeneration should be treated. Regardless of whether the patient is treated prior to cataract surgery, those patients should be followed closely with careful examination of the peripheral retina postoperatively following cataract removal.
Figure 21: Creating the Chorioretinal Adhesion of Retinal Tear with Cryotherapy Before Performing Cataract Surgery This figure presents the treatment with cryotherapy of a retinal tear that needs to be sealed prior to cataract surgery. The freezing and defrosting is observed with the indirect ophthalmoscope. (A conceptual slit beam has been added to this illustration to enhance the 3-dimensional nature of the view).
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CATARACT SURGERY IN PATIENTS WITH UVEITIS Rubens Belfort Jr.,M.D., in Sao Paulo, Brazil and Martinez Castro in Mexico have conducted extensive research on these patients. Cataracts develop frequently in patients with uveitis, either as a result of inflammation, the treatment of inflammation or both. There has been much controversy as to what to do, how to do it and when to operate in patients with cataract and uveitis, and whether intraocular lenses should be implanted in these patients. Professor Rubens Belfort Jr. considers that uveitis is one of the last categories for which surgeons have advised «don’t do it» when cataract surgery is considered. Cataract surgery has been regarded as contraindicated because of the initial bad results with intraocular lenses (IOLs) in patients with uveitis. Until about 10 years ago, most surgeons avoided cataract surgery with or without IOL implantation in these patients. There was concern about superimposing IOL implantation, with the inflammation which used to accompany it in many cases, on a seriously compromised and already inflamed eye. This concept has now changed. The development of current techniques for small incision cataract surgery, new types of IOLs, and advances in the management of patients with uveitis have changed the prognosis. The change is fortunate because cataracts are the major cause of loss of vision in patients with chronic uveitis (Fig. 22). Moreover, cataracts are potentially dangerous for patients with uveitis because they interfere with visualization of the fundus, denying the ophthalmologist the opportunity to identify macular lesions and to treat them adequately. When these pa-
Figure 22: Uveitic Cataract Cataracts caused by an inflammatory uveitic process generally occur with pigment deposits (P) on the anterior capsule of the lens (C) related to anterior synechiae that can immobilize the pupillary sphincter. The intensive use of topical steroids for the management of the uveitis can hasten the formation of such cataracts. Cataracts are the major cause of loss of vision in patients with chronic uveitis. Current techniques for small incision surgery, new types of IOL's and advances in management of uveitis enable their removal where previously this was contraindicated.
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tients finally undergo long-postponed surgery, usually with good anatomic success, central vision may not be recovered because of irreversible macular damage that had developed from chronic cystoid macular edema. Therefore it is critical for both the surgeon and the patient with uveitis to realize there is another reason for cataract surgery in addition to improving vision as much as possible. Removal of the cataract enables the the ophthalmologist to examine and treat the macula in order to forestall damage.
Method of Choice In theory, removal of the lens as a whole (intracapsular) could lead to less inflammation. In fact, careful extracapsular surgery with adequate cleaning of the lens material during surgery usually provides a better outcome. Most surgeons now prefer phacoemulsification to a classic extracapsular extraction of the cataract even in patients with uveitis. Belfort believes phacoemulsification leads to faster results and less inflammation, and he advocates phacoemulsification with or without an IOL. Intracapsular technique is no longer used except in some rare cases of lens-induced uveitis, in which inflammation is caused by the leakage of protein material from the lens.
Diagnosing the Type of Uveitis in the Pre-Operative Phase Belfort emphasizes that in the preoperative phase, it is very important for the surgeon to determine the exact type of uveitis the patient has in order to better predict the surgical outcome and minimize reaction. For
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instance, patients with ocular sarcoid have a much worse postoperative course than other patients. Therefore, a patient with sarcoidosis and uveitis, even in the absence of important uveitis, must be approached more carefully than patients with other types of uveitis. Other types of uveitis that can be effectively managed are Fuchs’ heterochromic cyclitis, intermediate uveitis, and posterior uveitis as well as most of the anterior essential uveities. Behcet’s disease and other vascular inflammations, which in the past were considered to have a bad prognosis, have shown much better results with current techniques.
Preoperative Management In general, the less inflamed the eye at the time of surgery, the better the prognosis. Ideally, every patient should be operated only after being inflammation-free for at least 3 months, although this is not possible in many cases. Uveitis is chronic, no matter what dose of steroids is used, and many patients must be operated even in the presence of some active uveitis. The goal is to have the eye as little inflamed as possible. Preoperative steroids, as eyedrops or even systemically, as well as immunosuppressive drugs have to be used in more severe cases. In patients who do not respond to steroids alone, Belfort uses systemic oral cyclosporin and oral prednisone therapy. In 20% of patients the use of an IOL is not advisable. This includes patients with granulomatous uveitis such as sarcoid, Vogt-Koyanagi-Harada syndrome, and sympathetic ophthalmia. Belfort also advises against using IOLs in patients with juvenile rheumatoid arthritis, who tend to have a chronic disease and may develop long-term complications.
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The Intraocular Lens Currently, IOLs can be used in at least 80% of patients with both uveitis and cataract. Selecting the right type of IOL is very important. Although PMMA lenses are well tolerated by the eye with uveitis, they may lead to more posterior capsule opacification than other lenses. Belfort recommends not using silicone in cases of uveitis because silicone lenses by themselves can cause uveitis and may aggravate previous intraocular inflammation, especially in heavily pigmented people. Belfort therefore prefers to use acrylic lenses in these patients. We do not yet have clinical trials or studies that establish conclusively the superiority of one lens material over another. Results appear not to be better with heparin-coated IOLs than with PMMA lenses in patients with uveitis. Considering that heparin-coated lenses are also more expensive, Belfort does not advocate using them in uveitis. CATARACT SURGERY IN ADULT STRABISMUS PATIENTS
Preoperative Judgment The treatment of co-existing cataract and strabismus traditionally has been managed with separate operations. Usually the cataract ex-
traction has been done first, followed later by a surgical correction of strabismus. As a matter of fact, we may even hesitate to remove a cataract in a patient who has had a deviated eye for a long period for two reasons: First, cataract removal may result in postoperative diplopia, and second, it is difficult to predict whether amblyopia may be present in the deviated eye, leaving us with a questionable prognosis. Successful combined cataract and strabismus surgery is highly feasible. The ideal patient for a combined approach must fill certain prerequisites: one, he or she must have a congenital strabismus rectifiable by surgery on a single muscle in each eye. Second, the patient must have an alternating deviation and equal fusion potential in each eye, determined either by knowing the patient's vision before the onset of the cataracts or by the results of the potential acuity meter (PAM) that should be about equal in both eyes (see figures 3 through 7). An equal potential acuity meter measurement in both eyes would seem to exclude amblyopia, thereby improving the chances for an optimal visual outcome. During combined cataract and strabismus surgery, if the patient continues to blink or squeeze the eyelids following the combined topical and intracameral anesthesia, you can obtain anesthetic control this a sub-Tenon's injection of lidocaine as illustrated in Figs. 33 and 34. The effect is almost instantaneous, and surgery can continue without delay.
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BIBLIOGRAPHY Boyd, BF.: Cataract Surgery in Diabetic Patients. World Atlas Series of Ophthalmic Surgery, published by HIGHLIGHTS,Vol. IV, 1999; 9:153-54. Boyd, BF.: Undergoing cataract surgery with a master surgeon: A personal experience. Highlights of Ophthalm. Journal, Vol. 27, Nº 1, 1999;2-3. Charlton, Judie: Cataract surgery and lens implantation. Editorial Overview, Current Opinion in Ophthalmology, 2000, 11:1-2. Fine, IH.: Cataract surgical problem: Consultation section. J Cataract Refractive Surg, 1997; 23:704. Gimbel, HV., Anderson Penno, EE: Cataracts: Pathogenesis and treatment. Canadian Journal of Clinical Medicine, September 1998. Gimbel HV., Basti S., Ferensowicz MA., DeBroff BM: Results of bilateral cataract extraction with posterior chamber intraocular lens implantation in children. Ophthalmology, 1997; 104:1737-1743. John K., Fenzl R.: Preoperative Workup. Cataract Surgery: The State of the Art. Edited by Gills, JP., Slack; 1998; 1:1-8. Lacava, AC., Caballero, JC., Medeiros, OA., Centurion, V.: Biometria no alto miope. Rev Bras de Oft. 1995;54:619-622. Masket S.: Preoperative evaluation of the patient with visually significant cataract. Atlas of Cataract Surgery, Edited by Masket S. & Crandall AS, published by Martin Dunitz Ltd., 1999, 1:3-5. Neumann D., Weissmann OD., Isenberg SJ., et al: The effectiveness of daily wear contact lenses for correction of infantile aphakia. Arch Ophthalmol. 1993;111:927-9.
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C h a p t e r 3: IOL Power Calculation in Standard and Complex Cases - Preparing for Surgery
IOL POWER CALCULATION IN STANDARD AND COMPLEX CASES PREPARING FOR SURGERY Making Patients Confident From the minute the patient considers undergoing surgery, fear is present. There is fear of the unknown and fear of someone operating on your eye. Jack Dodick, M.D., from New York, believes in the important influence of office personnel and environment on making patients confident and comfortable. Dodick strongly advocates hiring and training highlevel professional staff. When patients interact with highly competent staff at every encounter, they tend to conclude that the doctor must be very good because he has selected and trained his staff so well. Many doctors pay too little attention to the impressions staff make on their patients. They are tempted to cut corners by hiring clerks at low pay if they fail to realize that patients’ impressions of staff are integral to their impressions of their physician. In addition, the office environment should be tasteful. The impression patients have when they enter the office influences their feelings about their physician. An office that is dirty and cluttered reflects poorly on the practice. Dodick believes that once patients feel respected and comfortable with the expertise of the physician and his/her staff, they relax and decide they have come to the right place.
Patients Encounter with the Physician And in the encounter with the physician patients should feel respected and important. Even though the waiting room is busy, everything should seem unhurried when the patient is sitting in the chair across from the physician. The ophthalmologist should convey the impression that, at this time, the patient is the most important person. The physician’s ability to project a confident manner is also critical to success. Dodick believes it is an art to convey this confidence and professionalism to patients. It is partly done through certain inflections in the voice; perhaps it is easier to explain in reverse. Sometimes the doctor who does not feel totally secure in his ability to produce results may become a little defensive, and give more emphasis to potential complications than the real positive benefits of the operation. “Well, you have a cataract. As you know, you can have it operated on or not, and there are some complications that sometimes occur. For example. . .” Although potential complications are in fact true, the chance that these complications will occur is minimal. Dodick does not dwell on these rare potential complications. Instead, he emphasizes the
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very high probability of positive results when communicating with patients. He retains a position of objectivity in order that his own perspective will not unduly influence the patient. The patient must be informed of potential risks but with modern small incision cataract surgery, they are very unusual.
Ingredients of a Strong Relationship The physician’s ability to instill confidence and trust in patients, and an ability to articulately convey his confidence through the spoken word are the basic ingredients of a strong relationship between physician and patient. A fundamental question is how should the ophthalmologist approach patients who measure well on Snellen acuity, but still complain about their vision because of the very important factors of contrast sensitivity and glare we have already discussed. Dodick follows these basic steps. He first listens to the patient and tries to make a historical determination about how happy or incapacitated they are because of their vision. If patients claim to be very happy with their vision, Dodick goes no further. He merely instructs them that they, like everyone over 50, have some lens changes. He explains the basic anatomy of the human eye (Fig. 1-A), with its clear windows inside and outside, and the tendency of the inside window to become cloudy. The treatment, of course, is to replace the cloudy window with a clear window and thereby restore their vision. In approaching the question of when a cataract should be removed, Dodick reinforces the concept that in nearly all conditions, cataract surgery is 100% elective. The time to remove a cataract is the time that
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patients decide they are unhappy with their vision. Most people understand this, but often Dodick hears the question, “What would you do in my position?” Dodick handles this by looking the patient in the eye and responding: “This is a very simple question. If I were very happy with my vision right now, I would do nothing. If I were unhappy, I would decide in a minute to have cataract surgery.” Then patients fully realize that cataract surgery is truly an elective procedure.
Evaluating the Patient's Cataract Of course, giving patients this choice is predicated upon the fact that the ophthalmologist has conducted a thorough examination. With slit lamp biomicroscopy posterior subcapsular cataracts which strongly interfere with vision by inducing a great deal of glare are very easy to evaluate, whereas nuclear sclerotic cataracts are often difficult to evaluate on the slit lamp. People with posterior subcapsular cataracts can measure 20/20 or 20/25 on Snellen acuity because they are really looking through the little pinholes of the posterior subcapsular cages (Fig. 23A-B). The minute they see oncoming headlights while driving at night, for instance, the glare may diminish their functional vision to 20/100 or even 20/200. On the other hand, people with nuclear sclerosis, the most common form of cataract, tend to complain about contrast sensitivity rather than glare (Fig. 23C-D). Over the years Dodick has found that a good way to evaluate lenticular or media changes is to examine the red reflex of the patient by holding an ophthalmoscope about 12 to 14 inches from the eye and determining whether it is a bright red reflex, a gray reflex,
C h a p t e r 3: IOL Power Calculation in Standard and Complex Cases - Preparing for Surgery
Figure 23 A-D: Posterior Subcapsular Cataract (top, left and right). Cataract with Nuclear Sclerosis (bottom, left and right) Figures 23 A and B are three dimensional photographs of a characteristic posterior subcapsular cataract, seen with the slit lamp (top-left) and with indirect illumination also using the slit lamp (top-right). Patients with posterior subcapsular cataracts can measure 20/20 or 20/25 on the Snellen visual acuity chart in the examining room, because they are seeing through the little pinholes of the posterior subcapsular cages. When they are exposed to oncoming headlights while driving at night, the glare may diminish their functional vision to 20/100 or even 20/200. Figures 23 C and D are three dimensional photos of nuclear sclerotic cataract, viewed with diffuse illumination (left) and with the slit lamp beam (right). This is the most common form of cataract. Patients tend to be hindered more by loss of contrast sensitivity rather than glare. (Reproduced with permission from AAO's Basic and Clinical Science Course, Lens and Cataract, 1999, pp.42, 48, enhanced by HIGHLIGHTS).
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or a dark black reflex. This provides a good indicator of opacity. In some circumstances a
nuclear cataract can be better evaluated with this technique than with the slit lamp. Dodick does not rely on tests for contrast sensitivity when evaluating cataracts. Although conditions of glare can be simulated in a clinical setting, Dodick relies on the patient’s real life test experience instead.
Approaching the Day of Surgery Once Dodick and his patient have reached the mutual understanding that cataract surgery may be beneficial, the patient is in essence turned over to a series of highly trained, dedicated, professional staff who work closely with him. The next person the patient sees is a highly trained technician. The technician explains that a measurement is needed to determine the correct lens to implant into the eye, and they undergo an ultrasonography scan. When the test is completed, the patient is turned over to the surgical counselor, who has become a master at making patients comfortable and ready to approach the day of cataract surgery.
out glasses, by all means do not sacrifice their near vision just for providing 20/20. The availability of foldable multifocal IOL's makes this surgeon-patient understanding even more critical so that the visual advantages of these lenses need to be fully appreciated versus the disadvantages which exist but may be less significant. A similar situation presents with the alternative of monovision. If the surgeon contemplates using this method, which is a good alternative for many patients, it is important to make sure the patient understands how this works and be enthusiastic with this alternative. Final visual satisfaction with these methods, multifocal IOL's and monovision, will depend a great deal on the selection by the surgeon of the right patient for these alternatives. With multifocal IOL's patients are happier with bilateral implantation. With monocular implantation, it is preferable not to delay surgery in the fellow eye unless there is a major reason, because most patients feel very insecure with monocular vision and having only one eye operated.
DETERMINING IOL POWER (BIOMETRY)
Patient's Expectations It is essential to clarify to the patient what he/she may expect and what not to expect. Postoperative patient satisfaction is based on this pre-op surgeon-patient communication and understanding. What are the patient's daily needs and what final uncorrected visual acuity for distance and near he would prefer? Does he want to read without glasses? If so, then he must know he would not see perfectly clearly for distance. If he/ she are myopes and consequently read with-
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Ocular biometry must be performed prior to cataract surgery. There is no question that when well selected and properly done the ultrasonic methods afford us the best way of achieving the desired postoperative refraction. Determination of intraocular lens power through meaningful keratometer readings and axial length measurement through A-Scan ultrasonography has become a "standard of care". It is a challenging technique and crucial to the visual result and patient satisfaction.
C h a p t e r 3: IOL Power Calculation in Standard and Complex Cases - Preparing for Surgery
Postop Refractive Errors No Longer Admissible This is particularly true considering the high patient's expectations and the minimal astigmatism created by small incision cataract surgery, particularly phacoemulsification. Patients look forward to wearing spectacles postoperatively only under special circumstances. As emphasized by Centurion and Zacharias, postoperative refractive errors are
no longer admissible. In small incision techniques, cataract surgery has attained the status of refractive surgery. Therefore, exact determination of the IOL power to end up with the specific planned postoperative refraction is essential. The advent of multifocal foldable IOL's makes this even more of an important, though complex subject, as well as operating on eyes with different axial lengths: normal (Fig. 24), short as in hyperopia (Fig. 25 A-B), long as in myopia (Fig. 26).
Figure 24: Determination of IOL Power in Patients with Normal Axial Length (Normal Eyes) - Mechanism of How Ultrasound Measures Distances and Determines Axial Length The use of ultrasound to calculate the intraocular lens power takes into account the variants that may occur in the axial diameter of the eye and the curvature of the cornea. The ultrasound probe (P) has a piezoelectric crystal that electrically emits and receive high frequency sound waves. The sound waves travel through the eye until they are reflected back by any structure that stands perpendicularly in their way (represented by arrows). These arrows show how the sound waves travel through the ocular globe and return to contact the probe tip. Knowing the speed of the soundwaves, and based on the time it takes for the sound waves to travel back to the probe (arrows), the distance can be calculated. The speed of the ultrasound waves (arrows) is higher through a dense lens (C) than through a clear one. Soft tipped transductors (P) are recommended to avoid errors when touching the corneal surface (S). The ultrasound equipment computer can automatically multiply the time by the velocity of sound to obtain the axial length. Calculations of intraocular lens power are based on programs such as SRK-II, SRK-T, Holladay or Binkhorst among others, installed in the computer.
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Figure 25 A (above right): IOL Power Calculation in Patients With Very Short Axial Length (Hyperopia) In eyes with short or very short axial lengths as shown in Fig. 25 the third generation formulas such as Holladay 2 and Hoffer-Q seem to provide the best results. Holladay has discovered that the size of the anterior and posterior segments is not proportional in extremely short eyes (<20.0 mm). Only 20% of short eyes present a small anterior segment (nanophthalmic eyes); 80% present a normal anterior segment and it is the posterior segment that is abnormally short as shown here. (P) represents probe, (S) represents corneal surface.
Figure 25-B (below left): Concept of the Piggyback High Plus Intraocular Lenses In cases of very high hyperopia, a clear lens extraction may be done combined with the use of piggyback high-plus intraocular lenses. One (A), or two (B) or, some surgeons suggest, three or more intraocular lenses can be implanted inside the capsular bag (C). This piggyback implantation technique may solve the problems of having to implant a lens of over +30 diopters with its consequent optical aberrations, but the procedure may give rise to postoperative complications. Some prestigious surgeons have their reservations (see text).
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C h a p t e r 3: IOL Power Calculation in Standard and Complex Cases - Preparing for Surgery
The Challenge of the Complex Cases The use of refractive surgery on the cornea using a variety of techniques: excimer (Fig. 27), RK (Fig. 28), Intracorneal Ring Segments (INTACS - Fig. 29) makes ocular biometry even more complex. These refractive corneal refractive techniques change the parameters in these special cases as compared with those we use for normal eyes and make these special cases. Computerized videokeratography provides additional important data. The current acceptance of implanting IOL's in children following pediatric cataract surgery (Fig. 31) and the frequent use of vitrectomy with the use of silicone oil
(Fig. 32) frequently in Europe and infrequently in the U.S., also add unique and different difficult challenges, in performing an exact biometry in every individual patient's condition. When using ultrasound, axial length is determined by measurement of the reflection of the eye tissue interfaces with the ultrasonic beam (Fig. 24 - arrows). The A-scan must be carefully calibrated and the beam velocity must correspond to whether or not the patient is phakic, pseudophakic, or aphakic and may need to be modified in the special cases previously described. The ultrasound probe (T) has a piezoelectric crystal that electro-mechanically emits and receives high frequency sound waves. The sound waves travel through the eye until they are reflected back by any structure that stands in
Figure 26: IOL Power Calculation in High Myopia In high myopia with axial lengths higher than 27.0 mm the use of the SRK II formula with an individual surgeon's factor has shown good predictability of the refractive target. Probe (P), corneal surface (S).
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their way (represented by arrows). Assuming the average velocity of the sound waves in the eye being measured, and based on the time it takes for the sound waves to travel back to the probe (arrows), a distance can be calculated. The ultrasound equipment's computer can automatically multiply the time by the velocity of sound to obtain the axial length. At least three scans should be obtained which are within 0.15 mm of each other. Gimbel recommends that the A-scan should be measured twice by independent technicians if the axial length is unusually short (Fig. 25) (hyperopia) or long (Fig. 26) (myopia) (<22 mm or >25 mm), or if the difference between the two eyes is more than 0.3 mm, if the axial length measurement does not correlate with the refraction or the patient has difficulty with keeping the eyes open or with fixation.
The Most Commonly Used Formulas The most commonly used IOL formula was developed by Sanders, Retzlaff and Kraff and is known as the SRK formula, where p = A - 2.5L - 0.9K. "P" refers to lens implant power to produce emmetropia, "L" refers to axial length, "K" refers to average keratometric readings in diopters and "A" is a constant that is specific to the lens implant that is to be used. Several second and third generation lens power calculation formulas have been developed including the SRK2 and SRK/T, Hoffer Q, and the Holladay 2 formulas. Gimbel emphasizes that to avoid errors in lens power calculations not only must the biometry be accurate and the correct "A"
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constant used, but also the estimated anterior chamber depth (depending on the formula), preop refraction and age must be taken into account. Adjustments can also be made for a specific surgeon's technique. In the search for continuous refinement and accuracy of results, new methods based on laser interferometry may replace ultrasonography in the future.
Main Causes of Errors Zacharias and Centurion have pointed out that most postoperative refraction errors occur not due to errors in the formulas but to imprecise preoperative measurements. For each millimeter of error in biometry there is a -2.5 diopter error in the calculation of the IOL power. If more than one error occurs in the same examination there may be significant postoperative refractive errors. Keratometry in both eyes should be repeated when: • corneal curvature is less than 40.00 D or more than 47.00 D; • the difference of the corneal cylinder is more than 1.00 D between both eyes; • the corneal cylinder correlates poorly with the refraction cylinder. During the examination, the patient sits in front of the skilled technician performing the ultrasound test. He/she is asked to fixate at a point straight ahead. The ultrasound soft probe is positioned axially, touching the corneal epithelium as lightly as possible so as not to compress and thereby shorten the eye. It is useful to visualize the procedure laterally to make sure that the cornea is not being compressed (Fig. 24).
C h a p t e r 3: IOL Power Calculation in Standard and Complex Cases - Preparing for Surgery
Targeting Post-Op Refraction This parameter is the only one that the physician must decide upon by himself and feed into the computer. All the other parameters are measured or assumed values over which he has no control. When selecting a lens implant power Gimbel generally recommends that the surgeon target mild myopia and thus avoid inadvertent postoperative hyperopia. A patient who is hyperopic postoperatively will need spectacles for clear vision at any range, whereas a patient who is slightly myopic will have a range of clear vision corresponding to the degree of myopia. In all cases the patient must be counselled with regard to expectations of refractive changes and they should be counselled that they will generally need reading glasses or bifocals postoperatively as the implant has no power of accommodation, unless the patient's targeted postop refraction is around -2.00 on purpose.
Monocular Correction Holladay has pointed out that with monocular correction, there are two major considerations for determining what would be the best postoperative refraction for any patient. If we are only considering one eye (i.e., the other eye is amblyopic), targeting the postoperative refraction for approximately -1.00 to -1.50 diopters is probably the best choice. This is usually best because most people have visual needs for both distance and near; that is, they want to be able to drive and to read without having to wear glasses. If we target the patient's post-op refraction for -1.00 to -1.50, the patient will have 20/20 vision at approximately 2 to 3 feet, 20/30 vision in the distance, and 20/30 at 14 inches. With a normal size pupil of approximately 3 mm in the cataract age
group, these visual acuities are adequate with no additional glasses required. At times when they might need finer acuity, they can wear regular bifocals, which will correct them for distance and near. In older, more sedentary patients, two diopters of myopia may be a better goal. For these patients reading without glasses may be preferred to distance vision without glasses. The second reason for targeting the postop refraction to approximately -1.00 to -1.50, sometimes -2.00 diopters, is that, statistically, between 70% and 90% of patients will fall within + or -1.00 diopter error of this desired postoperative refraction. The errors, as mentioned previously, are primarily a result of our inability to make exact measurements on the living eye. Therefore, the patient will fall between plano and -2.00 diopters 90% of the time. This will assure most patients of useful vision without glasses. Hence, the error of the ultrasound measurement is best handled by choosing the postoperative refraction of -1.00. On the other hand, if we target for plano, which is the target that some physicians try to obtain, 90% of the patients will be between -1.00 and +1.00 diopters. When the patient's refraction is on the +1 side, he has less useful vision at any distance because he is hyperopic and does not have the ability to accommodate. Consequently, because it is very undesirable to have a hyperopic correction, targeting for -1.00 not only optimizes the best vision at all distances but also minimizes the chance for hyperopia that can result from the inaccuracies of ultrasonic measurements. Holladay's recommendation for choosing -1.00 to -1.5 as the postoperative refraction is based on one eye only, i.e. monocular conditions. When the vision in the other eye is good, its refraction must be considered for binocular vision. 45
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Binocular Correction In patients with Binocular Correction: one overriding rule when choosing an IOL power is that one should never aim for spectacles which give the patient a difference in the power between the right and left lens greater than three diopters. The reason for this is that even though the patient may have 20/20 vision in primary gaze, when the patient looks up or down, the induced vertical prism difference in the two eyes is so large that it will create double vision. Therefore, avoid anisometropia. Good Vision in the Non-Operated Eye In a patient who has good vision in the non-operative eye, one must target the intraocular lens power for a refraction within two diopters of his/her present prescription in the non-operative eye. This measurement should be two diopters, not three, due to our 1 diopter A-scan variability. For example, if we have a patient who is hyperopic and has +5 diopters correction in each eye, we cannot target the intraocular lens for a postoperative refraction of -1 diopter because this would produce a 6 diopter difference between the two lenses, resulting in double vision or confusion. Holladay recommends selecting the intraocular lens power to obtain a refraction which is approximately two diopters less than the non-operative eye. Consequently, on our patient who is +5 diopters in both eyes, we should target the postoperative refraction in the eye with the cataract for +3, so ther e is a 90% probability that there will be less than a 3 diopter difference. In contrast, if the patient were highly myopic in each eye, for example, -10.00 in both eyes, we should target the intraocular lens power to produce refraction of approximately
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-8.00. We have limited the difference in the spectacle lenses to a two diopter difference in the final prescription. Again, we are advised to target for a two diopter difference, not a three diopter difference, because there is approximately a one diopter tolerance in the accuracy of the ultrasonic measurement. When Cataracts in Both Eyes If the operation on the second eye is to be done shortly after the first, the IOL calculation is made as if he were monocular, as in our previous discussion. For example, with a patient +5 in both eyes, if the second eye is cataractous and it is planned that the patient would also need cataract surgery in that second eye within a short period of time, it would be wise to target for -1 in the first eye. When the vision in the operated eye exceeds the vision in the other eye, -1 lenses in both should be prescribed until the second eye is operated. Soon. This is not only true with intraocular lens surgery; it is true in all forms of refraction. The patient needs to understand what we are doing and to be a part of the decision process. One should never give a patient more than a three diopter difference in his/her spectacles unless he has previously worn such a prescription. One exception is a child who is under five or six years of age and who can adjust to this difference by turning his head rather than moving his eyes. Another is the patient with an alternating strabismus. We must continue in our efforts to avoid creating astigmatism by our surgery. If the patient is already astigmatic, try to avoid too much astigmatic imbalance (high plus at 90º in one eye and high minus at 90º in the other). This results in a vertical prism effect in reading and the need for prescribing a slab off prism. This problem has fortunately been significantly diminished with small incision surgery, particu-
C h a p t e r 3: IOL Power Calculation in Standard and Complex Cases - Preparing for Surgery
larly phaco, and with the application of refractive cataract surgery by placing the incision in the correct axis at the time of cataract surgery. This we will discuss under the major heading of "The Incision."
IOL POWER CALCULATION IN COMPLEX CASES Specific Methods to Use in Complex Cases Considering that there are no specific methods on which there is full agreement as to what to do in these patients, and after consulting different authorities in this field, we hereby recommend the use of third generation formulas, preferably more than one and that the highest resulting IOL power should be used for the implant. These formulas are preferably the Holladay 2, the SRK/T or the Hoffer formulas. Do not use a regression formula (e.g., SRK I or SRK II). We also recommend that you use central topography's flattest curve as a keratometric method unless you are fortunate to have all the information needed in order to use the "historical method." This reading is fed to the computer utilizing the selected formulas. The computer will then provide you with the power of the IOL to use. The modern formulas hereby recommended are already available in most of the computers available today to calculate IOL power. You just select the formulas you believe adequate which should be present within your equipment. The reason behind all these sophisticated and very careful IOL calculations in highly myopic patients with cataract is, of course, that although the cataract removal by itself can somewhat compensate for the high myopia, the
advantages of modern technology, the small incision extracapsulars and careful inspection of the peripheral retina allow us to perform a safe lens removal and provide an IOL implantation with a sufficiently desirable power to provide a specific patient with the very high quality of vision that we must demand of ourselves for the benefit of our patients.
Practical Method for Choosing Formulas in Complex Cases From a practical standpoint, if several formulas are available to the clinician, the first choice as recommended by Zacharias and Centurion are as follows: • short eyes: L <22.00 mm: Holladay 2 or Hoffer Q. These constitute 8% of cases. • L (axial length) between 22.00 and 24.50 mm; 72% of the cases: mean of the three formulas: Hoffer, Holladay and SKR/T. • L between 24.50 mm and 26.00 mm; 15% of the cases: Holladay 2 or SRK/T • L higher than 26.00 mm; 5% of the cases: SRK/T
High Hyperopia In eyes with short or very short axial lengths (Fig. 25) the third generation formulas such as Holladay 2 and Hoffer-Q seem to provide the best results. Observing high refractive errors in extremely short eyes (<20.0 mm), Holladay has discovered that the size of the anterior and posterior segments is not proportional, and has devised certain measurements to be used to calculate the parameters in these eyes. Assembling data from 35 international researchers Holladay concluded that only 20% of short eyes present a small anterior segment (nanophthalmic eyes); 80% present a normal anterior segment and it is the posterior segment 47
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that is abnormally short. This means that the formulas that predict a small anterior segment in a short eye provoke an 80% error margin, as they will predict an abnormally shallow anterior chamber which, in turn, can lead to hyperopic errors of up to 5 diopters. The Holladay 2 formula comprises the seven parameters previously described for IOL calculation: axial length, keratometry, ACD (anterior chamber depth), lens width, white-to-white corneal horizontal diameter, preoperative refraction, and age. This new formula has reduced 5 D errors to less than 1 D in eyes with high hyperopia. Although biometry is easy to perform, most errors in hyperopic patients occur because of probe compression. Zacharias and Centurion emphasize that only the corneal epithelium should be touched, without any resulting indentation (Fig. 25-A).
The Use of Piggyback Lenses in Very High Hyperopia For very short eyes (<22.00 mm in length) even though the Holladay 2 or the Hoffer Q formulas are a significant advance in calculating the IOL power needed, we do not have IOLs easily available with a power higher than +34 diopters because a higher diopter lens would have a marked, almost spherical curvature, that would cause major optical aberrations. Such lenses can be customized but still may cause undesirable optical aberrations. In these cases the piggyback method is employed, i.e., the implantation of more than one IOL in a single eye, dividing the total power among the different lenses, placing 2/3 of the power in the posterior lens and 1/3 in the anterior lens (Fig. 25-B). Gayton (1994) was the first to place two lenses in a single eye. He observed that placing multiple lenses in a single eye produces im-
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proved optical quality because there are fewer spherical aberrations than with very high diopter lenses. Measuring the position of piggyback lenses, Holladay observed that contrary to what he supposed -- that the anterior lens would occupy a more anterior position -- what effectively happens is that the anterior lens preserves its normal position while the posterior lens moves backwards because of the distensible nature of the capsular bag. The latter may accommodate more than two IOLs and there are cases of patients with four piggyback lenses in the same eye. Holladay's recommendation for calculating the power of lenses with the piggyback procedure in high hyperopic patients is to add 3 diopters to the total value of the pre-op IOL power calculation and divide the total by 3, placing 2/3 of the power in the posterior lens and 1/3 in the anterior lens. This facilitates the replacement of the anterior lens, if necessary, as it is the thinnest lens. The 3 diopters added to the total value are meant to roughly compensate the hyperopic error resulting from the space behind the posterior lens. This is calculated more precisely with the Holladay 2 formula. Joaquin Barraquer, M.D., in Barcelona, who often attends very complex anterior segment diseases referred to him from different parts of the world, has observed a substantial increase in depth of focus with the piggyback procedure as compared to the implantation of a single custom made lens. He has done both procedures. Barraquer as well as I. H. Fine, M.D., another master surgeon, are still cautious about the piggyback method. They feel that it is not yet clear how Elschnig pearls between the lenses will behave in the postoperative period if there is progressive capsular fibrosis. Recently, John Gayton, David
C h a p t e r 3: IOL Power Calculation in Standard and Complex Cases - Preparing for Surgery
Apple et al described the presence of interlenticular opacification in two pairs of piggyback lenses that had to be explanted from 2 patients with significant visual loss related to opacification between the optics. They were submitted for pathological analysis. Gross and histopathological examinations were performed, and photomicroscopy was used to document the results. Gross examination showed accumulation of a membrane-like white material between the lenses. Histopathological examination revealed that the tissue consisted of retained/proliferative lens epithelial cells (bladder cells or pearls) mixed with lens cortical material. They recommended three surgical means that may help prevent this complication: meticulous cortical cleanup, especially in the equatorial region; creation of a relatively large continuous curvilinear capsulorhexis to sequester retained cells peripheral to the IOL optic within the equatorial fornix; insertion of the posterior IOL in the capsular bag and the anterior IOL, in the ciliary sulcus to isolate retained cells from the interlenticular space. Echobiometry in highly hyperopic eyes, especially microphthalmic and nanophthalmic eyes, is still far from desirable.
without the use of a personalized correction factor have yet to be developed. Zacharias and Centurion emphasize that there are technical difficulties in performing the echobiometry of patients with high myopia, especially when they have a posterior staphyloma. In those cases they obtain extremely irregular retinal echoes that cannot provide certainty in terms of really correct results of the IOL calculation. In addition, a posterior staphyloma may not always coincide with the macula, so the higher measurement is not necessarily the correct one, as is the case with normal eyes. In these patients it is useful to perform B type ultrasound to identify the existence of a staphyloma and its relation with the macula. Equally important is to have an ultrasound probe with a fixation light. The patient is asked to fixate at the light -- which he will do with the macula -- facilitating the measurement. Lacava and Centurion studied 27 myopic eyes with an axial length of more than 26.50 mm, and found that 88% of the patients with whom they used the SRK/T formula were within the emmetropic criteria established by George Waring.
High Myopia
DETERMINING IOL POWER IN PATIENTS WITH PREVIOUS REFRACTIVE SURGERY
According to Zacharias and Centurion's experience, results of cataract surgery in highly myopic eyes with axial lengths higher than 31.0 mm with implantation of low or negative power IOLs may be successful, without any more operative or postoperative complications than normal eyes. The use of the SRK II formula with an individual surgeon's factor showed good predictability of the refractive target (Fig. 26). However, better formulas
Patients who have undergone excimer laser procedures, radial keratotomy or INTACS have had modifications to their corneal curvatures (Figs. 27, 28, 29). Accurate keratometric readings are fundamental in calculating IOL power. IOL power calculation for cataract surgery in patients previously submitted to refractive surgery by modification of the corneal curvature is a new challenge for the cataract surgeon basically because of two
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Figure 27: IOL Power Calculation in Patients After Excimer Laser Procedure In this group of patients even with the most advanced ultrasonic equipment, there is a degree of variation in the results of the IOL power calculation. This is the result of the varying modification in the curvature of the cornea after the excimer laser ablation (A). There is no universally accepted formula to calculate these patients' IOL power accurately. The standard methods used in normal eyes are inadequate in these patients. For alternative methods, consult text.
Figure 28: IOL Power Calculation in Patients After Radial Keratotomy Patients operated with radial keratotomy undergo corneal curvature changes that cannot be measured reliably with the standard methods. The data of the corneal curvature obtained from corneal topography are fed into a computer using third generation formulas to establish a more dependable calculation of the intraocular lens power. This illustration shows the correct way of using the ultrasound transducer (P) on the cornea placing it on the optical center midway between the corneal incisions (RK). For alternative methods of calculation see text.
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C h a p t e r 3: IOL Power Calculation in Standard and Complex Cases - Preparing for Surgery
Figure 29: IOL Power Calculation After an Intracorneal Ring Segment Procedure As with other refractive procedures on the cornea, this technique for correction of low myopia also modifies the central corneal curvature (arrows). Due to the limited correction power the INTACS can handle (miopias up to -2.5 D), it is presumed that the variability in the reduction of the central corneal curvature should not be very significant. Topography determines the present corneal curvatures. The surgeon uses the flattest keratometric reading as a reference in cases where the pre-refractive procedure keratometry cannot be obtained. This data is fed into the computer and with the use of the programs outlined in the text the power of the intraocular lens is determined. In this illustration we can see the ultrasound transducer (P) on the central cornea inside the area in which the intracorneal rings (IC) are placed.
features. 1) Patients who previously decided to undergo refractive surgery are more phychologically resistant to using spectacles to correct residual ametropia. Consequently, their expectations for cataract surgery are unusually high. 2) So far there is no universally accepted formula to calculate these patients' IOL power accurately. Routine keratometry readings do not accurately reflect the true corneal curvature in these cases and may result in
errors if used for IOL calculations. Therefore, standard keratometry readings should not be used for IOL calculations in these patients. If done, the standard IOL power-predictive formulas based on such readings commonly result in substantial undercorrection with postoperative hyperopic refraction or anisometropia both of which are very undesirable. Jack Holladay, M.D., a recognized authority on IOL power calculations and in all
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optical-refractive subjects in ophthalmology, considers that accurate determination of the corneal power in these patients is difficult and is usually the determining factor in the accuracy of the predicted refraction following cataract surgery. Providing this group of patients with the same accuracy of intraocular lens power calculations as we have provided our standard cataract patients presents an especially difficult challenge.
Methods Most Often Used There are three methods to determine the effective power of the cornea in these complex cases: 1) the clinical history method, also termed by Holladay "the calculation method"; 2) the contact lens method; and 3) the topog-
raphy method. Holladay believes that the calculation or "clinical history" method and the hard contact lens trial are the two more reliable of the three, because the corneal topography instruments presently available do not provide accurate central corneal power following PRK, LASIK and RKs with optical zones of 3 mm or less. In RKs with larger optical zones, the topography instruments become more reliable. The great majority of cases, however, have had RK with an optimal zone larger than 3 mm, so they should also qualify for this method.
The Clinical History Method The "clinical history" method is the most often used. In the "historical or calculation method", however, the keratometry reading
Figure 30: Posterior Capsulorhexis in Pediatric Patients Following the conventional steps of phacoemulsification, an appropriate intraocular lens for children is inserted (IOL) with the required power in compliance with the criteria of the practitioner following the guidelines in the text. Once the intraocular lens is located in the bag, and properly protecting the tissues with viscoelastics, a cystotome (C) is introduced through the limbal incision (I), and directed behind the IOL to perform a posterior capsule tear or posterior capsulorhexis (PC). This opening in the posterior capsule at the time of the phaco procedure can provide permanent improved vision to the child.
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C h a p t e r 3: IOL Power Calculation in Standard and Complex Cases - Preparing for Surgery
and refraction before refractive surgery must be known along with an accurate postoperative refraction which is not often the case. It is also important to keep in mind that at present, far more patients have had RK than PRK and LASIK combined. Also, our long-term follow-up of RK patients is much greater. The long-term studies of RK patients reveal that some have hyperopic shifts in their refraction and develop progressive against-the-rule astigmatism which may complicate the final vision of the patient operated for cataract, unless detected at the time of preoperative evaluation and corrected. The long-term refractive changes in PRK and LASIK are unknown, except for the regression effect following attempted PRK corrections exceeding 8 D. Whichever procedure the patient has had, the stability or instability of the refraction must be determined. When using the "clinical history or calculation method" a subtraction of the spherical equivalent (SEQ) change after refractive surgery from the original K-reading is done to determine the new "accurate" corneal curve. This, however, is not information easily found. It is useful and can be applied whenever refraction and the Kreading before the keratorefractive procedure are available to cataract surgeons. If this information is not available, which is not unusual, we recommend that the keratometry be measured with corneal topography and use the flattest curve of this reading as the new corneal curve to feed the computer that will then automatically provide us with the IOL power to use. Another downfall of the history method is that cataracts frequently cause induced myopia. This method, however, requires an accurate and stabilized refraction after the keratorefractive procedure and at the time we are contemplating cataract surgery. In many
cases, calculation is complicated by the progressive flattening that occurs in about 25% of RK patients. It is nearly impossible to separate these two factors and determine the impact of each on the refraction before cataract surgery.
The Trial Hard Contact Lens Method The second method often used, which is the trial hard contact lens method, requires a plano hard contact lens with a known base curve and is limited to patients whose cataract does not prevent them from being refracted to approximately +0.50 D. This usually requires a visual acuity of better than 20/80. The patient's spheroequivalent refraction is determined by standard refraction. The refraction is then repeated with the hard contact lens in place. If the spheroequivalent refraction does not change with the contact lens, then the patient`s cornea must have the same power as the base curve of the plano contact lens, since the base curve and front curve are the same in a plano contact lens. If the patient has a myopic shift in the refraction with the contact lens, then the base curve of the contact lens is stronger than the cornea by the amount of the shift. If there is a hyperopic shift in the refraction with the contact lens, then the base curve of the contact lens is weaker than the cornea by the amount of the shift. Example as Provided by Holladay The patient has a current spheroequivalent refraction of +0.25 D. When a plano hard contact lens with a base curve of 35.00 D is placed on the cornea, the spherical refraction changes to -2.00 D. Since the patient had a myopic shift with the contact lens, the cornea must be weaker than the base curve of the
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contact by 2.25 D. Therefore, the cornea must be 32.75 D (35.00 - 2.25), which is slightly different from the value obtained by the historical or calculation method. This method is limited by the accuracy of the refractions, which may be limited by the cataract.
The Method
Corneal
Topography
Current corneal topography instruments provide greater accuracy, compared to keratometers, in determining the power of corneas with irregular astigmatism. The computer in topography instruments provides a very accurate determination of the anterior surface of the cornea. The limitation of this method is that the computer in corneal topography provides no information about the posterior surface of the cornea. In order to accurately determine the total power of the cornea, the power of both surfaces must be known.
The Importance of Detecting Irregular Astigmatism Holladay has strongly recommended that biomicroscopy, retinoscopy, corneal topography and endothelial cell counts be performed in all of these complex cases. The first three tests are primarily directed at evaluating the amount of irregular astigmatism. This determination is extremely important preoperatively because the irregular astigmatism may be contributing to the reduced vision as well as the cataract. The irregular astigmatism may also be the limiting factor in the patient's vision following cataract surgery. The endothelial cell count is necessary to recog-
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nize any patients with low cell counts from the previous surgery who may be at higher risk for corneal decompensation or prolonged visual recovery. The potential acuity meter (PAM), super pinhole and hard contact lens trial are often helpful as secondary tests in determining the respective contribution to reduced vision by the cataract and the corneal irregular astigmatism. The patient should be informed that only the glare from the cataract will be eliminated. Any glare from the keratorefractive procedure will essentially remain unchanged.
IOL Power Calculation in Pediatric Cataracts How to optically correct patients with bilateral congenital cataracts and monocular congenital cataract has been a major subject of controversy for many years. Some distinguished ophthalmic surgeons 20 years ago were strongly against performing surgery in monocular congenital cataract followed by treatment of amblyopia with a contact lens. Visual results were so bad that children with this problem must be amblyopic by nature, they thought, and the psychological damage to the children and the parents by forcing such treatment was to be condemned. Surgery of bilateral congenital cataracts at a very early age followed by correction with spectacles and sometimes with contact lenses usually ended with no better than 20/60 vision bilaterally. This was again a source for belief that congenital cataracts either unilateral or bilateral were by nature associated with amblyopia, profound in cases of monocular cases and fairly strong in bilateral cataracts.
C h a p t e r 3: IOL Power Calculation in Standard and Complex Cases - Preparing for Surgery
When posterior chamber IOL implantation in adults became established as the procedure of choice, strong influences within ophthalmology were adamantly opposed to their use in children for the following reasons: 1) the eye grows in length with consequent significant change in refraction. It was considered impossible to predict such change and consequently, the accurate IOL power adequate for each child. 2) There was opacification of posterior capsule in most cases. This required a second operation for posterior capsulotomy and the presence of an IOL would impede proper surgical maneuvers. You will not find this concise history in any other book. I lived through it and therefore share it with you. The situation has now significantly changed. The previous failures with spectacles and contact lenses, the new developments in technology and surgical techniques and the fresh insight of surgeons of a new generation has led us to discard the previous thinking and very definitely implant posterior chamber IOL's in children. This has been made possible from the surgical point of view by the following developments: new medications that effectively prevent and/or control inflammation; the introduction of posterior capsule capsulorhexis introduced by Gimbel in North America promptly followed by Everardo Barojas in Mexico and Latin America (Fig. 30); high viscosity viscoelastics to facilitate intraocular surgery in smaller eyes; new, more appropriate IOL's for children and implantation in their capsular bag; more refined technology that leads to a less difficult calculation of the IOL power.
Different Alternatives The limitations in calculating these lenses powers (Fig. 31) is due to the fact that the eye grows after cataract surgery and therefore refraction will change. Two main methods of choosing an IOL power for pediatric patients are available: 1) Make the eye emmetropic at the time of surgery and thereby treat amblyopia immediately taking advantage of a much better visual acuity. This is followed later by an IOL exchange because of increasing myopia (growth of the eye). Even though there are more practical and efficient techniques for IOL exchange, as devised by Jack Dodick, M.D., this alternative is second choice. 2) Proceed with incomplete overcorrection of the eye at the time of surgery (treated with glasses or contact lenses) taking advantage of the trend toward emmetropization which will occur as the eye grows. By "incomplete" we mean leaving the eyes hyperopic. As the eye grows in length with age (axial growth), the myopization that takes place in an eye artificially rendered hyperopic will lead to emmetropia or close to normal refraction. This measure avoids myopic anisometropia that may lead to an undesirable change of IOL surgically. In the meantime, the temporary hyperopia is managed with standard spectacles or contact lenses.
Alternatives of Choice In the IOL power calculation in children younger than 1 year, keratometry is difficult and fortunately less important because the
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Figure 31: IOL Power Calculation in Pediatric Cataract The growth of the ocular globe is ecographically registered until 18 years of age. However, the lens continues growing throughout the life of the individual. In normal conditions, anterior chamber (A) depth is reduced as the lens increases in size. In pathological conditions such as the presence of cataracts the opposite may happen: the anterior chamber depth may increase due to reduction in the volume of the lens (C). In this illustration we can see the changes in the size of the globe through the shaded images that outline the growth of the eye by stages. At birth the axial diameter in the normal patient may measure approximately 17.5 mm, at three years of age it may measure 21.8 mm (X), at ten years 22.5 mm identified in (Y) and in normal adulthood nearly 24 mm (Z). In selecting the lens power to be used, some surgeons choose to make the child hyperopic (arrows) with the intention that his growth will compensate hyperopia with the passage of time and will be eventually closer to achieving an emmetropic eye. Others prefer to calculate an intraocular lens closer to emmetropia with the intention of keeping the child emmetropic during his growing years and prescribing eyeglasses in the future.
values change very rapidly during the first six months. Thus keratometry may be replaced by the mean adult average keratometry value of 44.00 D. Children less than two years old may be incompletely corrected +3.00 D to even +4.00 D; between three and four years old incompletely correct them +3.00 D in those closer to three and +2.50 D in those closer to four. In children closer to six or seven, who have little chance of recovering from any amblyopia present but who are the ones that more
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frequently suffer from a unilateral traumatic cataract, overcorrect them by +1.00 D. 3) A new method of management in pediatric cataracts is to render the eyes emmetropic from the very start and when axial length grows and makes the eye myopic, proceed to implant a second IOL with negative or minus power utilizing the piggyback technique and placing the new IOL in front of the primary IOL (Fig. 25- B).
C h a p t e r 3: IOL Power Calculation in Standard and Complex Cases - Preparing for Surgery
IOL Power Calculation Following Vitrectomy For the most part, IOL power calculation in eyes that develop a cataract following vitrectomy is straightforward. The intravitreal gas is reabsorbed and slowly replaced by aqueous. If silicone oil was used instead of perfluorocarbons, when the oil is removed, aqueous fills the vitreous cavity. Since the refractive indices of aqueous and vitreous are identical (1.336), no corrections are needed in the calculation of the IOL power. But what if silicone oil is present in the vitreous cavity? Lihteh Wu, M.D., has pointed out that anywhere from 60% to 100% of eyes have been reported to develop cataract following silicone oil tamponade. Up to 25% of eyes with silicone oil tamponade, especially those with retinal detachment secondary to necrotizing retinitis, will require permanent tamponade. Several authors have reported unpredictable refractions following cataract extraction in silicone-filled eyes when traditional formulas are used. In one study the axial length was measured prior to silicone oil tamponade, and the IOL power was calculated using the traditional formulas. In these eyes the average postoperative refraction was about +4.00 diopters (with a range of +2 to +6 D). These results were more hyperopic than had been predicted and the change is associated with the different refractive index of silicone oil. If the silicone oil was later removed then the postoperative refraction was only off by 0.5 to 1 D. Drs. Melissa Meldrum, Tom Aaberg, Anil Patel, and Janet Davis have described and proposed correction factors for
the calculation of an intraocular lens implant in a silicone filled eye (Fig. 32). They recommend: (1) the use of a modified ultrasound velocity in silicone oil in the calculation of axial length, (2) the use of convexoplano IOL's, and (3) the addition of a constant to compensate for the refractive index of silicone oil. The velocity of sound in a medium is inversely related to the medium’s refractive index. Since silicone oil has a higher index of refraction than vitreous, it slows down sound velocity. For instance, sound velocity in silicone oil is 986 m/s compared to 1532 m/s in aqueous. If we recall, the velocity of sound is preset in the computer in the ultrasound machine. If no modification is made, the eye appears to be longer than it actually is. Consequently, the wrong IOL may be implanted. Drs. Meldrum, Aaberg, Patel, and Davis also explain why the choice of IOL is important. When convexoplano lenses are used, the anterior surface of the lens is solely responsible for the refractive power of the lens. Thus the presence of silicone oil in the vitreous cavity has no effect on the refractive power of the IOL. On the other hand, when biconvex lenses are used, the posterior surface also contributes to the refractive power of the lens. The refractive power of the posterior surface depends on the difference between the refractive indices of the IOL and the vitreous or vitreous substitute. Since silicone oil has a higher index of refraction than vitreous, the posterior refractive power of the lens is reduced. The use of a biconvex lens requires further correction. Meldrum, Aaberg, Patel, and Davis make the following recommendations.
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• •
•
Measure the axial length using the velocity of sound in silicone oil. Calculate the IOL power to achieve emmetropia using the traditional formulas. To this IOL power, a correction factor must be added to obtain the IOL power to achieve emmetropia in silicone oil. The correction factors range from 2.79 D to 3.94 D, for axial lengths from 20 mm to 30 mm. Choose a convexoplano IOL if possible. If another type of le1ns is used, another correction factor must be added to obtain the total power of the IOL in the presence of silicone
Figure 32: IOL Power Calculation in Patients After Vitrectomy Procedure With Silicone If the patient is in the process of undergoing this procedure it is recommended to calculate the intraocular lens before using silicone in the vitreous cavity (V) and extracting the lens (C). Polymethylmethacrylate lenses (PMMA) are recommended. Silicone foldable IOL's are not recommended because the silicone oil in the vitreous cavity sticks to the intraocular lens and sometimes causes opacities. In the calculation of these lens powers there may be differences in excess of 5-7 diopters. Errors can be frequent because if the vitreous cavity (V) is not filled completely with silicone (S), the movement of the bubble can induce errors in the calculation of the lens. In addition, in the eye filled with silicone, the ultrasound waves travel slower (arrows). This affects the axial diameter measurement during IOL power calculation. For alternative methods of IOL power calculation, see text.
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oil. For a convexoplano lens no additional correction factor is required. For instance, let us suppose that a patient requires indefinite intraocular tamponade with silicone oil and develops a cataract. Using the traditional formulas, assuming that the IOL power is calculated to be 22 D based on a measured axial length of 23 mm. To this 22D we must add a correction factor of 3.64D (Meldrum et al) to correct for the axial length. Thus, for this patient a 25.5 D convexoplano lens should be implanted in order to achieve emmetropia in the presence of silicone oil. No additional correction factor for the IOL design is necessary.
C h a p t e r 3: IOL Power Calculation in Standard and Complex Cases - Preparing for Surgery
RECOMMENDED READING Mendicute J, Cadarso L, Lorente R., Orbegozo J, Soler JR: Facoemulsificación, 1999.
BIBLIOGRAPHY Boyd, BF.: Undergoing cataract surgery with a master surgeon: a personal experience. Highlights of Ophthalm. Bi-monthly Journal, Volume 27, Nº 1,1999;3. Brady, KM., Atkinson, CS., Kilty, LA., Hiles, DA: Cataract surgery and intraocular lens implantation in children. Am J. Ophthalmol, 1995;120:1-9. Buckley, EG., Klombers, LA., Seaber, JH., et al: Management of the posterior capsule during intraocular lens implantation. Am J Ophthalmol, 1993;115:722-8. Dahan, E., Drusedan, MUH.: Choice of lens and dioptric power in pediatric pseudophakia. J Cataract Refract Surg, 1997;23:618-23. Gayton, JL.: Implanting two posterior chamber intraocular lenses in microphthalmos. Ocular Surgery News, 1994:64-5. Gayton JL., Apple DJ., Peng Q., Visessook N., Sanders V., Werner L., Pandey SK., Escobar-Gomez, M., Hoddinott D., Van Der Karr M.: Interlenticular opacification: Clinicopathological correlation of a complication of posterior chamber piggyback intraocular lenses. J Cataract Refract Surg, 2000; 26:300-336 ©ASCRS and ESCRS. Gimbel, HV: Posterior continuous curvilinear capsulorhexis and optic capture of the intraocular lens to prevent secondary opacification in pediatric cataract surgery. J Cataract Refract Surg, 1997;23:652-656. Gimbel, HV., Basti, S., Ferensowicz, MA., DeBroff, BM.: Results of bilateral cataract extraction with posterior chamber intraocular lens implantation in children. Ophthalmology, 1997; 104:1737-1743.
Grinbaum A., Treister G., Moisseiev J.: Predicted and actual refraction after intraocular lens implantation in eyes with silicone oil. J Cataract Refract Surg, 1996; 22:726-729. Grusha YO., Masket, S., Miller, KM: Phacoemulsification and lens implantation after pars plana vitrectomy. Ophthalmology 1998;105:287-294. Holladay, JT: Intraocular lens power in difficult cases. Atlas of Cataract Surgery, Edited by Masket & Crandal, Published by Martin Dunitz, 1999, 19:147-158. Holladay JT., Gills, JP., Leidlein, J., Cherchio, M.: Achieving emmetropia in extremely short eyes with two piggyback posterior chamber intraocular lenses. Ophthalmology, 1996; 103:1118-1123. Hoffer, KJ: Intraocular lens power calculation for eyes after refractive keratotomy. J Refract Surg, 1995;11:490-3. Hoffer, KJ.: The Hoffer Q formula: A comparison of theoretic and regression formulas. J Cataract Surg., 1993; 19:700-711. Hoffer, KJ: Ultrasound velocities for axial length measurement. J Cat Refract Surg, 1994;20:554-562. Kora, Y., Shimizu, K., Inatomi, M., et al: Eye growth after cataract extraction and intraocular lens implantation in children. Ophthalmic Surg, 1993;24:467-75. Lacava AC., Centurion, V.: Cataract surgery after refractive surgery, Faco Total, Editora Cultura Medica, 2000;269-276. Lyle WA, Jin GJC.: Intraocular lens power prediction in patients who undergo cataract surgery following previous radial keratotomy. Arch Ophthalmol 1997; 115:457-61. McCartney, DL., Miller, KM., Stark, WJ., et al: Intraocular lens style and refraction in eyes treated with silicone oil. Arch Ophthalmol 1987; 105:1385-1387.
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Meldrum, LM., Aaberg, TM., Patel A, Davis, JL.:Cataract extraction after silicone oil repair of retinal detachments due to necrotizing retinitis. Arch Ophthalmol 1996;114:885-892. Olsen T., Thim K., Corydon L.,:Theoretical versus SRK I and SRK II calculation of intraocular lens power. J. Cataract Refract Surg, 1990;16:217-225. Sanders DR, Retzlaff J, Kraff MC, Gimbel, H., Raanan, M.: Comparison of the SRK/T formula and other theoretinal and regression formulas. J Cataract Refract Surg., 1990; 16(3):341-346. Wu, L: IOL power calculation after vitrectomy. Guest Expert, Boyd’s, BF, The Art and the Science of Cataract Surgery, HIGHLIGHTS OF OPHTHALMOLOGY, 2001. Zacharias W., Centurion, V.: Biometry and the IOL calculation for the cataract surgeon: Its importance. Faco Total, 2000; 66-88.
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C h a p t e r 4: P rev e n t i n g I nf e c t i o n and Inflammation
PREVENTING INFECTION AND INFLAMMATION Use of Antiseptics, Antibiotics and Antiinflammatory Agents Endophthalmitis following cataract surgery is a rare complication. When it occurs, however, it becomes the most serious postoperative complication. We will discuss its prevention in this chapter and its management in the chapter on Complications from Cataract Surgery. The use of preoperative, intraoperative and postoperative antibiotics and antiinflammatory agents and the very careful cleaning of the lids are generally accepted as the standard of care in patients undergoing cataract surgery.
Effective Preoperative Antibiotic Treatments There is no agreement as to which is the most effective type of antibiotic as well as the dosage and route of administration to prevent postoperative infectious endophthalmitis. We do know, however, that aminoglycosides are toxic to the healing cornea while fluoroquinolones are not. The former have also gaps in the antibacterial spectrum of activity and the latter (i.e. ciprofloxacin and ofloxacin) are more potent for a wide spectrum of bacteria with less toxicity. With regard to prophylaxis in an era of increasing use of small incision cataract surgery where corneal incision without conjunctival protection over it is becoming the proce-
dure of choice for a large number of surgeons well trained in phaco, the key factors to consider are that most infections come from the patient's own flora. Consequently, we must effectively kill bacteria in the skin, lids and ocular surface before making an incision in the eye itself. For this purpose, you may place 5% Betadine solution inside the fornix and leave it there for 2 minutes before washing it out of the eye. This is followed by painting the lids with 10% povidone-iodine solution. Peter McDonnell, MD., has pointed out that endophthalmitis is difficult to study scientifically, because it occurs so rarely. Al Sommer, M.D., the Dean of the School of Public Health at Johns Hopkins University, has emphasized that to do a prospective, randomized trial in order to prove that a specific management lowers the risk of endophthalmitis, is close to impossible. There are almost no scientific data proving that various strategies clearly reduce the risk of this complication. Such data are even harder to obtain now because, as incision sizes have gotten smaller, the risk of endophthalmitis has dropped. But as incision sizes have dropped, so has the time that it takes for surgery. This, of course, reduces the risk. Henry Perry, M.D., has also brought out another important point: In patients where the posterior capsule breaks or there is need for a vitrectomy, those patients should be treated with extra antibiotics because the risk for infection significantly increases depending on whether it is just the capsule that has ruptured or whether you actually had to do a vitrectomy. 63
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Regimens Recommended Considering that there are so many alternative regimens for minimizing the development of infection, depending on the personal choices of different successful surgeons, I am hereby presenting what I consider two alternatives that appear to be effective and safe.
Gills Formulas to Prevent Infection 1) For High Volume Cataract Surgery As proposed by James Gills, M.D., after years of profound clinical analysis of this subject on many thousands of his own patients. Gills' regime is complex particularly when it comes to the preparation of two antibiotic mixtures with two antiinflammatory agents (NSAIDS) for injection into the anterior chamber at the end of the operation. The accurate preparation, mixture and exact dilution of a variety of medications that needs to be done with absolute accuracy and in very small doses for injection routinely into the anterior chamber is a big step forward in minimizing endophthalmitis, based on Gills' extensive experience. The disadvantage is, however, that such multiple steps of preparing these mixtures by operating paramedical personnel in some large institutions where not only ophthalmic surgery is performed may be somewhat risky. A small human error is feasible, particularly on the side of mistakenly applied larger doses, which may lead to toxicity of the ocular tissues. In large private eye centers, where the paramedical personnel is exclusively dedicated to high tech-
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nology ocular surgery, Gills outline is an excellent measure to follow. The following is his step by step procedure. 1) Gills considers that filtering all the irrigating solutions through a 0.2 micron millipore filter is a major step forward in minimizing infection, particularly endophthalmitis. Following his use of filtration, the incidence of endophthalmitis at Gills Institute has significantly reduced from 1-2 per 1000, which was the same as the national average in the U.S. to an overall incidence of 1 in 8000 to 10,000. 2) After years of successfully using antibiotics (gentamicin and vancomycin) in the irrigating solution, Gills has changed to what he considers maximum security, which is as follows: A) Preoperatively, 15 minutes prior to transfer to the operating room: a) Neosynephrine 10% one drop. b) Ocuflox 0.3% mixed with Indocin, one drop. This combination of Ocuflox (a fluoroquinolone) and Indocin (a non-steroidal) is prepared as follows: Reconstitute 1 mg of Indocin with Ocuflox. Reinject into Ocuflox bottle and use one drop of this mixture. B) In the Operating Room a) Tetracaine: 0.5% 1 gtt x 3 (3 min. apart with final drop instilled just prior to beginning). b) Betadine BSS: 1 gtt x 3 (2 gtts at the beginning of the case, 1 gtt at the end). Preparation: Draw up into the syringe 5 cc of BSS followed by 5 cc of Betadine solution 10%. Change needle to 18 gauge filter needle wil filter and inject into sterile empty vial. Use the drops on the eye as outlined above but obtained from this prepared mixture.
C h a p t e r 4: P rev e n t i n g I nf e c t i o n and Inflammation
c) Cyloxan (antibiotic): Instill one drop at the end of the operation. d) Intraocular anesthesia (Intracameral): Irrigated inside the anterior chamber (see Chapter 6). Gills no longer uses antibiotics in the irrigating solution. Instead, he feels there is a more effective control by using a combination of antibiotics and antiinflammatory drugs directly injected into the anterior chamber at the end of the operation. This combination of drugs is obtained as follows: f) Post-op Anterior Chamber Injection of Indomethacin, Solucortef and Two Antibiotics • Draw up 14.4 ml BSS into a syringe and inject 12.4 ml of this BSS into an empty sterile bottle. • Use the remaining 2 ml to reconstitute two 1 mg vials of Indomethacin. • Add both of the 1 ml vials of Indomethacin solution to the 12.4 ml bottle containing BSS making 14.4 ml of total volume. • Add 8 gtts of Solucortef 125 mg/ml (8 minims using TB syringe), 0.06 Cephtazidime 50 mg/ml. • 0.1 ml Vancomycin 500 mg/10 ml to the 14.4 ml bottle of Indomethacin solution. • Dosage per patient: 0.50 ml of this mixture is injected into the anterior chamber at the end of the operation. g) Recovery Room: Polytracin ointment x 1. In doses higher than those described in this outline, Vancomycin and Cephtazidime would interact and precipitate out of solution. Gills states that he has no problems with the minute concentrations used for intraocular injection. At the end of the operation, topical Betadine® drops are instilled in the eye. Betadine eliminates flora in the cul-de-sac so
they cannot enter the soft eyes that may occur within the first hour after surgery. During this critical period it is important to make sure that the eye is clear and clean. C) Oral Medications: These are instilled before the antibiotic ointment. Ibuprofen 200 mg ÷ tablet given pre-op and ÷ tablet postop unless contraindicated.
2) Non-Complex, Effective and Safe Alternative for Prevention of Infection The regimen that follows is practical and effective, one which every ophthalmic surgeon may use with excellent results. 1) Asepsis Follow the same routine previously outlined for thorough cleaning of lids and skin with soap and 10% povidone iodine solutions. The same applies for use of 5% Betadine 1 drop topically, Betadine 5% solution inside the fornix leaving it there for 2 minutes before washing it out of the eye. 2) Preop antibiotics: none. 3) Filtration of irrigating solution If the micropore filter is available, by all means use it as recommended by Gills. 4) Intracameral irrigation at end of operation Yes. Irrigate the anterior chamber with an effective mixture of: A) One antibiotic and one steroidal antiinflammatory mixture containing: a) Gentamicin 0.5 ml drawn from a vial containing 40 mg / ml. b) Prednisoloneacetate (Depomedrol) 0.5 ml solution from a vial containing 40 mg / ml.
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This combination is easy to use, it provides very little risk of confusion and is most effective. 5) Topical instillation after intracameral irrigation In cataract surgery there are many ways to reduce the ocular surface flora which is the main source of contamination that may lead to endophthalmitis. It is also quite clear the usefulness of Povidone-Iodine as an antiseptic in the skin and lids and Betadine gtts topically preoparatively as outlined previously. The use of preoperative antibiotics has never been a subject of consensus essentially because there is no fundamental evidence that they really contribute to minimize the risk of infection.
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recommended. Both of these antibiotics are very effective. You may use one or the other. They may be instilled immediately following surgery and started four times a day within one hour of surgery. Antimicrobials should be used only for the shortest period of time needed to obtain the desired effect and should never be tapered but simply discontinued. Do not prescribe them at a frequency of less than four times daily. Antibiotics in the first seven days may be used in combination with a steroid. However, once you discontinue the topical application of the antibiotic within seven days, if everything looks well, the patient has to continue with steroids.
Antibiotics Most Commonly Used
Most Frequently Used Anti-inflammatory Agents
As to the use of postoperative antibiotics which is the subject we discuss here, the subconjunctival injection of antibiotics is not recommended by the majority of experts. The general consensus, however, is that immediately following cataract surgery, the postoperative use of antibiotics and antiinflammatory agents applied topically is an important component of the formula for successful results. Antibiotic ointment used immediately at the end of surgery is certainly the preference of most surgeons. The antibiotics most commonly used today in the form of drops are Ciprofloxacine (Ciloxan from Alcon) or Ofloxacine (Ocuflox in some countries or Oslox in others , manufactured by Allergan). The routine use of antibiotic drops q.i.d. for seven days is the dosage
The most frequently used antiinflammatory agents applied topically are Prednisolone Acetate 1%, commercially known as Prednefrin Forte by Allergan or Econopred by Alcon. These may be started promptly following surgery, so that the medication starts its effects immediately and continued depending on the clinical findings and the surgeon's individual preference. In cataract surgery, there is an inherent difficulty in establishing consensus guidelines. Those outlined above are the most generally accepted by advanced surgeons. It is important that the antibiotics, particularly the fluoroquinolone family, which are indeed very effective as an antimicrobial medication, be used no more than seven days, unless there is a specific indication to continue the antibiotic.
C h a p t e r 4: P rev e n t i n g I nf e c t i o n and Inflammation
Antibiotics in Irrigating Solutions The previously widely used practice of using antibiotics in irrigating solutions are of questionable value. Their use has not been proven to be effective, mainly because the concentration and the duration or the exposure of the antibiotic to the bacteria is insufficient to achieve a killing effect. A much better procedure is to instill within the anterior chamber a combination of antibiotic and antiinflammatory agent as outlined previously. There also seems to be a general consensus not to use Vancomycin in the irrigating solutions or for irrigation of the anterior chamber immediately following surgery. Prospective studies seem to indicate some potential toxicity particularly a clinical significant cystoid macular edema and decreased best corrected visual acuity in cataract patients receiving Vancomycin in the irrigating solutions as compared with controls. This is not a proven fact but it is a potential for concern that has been expressed by the Centers of Disease Control in the United States.
Patching Following phacoemulsification, patching is not used unless the patient lives very far away and may be at risk for trauma during his trip back home. Practically all patients today are operated in outpatient surgical centers or eye clinics that have their own operating room and they go home without patching and start using the topical antibiotics and antiinflammatory agents immediately after getting home so that the medication will start with their effect immediately.
Postoperative Antiinflammatory Agents We already described the use of antiinflammatory agents by irrigation into the anterior chamber immediately following the operation. Gills uses a combination of nonsteroidal antiinflammatory agents (Indomethacin) and a steroidal medication within the anterior chamber, mixed with two antibiotics. In the other more simple and very effective alternative which we have outlined, 0.5 ml of Prednisolone Acetate (Depomedrol) combined with 0.5 ml of antibiotic (Gentamycin) are irrigated intracamerally immediately following the operation. Postoperatively, the most effective antiinflammatory agents is a combination of Prednisolone Acetate 1% q.i.d. gradually tapered over eight weeks and a non-steroidal antiinflammatory drug such as Voltaren® q.i.d. for two weeks. Either Voltaren or Acular® are two commonly used and effective medications. It is also known that topical diclofenac can reduce pain, burning and inflammation. It may also be effective in reducing photophobia after pupil dilation. The mechanism is not known. However, the use of diclofenac alone is not sufficient to eradicate all inflammation. Supplemental topical steroid is necessary to completely control inflammation. This combination of postoperative medications applied topically not only contribute to the prevention of inflammation and infection but also significantly contribute in the patient's postoperative comfort.
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BIBLIOGRAPHY Boyd, BF.: Cataract/IOL Surgery, Section V-A, World Atlas Series of Ophthalmic Surgery, Highlights of Ophthalmology, Vol. II, 1996; 5:17. Chitkara DK., Jayamanne DGR., Griffiths PG., Fsadni, MG.: Effectiveness of topical diclofenac in relieving photophobia after pupil dilation. J Cataract Refract Surg 1997; 23:740-744. Gills, JP.: Pharmacodynamics of cataract surgery, Cataract Surgery: The State of the Art. Slack; 1998; 3:19-22. Lane, S., et al: Antibiotic prophylaxis in ophthalmic surgery, Ocular Surgery News, Special Supplement, Jan. 2000. O'Brien, TP, et al: Antibiotic update, current treatment modalities in ophthalmic surgery, Ocular Surgery News, Special Supplement, May 1998. Perry, HD., Hoffman, J. et al: Choosing an antibiotic for perioperative use, Ocular Surgery News, Supplement on Antibiotics, July 1998.
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PROCEEDING WITH THE OPERATION PREPARATION, SEDATION AND ANESTHESIA Preparation of Patient Unless the patient is scheduled for general anesthesia or is likely to be operated under very heavy sedation (non-airway supported) it is unnecessary to keep these usually older, fragile patients fasting for a large number of hours. This only contributes to fatigue and anxiety. It is also contraindicated to have the patients remove all their clothes. This interferes with the patient's sense of privacy and contributes to further anxiety as to what is to come. The patient is made comfortable in the holding area, where he or she is met by the attending nurse, who then explains what is going to transpire. Presurgical checks are conducted, and the nurse instills Neosinephrine 10% and tropicamide 1% two drops each in order to dilate the pupil and one drop of antibiotic and of Betadine solution, depending on the surgeon's preference. This subject is discussed in Chapter 4. Long acting pupillary dilating agents such as cyclopentolate, atropine, homatropine or scopolamine have no role in today`s small incision surgery. The patient is then transported to another holding area in the operating room suite either by walking or on a lounge chair on wheels. There the patient is met by the anesthesiologist, who explains that an intravenous line will be started and administers sedative
agents which vary according to the anesthesiologist's and surgeon's choice. In the holding area, Jack Dodick, M.D. in New York, applies a prudent amount of ocular compression to the eye and orbit for 10-15 minutes. He finds this very beneficial in lowering the intraocular pressure. This maneuver lowers the volume of the fluid inside of the eye and orbits thereby leading to a hypotensive eye. This creates a more favorable surgical environment. This maneuver was previously done using Honan's ballon in conjunction with peribulbar or retrobulbar injection of local anesthetic, procedures no longer used in small incision cataract surgery. The patient is made comfortable in the reclining chair which is very much like a first class seat on an airplane that reclines in an almost 180 degree position. Other surgeons prefer to place the patient on an operating table specially adapted to their needs and whether they operate from above or on the side.
Sedation What sedation to administer depends on the individual patient's emotional profile, which the surgeon should have detected during his preoperative evaluation. In most cases, 5 mg of Valium per mouth on arrival to the clinic leads to sufficient relaxation so that he or she feels comfortable during surgery. Dodick prefers for the anesthetist to administer a small dose, 1 mg, of Versed intravenously. Versed, like Valium, is a member of the benzodiazepine family, but it has a much
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shorter half-life. Whereas valium takes up to 24 hours to be metabolized by the liver, Versed is totally out of the body in less than 2 hours. The patient is totally sedated for about 10 minutes and the patient is wide awake and alert after 10-15 minutes, which is the time the operation lasts. The drug is gone from the system within 2 hours. With valium, on the other hand, patients sometimes feel groggy for a day or two.
Pupillary Dilation Pupillary dilation is critical to the success of ECCE, especially phacoemulsification. Cycloplegic/mydriatic drops, administered preoperatively, effectively dilate the pupil, while topical nonsteroidal antiinflammatory drops can help to maintain dilation during surgery. These medications are instilled topically at the time of preparation of the patient before entering the operating room.
ANESTHESIA Topical All patients have two or three drops of proparacaine or tetracaine instilled in the eye, regardless of the type of anesthesia the surgeon decides to use. One drop every minute x 3 is a standard protocol (Fig. 35).
Selection of Anesthetic Method There are a variety of anesthetic methods known to all of you. We will list them here and proceed to identify those that no longer have a place in small incision cataract surgery. They are:
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1) Blocks by Injection Anesthesia with Sharp Metal Needles a) Retrobulbar: no longer used except in exceptional cases. b) Peribulbar: no longer used. c) Parabulbar: no longer used. d) Van Lint, O'Brien, Nadbath for controlling lid contraction: no longer used. e) Hyaluronidase: after many years of recommending its use, it has been finally shown that hyaluronidase is not an important factor in obtaining akinesia more promptly or having a more lasting effect.
2) Sub- Tenon's with a Flexible Needle This is a highly effective anesthesia mostly used in combination with topical anesthesia by surgeons who are either beginning or already are in the transition period of ECCE to phacoemulsification. This combination is also the procedure of choice by surgeons who perform extracapsular extraction or small incision manual extracapsular. Prospective, randomized studies have concluded that single-quadrant, direct subTenon`s injection of anesthetic is as rapid and effective as retrobulbar injection for cataract surgery (Figs. 33 and 34). It provides better anesthesia with comparable akinesia. The most common complications are chemosis and subconjunctival hemorrhage, but no major complications are encountered. The dispersion of anesthetic fluid under Tenon's is effective enough to substantially diminish lid discomfort. For these reasons, Sub-Tenon's anesthesia using a flexible cannula has replaced retrobulbar and peribulbar except in very unusual cases.
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Figure 33 (above right): Sub-Tenon's Local Anesthesia with Flexible Cannula - Surgeon´s View Forceps (F) lift the conjunctivaTenon´s capsule in the inferior nasal or inferior temporal quadrants between the rectus muscles 3 mm from the limbus. A small 1 mm buttonhole is cut with scissors (not shown). A Greenbaum flexible cannula (C) is advanced (arrow) through the buttonhole until conjunctiva and Tenon´s fits snugly over the hub of the syringe. 2.5 cc of local anesthetic is infused quickly, creating a gush of fluid using the "bolus" technique. If additional anesthesia/akinesia is needed during surgery, the cannula may be re-introduced.
Figure 34 (below left): Sub-Tenon's Local Anesthesia with Flexible Cannula - Cross Section View This cross section view of the left eye shows the position of the flexible Greenbaum cannula during infusion of anesthetic. The cannula (C) is directed posteriorly and fluid infused (white arrow) in the sub-Tenon´s space. Inset 1 shows the flexible nature (black arrow) of the cannula which provides virtually no risk of globe perforation or retrobulbar hemorrhage. Inset 2 shows the rounded, blunt tip with Dshaped port of the half-round cannula.
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Technique Tenon's
for
Performing
Sub-
When performing a Sub-Tenon's local anesthesia, 1.5 ml of lidocaine is injected. Under topical anesthesia, a small incision is made in the fused conjunctiva/Tenon's capsule 3 mm from the limbus (Fig. 33). If the surgeon is right handed, it is easier to perform the incision at the inner lower quadrant between the rectus muscles in the right eye and at the lower temporal quadrant in the left eye. If the surgeon is left handed, it would be the opposite. The surgical plane of Tenon's attachment to the sclera is carefully dissected and the cannula is advanced through this apperture (Fig. 34). It is very important that the cannula is always in sub-Tenon's plane. Otherwise, if it is only under the conjunctiva, the flushed anesthetic solution will backflush or will infiltrate all throughout the subconjunctival space, where it becomes ineffective and creates chemosis. The cannula is advanced under Tenon's until the conjunctiva/Tenon's fits snugly over the hub of the 3 cc syringe. 1.5 cc of the local anesthetic is infused using the "bolus" technique. The anesthetic is infused quickly creating a gush of fluid that spreads throughout the retro and parabulbar spaces (Fig. 34).
Unassisted Topical Anesthesia Most ophthalmic surgeons, when using unassisted topical anesthesia, in which only drops are administered, use it only when performing phacoemulsification and IOL implantation through a clear cornea tunnel incision. The increased acceptance of topical anesthesia is directly related to the somewhat
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wider popularity of the clear corneal tunnel incision as first emphasized by I. Howard Fine, M.D., (Oregon, USA). Most surgeons who use this incision now do it from the temporal side, which requires a series of readjustments in the operating room. This procedure requires the use of a foldable IOL. A corneal tunnel sutureless valve incision no larger than 3.0 mm is recommended. Otherwise, corneal complications may arise and the incision would not be self-sealing.
Advantages of Unassisted Topical Anesthesia This term refers to the use only of anesthetic drops to obtain sufficient anesthesia to perform the cataract operation. Edgardo Carreño, M.D., Professor of Ophthalmology at the Funcacion Los Andes, Santiago, Chile and a phacoemulsification expert, considers that the use of topical anesthesia using a clear corneal tunnel self-sealing valve incision is a significant advance in cataract surgery. With topical anesthesia, visual recovery is immediate. Other advantages as outlined by Carreño: 1) It prevents the well-known complications of retrobulbar and peribulbar injections 2) It lowers the time of operating room use thereby lowering costs. 3) There is no immediate postoperative ptosis, which with retrobulbar or peribulbar and Van-Lint-O'Brien infiltrations lasts from 6-8 hours due to temporary akinesia of the lids (as contrasted with the late postoperative ptosis which is related to the bridle suture on the superior rectus). It provides for immediate postoperative visual recovery which, again, is its main advantage.
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Disadvantages of Unassisted Topical Anesthesia Many surgeons who have performed cataract surgery utilizing "unassisted" topical anesthesia, that is, topical drops alone, agree with Paul S. Koch, M.D., that pure, unassisted topical anesthesia is fairly disappointing. He estimates that one out of four patients have some sensation during the operation. Sometimes, patients feel pressure build up in the eye during injection of viscoelastic. Some feel iris manipulation. Others are aware of the sensation of the lens being implanted into the eye. Koch found that he felt uncomfortable operating on these people, because he never knew in advance who would be comfortable and who would not. Other disadvantages and limitations as outlined by Carreño are: 1) Only a highly experienced surgeon should operate with topical anesthesia. The eye can move, which makes the operation more difficult. If the eye movement occurs while capsulorhexis is being done, an undesirable capsular tear may take place leading to failure of this important stage of the operation. 2) The most controversial argument against topical anesthesia is an intraoperative complication. Consequently, the surgeon must be highly skilled so as to: a) expect as few intraoperative complications as possible. b) be able to convert to another method of anesthesia during the intraoperative stage. Topical anesthesia by itself may be insufficient for the surgeon to adequately handle intraoperative complications. 3) Topical anesthesia is not indicated in all patients. This is particularly true in anxious, stressed patients, people with hearing limitations, children and very young patients.
4) The presence of a very opaque cataract is a contraindication to the use of topical anesthesia (Fig. 1-B). This is because the surgeon depends on the patient's capacity to visually concentrate on the operating microscope light in order to avoid eye movement during the operation. If he/she cannot fixate well on the microscope light and maintain that fixation, the eye will move. This may lead to complications. In essence, adequate selection of patients is fundamental when considering the use of topical anesthesia.
The Anesthetic Procedure of Choice It is the general consensus today among surgeons experienced with phacoemulsification that a combination of topical anesthesia (proparacaine 1% or tetracaine 1%) and 0.5 cc of 1% unpreserved lidocaine irrigated into the anterior chamber through a 30-gauge cannula (Figs. 35 and 36) is the anesthetic procedure of choice for small incision cataract surgery, particularly phacoemulsification. This important breakthrough in ophthalmic anesthesia was introduced by James Gills, M.D. in 1997.
Technique for Irrigation of Lidocaine in AC Dodick first makes a clear cornea incision using a 2.7 mm diamond knife. He believes that the non-preserved lidocaine irrigated into the anterior chamber anesthetizes the nerves of the iris and the ciliary body. The pressure waves that ensue during irrigation and aspiration in the midst of the phaco operation can sometimes impinge upon those nerve fibers and lead to discomfort. In addition, Dodick has
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Figure 35: Topical Anesthesia Unaided topical anesthesia is now a commonly used method in small incision cataract surgery because it is user friendly and comfortable for the patient. Only expert small incision surgeons should use it without the aid of another method. Most surgeons prefer to use topical anesthesia combined with intracameral anesthesia (Fig. 36) in small incision cataract surgery. This illustration shows the use of anesthetic drops (A) such as proparacaine or tetracaine, one drop every 10 minutes, 30-45 minutes preoperatively.
observed that this anesthesia inside the eye helps dull the patient’s sensitivity to the bright light of the microscope by temporarily blocking some photoreceptor cells. The rest of the operation is continued through the same clear cornea incision. Intraocular unpreserved lidocaine irrigated into the anterior chamber as outlined has been proven safe and convenient. Even though a few researchers (i.e. Gillow et al, Boulton et al) have concluded that the routine use of intracameral lidocaine as a supplement to topical anesthesia in routine phacoemulsification does not have a clinically useful role, these experiences constitute a significant minority and are based on postoperative questioning of patients concerning discomfort or by well documented trials but in medium 76
number of patients and by different surgeons. In papers published based on monitoring patient discomfort, not by a subjective questionaire, but by objectively measuring vital signs during surgery. the data support the conclusion that patients operated with anterior chamber irrigation of unpreserved lidocaine feel comfortable during the procedure, despite having had no intravenous sedation and regardless of sex or age and dismiss the subjective nature of postoperative questioning patients concerning discomfort. In view of the small controversy existing, we must rely on the proven extensive experience of well known, prestigious, cataract surgeons such as James Gills, M.D., and Paul Koch, M.D., here presented. An alternative technique for intracameral irrigation of 0.5 cc of 1% lidocaine is the
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Figure 36: Use of Intracameral Anesthesia After instilling anesthetic drops on the conjunctiva and cornea (Fig. 35) the surgeon enters the anterior chamber through the ancillary incision (I) (Fig. 41-A) using an insulin syringe with a 30 gauge cannula (C). This maneuver is
one proposed by Paul S. Koch, M.D (Fig. 36). He uses a 15º blade in his left hand and .12 forceps in the right hand. The blade is placed where he wants the sideport entry incision and the forceps 180º away from that, resting on the peripheral cornea (Fig. 36). The forceps are only pressed against the cornea. They do not grab it, because the purpose of the forceps is only to provide counter pressure for the incision. The blade is then used to make an incision approximately 1 mm wide and 1 mm long, beginning in the peripheral clear cornea. That incision is completely comfortable, because it is no more than a corneal manipulation, and the cornea is still anesthetized from the original drops given in the holding unit. Then, 0.5 cc of 1% unpreserved lidocaine is irrigated into the anterior chamber through a
done with the aid of fine toothed forceps (F) in the contralateral side of the ancillary incision acting as counterpressure. One dose of 0.5 ml of 1% unpreserved lidocaine is irrigated into the anterior chamber. The preliminary marking of the main incision is shown in (A).
30-gauge cannula (Fig. 36). Most of the time, the patient does not feel anything, but sometimes, either because of intraocular pressure changes or the effect of direct flow onto the iris, the patient may feel a little discomfort. This is not a matter of concern because in a matter of seconds the discomfort dissapears. Koch squirts the little extra lidocaine that remains in the syringe on the surface of the cornea, providing additional topical effect. The eye is not paralyzed, and an occasional patient may move it, but this is not nearly the problem that it is with topical anesthesia. The lack of discomfort makes it unnecessary for the patient to want to move the eye, and Koch as well as Gills have found that cooperation in keeping the eye still is excellent.
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Injection of Viscoelastic The eye anesthetizes quickly, and the anesthesia is very profound. Usually in less than 10 seconds, the eye is already anesthetized, and the viscoelastic injection is performed quite comfortably.
What Can be Done with the Combined Anesthesia Because the combination of topical and intracameral irrigation anesthesia is so effective, the surgeon can perform cataract surgery, lens implantation, iris manipulation, and even vitrectomy if a complication arises usually without any further injection of anesthetic. If a patient does feel some discomfort, a second irrigation may be performed. Patients with mental retardation and those with deafness have been successfully operated with this anesthetic combination as long as the surgeon takes the time to explain prior to surgery that he wanted them to look at the light and keep looking at the light.
Side Effects of the Combined Anesthesia Lidocaine has an effective duration of up to 4 hours. Patients may not see very well immediately after the operation, but then a few hours later the vision really improves. Koch has concluded that patients have a temporary, neuro-sensory, retinal blockade causing transient blurring of vision following the operation. He has postulated that the anesthetic may diffuse back to the retina and perhaps has a direct effect on the ganglion cells. Gills had a patient with an open posterior capsule who had significant vision loss for about 24 hours after the
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operation. This clinical observation may support Koch's hypothesis, because in the absence of a posterior capsule the lidocaine could diffuse back toward the retina that much more easily. As the lidocaine wears off, the visual acuity and contrast sensitivities recover.
How to Manage Patients Who Feel Pain and Discomfort If the patient continues to blink or squeeze the eyelids following the combined topical and intracameral anesthesia, you can control this with the sub-Tenon's injection of lidocaine as illustrated in Figs. 33 and 34. The effect is almost instantaneous, and surgery can continue without delay.
PHOTOTOXICITY IN CATARACT SURGERY Since all cataract surgery is done under the microscope, we should clarify here the practical and clinical aspects of light or phototoxicity from the surgical microscope. It has been demonstrated that in some patients and under specific circumstances, toxicity from the light of the microscope can affect the macula. This is seen with fluorescein angiography, which shows an area of pigment abnormality usually below the fovea. The visual field in these patients shows that in this area there is severe to moderate phototoxic damage to the photoreceptors. Without these tests, phototoxicity can be difficult to determine and to see. The major factors involved with phototoxicity are the time of exposure, the tilt and the illumination intensity. (It is important to realize how hard it is to get away from the macular area if we are centered over the pupil).
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The microscope has three light sources: the two side lights and the coaxial beam. Each of these light sources produces a focal point of illumination on the retina. It is not the time length of the operation that is important. It is the time the light is focused on one particular area of the retina which is critical. In addition, within the period which any one operation lasts, sequential light exposure to the same retinal area is additive. If we turn on the light on one spot for three minutes, turn it off and then turn it on that same spot for another four minutes, the effects of those exposures are additive. If, in a certain patient and with a certain intensity of light from the microscope, we expose one macular area during three minutes, we may have no lesion whatsoever but if the total exposure extends to seven and a half to eight minutes, a lesion may occur. In the human eye, with the standard surgical microscopes on maximum intensity of light, it probably only takes four to eight minutes to produce a retinal lesion. Most phototoxic burns are seen in the inferior part of the fovea. We should leave the light source on the lowest setting. The potential for trouble related to phototoxicity in cataract surgery is not often recognized. The patient may have 20/25 vision postoperatively and still complain that he does not see adequately. Only after fluorescein angiography and a visual field can we then explain why these patients complain. Even the most experienced of us need to be aware of the potential for phototoxicity and take the steps to avoid it.
BIBLIOGRAPHY Anders, N., Heuermann, T., Ruther K., Hartman, C: Clinical and electrophysiologic results after intracameral lidocaine 1% anesthesia. Ophthalmology 1999; 106:1863-1868. Boulton JE., Lopatatzidis A., Luck J., Baer RM.: A randomized controlled trial of intracameral lidocaine during phacoemulsification under topical anesthesia. Ophthalmology, 2000; 107:68-71. Boyd, BF.: Cataract/IOL Surgery. World Atlas Series of Ophthalmic Surgery, HIGHLIGHTS OF OPHTHALMOLOGY, Vol. II, 1996; 5:21-22. Boyd, BF: Significant developments in local anesthesia. Highlights of Ophthalmol. Bi-Monthly Journal, Vol. 23, Nº 6, 1995 Series, pp 55-62. Carreño E.: Phacoemulsification Sub-3 technique. Guest Expert, Boyd’s BF., The Art and the Science of Cataract Surgery, Highlights of Ophthalmology, 2001. Fichman RA: Use of topical anesthesia alone in cataract surgery. J Cataract Refract Surg, 1996; 22:612-614. Gillow T., Scotcher SM., Deutsch J., While A., Quinlan MP: Efficacy of supplementary intracameral lidocaine in routine phacoemulsification under topical anesthesia. Ophthalmology, 1999; 106:21732177. Gills JP., Cherchio M., Raanan MG.: Unpreserved lidocaine to control discomfort during cataract surgery using topical anesthesia. J Cataract Refract Surg. 1997; 23:545-550. Gills JP., Martin RG., Cherchio M.: Topical anesthesia and intraocular lidocaine. Cataract Surgery: The State of the Art, Slack; 1998; 2:9-17. Koch, PS.: Anesthesia. Simplifying Phacoemulsification, 5th ed., Slack; 1997; 2:12-26.
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Koch, PS.: Anterior chamber irrigation with unpreserved lidocaine 1% for anesthesia during cataract surgery. J Cataract Refract Surg. 1997; 551-554. Koch, PS.: Preoperative and postoperative medications of anesthesia. Current Opinion in Ophthalmology 1998; 9;1:5-9. Koch, PS.: Preoperative Preparation . Simplifying Phacoemulsification, 5th ed., Slack; 1997; 1:1-11. Masket S.: Ocular anesthesia for small incision cataract surgery. Atlas of Cataract Surgery, Edited by Masket-Crandall, Published by Martin Dunitz Ltd., 1999; 15:111-114. Naor J., Slomovic AR.: Anesthesia modalities for cataract surgery. Current Opinion in Ophthalmology, Vol. 11 Nº 1, Feb. 2000. Tseng SH., Chen FK: A randomized clinical trial of combined topical-intracameral anesthesia in cataract surgery. Ophthalmology 1998; 105:2007-2011.
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PHACOEMULSIFICATION WHY SO IMPORTANT? Phacoemulsification is the "state of the art" operation of choice for cataract surgery in academic institutions and private eye centers worldwide. Ophthalmologists in training (Residencies and Fellowships) receive training in phacoemulsification first and manual extracapsular as a second choice. COMPARING PLANNED EXTRACAPSULAR WITH PHACO EXTRACAPSULAR With planned extracapsular extraction an 8-9 mm limbal incision is performed, preceded by a conjunctival flap (either limbal based or fornix based). The anterior capsule is usually opened with a "can opener" capsulorhexis technique. Some surgeons have developed the expertise to do a continuous circular capsulorhexis. The nucleus is then expressed with gentle pressure inferiorly such that the lens is subluxated in its entirety into the anterior chamber and out of the eye through a superior limbal incision (Fig. 37). Aspiration is used to remove the remaining cortex from the capsular bag and viscoelastic is irrigated into the anterior chamber and capsular bag (Fig. 38). A PMMA intraocular lens implantation is performed (Fig. 39) and the wound is sutured. In planned extracapsular, which is still ably and successfully performed by a significant number of ophthalmic surgeons, the final
visual recovery takes place slowly through a period of 5 to 6 weeks. In small incision manual extracapsulars such as with Blumenthal's MINI NUC and Gutierrez manual phacofragmentation, a foldable IOL may be implanted. Both of these procedures are fully presented in the Section on Manual Extracapsular Extraction in this same Volume following Phacoemulsification. Visual recovery is much more rapid. ADVANTAGES OF THE PHACO TECHNIQUE The phacoemulsification technique offers the following benefits and advantages over planned extracapsular as outlined by Edgardo Carreño: 1) it is performed through an incision 3mm or less in size which is self-sealing and watertight thereby improving safety during the procedure. 2) It is significantly less invasive thereby leading to much less ocular trauma and consequently less postoperative inflammation. 3) It results in minimal or no induced astigmatism. 4) It provides much more rapid visual and physical recovery and prompt refractive stability. The visual recovery is immediate if topical anesthesia is used. All these advantages lead to an important increase in the patient's quality of life. In addition, a smaller incision also may reduce the risk of endophthalmitis.
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Figure 37: Planned Extracapsular With planned extracapsular, the anterior capsule is opened with a "can opener" capsulorhexis technique. The nucleus is expressed with gentle pressure inferiorly. Pressure (black arrow) is applied on the posterior wound lip. The nucleus (N) is slid out of the eye (white arrow). The incision shown here is medium in size (5-6 mm) and allows implantation of a PMMA IOL. A full incision extracapsular is 8-9 mm in arc.
MAIN TECHNICAL DIFFERENCES ASSOCIATED WITH PHACO The opening of the anterior capsule is done as a continuous curvilinear capsulorhexis (CCC) as described by Gimbel et al (see Figs. 43, 44, 45). An ultrasonic probe (Figs. 50-A and B) is used to emulsify the nucleus and draw it out of the eye through an aspiration port (Chapter 8). This allows the removal of a 10 mm cataract through a 3 mm incision (or less). Because the integrity of the anterior chamber is maintained throughout the procedure, the intraocular pressure is subject to less fluctuation and poses much less of a risk for suprachoroidal hemorrhage.
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Removal of the lens by phacoemulsification is followed by placement of a posterior chamber foldable intraocular lens implant through a 3 mm incision. The wound may require one or no sutures. Variations of technique may involve a superior limbal incision with dissection of a sclero corneal tunnel to form a self-sealing valve incision, a clear corneal incision with corneal tunnel and selfsealing valve incision (with experienced surgeons) and the scleral tunnel incision which is used increasingly less but is a safe procedure for difficult cases (Figs. 40, 41, 42). The limbal and the corneal incision are either placed at 12 o'clock or in the superior temporal quadrant. The limbal incision and tunnel is the proce-
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Figure 38 (above right): Irrigation with Viscoelastic Before insertion of the intraocular lens, fluid in the anterior chamber and within the capsular bag is replaced with a viscoelastic liquid. A cannula (C) is placed into the capsular bag at position (B) and viscoelastic (V) injected (arrows). The cannula is inserted across the anterior chamber to a position (A) and as the cannula is withdrawn, viscoelastic (V) is injected (arrows). Replaced fluid (F) flows out through the incision. The viscoelastic will help to protect corneal endothelium, posterior capsule and iris during insertion and intraocular manipulation of the lens implant.
Figure 39 (below left): IOL Implantation in Planned Extracapsular Following aspiration of the remaining cortex from the capsular bag and deepening the anterior and posterior chambers with viscoelastic as shown in Fig. 38, the intraocular lens is inserted into the capsular bag. The inferior loop is directed into the capsular bag inferiorly (arrow). The superior loop shown here is then inserted into the superior capsular bag.
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dure of choice for surgeons in the transition stage or who do not have a large cataract surgical volume because it allows conversion into extracapsular if necessary. Enlargement of a corneal incision in order convert to an extracapsular extraction, often results in intolerable postoperative astigmatism. Both standard polymethylmethacrylate (PMMA) or foldable (acrylic, silicone or hydrophilic) intraocular lenses may be used. A foldable lens allows for an even smaller incision and less risk of postoperative astigmatism as a result of wound construction. Because of the watertight wound construction of this method and the stability of the anterior chamber during phacoemulsification, this technique is amenable to topical anesthesia in a cooperative patient (Fig. 35) or a combined topical and sub-Tenon's local anesthesia, (Figs. 33, 34) or a combined topical and intracameral anesthesia ( Fig. 36) advised by Gills. The choice mainly depends on the experience and skill of the surgeon , but there may be special considerations such as difficulty in communication with the patient and in cases complicated by a patient's poor general health.
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tion is equipment and instrument-dependent as well as team-dependent, because the team assisting with surgery must fully understand all the steps of the operation and, by all means, how the phaco machine works.
The Importance of Mental Attitude Understanding the workings of the phaco machine requires a complete change in mental attitude and the undergoing of a rigorous training not only in the surgical technique, but learning to use two feet (microscope and pedal) instead of one (microscope). The surgeon must also be attentive to the perception of different sounds emitted by the machine, each one signaling a different function and parameters which in turn the surgeon must act upon. It is essential for the physician to understand exactly how to obtain the optimal use of the machine, the rationale behind it, the fluid and phacodynamic processes within the machine and the eye and how to manage safely the equipment, safely, including the various handpieces and, of course, the phaco power, and the irrigation and aspiration (see Figs. 49A through 65).
LIMITATIONS OF PHACOEMULSIFICATION
Motivation to Undertake this Task
Surgeons who have a successful clinical practice, ample experience and well earned prestige and are using planned extracapsular are understandably reticent and apprehensive about shifting from a technique they already master to one which depends a great deal on the understanding of how the phaco machine functions. 50% of the success in doing phacoemulsification depends on the proper use of the equipment at each stage of the operation. Ophthalmic surgeons are used to depend on their surgical skill. It is part of their self-esteem. As emphasized by Centurion, phacoemulsifica-
This is not an easy task. The multiple mechanical functions of the equipment are not "friendly" to those physicians who , althoufh excellent surgeons, are not mechanically minded. Only the knowledge that such a change, if successfully done, will be best for his/her patients can serve as the motivation to undertake such a significant step. For all these reasons, many excellent surgeons decide not to enter into phaco, and many others have the equipment available in their eye center or hospital but allow it to remain idle.
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In order to overcome these negative aspects of phacoemulsification, it is fundamental to have a smooth transition into phaco. In order to achieve it, it is essential that you read and reread the next chapter (Chapter 7), which presents the very best ways to achieve a successful transition with little stress or apprehension.
The significant economical savings to the patient from lost working hours with ECCE vs almost immediate recovery with phaco and the improved quality of life with phaco are other major important contributions. All these are important features to consider when the socalled expenses for both operations are taken into account.
Comparison of Costs - Phaco vs ECCE One of the strong limitations of phaco has been the cost of not only the phaco equipment but also the supplies related to its use. This is important for a significant number of ophthalmologists when operating on patients who are not economically advantaged.
Fixed Costs with ECCE Let us analyze, however, the updated situation related to costs of performing phacoemulsification, and compare it with the costs of the supplies needed to perform extracapsular extraction. With the latter, there is the cost of very fine sutures, which are unnecessary in phaco; there is the cost of local anesthesia involved with either a retrobulbar or a paraocular injection versus phaco in which only topical sometimes with intracameral anesthesia is utilized. The cost of the postoperative injection of steroid in the fornix often done following extracapsular is also unnecessary with phaco although the trend now is to inject steroid in the anterior chamber (see Chapter 5). The cost of even a fairly short stay in the recovery room following the often used sedation needed with an extracapsular extraction for anxiety is higher than in patients with phacoemulsification who have had only topical anesthesia without sedation and walk to their home within a few minutes following surgery.
Phaco's Progressively Decreasing Investment What about the high expenses with phaco equipment? There was a time when the equipment or phaco machine required a significant investment. The supplies or tubing needed for each patient was also a heavy expense when performing several cases. All this has changed due, in great part, to the ingenuity and understanding by the industry that these high expenses and initial investment were a significant barrier which prevented more ophthalmic surgeons from adopting phaco. At present, most of the companies that manufacture phaco units are helping physicians and hospitals to acquire the equipment and supplies. The equipment is made available at much more reasonable prices than their real sales cost, with the understanding that there will be a monthly utilization by the surgeon of the phaco supplies of that particular manufacturer. In addition, the manufacturer provides advice and hands-on-training by experts to the surgeon so that he/she will be able to enter into the transition period (Chapter 7) utilizing his/ her own personal equipment acquired from that manufacturer. The "tubing" which previously had to be discarded after each operation is no longer a problem cost-wise. Now it may be used for as many as 60 cases in the same day. No re-
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sterilization is needed. The tubing may be used without replacement for a complete day of phaco surgery. Upon completion of all the phaco cases in one day, the tubing must be discarded. Therefore, by programming the surgeon´s cases accordingly, a great deal of savings can be made. All of this makes the phaco technique more accessible to a larger number of surgeons. We still have to cope, however, with the needs of surgeons in countries in which the gross national product is very low.
Major Limitations in Non-Economically Advantaged Countries Experts in programs for rehabilitation of sight in large numbers of indigent patients-such as Francisco Contreras, M.D. in Peru, Everardo Barojas, M.D. in Mexico, Juan Batlle, M.D. in the Dominican Republic, Newton Kara, M.D., in Brazil,-- all of whom are magnificent surgeons with a large private practice but also do a great deal of service to the communities, have stated that most patients in this category earn no more than US$1.00 (one dollar) a day and that the maximum that can be charged to a patient for a cataract operation should be what that particular patient earns in one month.
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This is important information that needs to be appreciated by cataract surgeons throughout the world interested not only in the progress of the technology of our profession but also in the humanitarian aspects of what we do best which is ophthalmology. It is also of great interest as outlined by Contreras that the number of phaco operations being performed has increased in those countries with the highest gross national product per person. In countries where earnings by patients are low, phaco is still behind. In many countries, only 5 to 10% of the population can afford phacoemulsification in spite of the facilities that we have outlined. Of the rest, thirty percent of the population has a mid-level of income, 30% are very poor, and 30% of the population are in extreme poverty. As we continue to progress in the technological developments of ophthalmology, which is a blessing, we also need to be aware of the limitations existing in the populations of many countries throughout the world. An exemplary case is that achieved by Professor Arthur Lim, M.D., in Singapore, who has put together significant funds from private organizations and has trained large numbers of young ophthalmologists to learn these modern techniques to combat blindness in South East Asia and China.
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BIBLIOGRAPHY Centurion V: Importance of mental attitude and motivation in phacoemulsification. Faco Total, pp. 57. Centurion, V.: The transition to phaco: a step by step guide. Ocular Surgery News, Slack, 1999. Carreño E.: Phacoemulsification Sub-3 technique. Guest Expert, Boyd’s BF., The Art and the Science of Cataract Surgery, Highlights of Ophthalmology, 2001. Drews, RC: Medium-sized and small incision extracapsular extraction without phaco. World Atlas Series of Ophthalmic Surgery of Highlights, by Boyd, BF, Vol. II, 1995; 5:54-56. Gimbel, H: Posterior Continuous Curvilinear Capsulorhexis (PCCC). World Atlas Series of Ophthalmic Surgery of Highlights, by Boyd, BF, Vol. II, 1995; 5:96-97.
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PREPARING FOR THE TRANSITION GENERAL OVERVIEW AND STEP BY STEP CONSIDERATIONS Complete comprehension of what is presented in this chapter is essential for the successful undertaking of phacoemulsification. Before you read it, we strongly recommend that you first read Chapter 6 which refers not only to the unquestionable advantages of phaco but to its limitations, most of which are related to the challenge of understanding how the phaco machine works and how to attain its optimal use.
Equipment - Dependent and Phase-Dependent Technique The transition from planned extracapsular extraction to phacoemulsification fundamentally refers to the gradual change that the ophthalmic surgeon who already masters the planned extracapsular must undertake in order to dominate the new technique of phaco, which is equipment-dependent. This transition should be progressive and atraumatic. As the surgeon advances step by step, he or she should never go on to the following step if he has not dominated the previous step. This operation is also a phase-dependent technique, as emphasized by Centurion. Each phase must be completed with the precision of a watch maker. If you pass on to the following step without mastering the previous step, complications may arise with consequent failure and grief. This learning curve is achieved with effort, dedica-
tion and proper training to perform each phase of the transition well. Outlining the steps necessary in the transition from extracapsular surgery to phacoemulsification, we will present you a detailed picture of what it really takes to enter into the transition and to master the learning curve. We will describe and fully illustrate each one of the steps in sequence. For young ophthalmologists who enter directly into phacoemulsification in their training, this "bitter pill" of changing from planned extracapsular to phaco is an experience they will fortunately miss. But when they later teach others who have not been trained in phaco, but learned and have spent their career doing extracapsular instead, they need to recognize - as we do in this presentation - the difficulties their colleagues face, and teach accordingly. Extracapsular surgeons still constitute the majority of ophthalmologists worldwide.
Mental Attitude The surgeon must be absolutely convinced that changing from planned extracapsular to phacoemulsification will be best for his patients, particularly because of a very rapid visual recovery and physical rehabilitation back into normal life. As long as the surgeon is not completely persuaded of the reasons why he wants to take this crucial step in his professional development, he will never attain a positive experience during the transition with
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maximum safety, low risk and high benefits for the patient and minimal stress for him/herself. The fact that phaco also significantly shortens the waiting period for cataract surgery in the second eye, that it has 50% fewer complications than ECCE and that the operation can be done while the cataract is still in its early stages (20/40 vision, lowered contrast sensitivity and glare intolerance) should be another strong incentive to adopt phaco (See Chapter 6). The usual reasoning that the planned extracapsular surgeon assumes are thoughts like: "If I do so well with planned extracapsular, why change?". This is particularly true when your practice is mostly composed of private patients, some of them important persons in the community and no risks can be taken. The successful extracapsular surgeon continues to find reasons for not making the change, such as: "I have very little postoperative astigmatism with planned extracapsular, so why get into the problem of operating with a smaller incision and the difficulties that may arise?" "The visual recovery comparing the two techniques after several weeks is about the same; I am not in a hurry for my patient to attain a prompt visual result as long as the final visual recovery will be the same." "It is better for the patient to have a good planned extracapsular than a bad phaco." "I know that with planned extracapsular I will have practically no complications, but I am not so sure that such will be the case with phaco, particularly in the early cases." In essence, the surgeon has to make his/ her decision rationally and on his or her own initiative. This will provide the stimulus and the perseverance in order to enter into the learning curve and the perseverance to eventually master what is considered one of the best
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operations in the field of medicine. Once the decision is made, it must be followed through with firmness and resolve.
UNDERSTANDING THE PHACO MACHINE A successful phacoemulsification depends essentially on two factors: 1) the surgeon's skill; 2) the surgeon's and his team's understanding of how the phaco machine works. It is fundamental for the surgeon to have a thorough and practical knowledge regarding the specific equipment that he is using and how the technology of phaco machines in general operates.
Becoming Familiar with the Equipment Becoming first familiar with the phaco machine in an experimental laboratory first, is the best way to learn and understand how the equipment works. This has been reemphasized once and again by Virgilio Centurion M.D., one of the world's best cataract surgeons who has dedicated a great deal of his valuable time to teach the transition through courses and publications. His recommendation is to practice first in the laboratory the use of both hands and the four positions of the phaco machine foot pedal so as to become familiar, comfortable, and adept with the parameters of the machine (Figs. 52, 53). For more sensitive control of the phaco machine foot pedal, use a shoe with a thin sole (keep it in the operating room) and use your dominant foot (equivalent to the dominant hand). Control the surgical microscope with the non-dominant foot.
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Practice using both hands can be attained with pig eyes and synthetic eyes in synthetic heads, often coached by the company representative from whom you acquired the phaco machine and equipment. The surgeon can also practice with a human ocular globe supplied by large Eye Banks or with pig eyes removed soon after the animal is sacrificed. These globes should be refrigerated, not frozen, with the cornea protected with a sponge. When placed in a 700 W microwave oven for 4 seconds, the lens develops a subcapsular cataract. After 9 seconds, 50% of the lens will be opaque and hard.
Two Hands, Two Feet and Special Sounds The surgeon should dedicate appropriately extensive time in the laboratory towards acquiring complete self-assurance in the use of the machine, coordinating his or her hands and the two foot pedals. Additional time may be used to practice how to make the new, smaller incision, the capsulorhexis and other surgical steps. Phaco is mostly a two-handed technique, so you must become trained and develop reflexes to use both of your hands and both of your feet, together. During training in the laboratory, the surgeon grasps how the machine works during each step of the operation, learns the method for introduction of the phaco tip and the most comfortable position in which to place the handpiece; why and when to elevate or lower the height of the fluid bottle, when to increase or decrease the flow of fluid or the vacuum and when to increase or decrease the power of the phaco. These parts of the learning curve are mastered in the laboratory so as to really understand and become fully adept with the functions of the equipment before entering the patient's eye.
While learning to use the machine's foot pedal you must also perceive the significance of the sounds of the machine which vary depending on the surgical step or stage, such as the balance of flow when the phaco tip is not occluded (Figs. 57, 58), and the sounds alerting the surgeon to changed in fluid dynamics when there is occlusion of the tip. In each instance, the surgeon receives a sonic feedback, constantly informing him about the state of the fluid dynamics in the eye (Figs. 59, 60). So the surgeon must learn to use both hands, both feet, and to listen to the phaco machine. In essence, experimental training first in the laboratory is the best investment the surgeon can make to shorten and successfully transverse the learning curve. It is a necessary experience to learn the workings of the equipment fully. Its main aim is not that of learning the surgical technique at this stage. That comes later. We must not improvise or try to learn the use of a phaco machine in the operating room. The surgeon should not begin learning the use of the machine directly on a patient's seeing eye.
Main Elements of Phaco Machines Their Action on Fluid Dynamics In this chapter we will thoroughly discuss the optimal use of the phaco machine and the rationale behind it, the three elements of most phaco systems (irrigation, aspiration and ultrasonic energy), fluidics and phacodynamics, the importance of and understanding of the Surge Phenomenon. The rationale behind high vacuum - low ultrasound power technology, the new technology of the peristaltic pump, particularly in the three main equipment sources available such as the Alcon's Legacy 2000, Allergan's Prestige (and the Sovereign) and Storz Millennium and some useful informa-
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tion about the new phaco tips and their contribution toward a better operation.
Hydrodissection and Hydrodelineation
COMPARISON OF SURGICAL TECHNIQUES FOR TRANSITION VS EXPERIENCED SURGEONS
These techniques remain essentially the same for the transition and in advanced surgeons (Figs. 46, 47, 48).
Epinucleus Removal There are several techniques in phacoemulsification that remain practically the same for the surgeon who is undergoing the transition and those who are more experienced. On the other hand, there are stages of the operation in which there are definite variations for the experienced surgeon, some of them minor, others moderate and others major. We have divided the subjects into two (2) groups: 1) those that are the same for all surgeons and 2) those that vary depending on the skill of the surgeon for this particular operation.
Techniques Which Are the Same for the Transition and for Advanced Surgeons Capsulorhexis These parts of the technique are practically the same for both groups, with slight individual variations (Figs. 43, 44, 45). The main feature that may vary is the size of the capsulorhexis. Some very advanced surgeons do a small capsulorhexis, while in the transition a somewhat larger capsulorhexis is advisable, depending on the size of the IOL to be implanted.
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This technique does not vary substantially in the transition from that used by advanced surgeons (Fig. 69).
Cortex Removal The technique is the same for both groups (Figs. 70, 71). It is important not to feel overconfident at this stage and by all means avoid being aggressive.
Techniques that Vary According to the Skill of the Surgeon Anesthesia In the transition, the surgeon may use parabulbar or Sub-Tenon's (flush) anesthesia using Greenbaum's cannula (Figs. 33, 34), particularly because conversion to ECCE may be needed. It is only advanced surgeons who may use topical anesthesia alone or combined with intracameral irrigation anesthesia (Figs. 35, 36).
Fixation of the Globe In the transition, the surgeon does need to fixate the globe, passing a suture through the superior rectus, versus the experienced surgeon who does not need to do so.
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The Incision Sclero corneal tunnel, limbal tunnel, corneal tunnel: these three types of incisions depend on the skill and experience of the surgeon. In the transition it is important to use the stepped incision starting at the limbus and performing a sclero corneal tunnel based on a limbal incision, in case there is need to revert to a ECCE. During the transition, it is always important for the surgeon to know that he/she may revert to ECCE whenever they feel uncomfortable with the surgery at any specific stage. Only more advanced surgeons should do the corneal incision and tunnel (Figs. 40, 41, 42).
Type of IOL Foldable lenses should only be used by advanced surgeons. PMMA oval lenses 5.0 x 6.0 mm are the standard in the transition (Fig. 72-A).
Nucleus Removal There are many different techniques that may be utilized by advanced surgeons. They will be discussed in a separate chapter. For the transition, the basic technique to use when beginning phaco is the "divide and conquer" into four quadrants. "Divide and conquer" is usually done with two hands (Fig. 56). The surgeon must also learn, however, how to perform this technique with one hand.
SURGICAL TECHNIQUE IN THE TRANSITION Anesthesia During the transition it is advisable that the surgeon utilize the type of anesthesia with which he/she feels more safe and in better control (Figs. 33, 34). It is unnecessary to add a new source of stress or immediate change at this stage of the procedure. Nevertheless, when the surgeon is in charge of the situation and masters the phaco technique, it is ideal to use topical anesthesia because of its ability to provide immediate visual recovery. The combined use of topical anesthesia and intracameral anesthesia is more effective than topical anesthesia alone and should be tried before the surgeon attempts to operate using topical anesthesia alone (Figs. 35, 36). I recommend that
you consult Chapter 5 on this important aspect of the operation.
The Incision How to Make a Safe Transition from Large to Small Incision Role of the Ancillary Incision This is an important step in performing phacoemulsification. Although there are techniques to perform it with only one hand, phaco is fundamentally a two-handed procedure. The ancillary incision is made before the main incision is performed. As shown in
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Fig. 41, this incision serves as an entry for a second instrument which is necessary for maneuvers to remove the nucleus (Fig. 56). This wound is also utilized in irrigation of the anterior chamber with intracameral local anesthetic as explained in Chapter 5 and illustrated in Fig. 36, and for the insertion of viscoelastic previous to making the main incision and during several other steps of the operation. However, some advanced phaco surgeons do not perform hydrodelamination and remove the epinucleus usually during the emulsification of the nucleus. At the end of surgery, the ancillary incision also serves to inject fluid into AC to test for leaks in the wound (Fig. 73).
The Main Incision During the early stages of the transition, the surgeon should plan to start the operation as a phaco but learn how to convert to the planned extracapsular he or she is accustomed to do successfully if this becomes necessary. This will provide additional comfort and con-
fidence. The surgeon may start with a small stepped limbal valvulated incision slightly larger than the phaco tip (Fig. 42) even though he knows that he plans to convert to his usual planned extracapsular. It is not advisable to start the transition with a corneal incision because, upon enlarging it, the resulting astigmatism may be severe. The more anteriorly located the incision, the more astigmatism the patient may end up with. By starting the transition with a limbal incision, the surgeon will use the same area for the incision that he is accustomed to use in his planned extracapsular but will make the incision valvulated (stepped) and smaller than th e usual extracapsular (Figs. 40, 41, 42). The surgeon must master the technique of the small incision valve like incision at the limbus, so that it can be part of his armamentarium in the future (Fig. 40-C). Once the surgeon is certain that he will not need to convert from phaco to planned extracapsular and therefore will not need to enlarge the incision, he may choose to make a corneal incision if he wishes, but not before (Fig. 40-C). This is what we refer to as a safe transition from a large to a small incision, a transition that must
Figure 40 A-C (See Facing Page 101): Phacoemulsification Incisions - Surgeon’s and Cross Section Views Figure A - Limbal Incision (left, above and below): The incision of choice during the transition period and which may continue to be utilized successfully by the surgeon is a stepped limbal incision, slightly larger than the size of the phaco tip, (L-above left). The incision is placed in this location so that if the surgeon feels uncomfortable with the surgery at any stage of the transition into phaco, the limbal incision may be extended to convert to ECCE in his/her first steps of transition without complications. The cross section view below, left, shows the stepped limbal tunnel incision, valvulated and self-sealing. Unless it is made larger, no suture may be needed or perhaps one suture. The three steps to make a valvulated incision starting at the limbus are the same than those shown in Fig. B below for the scleral tunnel incision, except that the length of point 2 in the second plane or tunnel is shorter. Figure B - Scleral Tunnel Incision (center above and below): The scleral tunnel incision involves a three step entry into the anterior chamber creating a 5.5 mm long valvulated self-sealing wound. The first step (1) is a straight or “frown” shaped vertical groove scleral incision at about 1.5 mm posterior to the limbus. The second plane of the incision (2) is dissected at constant depth (300
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microns) toward and into the clear cornea for about 1 mm. The blade should be parallel to the iris plane. The third step is a penetrating incision into the anterior chamber (3) with the blade obliquely to the iris plane. This type of incision is no longer frequently used. It used to be the most popular incision, but then we learned that the self-sealing valvulated action of the incision is not related to the length of the tunnel outside of the cornea but within the cornea. Figure C - Corneal Tunnel Sutureless Incision (above right): The 3.2 mm long corneal tunnel incision (C) also creates a valve which is self-sealing. As seen in the cross section (below right) a vertical groove (1) is made in the clear cornea followed by a second plane incision (2) approximately oblique to the iris plane. This corneal incision should not be used in the transition period but can be used advantageously by more experienced surgeons whose ability to perform each step of phacoemulsification adequately practically assures that there will not be any need to convert to an ECCE. If a corneal incision as shown in (C) is made and the surgeon has to convert, the enlargement of the corneal incision to finish the operation as an extracapsular may lead to major astigmatism. Figure A (limbal) and C (corneal tunnel) are either performed at 12 o'clock as shown in this plate or located in the superior right quadrant. This is preferred by many surgeons who feel that this location facilitates their surgical manipulations.
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Figure 41-A: Making the Ancillary Incision This is a most important stage of phacoemulsification since the operation itself is mainly a two-handed technique. The steps involved are: 1) First, mark the limbal area (A) where the limbal stepped main incision will be made (Figs. 41 B and 42) between 9 and 12. In the transition it is recommended to place the stepped incision at 12 o'clock as shown here. 2) Make the ancillary incision (I) always at 3 o'clock. This is performed with a special 15 º blade designed for paracentesis (K). 3) Proceed to perform the limbal valvulated stepped incision and enter the anterior chamber, as shown in Figs. 41-B and 42 (surgeon's views). The ancillary incision serves to introduce a second instrument as shown in Fig. 67, inject intracameral local anesthesia as shown in Fig. 36 and irrigate viscoelastic into the anterior chamber.
Figure 41 B: Initial Stages of SelfSealing, Stepped, Valvulated Tunnel Incision at the Limbus - Surgeon's View This surgeon's view shows the Crescent knife blade (K) entering the first incision (1) just at the limbus. The blade is advanced (red arrow) for some distance in the plane of the cornea, and a tunnel (blue arrows) is created. This forms the second step (2) in the three-step incision. The knife does not enter the anterior chamber at this stage.
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Figure 42: Final Step of Self-Sealing, Stepped, Valvulated Tunnel Incision at the Limbus Performed with the Diamond Knife - Surgeon's View A diamond knife blade (D) enters the first incision (1), the second tunnel incision (2), and is then directed slightly oblique to the iris plane and advanced (arrow) into the anterior chamber. This forms the internal aspect of the incision into the chamber (A). This is the third sted (3) in the three-step self-sealing incision.
be undertaken step by step as the surgeon progresses in his learning curve (Figs. 40, 41, 42). Later, as he progresses and learns to master phacoemulsification, the surgeon is ready to make two significant changes in the technique: 1) Operate from an oblique position and make the incision in the upper right quadrant, temporally as shown in Figs. 41-B and 42; 2) Perform a corneal incision (Fig. 40-C) instead of a limbal incision (Figs. 40-A, 41-B, 42
Role of Conjunctival Flap In the early stages of the transition, the surgeon may prefer to start with a small fornix based conjunctival flap from 10:00 to 2:00 o'clock, and place light cautery under each edge of the flap. If the limbal incision is extended because one of the initial phaco steps becomes a source of problem and there is need for conversion to ECCE, there will be less bleeding.
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Figure 43: Continuous Curvilinear Anterior Capsulorhexis with Cystotome - Step 1 Anterior capsulorhexis is one of the steps of phacoemulsification that is practically the same both for the surgeon beginning with the transition or the more advanced surgeon, with the exception that some advanced surgeons prefer to do a smaller capsulorhexis. The technique shown here is the initial step performed with the cystotome-needle (see Fig. 97). In the transition, it is recommended that it be continued with forceps as shown in figures 44 and 45. With an irrigating cystotome, the center of the anterior capsule is punctured creating a horizontal Vshaped tear. The tear is extended toward the periphery and continued circumferentially in the direction of the arrow. In the surgeon's transition stage, the cystotome is introduced through a 3.5 to 4.0 mm limbal incision. The initial puncture of the anterior capsule with the cystotome needle shown here as made in the mid periphery is the technique initially utilized by the pioneers of capsulorhexis and is shown here in this form for historical reasons. The present method has been modified to start the puncture in the center, as a frontal incision shown in Fig. 98. This leads to better results and facilitates the maneuver.
Anterior Capsulorhexis This again is a vital step in the transition. Changing from the can opener capsulotomy (Fig. 37) to the anterior continuous circular capsulorhexis (CCC) is one of the fundamental steps in the transition (Figs. 43, 44, 45). The surgeon must learn first by practicing capsulorhexis on the skin of a grape or by using a very thin sheet of plastic wrap such as the one that covers some chocolate candies. Once the surgeon understands the concept of the technique and can do it in the laboratory, he or she may begin to use it for the patient. The surgeon must keep in mind that the space needed to adequately maneuver the cystotome (Fig. 43) or the capsulorhexis forceps (Figs. 44, 45) in order to do a proper continu-
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ous circular capsulorhexis is larger than the wound or paracentesis required to simply introduce a cystotome and perform a can opener capsulotomy. It is highly recommended to make the capsulorhexis under sufficient viscoelastic . The latter should be injected into the anterior chamber as a first measure before trying the capsulorhexis (Fig. 2). It is also fundamental not to begin with dense, hard cataracts where it is difficult to see the edge of the capsulorhexis. It is prudent to try performing this procedure over and over again in cataracts that are less dense until the surgeon is able to perform them in eyes with poor visualization of the edge of the capsule. Because the surgeon, in the initial stages that we are discussing here, will most probably
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Figure 44 (above right):Continuous Curvilinear Anterior Capsulorhexis with ForcepsStep 2 After having made the initial tear of the anterior capsule with an irrigating cystotome in the center of the anterior capsule, the tear is extended toward the periphery in a circular direction, this time utilizing forceps as shown in this figure. The tear is extended toward the periphery and continues circumferentially in a continuous manner for the remaining 180 degrees, as initially described by Gimbel.
Figure 45 (below right): Continuous Curvilinear Anterior Capsulorhexis with Forceps Step 3 The flap of the capsule is flipped over on itself. The forceps engage the underside of the capsule. The tear is continued toward its radial segment. In the transition, beginning surgeons are encouraged to use forceps as shown in figures 44 and 45 in order to perform the continuous circular capsulorhecis (CCC). Viscoelastic is essential in this maneuver. The correct size of the CCC is 5.5 mm to 6.0 mm. A larger CCC, would be undesirable because the nucleus may come out of the bag too quickly, forcing the surgeon to do emulsification in the anterior chamber which may lead to endothelial damage. For the early steps of the transition, when the surgeon may have to convert to ECCE, it is important to perform two relaxing incisions radially at 10 and 2 o'clock in the anterior capsule, in order to facilitate the removal of the complete nucleus in an ECCE if necessary.
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need to convert to ECCE, it is important that he perform two relaxing incisions radially in the anterior capsule at 10 and 12 o'clock following the CCC, in order to facilitate the removal of the complete nucleus with a planned manual extracapsular. If these relaxing incisions in the anterior capsule are not done, the surgeon may confront serious problems in removing the nucleus (Fig. 37).
Hydrodissection Once the surgeon is able to perform a circular continuous capsulorhexis (CCC) without problems, he is ready to go into the next step, which is hydrodissection (Figs. 46, 47, 48). This step should not be undertaken before mastering the capsulorhexis. If not, tears in the anterior capsule may extend towards the equator when performing the injection with fluid to do the hydrodissection. The surgeon should have clearly in mind the anatomy of the crystalline lens and what is it that he is after with hydrodissection (Fig. 1). With this maneuver, by using waves of liquid (Figs. 46, 47, 48) we wish to separate the anterior and posterior
capsules from the cortex (Figs. 46, 47) and the nucleus from the epinucleus (Fig. 48). When this is achieved, the nucleus is liberated so that it will be free for the ensuing maneuvers of rotation, fracture and emulsification, all of which will come as the next steps in the procedure (Figs. 55, 56). As long as the surgeon is not sure that the nucleus has been freed of its attachments through the hydrodissection and will rotate easily, he should not proceed to try to rotate it mechanically because this may lead to rupture of the zonules. Also, if the nucleus is not separated from the cortex by hydrodissection (Fig. 48), the surgeon should not proceed to apply the phaco ultrasound to the nucleus because he or she may well meet with complications by extending the effects of ultrasound not only to the nucleus but peripherally to the cortex. This can lead to the feared rupture of the posterior capsule. Instead, the surgeon should decide to convert to a ECCE. Although Fig. 47 shows hydrodissection through a corneal tunnel (surgeon's view), keep in mind that all maneuvers during the transition are done with a limbal incision, as shown in Figs. 40 A, 41, 42.
Figure 46 : Hydrodissection - Stage 1 - Separation of the Anterior and Posterior Capsule from the Cortex Cross Section View A 25 gauge cannula is placed through the continuous circular capsulorhexis under the anterior lens capsule (A). Fluid is infused as shown by the pink arrows in order to separate the anterior capsule from the cortex. A wave of fluid shown by the pink arrows and identified as (W) extends along the posterior capsule, separating the posterior capsule (P) from cortex (C).
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Figure 47 (above left): Hydrodissection of the Lens Capsule from the Cortex During Phacoemulsification - Surgeon's View This is a surgeon's view of what is shown in figure 46 in cross section view. Following circular curvilinear anterior capsulorhexis, a cannula (C) is inserted into the anterior chamber. The cannula tip is placed between the anterior capsule and the lens cortex at the various locations shown in the ghost views. BSS is injected at these locations (arrows) to separate the capsule from the cortex as shown in Fig. 46. The resultant fluid waves (W) can be seen against the red reflex. These waves continue posteriorly to separate the posterior capsule from the cortex.
Figure 48 (below right): Hydrodissection Stage 2 - Separation of Nucleus and Epinucleus and the Cortex In this stage, the cannula is advanced beneath the cortex (C) and the infusion with BSS is started in order to separate the nucleus (N) from the epinucleus (E). The pink arrows between these two structures, nucleus (N) and epinucleus (E), show the flow of fluid. The gold "ring" of fluid separating the nucleus from the epinucleus is here identified as (GR).
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THE MECHANISM OF THE PHACO MACHINE Getting Ready to Use Phaco During Transition
Optimal Use of the Phaco Machine
We have already emphasized the crucial importance of understanding how the phaco machine works in order for the surgeon to perform phacoemulsification successfully. This is a task every cataract surgeon must undertake when contemplating the use of phaco in his/her
The Rationale Behind It Main Functions
Figure 49-A: The Principles of How the Phaco Machine Works This conceptual view shows the three main elements of most phaco systems. (1) The irrigation (red): Intraocular pressure is maintained and irrigation is provided by the bottle of balanced salt solution (B) connected via tubing to the phaco handpiece (F). It is controlled by the surgeon. Irrigation enters the eye via an infusion port (H) located on the outer sleeve of the bi-tube phaco probe. Height of the bottle above the eye is used to control the inflow pressure. (2) Aspiration (blue): (I) enters through the tip of the phaco probe, passes within the inner tube of the probe, travels through the aspiration tubing and is controlled by the surgeon by way of a variable speed pump (J). The peristaltic type pump is basically a motorized wheel exerting rotating external pressure on a portion of the flexible aspiration line which physically forces fluid through the tubing. Varying the speed of the rotating pump controls rate of aspiration. Aspirated fluid passes to a drain (L). (3) Ultrasonic energy (green) is provided to the probe tip via a connection (M) to the unit. All three of these main phaco functions are under control of the surgeon by way of a multi-control foot pedal (N).
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patients. It must be achieved first in an experimental laboratory before attempting to operate on humans with seeing eyes, as emphasized by Centurion.
Edgardo Carreño, M.D., one of South America's top phaco surgeons and teacher, describes the three main functions of the
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Figure 49-B (previa Fig. 1-1, p.3 libro Seibel on Phacodynamics): The Rationale Behind the Phaco Machine In this diagramatic figure from Seibel's excellent book on Phacodynamics, you can clearly observe the mechanical workings and rationale behind the function of the phaco machine, as explained in Fig. 49-A, its figure legend and the text. The ultrasound energy coming from the handpiece emulsifies the cataract (Fig. 50-B) so that a 10 mm cataract may be removed by the aspiration port and line through a 3 mm or smaller incision. A fluidic circuit counteracts the heat build up caused by the ultrasonic needle and removes the fragmented or "emulsified" lens material via the aspiration port and aspiration line while maintaining the anterior chamber. The fluid is supplied via the irrigation port and line by the elevated irrigating bottle, which is controlled by the surgeon elevating it or lowering it. This fluid circuit is regulated by the aspiration pump. (After Seibel, B.S., Phacodynamics, 3rd Ed., 1999, p. 3, Slack, as modified by HIGHLIGHTS).
phaco machine: 1) irrigation; 2) aspiration; and 3) fragmentation of nucleus. This is clearly shown in Figs. 49-A and 49-B. Irrigation is done with the irrigation bottle, aspiration with the aspiration pump and fragmentation with ultrasonic energy through the titanium needle present in the
phaco tip of the hand piece (Figs. 50-A and 50-B). Many types of phaco tip shapes have been created to more efficiently handle nuclear extraction, as shown in Fig. 51. A command pedal, which is controlled by the surgeon’s foot, guides the machine into the following four positions: 0 (zero) which is at
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Figure 50 A (above left): The Phaco Handpiece This diagramatic figure clearly shows the different components of the phacoemulsification handpiece. The phaco needle is manufactured with various degrees of bevel, angulations and shapes, as shown in Fig. 51. The probe tip is hollow with the distal opening functioning as the aspiration port. Irrigation fluid flows through two ports located 180º apart on the silicone irrigation sleeve. The irrigation sleeve hub shown here in blue threads the sleeve onto the handpiece body outer casing. The phaco needle threads directly into the internal mechanism of the handpiece containing the ultrasound generator. The ultrasound power oscillates between 25.000 and 60.000 times a second (Hz). This energy is transmitted along the handpiece into the phaco needle in such a way that the primary oscillation is axial.(After Seibel, B.S., Phacodynamics, 3rd Ed., 1999, p. 99, Slack, as modified by HIGHLIGHTS).
Figure 50 B (below right): Mechanism of Action of Phacoemulsification Probe Tip Phacoemulsification involves the use of a probe tip (T) which vibrates very rapidly and acts as a jackhammer and emits heat to break up lens material (L) into fragments (F). Fragments are aspirated from the eye via the center of this probe tip which is hollow (black arrow). An outer sleeve (S) provides for passage of infusion fluid. Fluid enters the eye (white arrow) via infusion ports (P) in this outer sleeve. The infusion fluid constantly replaces any aspirate removed from the eye to maintain a stable intraocular pressure.
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Figure 51: New Phaco Tips Many types of phaco tip shapes have been created in an attempt to more efficiently handle nuclear extraction. Different types include various degrees of bevel, angulations, and shapes of the tip. Examples include: A-straight round tip, B- 15º bevel, C-30º bevel, D-45º bevel, E-bent 45º tip, F-rectangular tip, Genlarged bevel tip, and H-another enlarged bevel tip. The beveled tips provide an oval shaped aspiration opening with gradually increasing areas of contact (areas shown in blue) to nuclear material. Angled or bent tips attempt to allow access of the tip to more peripheral locations within the capsular bag.
rest; position 1 for irrigation, position 2 for irrigation-aspiration and position 3 for irrigation, aspiration and phacoemulsification (Figs. 52 and 53). The first function (irrigation) controlled by the foot pedal is provided by a bottle with BSS. The liquid flows by gravity. The amount of liquid that reaches the anterior
chamber depends on the height of the bottle, the diameter of the tubing and the pressure already existing in the anterior chamber (Figs. 49-A, 49-B, 54). The flow rate into the eye is determined by the balance of the pressure in the tubing - regulated by the height of the bottle, and the back pressure in the anterior chamber. When the two are
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Figure 52 (above left): Basic Phaco Foot Pedal Functions The foot pedal controls inflow, outflow, and ultrasonic rates. With the foot pedal in the undepressed position, the inflow valve is closed, the outflow pump is stationary, and there is no ultrasonic energy being delivered to the phaco tip. With initial depression of the pedal (1), the irrigation line from the raised infusion bottle is opened. Further depression of the pedal (2), starts and gradually increases the flow rate of the aspiration pump to a maximum amount preset by the surgeon. Further depression of the pedal (3) turns on increasing ultrasonic power to the phaco tip for lens fragmentation.
Figure 53 (below right): New Dual LinearLateral Pedal Control A new pedal control separates the inflow-outflow and ultrasonic power functions. The inflow (1) - outflow (2) function is controlled by pedal depression, with increasing outflow availability incurred with increasing pedal depression. Inflow will match outflow rates. Increasing ultrasonic power is applied by doing a lateral rotation of the foot pedal (3). The lateral rotation of the foot pedal (3) is shown in the ghost view. Separating these functions allows the surgeon to apply varying amounts of ultrasonic power with varying inflow-outflow rates. With the depression only type pedal, ultrasonic power is only engaged with maximum inflow and outflow. There are phacoemulsification maneuvers when this is not desirable. A low inflow-outflow rate, for instance, may be desired when engaging ultrasound.
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equal, there is no flow. If there is leakage or aspiration of fluid from the anterior chamber, the pressure there drops, and fluid in the tubing flows in to restore the pressure in the AC, and, indirectly thereby, the volume. The tubing is purposely made wide enough so that it impedes the flow of the BSS only slightly under normal rates of flow. It does limit maximum flow - during anterior chamber collapse for example, unfortunately, however.
Figure 54: Irrigating Bottle Height Related to Flow Rate Hydrostatic and Hydrodynamic Stages Bottle height (C) has the important function of providing constant chamber pressure during all phases of surgery, including during times of sudden changes in outflow rates. Maintenance of safe intraocular pressure is important in both "hydrostatic" (A - no fluid moving within the fluidic circuit) and "hydrodynamic" situations (B - fluid moving within the circuit). A bottle height of 45cm above the eye will provide an approximate 30mmHg of intraocular pressure (I) when no fluid is moving in the circuit (hydrostatic state A) when there is no aspiration taking place and the aspiration pump (E) is off. When the aspiration pump (J-arrows) is turned on, (hydrodynamic state B), the intraocular pressure (M) will go down, for example to 20mmHg, depending on the outflow rate. Arrows depict fluidic inflow (red) and outflow (blue) in the system. This is because the intraocular pressure decreases proportionally as the flow rate increases (Bernoulli's equation). Therefore it is important to maintain a constant IOP, to increase the bottle height when using a high phaco outflow rate. Likewise, the bottle height should decrease when the aspiration (outflow) rate is decreased. The black arrows on the tube (J) indicates drainage.
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The second function, which is aspiration, is provided by a pump, which creates a difference in pressure between the aspiration line and the anterior chamber. The pumps may be a peristaltic pump, a Venturi pump, a diaphragm pump, a rotary vane pump, or a scroll pump. The peristaltic pump has become the most widely known and used. Many feel it is safer. Just like inflow, a base level of suction occurs whenever the pump is activated, depending on how hard the pump is working. When there is occlusion of the tip with the foot pedal in the aspiration position (position 2), the pump will continue to pump and crate more and more suction until the material which is provoking the occlusion is aspirated, or until the suction in the tubing reaches the maximum that the surgeon has preset on the control panel (Figs. 59, 60, 61). This latency period before reaching maximum suction level provides a greater security margin allowing the surgeon to take immediate action in case the tip grasps (and sucks in) the iris or the posterior capsule instead of grasping the lens mass. In order to perceive what happens to the fluid dynamics when the phaco tip is not occluded, please see Figs. 57, 58. The reason for limiting the maximum suction pressure is to limit the rush of fluid out of the eye the moment the fragment which occluded the tip is aspirated. This provides the surgeon the opportunity to stop aspiration and avoid collapse of the anterior chamber. The third function of the phaco machine - the production of ultrasonic vibrations leading to fragmentation of the lens is carried out by a crystal transducer located in the handpiece, which transforms high frequency electrical energy into high (ultrasonic) frequency mechanical energy. The crystal drives the titanium tip of the phaco unit to oscillate in its anterior-posterior axis.
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It is precisely the anteroposterior oscillation of the phaco tip which produces the emulsification (Figs. 50-B, 55, 56, 67, 68).
Parameters of the Phaco Machine What are the phacoemulsification machine parameters? How are they utilized? These parameters need to be set and reset depending on the type of cataract: soft, medium-hard, very hard, (as shown in Fig. 2); the stage of the operation; and also, importantly, the various situations which the surgeon must solve. These parameters are: 1) the amount of ultrasonic energy applied to the nuclear material for its emulsification. It is expressed as a percentage of the phaco machine’s available power and it determines the turbulence which is generated in the anterior chamber during surgery. It is ideal to use the least amount of power possible during the operation. This is possible by combining other functions of the machine and maneuvers within the nucleus to facilitate fracture and emulsification of the lens. The use of excess phaco energy may result in damage to structures beyond the nucleus, such as the posterior capsule and the endothelium. 2) The aspiration flow rate. This measures the amount of liquid aspirated from the anterior chamber per unit of time. In practical terms, this determines the speed with which the lens material is sucked in into the phaco tip. This is synonymous with the power of "attraction" or suction of the lens fragments into the irrigation-aspiration handpiece (Fig. 61). High maximum flow rates may result in collapse of the anterior chamber if the irrigation cannot keep up. 3) The third parameter measures the vacuum or negative pressure created in the
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Figure 55: Varying Ultrasonic Settings While Proceeding Through a Nucleus of Varying Density During the Creation of a Furrow or Groove Under surgeon control via the foot pedal, the ultrasonic power can be varied during creation of a trans nuclear groove to accommodate the varying density of the nucleus encountered at each location. For example, when beginning the furrow (A) 30% power is all that is required initially in the low density peripheral portion of the nucleus (P). Note slight depression (arrow) of the foot pedal (1) to obtain this power setting. As the phaco tip is progressed toward the central nucleus, ultrasonic power may be increased to 60% as it encounters more dense epinuclear material (E). Note increased foot pedal depression (arrow) to increase power (2). When the phaco enters the densest central portion of the nucleus (N), ultrasonic power may be increased up to 90-100% by further depression (arrow) of the foot pedal (3). As the phaco tip again encounters less dense material on the distal side of the nucleus near the epinucleus (E), ultrasonic power is again reduced to perhaps 60% to efficiently remove that material. The foot pedal depression is reduced to lower the power (4). Varying the power to just the minimum level required at each stage avoids excessive intraocular ultrasonic power, provides for a safer extraction, and avoids possible abrupt engagement of the tip with epinucleus and nearby the posterior capsule.
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aspiration line and actually determines the force with which the material is fixated onto the orifice in the phaco tip. This is known as fixation power or grasp and depends on the aspiration force (Figs. 59-60, 61). The higher the aspiration pressure, the more rapid the aspiration flow, and the less the amount of time it takes to obtain the maximum vacuum power. If the occlusion at the tip is broken or interrupted, due to the negative pressure in the aspiration line, fluid is rapidly sucked out of the eye. This may lead to collapse of the anterior chamber with risk of damage to the corneal endothelium as well as the posterior capsule. This is known as the Surge Phenomenon (Figs. 61-65).
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in order to keep the nucleus fragments close to the phaco tip and prevent the vibrating effect from repelling the fragments from the tip opening. We need a higher flow of aspiration to bring the fragments of the nucleus to the tip of the handpiece and make the procedure faster.. In this Memory 2, we also need higher vacuum since here we need to have good grasping power to hold the fragments against the phaco tip so that we can proceed to emulsify them. Memory 2 is the memory for fragment mobilization and emulsification. In Memory 3: removal of epinucleus, all the parameters are lowered considering that the epinucleus is soft. Memory 3 is specifically for the epinucleus, whenever it exists.
How to Program the Machine for Optimal Use
Fluid Dynamics During Phaco
We have already discussed the phacoemulsificator’s settings which include the ultrasonic power, the aspiration flow, which is the power of attraction and the vacuum, which is the grasping power. In order to perform a rational phaco, we must know how to program or calibrate the "memory" of the machine. There are three memories in the machine. Memory 1 is for sculpting the nucleus( Figs, 55, 56), Memory 2 is for fragmentation, mobilization and emulsification of the nuclear fragments (Figs, 67, 68) and Memory 3 is for removal of the epinucleus, when this exists (Fig. 69). In Memory 1: nuclear sculpting, we need high ultrasound power with low flow and low vacuum since at this stage we do not need any fixation or attraction power. In Memory 2: nuclear fragmentation, however, we need low ultrasound or phaco power
Michael Blumenthal, M.D., has made profound studies on this most important subject. Its understanding really makes a difference between success and failure in small incision cataract surgery, particularly in phacoemulsification. There are two factors specifically involved: 1) the amount of inflow and 2) the amount of outflow during any given period of the surgery. Fluid dynamics are responsible for the following intraocular conditions during surgery: a) fluctuation in the anterior chamber depth; b) turbulence; c) intraocular pressure. Blumenthal has pointed out numerous times that zero fluctuation is the target to be achieved in surgery, insuring that intraocular manipulations are most effective and accurately performed as well as keeping steady and natural the intraocular architecture and relationship between various tissues (Figs. 57-60).
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Figure 56: Use of Different Phacomachine Parameters to Sculpt the Nucleus for Making Quadrants Memory 1 - Divide and Conquer Technique A linear vertical furrow is made in the nucleus from 6 to 12 o'clock. A second furrow in the lens is made perpendicular to the first using the phacoemulsifier probe. The phaco probe (P) and manipulator (M) engage opposite sides of the furrow inferiorly. Force is applied with the instruments in opposing directions (arrows) to crack (C) the nucleus along the length of the furrow. Additional manipulations of this type further lengthes and deepens the crack. The lens is rotated 90 degrees within the capsular bag and a crack is made in the second furrow in the same manner (not shown). (The incision during transition should be limbal based. Corneal incision shown here is for advanced surgeons.) The parameters of the machine used to create the furrows in the lens are shown in the figures within the rectangular table immediately above this figure. At this stage, the surgeon uses Memory 1 which is shown digitally in the machine as 1. The digital figure under U.S. refers to the ultrasound power utilized at this stage in order to create the furrows in the nucleus. ASP refers to the aspiration flow rate, and the VAC shown on the machine refers to the amount of vacuum. These parameters are identified in the rectangle next to Fig. 56. By cracking the lens furrows at their base, the surgeon creates four separate quadrants of nuclear material. Manipulation of each quadrant for individual removal is carefully guided by use of flow and vacuum. Flow is used to move a quadrant to the phaco tip (P). Once engaged, vacuum is used to impale and manipulate the quadrant for safe removal.
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Fluctuation in the anterior chamber depth is the consequence of the following conditions: the amount of outflow exceeds the amount of inflow in a given period. As a result, the anterior chamber is reduced in depth or collapses (Figs. 62 and 63). When the amount of outflow is reduced below the amount of inflow, the anterior chamber depth is recovered (Fig. 65). This phenomenon, when repeating itself, increases fluctuation. When fluctuation occurs abruptly, as in the sudden release of blockage of the phaco tip in aspiration, this is called Surge (Figs. 61-65).
Fluidics and Physics of Phacoemulsification Barry S. Seibel, M.D., in his classic book Phacodynamics, presents perhaps the
most complete study on the physics on phacoemulsification and the fluid dynamics involved. This must reading for anyone who wants to delve more deeply into this subject. Seibel points out that phacoemulsification surgery is essentially the integration of two basic elements: 1) you use ultrasound energy in order to emulsify the nucleus; 2) you utilize a fluidic circuit in order to remove the emulsified material through a small incision while maintaining the anterior chamber depth integrity. This fluidic circuit is provided by an elevated bottle of BSS that produces not only the volume of fluid within the circuit but also provides the pressure in order to maintain the anterior chamber hydrodynamically and hydrostatically. When outflow and inflow are balanced, the pressure of the anterior chamber is proportional to the height of the bottle (Figs. 49-A, 49-B).
Figure 57 : Fluid Dynamics - Balance of Flow When the Phaco Tip Is Unoccluded - Hydrodynamic Balanced System When the phaco tip is unoccluded (D), the outflow rate of fluid from the eye (blue arrows) is determined by the rate (G) of pumping action of the peristaltic pump (F) under surgeon control. In the unoccluded "hydrodynamic" balanced system, inflow (red arrows) from the infusion bottle (B) will replace (C) the aspirated fluid at the same rate, to maintain the constant intraocular pressure determined by the height of the bottle above the eye. In this unoccluded case, the rates of inflow and outflow are equal.
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This fluidic circuit is regulated by a pump which not only washes the emulsified substances but also provides a highly useful clinical purpose. When the tip of the phaco handpiece is not occluded, the pump produces certain currents within the anterior chamber, which are measured in milliliters per minute, which are responsible for attracting the nuclear fragments towards the phaco tip. When a fragment completely occludes the phaco tip, the pump provides a vacuum which is measured in mm Hg, which holds the fragments firmly against the phaco tip (Figs. 57-60). There are two main types of pumps utilized during phaco: The Flow pump and the Vacuum pump. The Flow pump, responsible for the direct control of flow, physically regulates the fluid within the aspiration line by direct contact between the fluid and the mechanism of the pump. Even though the scroll pump is the latest type of flow pump, the one traditionally known as the peristaltic pump is the more commonly utilized. One of its important characteristic is the capacity to control the flow of fluid as well as the vacuum. This allows the aspiration flow to be independent of the height of the bottle of fluid. Nevertheless, it is dependent on the degree of occlusion of the phaco tip. Aspiration flow diminishes when the degree of occlusion at the phaco tip increases and aspiration stops completely when the occlusion at the phaco tip is total (Figs. 59, 60). These pumps have in common a drainage cassette adapted to the aspiration line. The pumps are connected to the cassette and produce a suction which in turn propor-
Figure 58: Fluid Dynamics - Balance of Inflow and Outflow During Phacoemulsification - Tip Unoccluded - Hydrodynamic Balanced System This view is a close-up complement of what is illustrated in Fig. 57. The anterior chamber during phacoemulsification is a closed system in which there is both intake and output of liquid and where the pressure must be controlled. With nothing occluding the tip of the phaco handpiece (P), vacuum pressure is zero (table point 1), At this point, the inflow (green arrow) equals the outflow (red arrow) of the phacoemulsification probe, and the pressure in the eye is maintained and constant (table levels 2 and 3).
tionally regulates the flow of aspiration when the port of aspiration is not occluded. When the port of aspiration is occluded, the flow ceases and the suction is transferred to the cassette by means of the aspiration line to the occluded tip (Figs. 57-60). 117
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Figure 59 (above left): Fluid Dynamics - Balance of Flow When the Phaco Tip Is Occluded with Lens Material - Hydrostatic Closed System When a piece of nuclear material (N) is drawn to and blocks (occludes) the aspiration port of the phaco tip, fluid balance is still maintained within the eye. Although the pump (F) is still running, it can no longer providing fluid outflow (D) because the system is blocked, but it is now providing vacuum pressure, holding the occluding fragment. In the balanced "hydrostatic" closed system, inflow (C) ceases at the same time since it now has nowhere to move. Controlled intraocular pressure is maintained via the inflow line to the level determined by the height of the bottle (B) above the eye. Equal zero rates of inflow and outflow is revealed by no drainage (G) from the occluded yet balanced system.
Figure 60 (below right): Fluid Dynamics Balance of Inflow and Outflow During Phacoemulsification - Tip Occluded With Lens Material - Hydrostatic Closed System This view is a close-up complement of the fluid dynamics shown in Fig. 59. When the tip of the phacoemulsification probe is occluded with nuclear material (L), the vacuum pressure rises to a level to which the machine is set (table - arrow - 1), and the inflow and outflow rates go down (table 2 and 3 - green and red arrows). With the aspiration port occluded, no fluid can enter or exit the eye.
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Importance of and Understanding the Surge Phenomenon The Surge phenomenon occurs when a fragment of nuclear material is suddenly displaced from occlusion through the aspiration tip at the handpiece of the phaco machine,
thereby giving rise to a sudden elevation of the output of fluid from the anterior chamber (Fig. 61). The output of fluid suddenly becomes larger than the input of fluid. This differential results in sudden collapse of the anterior chamber and can lead to serious complications (Figs. 62, 63).
Figure 61: Mechanism of the Undesirable Surge Phenomenon One problem area of the closed phaco system occurs during abrupt dislodging of an occluding piece of lens material so othat it no longer occluds the aspiration port of the phaco tip. A sudden drop in intraocular pressure occurs as the fluid rate into the eye fails to immediately match the sudden fluid rate out of the eye. This is known as the Surge Phenomenon. (A) Shows a piece of lens material occluding the aspiration port of the phaco tip and is held in place by vacuum pressure created by the operating pump (D). (Note there is no drainage (E) from the blocked system.) Infusion from the irrigating bottle (C) has ceased, but is still providing controlled intraocular pressure due to its elevated position above the eye. With sufficient vacuum pressure from the pump and/or emulsification from the ultrasonic energy, the nuclear piece will abruptly enter the aspiration port and the fluid system will once again open (B). Because the plastic infusion/ aspiration lines and the eye walls are flexible in absorbing the sudden inflow-outflow pressure differential, there occurs a moment when the infusion fluid (G-small arrow) does not effectively enter the eye fast enough to replace the fluid suddenly moving out of the unblocked system (F-large arrow). Outflow rate from the force of the pump is momentarily greater than the replacing infusion rate. This out of balance system (out of balance in not providing constant intraocular pressure) in which the eye momentarily absorbs the inflow/outflow rate differential, may traumatically collapse the eye for a short period. (See Figs. 62 and 63).
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Figure 62 (above left): Physical Problems Caused by Surge During the Surge Phenomenon when a nuclear piece (F) is abruptly aspirated from the eye, the anterior chamber may collapse due to a sudden loss of intraocular fluid. The cornea (C) may cave in, resulting in possible endothelial cell damage if it comes near the phaco probe. The posterior capsule (D) may also be damaged from anterior displacement toward the instrument. The fluid outflow rate must be brought under control, and the inflow rate (small red arrow) and outflow rate (large blue arrow) are again equalized with the eye repressurized, to reestablish a balanced system with constant, controlled intraocular pressure is not maintained.
Figure 63 (below right): Problem of Surge During Phacoemulsification This view is a close-up complement of what is shown in Figs. 61 and 62 and explained in their respective figure legends. Here we perceive more clearly the complications within the eye caused by the outflow surge phenomenon. Surge may occur after a fragmented piece of lens nuclear material is suddenly no longer occluding the aspiration port. Aspiration occurs abruptly and the vacuum usually goes to 0 (table point 1 - blue arrow). This sudden aspiration of too much liquid from the eye (large red arrow within the a.c.) is greater than the rate at which the inflow can replace the liquid aspirated (small green arrow in phaco probe). Notice that the table shows the outflow rate is large at this stage (table point 3 red cube and arrow) and the inflow rate (table - point 2 green cube and arrow) has not caught up with it. This differential causes the posterior capsule to move forward (E) and the corneal endothelium to move inward (D), which can result in severe complications.
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When the phaco tip is not occluded, excess vacuum is zero (0), (Fig. 58) but the flow of aspiration is very high with a large quantity of flow going in and out from the anterior chamber. Note the distinction between the normal suction, or vacuum, pressure which always exists in Positions 2 & 3, and which must exist to produce the normal aspiration flow we speak of, with the extra "vacuum" pressure which builds up when there is tip occlusion. When the phaco tip is occluded with nuclear material, the outflow of fluid stops and the vacuum rises to the maximum level to which the machine was originally calibrated and which we previously described (Fig. 60). This high vacuum aids the rapid emulsification of the nuclear fragment with or without ultrasound. When there is much more sudden outflow of fluid from
the anterior chamber than the inflow, the chamber collapses with possible rupture of the posterior capsule and damage to the endothelium (Figs. 61-65).
Lessening Intraoperative Complications from the Surge As emphasized by Centurion, the latest generation of phacoemulsification machines make surge control possible (Figs. 64, 65). With these machines it is possible to work with a high vacuum of more than 300 mm while maintaining a steady flow rate. When the last part of the nuclear material goes through the phaco tip, a sensor located at the aspiration line signals a micro processor to slow the rate of the pump. Sometimes there is some reflux in the process of maintaining the
Figure 64: Technical Solution to Prevent the Undesirable Surge Phenomenon One technical solution for eliminating the surge phenomenon involves the use of a high-tech microprocessor. (Fig. A) When a nuclear piece (F) occludes the aspiration port and then suddenly (B) is aspirated (F-arrow) by the vacuum pressure of the pump (P), a sensor (E) located on the aspiration line signals a microprocessor (G) in the unit that an abrupt surge in aspiration flow has begun to take place. Within milliseconds, the microprocessor directs the motor of the pump (P) to slow down. The reduction in aspiration rate resulting from the slowed pump occurs before the eye can collapse from any volume differential encountered between sudden inflow and outflow rates. The potentially dangerous surge phenomenon is avoided. This elimination of the surge phenomenon allows the surgeon to safely use higher vacuum rates (necessary in some situations) with a reduction in the need to use potentially damaging high ultrasonic power settings. Surgery becomes safer and faster.
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same intraocular pressure. This high speed mechanism insures that the pressure is always the same inside the eye. As emphasized by Barry Seibel, the surge phenomenon occurs in positions 2 or 3 of the foot pedal when a nuclear fragment totally occludes totally the phaco tip. Vacuum builds up in the aspiration line, the lens material is emulsified sufficiently so that it is quickly drawn within the phaco tip, the occlusion is broken, and there is a sudden surge of aspiration, emptying the anterior chamber.
The surge phenomenon is more of a concern when you utilize a conventional tip with the 0.9 port with high vacuum and flow of aspiration. It is less of a problem when you utilize the irrigation-aspiration tip with the smaller opening (0.3 mm). In addition, it is possible to diminish the propensity for surge during phaco by utilizing a more resistant type of tip such as the Microflow or the Microseal or with the systems ABS which we describe in Chapter 8, (Fig. 84).
Figure 65: Advances in Equipment Technology to Prevent the Surge During Phaco This is a close-up view of the anterior segment showing what is illustrated and explained in Fig. 64 and its figure legend. The latest generation of phacoemulsification machines make surge control possible. During the problem period when the last part of the nuclear material is aspirated through the phaco tip, a sensor signals a microprocessor to slow the rate of the vacuum pump. As a consequence, when the nuclear material no longer occludes the phaco tip and the sensor detects that the vacuum pressure is dropping suddenly (table point 1 blue arrow and block), the sensor instantly sends a signal to the pump to slow the outflow rate (broken red arrow next to phaco tip). The outflow rate (table point 3 - broken red arrow and block) is thereby moderated to allow the inflow rate time to catch up (table point 2 green arrow and block ). This control of the pump action allows inflow and outflow rates increase together in a more equal fashion during this moment of potential negative surge. This makes surgery much safer, quicker and easier.
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NUCLEUS REMOVAL APPLICATION OF PHACO FRACTURE AND EMULSIFICATION This is really when the surgeon begins to utilize the ultrasound energy in the phaco machine and apply it within the patient's eye. During the transition period, this is a step that should be preceded by a good number of hours of practice in the experimental laboratory until the surgeon is confident in the application of the ultrasound energy. It implies that he or she
has been able to successfully perform all the previous steps over and over again in different patients. This experience will serve the surgeon as the requisite basis for success in the emulsification and removal of the nucleus in the present patient. In removing the nucleus the surgeon first attempts to divide the nucleus by fragmenting it into smaller portions that in due time will then be emulsified individually (Figs. 55, 56, 66, 67, 68). If the fracture or division of the nucleus has been incomplete and has resulted in large pieces or incomplete fractures, the surgeon will not be able to perform the pha-
Figure 66: The Role of Cavitation in Breaking the Cataract Inside the Bag There are two forces involved in emulsifying a cataract. One is the mechanical force of the ultrasound as shown in Figs. 55 and 56 and explained in their respective figure legends; and 2.) the mechanism of cavitation. The magnified section of cataract presented here shows that as the phaco tip makes its tiny ultrasonic movements, the energy releases bubbles (B) inside the nucleus creating cavities (C). The build-up of bubbles inside the nucleus creates new hollow spaces (C) in the lens structure, the phenomenon of cavitation. This cavitation facilitates the break-up and destruction of the cataract. Some of the new phaco tips as shown in Fig. 51 are designed to produce more cavitation. The one shown in this figure is one of the best, designed by Kelman for the Alcon phaco machines. It has a very thin tip with a 30 degree bend. It is particularly effective in hard nuclei because of its enhanced cavitation.
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coemulsification successfully or he will need to use so much ultrasound energy that there may be endothelial damage. Present techniques of phacoemulsification are precisely geared to avoiding the use of large amounts of ultrasound energy. There are different techniques for the fracture of the nucleus. In the end, the surgeon will decide which one he prefers or feels more secure with. Often, it depends on the type and maturity of the cataract. At this stage of the transition, when the surgeon is only beginning in his experience in fracturing and dividing the lens to apply the ultrasound, the most recommended procedure is to divide it into four quadrants, the well known "divide and conquer" first presented by Gimbel (Fig. 56). Later, the surgeon will be able to utilize other modern techniques which also use high vacuum and low phaco but which may be too difficult in the transition. At this stage of division or fracturing of the lens in the transition, it is recommended that the surgeon use Memory 1 of the phaco machine (Fig. 56) which implies a discretely high amount of ultrasound, low or no vacuum, low aspiration and the conventional height of the bottle (65-72 cms).
The Divide and Conquer Technique In the "divide and conquer" technique, the phacoemulsification instrument is used to create a deep tunnel in the center or the upper part of the nucleus. The nucleus is split into halves, sometimes fourths, and even occasionally into eighths. Splitting the nucleus is safer for the endothelium and easier to learn, especially for the less experienced ophthalmologist converting from planned extracapsular surgery to phacoemulsification. It is easier to keep smaller particles away from the endothelium
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without having to push them against the posterior capsule than it is to emulsify a large, cumbersome nucleus. The nuclear fracturing techniques developed by Gimbel are in part possible because of the CCC (capsulorhexis) technique that Gimbel and Neuhann originated. The mechanical fracturing of the lens causes extra physical stress within the capsule, and that cannot be done without great risks of tears extending around posteriorly unless you have a proper CCC. There is almost an interdependence of these two methods. The fracturing techniques have not only provided more efficiency in phacoemulsification in routine cases; they have also made phacoemulsification in difficult cases safer and more feasible. Gimbel clarifies that not only are there lamellar cleavage planes corresponding to the different zones of the lens, but also there are radial fault lines corresponding to the radial orientation of the fibers, as first described by Drews. Until the development of these nuclear fracturing techniques we had not taken advantage of this construction (Figs. 55,56,67,68). The lens fractures quite readily in radial or pieshaped segments (Fig. 67). To accomplish this radial fracturing, the surgeon must sculpt deeply into the center of the nucleus and push outwards (Fig. 56). Sculpting is used to create a trench or trough in the nucleus. Then the surrounding part is divided into two hemisections. The separation must occur in the thickest area of the lens located at the center of the nucleus (Figs. 103 and 104). An additional consideration with these types of nuclear fractures is whether the segments should be left in place until all the fracturing is complete or whether they should be broken off and emulsified as soon as they are separated. With a lax capsule and particularly with a dense, or brunescent nucleus (Fig. 2),
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Figure 67 (above left): Emulsification of Lens Fragments This surgeon's view shows the management of the lens quadrants. The apex of each of the four loose quadrants is lifted, the ultrasound phaco tip is embedded into the posterior edge of each and by means of aspiration the surgeon centralizes each quadrant for emulsification.
Fig. 68 (below right): Emulsification of Lens Fragments In this cross-section view you can see the loose quadrants ready for emulsification by phaco as illustrated through a surgeon's view in Fig. 67. Here you see a viscoelastic (V) being injected via a cannula (C) into the cleavage created by hydrodissection of the posterior nucleus from the posterior cortex and epinucleus as shown in Fig. 47 (blue arrow). The "viscoelastic sandwich" helps protect the posterior capsule to prevent its rupture when the nucleus is undergoing manipulation and emulsification. Note viscoelastic liquid filling the anterior chamber (blue arrow). The parameters of the phaco machine at this stage of emulsification of lens quadrants with aspirationfragmentation of the nucleus are shown within the rectangular table immediately above this figure. Memory 2 is shown digitally in the machine and by sound as 2. U.S. refers to the ultrasound power used. ASP is identified as the flow rate and VAC as the amount of vacuum, all specifically at this stage.
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Gimbel considers that it is safer to leave the segments in place to keep the posterior capsule protected. The segments are easier to fracture if they are held loosely in place by the rest of the already fractured segments still in the bag (Fig. 105).
Emulsification of the Nuclear Fragments If the surgeon has been successful in the fragmentation of the nucleus, the next step is to emulsify the pieces of segments of the divided nucleus. He may do this with the linear continuous mode or with the pulse mode. The latter done during the transition provides more security for the surgeon and allows him to use less ultrasound which is the definite tendency at present. The surgeon may later slowly begin to utilize other more specialized techniques known as the different "chop" techniques which we will discuss later. These techniques facilitate much more the emulsification of the segments or pieces of the fractured nucleus than the divide and conquer but they are a little more complex. During this step of emulsification of the nuclear fragments, the surgeon may use Memory 2 in the machine which delivers low ultrasound, high vacuum, and a larger flow of aspiration, with a conventional height of the bottle of fluid (Figs. 67, 68).
FINAL STEPS Aspiration of the Epinucleus It is during this specific step that there is a higher incidence of rupture of the posterior capsule for the surgeon in the period of transi-
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tion. This is due to his lack of familiarity with handling large fragments of epinucleus and cortex since in the planned extracapsular extraction he is accustomed to remove a large and complete nucleus that includes all the epinucleus and a significant amount of cortex. During the transition, the surgeon has to manage safely the irrigation-aspiration handpiece. Later, when he masters the technique, he may aspirate the epinucleus and cortex by maintaining the aspiration with the tip of the phaco handpiece. For this stage of the aspiration of the epinucleus, the surgeon will use Memory 3 which means very low or no ultrasound power, a moderate to high vacuum, and high flow of aspiration, with the bottle of fluid maintained at the conventional height (Fig. 69).
Aspiration of the Cortex This step is closely related to the previous one (Figs. 70, 71). There can also be a larger incidence of posterior capsule rupture during this stage since the surgeon does not have the epinucleus as a barrier which up to a few seconds before was protecting the posterior capsule. The surgeon should use a larger quantity of viscoelastic whenever required with the purpose of protecting the posterior capsule. During the transition period, he may help his maneuvers by using the Simcoe cannula with which the planned extracapsular surgeon usually feels safe. This cannula may be introduced through the ancillary incision. The Simcoe cannula has the disadvantage, though, that the aspiration hole or aperture is smaller than that of the irrigation-aspiration handpiece of the phaco machine. Consequently, the aspiration of the masses of cortex may become more difficult and slow. During this stage, the sur-
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Figure 69 (right): Epinucleus Removal Once the nucleus has been extracted, similar flow and vacuum presets are used to remove the epinucleus. Moderated control of flow, then vacuum are essential to a successful and safe removal as identified in the parameters above this figure. Higher flow and vacuum rate are inappropriate for engaging the epinucleus located so close to the posterior capsule (R) and iris. Too low a flow and vacuum will fail to engage the epinucleus. A moderate flow rate is used to draw (arrow) the distal epinucleus (C) to the phaco tip (P) without pulling in the capsule or iris. Once the phaco has engaged the epinucleus, moderate vacuum is used to maintain its grip on the epinucleus to remove it as a whole, as centrally in the pupil as possible. Too high a vacuum may abruptly break away a piece of the epinucleus and penetrate the epinuclear bowl and threaten the posterior capsule beneath. Too low a vacuum setting during removal may lose its grip on the epinucleus and lengthens surgery. During the transition stage, use a limbal incision. The corneal incision in this figure is for experienced surgeons. During epinuclear removal use Memory 3, as shown.
Figure 70 (left): Phacoemulsification - Removal of Residual Cortex in Transition The ultrasound tip is exchanged for an irrigation-aspiration tip (I/A), which is smaller and finer than the ultrasound tip. The anterior edge of cortex is engaged at the 6 o’clock position. The instrument peels cortex from the posterior capsule and removes it using the Memory 4 setting. The parameters are shown in the rectangle above this figure. Please observe that the vacuum is significantly increased and the aspiration and flow rate are moderately higher than the step shown in Fig. 69. This figure shows (for didactic purposes) a larger amount of cortex than the experienced surgeon has to deal with. This mass of cortex is what may be seen during the transition phase which is the step of the operation we discuss in this chapter. The experienced surgeon performs a more effective hydrodissection and frequently does not need to perform irrigation/aspiration because little cortex remains. He/she remove the epinucleus usually during the emulsification process.
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Figure 71: Phacoemulsification - Irrigation/ Aspiration of Residual Cortex Residual cortex (C) is removed from the capsular bag using curved Irrigation/Aspiration probes. A slightly curved tip is used to gently aspirate residual cortex nasally and temporally. Residual cortex located in the hard-to-reach aspects of the superior capsular bag are reached with a very curved I/A probe tip. The machine parameters used at this stage are shown with Fig. 70, and correspond to Memory 4. The corneal incision shown here is for surgeons experienced enough that no conversion to extracapsular is expected. For surgeons in their transition period, a limbal incision is more prudent.
geon should use Memory 4 in the setting of the machine which means zero phaco power, maximum vacuum and the highest flow of aspiration as compared with all the previously mentioned memories. The fluid bottle is maintained at the conventional height.
Intraocular Lens Implantation For the surgeon in the stage of transition, it is advisable to begin by implanting PMMA IOLs either of the ovoid shape (Fig. 72-A) or with round optics of a fairly small diameter. The ovoid 5 x 6 lens shown in Fig. 72-A is just right.
Enlarging the Incision and Implanting the Lens In order to accomplish this the surgeon needs to extend the small incision with which he started,
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to 5.2 mm. A 5.2 mm knife blade will do this most accurately. In extending the arc of the incision, the surgeon must maintain the valvelike, auto-sealing characteristics present in the original small incision. The PMMA IOL implantation is performed as shown in Fig. 72-B. After this stage has been mastered, the surgeon may then change to implantation of the foldable lenses but this must be done only after the surgeon is completely satisfied with his phaco technique.
Removal of Viscoelastic Throughout the different stages of this procedure, the presence of viscoelastic in the anterior chamber is always a measure to keep in mind in order to prevent or minimize damage to the surrounding structures during surgical maneuvers, particularly the corneal endothelium. When removing viscoelastic from the anterior chamber, the phaco machine must be
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in zero phaco or ultrasound, high vacuum, very low aspiration and the bottle of fluid should be significantly lower. After all the surgical steps have been accomplished, it is important, as we all know, to remove the viscoelastic in order to avoid a high intraocular pressure postoperatively, with subsequent corneal edema, blurred vision and pain during the first postoperative days. Even though this measure of removing all the viscoelastic has been emphasized over and over again in lectures and published papers, there are still surgeons who are not fully aware of the importance of taking this step and the consequent complications.
Closure of the Wound If a good incision has been made, valvelike, auto-sealing and waterproof, no suture will be absolutely necessary even in those cases where the wound has been extended to an arc of 5.2 mm for the PMMA IOL implantation as shown in Figs. 72-A and B. As long as these two requisites are met, that is, extending the incision to 5.2 mm with a special knife blade of that size and maintaining a valve-like, autosealing incision, there is little danger of complications without sutures. Nevertheless, if the surgeon is not sure he has made a valvulated
Figure 72 A: The Ovoid PMMA IOL for Implantation During the Transition During the transition period, the limbal incision is enlarged to 5.5 mm size and a 5 x 6 mm ovoid PMMA lens (Fig. 72-A) is implanted through this incision. The optical zone should not be smaller.
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Figure 72 B: PMMA IOL Implantation in Transition Period Before implanting the PMMA IOL, the surgeon should irrigate, with machine parameters of U.S. zero power, ASP 50 and VAC 500. After irrigation, the surgeon introduces viscoelastic in the A.C. and bag before IOL implantation. Lubricate the lips of the incision with viscoelastic first. The use of foldable IOL's introduced through a clear corneal incision is a goal to be tried and attained later, when the surgeon feels more comfortable with his surgical technique.
incision from the beginning (3 steps Fig. 40-A and 42 A-B), even a 3 mm incision with no sutures will leak. If so, to leave the patient without any sutures would be to take an unnecessary risk. It is more prudent to place two or three 10-0 nylon sutures in the wound and they may be removed early in the postoperative stage. This decision really depends on the ability of the surgeon to create a valve-like, self sealing incision.
What to Do if Necessary to Convert When the surgeon decides to convert from phaco to extracapsular,, viscoelastic is placed in the anterior chamber. The incision is 130
enlarged to one side and 2 or 3 sutures are placed (pre or post placed). The incision is completed to the other side and 2 or 3 more sutures are put in place (pre or post placed ). The two superior sutures are placed at either end of the "valve incision", so that irrigationaspiration (I + A) can be performed unhindered at that site. These two sutures are tied with a slip knot prior to I & A, and then loosened to place the IOL. The other sutures are tied and knots buried before I & A. At the end of the operation an additional suture can be placed if the incision is not secure. To reduce risks, the surgeon may preplace the 3 10-0 nylon sutures across a grove on each side first, before enlarging the incision.
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Testing the Wound for Leakage
incision. The small conjunctival flap is then advanced over the incision.
Before considering that the surgery is over, it is important to be sure that no leakage exists either through the main incision or through an ancillary incision, under the microscope. This is done by cleaning and drying the incision with a Weck-cell sponge, removing the viscoelastic and slightly overfilling the anterior chamber with BSS after the viscoelastic is removed and exerting mild pressure over the cornea with the sponge (Fig. 73) or using fine forceps to lightly "dance on" the cornea. At this time one can observe if there is any wound leak (Fig. 73). If the surgeon finds that there is a leak, the best way to solve it is by injecting BSS into the lips of the incision to hydrate the tissues and force the incision closed. This works even better for the small ancillary
Immediate Postoperative Management
Figure 73: Incision
After instilling antibiotic ointment and topical antiinflammatory drops, the eye may be patched if local anesthesia such as retrobulbar, peribulbar or sub-Tenon's were used. If only topical anesthesia or topical combined with intracameral irrigation anesthesia was used (Figs, 35, 36), you may leave the patient without any patch. This facilitates the postoperative use of antiinflammatory drops by the patient. The use of subconjunctival or parabulbar injection of antibiotics and steroids immediately following surgery, is no longer accepted as necessary, as was outlined in Chapter 4.
Evaluation of Leak Proof
This figure shows the surgeon checking to test if the incision is really leak proof, by doing the following: 1) after drying the lips of the incision, exhert light pressure over the cornea with Weck sponge. The "shadow" image represents the sponge delicately "dancing" over the cornea. Look for any fluid escaping through the wound. 2) inject fluid through the paracentesis and observe if any drops of fluid come out through the previous incision. If a leak is found, the surgeon must suture the wound.
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RECOMMENDED READINGS
Seibel, BS: Phacodynamics: Mastering the Tools and Techniques of the Phacoemulsification Surgery, Third Edition, 1999.
BIBLIOGRAPHY Barojas, E: Importance of hydrodissection in phaco. Guest Expert, Boyd’s BF The Art and the Science of Cataract Surgery of HIGHLIGHTS, 2001. Benchimol, S., Carreño, E: The transition from planned extracapsular surgery to phacoemulsification. Highlights of Ophthalmol. International English Ed., Vol. 24, 1996, Nº 3. Carreño, E.: From can opener to capsulorhexis: the crucial step in the phaco transition. Course on How to shift successfully from mannual ECCE to machine-assisted small incision cataract. AAO, Oct. 1999. Carreño, E.: Hydrodissection and hydrodelineation. Guest Expert, Boyd’s BFThe Art and the Science of Cataract Surgery of HIGHLIGHTS, 2001. Centurion, V.: The transition to phaco: a step by step guide. Ocular Surgery News, Slack, 1999. Drews, RC.: YAG laser demonstration of the anatomy of the lens nucleus. Ophthalmic Surgery 1992. 23:822-824. Koch, PS: Hydrodissection. Simplifying Phacoemulsification. Fifth Edition, Slack, 1997, 8:8798.
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C h a p t e r 8: Instrumentation and Emulsification Systems
INSTRUMENTATION AND EMULSIFICATION SYSTEMS INSTRUMENTATION
Fixation Ring
Phacoemulsification uses many of the same instruments that are used in conventional extracapsular cataract surgery. We will not refer to them in this chapter because every cataract surgeon is fully familiar with such instruments. This chapter is exclusively focused toward those instruments especially created for phacoemulsification surgery or those that may have common features for both techniques, extracapsular and phaco, but that have required modifications for the surgeon to undertake successful phacoemulsification surgery. There are multiple variations of each type of instrument. Consequently, rather than referring to the instruments by the name of their creators or proponents, we will focus here on the specific characteristics needed for phaco surgery. These instruments are:
Its use is optional but it may be quite helpful during the construction of the limbal or the clear cornea tunnel incision because it produces fixation of the globe throughout the circumference of the ring. The most popular fixation ring is the Fine-Thornton (Fig. 75). If the surgeon prefers not to use the fixation ring, the globe may be fixed with very fine 0.12 toothed forceps.
Eye Speculum It is very important to have the right eye speculum (Fig. 74). Since topical anesthesia is utilized by most experienced phaco surgeons, the speculum must have a lock to prevent the lids from closing and squeezing during surgery. The speculum should not interfere with the surgeon's movements and instrumentation when operating in the upper temporal quadrant, which is the approach mostly utilized today.
Knives and Blades There are two options for the knives and blades (Figs. 76-77): 1) utilize stainless steel disposable knives (Fig. 76); 2) use diamond knives which can be re-sterilized (Fig. 77). Both types of knives and blades have their advantages and disadvantages. The selection really depends on the preference of the surgeon. The disposable stainless steel blades and knives have reached a very high level of quality and precision. They may be re-sterilized for a small number of cases, certainly no more than four or five. They require a lower initial investment and less care when handling by the nurses and assistants. Nevertheless, when we are going to make a clear corneal incision and tunnel, it is recommended to use a diamond knife which can be calibrated (Fig. 77). Those knives and blades can be manufactured with different parameters. Those for paracentesis (Fig. 76 B) have an angulation of 30 degrees.
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Figure 74 (left): Eye Speculum Phaco surgery using topical anesthesia requires that the eye speculum design offer sufficient aperture for operating from the side, which is always done from 9 to 12 o’clock, whether right or left eye. The speculum has a lock and strong arms to keep the eye open in case that the patient squeezes the lids.
Figure 75 (right): The Fine-Thornton Fixation Ring Some surgeons find this fixation ring useful, particularly during the construction of the limbal or the clear cornea tunnel incision. Other surgeons prefer to fixate the globe with a forceps.
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Crescent knives (Fig. 76-C) have a rounded point which is fundamental in the construction of the tunnel in the incision as shown in Fig. 41B, Chapter 8. The disposable knives with sharp points range from 2.6 to 3.2 mm (Fig. 76-A). They are particularly useful in the small incisions when utilizing different sized phaco probes and tips as shown in Figs. 82 A and B. The 5.2 mm blunt point blades as shown in Figs. 76-D may be highly useful to enlarge the incision in case of PMMA 5.5 mm intraocular lens implantation or larger as shown in Fig. 72 A. There is, however, an increasing tendency to utilize diamond knives because the surgeon is able to obtain a perfect incision. The knives also last for a long time.
Consequently, for surgeons who do a major amount of surgery, the diamond knife may be, in the end, economically more efficient. In Fig. 77 you may see diamond knives designed for various purposes, 77-A for paracentesis or side port incision (also shown during surgery in Fig. 41-A); Fig. 77-B for a 3.2 mm incision or slightly smaller as in Carreño's Phaco Sub-3 technique, also shown in Fig. 40 C. Fig. 77-C shows the crescent type of knife, also seen in the surgical steps in Fig. 41-B and Fig. 42. Very narrow sharp pointed blades are being developed to perform the 1 (one) mm incisions to be used with Dodick's PhotoLysis recently approved by the FDAusing a special ND-YAG laser.
Figure 76: Stainless Steel Disposable Knives for Phacoemulsification (A) Knife to make a 3.2 mm primary incision. (B) Blade with a 30 degrees angulation for paracentesis or sideport incision to allow introduction of the second instrument (manipulator or chopper) and other purposes such as viscoelastic injection. (C) Crescent knife. The rounded point is fundamental in the construction of the tunnel incision. (D) This 5.2 mm blunt point blade may be highly useful to enlarge the incision in case of PMMA 5.0 x 6.0 mm optics as the one shown in Fig. 72-A intraocular lens implantation or larger .
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Figure 77 (left): Diamond Knives (A) Utilized for side port or paracentesis incision (also shown during surgery in Fig. 41-A). (B) This blade is used for 3.2 mm incision or slightly smaller as in Carreño's Phaco Sub-3. This knife is also shown in Fig. 42. (C) Crescent diamond knife with rounded point fundamental in the construction of the tunnel incision( also shown in Figs. 41-B and 42).
Figure 78 A (right): Hydrodissection Cannula Under the Anterior Capsule. For this purpose it is recommended to use a 25 G flat tip cannula. Observe how the cannula enters below the edge of the capsulorhexis performed on the anterior capsule. The surgeon then injects the BSS to separate the capsule with the cortex from the nucleus.
Hydrodissection Cannula This special cannula is shown in Fig. 78-A and in Figs. 46 - 48. These cannulas are especially made with a rectangular and 27 G diameter that facilitates the injection of liquid to separate the anterior capsule from the cortex. They are re-sterilizable. They should be connected to a 3 or 5 cc syringe to allow a better effect from dispersion of liquid. For hydrodissection, there are also other special cannulas in the form of "J" which may be useful for specific maneuvers as shown in Fig. 47.
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Cystotomes or Capsulorhexis Forceps There are several alternatives to the selection of cystotomes. One group is already designed and manufactured for this purpose, with 25, 27 and 30 G calibers. Some surgeons prefer to bend the tip of an insulin needle, which provides a very sharp point. The main characteristic of the cystotome is that it must be very sharp to facilitate the creation of the first capsular flap during capsulorhexis and enable the surgeon to continue performing a curvilinear capsulorhexis. These cystotomes must be easily adjustable to the needs and comfort of the surgeon in his/her maneuvers.
As to the capsulorhexis forceps (Fig. 78 B-C) there is a large variety and types of designs. The best known is the Utratta-Kershner forceps (Fig. 78-B left). The main characteristic of all capsulorhexis forceps is that they have very fine, resistant arms and tips that prevent trapping of the iris. Curved ends are highly useful so that the surgeon can manipulate more comfortably within the anterior chamber. In any case, they must be easily connected to a syringe that contains air or balance salt solution for injection in addition to the conventional viscoelastic, when the surgeon feels it is needed. There are other very useful capsulorhexis forceps such as the ones designed by Gimbel (Fig. 78 C), the Masket, the Corydon and several designed by Buratto.
Figure 78 B-C: Capsulorhexis Forceps (A) The Utratta-Kershner's forceps. (B) The Gimbel's forceps. All capsulorhexis forceps have very fine, resistant arms and the end of the tips are slightly curved (see inset) that will prevent trapping of the iris. Please observe the special design that is highly useful to manipulate more comfortably within the anterior chamber. Other popular capsulorhexis forceps carry the name of Masket, Corydon and Buratto.
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Nuclear Manipulators or Choppers (Second Instrument) These ancillary instruments are absolutely essential in order to adequately perform the maneuvers necessary to remove the nucleus, as described and illustrated in Chapter 9. There is a large variety of types and designs. These instruments are introduced into the anterior chamber through the ancillary or side port incision. The purpose of this second instrument, either the manipulator shown in Fig. 79
or the chopper shown in Fig. 80, is to facilitate the bimanual maneuvering and rotation of the nucleus, as well as allowing the chopping of it intofragments that are going to be emulsified. In Fig. 79 we show two well known lens manipulators: 79-A is the Lester instrument and Fig. 79-B is the Osher. In Fig. 80, you may see different types of choppers: 80-A the Fukasaku chopper and 80-B the DodickKamman chopper. Some of these instruments have a blunt tip, some longer or shorter length tips. All of them must have angulation as a common char-
Figure 79: Nuclear Manipulators (A) Shows the Lester nuclear manipulator. (B) The Osher manipulator. These are two of the most popularly used ancillary instruments essential to perform the bimanual maneuvers to remove the nucleus, as described in Chapter 9. These nuclear manipulators are essentially used in the non-chopping techniques.
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Figure 80: Choppers In this illustration you may see two of the most popularly used choppers (second or ancillary instruments) ustilized by the surgeon in the bimanual technique of removal of the lens nucleus with the chopping method as described in Chapter 9. (A) Shows the Fukasaku chopper. (B) shows the Dodick-Kamman chopper. Please observe that all the tips have a small diameter angulation (0.25 - 0.50 mm). they have a blunt tip which is able to cut or slice the nucleus. They must have sufficient strength in the tip to create and lead the forces of traction and rotation of the nucleus. All surgeons have available both types of ancillary instruments, the nuclear manipulators and the choppers, to use in the procedure that he/she decides for a specific patient.
acteristic, with the angulated tip being of very small diameter (0.25 - 0.50 mm). The tip is able to cut or slice the nucleus. They must have sufficient strength or resistance in the tip to create and lead the forces of traction and rotation of the nucleus and they must be smooth and blunt on the posterior surface in order to avoid damage to the surrounding tissues. Some surgeons have available both types of instruments, manipulators and choppers, depending on the type of surgery they are doing, because
although the surgeon has his procedure of choice, he/she is not bound to rigorously follow that same procedure in all cataracts. The surgeon has to adapt to different circumstances and situations. Other commonly known choppers are those of Seibel, Nagahara, Nichamin. There are some hooks that are specifically utilized for rotation of the nucleus. They need to be angulated and have the shape of a shirt button. The best known is the Lester.
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Forceps and Cartridge Injector Systems for Insertion of Foldable Intraocular Lenses Small incremental advancements continue to take place for placement of foldable IOL’s through small incisions. There is a definite trend toward the development of separate instruments for folding and inserting IOL’s rather than using the insertion device to fold the IOL. The majority of foldable lenses are inserted either by forceps designed by out-
standing cataract surgeons for this purpose (Fig. 81) or by a combination of instruments designed by the manufacturer to facilitate folding and insertion known as cartridge injector systems. Examples of often used forceps are shown in Fig. 81 and injectors in Fig. 82. Dodick prefers to use forceps to implant Alcon's AcrySof (acrylic foldable IOL). Other very popular and useful forceps are the Fine Universal III forceps (Rhein Medical, Tampa, Fla.) and the Buratto insertion forceps (American Surgical Instruments. Westmont, Illinois). The latter is used specifically for the acrylic lens.
Figure 81: Forceps for Insertion of Foldable IOL's There is a large variety of instruments designed for this purpose. The right design is related to the type of IOL you will be using. Here we present the Osher-Seibel folding forceps (A) with a curved design to easily fold most soft intraocular lenses. For the insertion, we shows the Blaydes angled lens forceps (B) that will help the surgeon to gently insert the IOL in the bag.
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Figure 82 AB (right): Injectors for Insertion of Foldable IOL's (A) The Allergan Unfolder. Sapphire Series Foldable IOL Implantation System: With very soft tip and design, the Unfolder Sapphire offers excellent control during the implantation of Allergan’s acrylic foldable intraocular lens. In this surgeon´s view we are presenting the Sapphire model for the acrylic IOL. Once the IOL is unfolding inside the capsular bag, the cartridge should be rotated with the tip aperture facing down to permit a smoth ejection of the IOL. (B) The Alcon Monarch Model. Foldable IOL Implantation System: The Monarch system´s design allows the acrylic foldable IOL to blossom out of the tip aperture in a safe, controlled way with no haptic harm. The injector tip is introduced through the phaco incision asobserved here, rotated and advanced to the center of the capsular bag were the lens is slowly injected and unfolded on one plane into the bag. Alcon is also continuing to develop finer injection through its high technology capabilities.
Figure 82 C (left): Alcon’s Acrylic System to Fold IOL's This special device allows the surgeon to carefully fold the acrylic IOL previous to its insertion. The IOL is positioned in the top center of the Acrypack. The optics of the IOL is shown here. Once in position the two arms of the Acrypack are slightly compressed and allow the surgeon to fold the IOL like a Mexican “taco” or a cigar. With the help of the insertion forceps (Fig. 81) you may then catch the lens not halfway but slightly closer to the folded part of the lens.
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Cartridge Injector Systems Some of the newest advances in lens insertion technology surround the use of cartridge injector systems. Fine, Lewis and Hoffman believe that there are many perceived advantages of implanting foldable IOLs with injector systems, as compared with folding forceps. These advantages include the possibility of greater sterility, ease of folding and insertion, and implantation through smaller incisions. Greater sterility with injector systems is believed to occur because the IOL is brought directly from its sterile package to its sterile cartridge and inserted into the capsular bag without ever touching the external surface of the eye, as is the case for lenses in folding forceps. Although this advantage would suggest a lower rate of endophthalmitis with injector systems, recent clinical studies have shown no significantly different rate of bacterial contamination of the anterior chamber after implantation of silicone lenses with a forceps versus an injector. Perhaps the most appealing advantage of injector systems is that the lens can be loaded by a nurse or technician without the use of an operating microscope, further streamlining the procedure. In addition, inserting foldable lenses with a cartridge device is generally felt to be easier than insertion with forceps, and these lenses can usually be implanted through a smaller incision when delivered by means of an injector, compared with an insertion forceps.
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Allergan's foldable three piece silicone lens (monofocal or multifocal - AMO Array) with PMMA haptics may be implanted with AMO's Unfolder Phacoflex injector system. Allergan's acrylic foldable IOL (Sensar and Clariflex lenses) may be implanted with a new injector now available and known as the Unfolder Sapphire, as described by Centurion (Fig. 82-A). These injectors are resterilizable (as are the forceps, of course). Alcon’s popular 5.5 mm AcrySof IOL may be implanted with one of its injectors such as the Monarch (Fig. 82) or with a standard cartridge through a 3.0 mm incision. Some have reported injecting this lens through a 2.8 mm incision. Many surgeons use Alcon’s Acrypack (Fig. 82) when implanting the AcrySof lenses. The Acrypack serves to first fold the IOL. The surgeon then uses a forceps (Fig. 81) to implant the already folded IOL. The Alcon AcrySof lens, which requires 3.5 to 4.0 mm incisions for 6.0 mm optics and 3.2 to 3.5 mm incisions for 5.5 mm optics, is now packaged in a wagon wheel dispenser. The easiest folding instrument to use for these lenses is the Rhein folder, because its tips have been extended to make it easier to remove the lens from the wagon wheel package. The forceps can be turned with the tips down in the nondominant hand. The tips go into the slots on both sides of the optics, so that the lens can be picked up and placed on a drop of viscoelastic. The forceps are then turned so that the tabs are down. The lens is grasped and folded, and then the insertion device in the dominant hand is used to insert the lens.
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Figure 83: Phaco Probe and Tip - Diverse Design and Diameters Here we may observe and compare a standard phaco tip (A) with 3.2 mm in diameter and a 3.5 mm incision width usually employed in scleral or limbal tunnel incisions. In (B) we present the angled Kelman phaco tip attached to a finer phaco probe inserted through a 2.6 mm corneal tunnel incision.This tip allows a smaller incision with less peri-incisional fluid escape. It also gives rise to less heat transmission to the lips of the wound.
THE PHACO PROBES AND TIPS In Fig. 83 you can see two different types of phaco probes and tips. In Fig. 83 (left), there is a larger caliber probe with a straight tip. This is particularly used when the incision is predominantly limbal. The incision is slightly larger than the one mostly utilized today which is the corneal incision shown in Fig. 83 (right). The probe in Fig. 83 (left) using a standard
phaco tip emits more heat which could harm the corneal lips. The phaco probe and tip, shown in Fig. 83 (right), is narrower and can, therefore, be utilized in smaller corneal incisions such as the 2.6 mm shown in Fig. 83 (right). The popular angled Kelman tip shown here has a high capacity to cut the tissues and is very useful in more dense cataracts. It allows the use of a finer probe because there is less contact with the lips of the wound and less heat damage.
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Figure 84: The Phaco Probe and Tips - Several Models for Different Uses The phacoemulsification probe and its components is shown in detail to the left. Standard Tip (T). The Standard tip (T), attached to it, is employed in cataracts with moderately dense nucleus. Its large diameter (5.2 mm) requires a wider incision. Probe’s Aspiration port (AP), Irrigation port (IP), silicone Sleeve (S), Handpiece (H), Irrigation line (I), Aspiration line (AL) and the Ultrasound line (U). It is important to understand its mechanism in order to manipulate this instrument with extreme accuracy. To the right you find several phaco tips for different purposes related to the type of cataract and the technique utilized. The Micro-Flow Tip (A) has some spiral grooves that always provides cool fluid that flows around the needle, thereby diminishing the heat around the incision. The Mackool-Kelman tip (B), has a teflon coat to diminish the heat that could harm the cornea. This is one of the latest generation phaco instruments. The transformation of energy always involves some dispersion which generates some heat. The Aspiration Bypass System (ABS) shown in (C), is also a new model 3.2 mm in diameter with a 0.25 mm side hole (encircled in red) which contributes to prevent the collapse of the anterior chamber (this micro-hole also aids in controlling the temperature diminishing the heat over the structures in the anterior chamber). The Surge phenomenon or A.C. collapse might be produced with larger aperture side holes (0.85 mm) in the tip. This does hot happen with these new devices. The Flare tip (D) was designed to perform faster and better contact with the nucleus while making the groove (D & C procedures) and the chopping techniques. The broader angle of contact between this tip and the nucleus is more effective in softer nucleus. The Kelman angled phaco tip (E), optimizes the ultrasound effect during the procedure and permits a better cavitation. It is more efficient in hard nuclei. The curved tip model allows more contact with the tissues (internally and externally) and less possibilities of traction to the zonule.
Phaco Tips The different components of the phaco probe are shown in Fig. 84 left . Please observe the standard tip (T). The probe is also shown in detail in Figs. 50-A and 50-B in Chapter 7. With the advent of chopping techniques in phacoemulsification, there has been increasing interest in the development of new tips for different uses and purposes. There is a large variety of phaco tips, and each one has its reason for being. Chopping procedures are facilitated by selecting the right tips from a
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variety of them as shown in Figs. 51 and 84. Depending on the surgeon’s technique and circumstances of the case, they all can contribute to better control in maneuvering of the nucleus. In figure 84 (right) and Fig. 51, you may see the most important tips. Fig. 84 A is the Microflow tip, 84 B is the Mackhool-Kelman phaco tip, 84 C is the Aspiration Bypass System (ABS), 84 D the flare head phaco tip, and 84 E is the popular Kelman angled phaco tip. Their specific features are presented in the caption of Fig. 84.
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Surgical Principles Behind the Different Phaco Tips
they offer more safety and control. The most popular are:
The different uses for each of these different tips are described in the caption of Fig. 84. The main variations in phaco tips are related to :1) Angulation. 2) Shape. 3) Size and 4) Thickness. And 5) The existence or not of a protective insulated cover that facilitates cooling so as to minimize the transfer of heat to the surrounding tissues, essentially the corneal lips of the wound.
1) Kelman's Miniturbosonics
The Importance of Angulation and Beveling The more beveled is the tip the larger the cutting surface and the larger the area which must be occluded at the tip. Those ranging from 0º to 15º do not cut much but they occlude more easily. They are, therefore, ideal for soft cataracts and for some chopping techniques in which a maximum capacity for occlusion and high vacuum is necessary. Tips with more angulation and bevel such as 45 degrees have a high capacity to cut the tissues and are very useful for the maneuvers of phacofracture in dense cataracts and in the Divide and Conquer techniques. Nevertheless,these tips offer a higher risk of posterior capsule rupture precisely because they are so sharp and highly cutting. Importance of Shape and Size New developments are oriented to microtips and the Mackool system because
Turbosonics
and
These tips have a curved shape that attains larger contact with tissue surface, internal and external, leading to more cavitation even though the ultrasound energy used may be the same as compared when using the standard tip. Higher cavitation allows destruction of the nucleus beyond the area of touch. The miniturbosonics is essentially the same style of tip but with lesser diameter. The main advantages of these tips are: 1) US energy is optimized leading to increased cavitation. 2) Better cutting and slicing of tissues in very hard nuclei. 2) Micro Tips
They all have smaller internal and external diameters as compared with conventional tips. Main Advantages: You can work with smaller incisions and attain greater stability of the anterior chamber because these tips have more resistance to the passing of lens fragments leading to less risk of the Surge phenomenon. They do require, however, more vacuum in order to obtain similar tissue fixation than when using a conventional tips. These micro tips are the ones indicated for use with the Mackool cassette system that by definition has tubes with narrower inner surfaces and thicker outer surfaces, facilitating the use of higher vacuum and reducing Surge.
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PHACOEMULSIFICATION SYSTEMS
Figure 85: Shown above are the three most advanced phacoemulsification machines and systems. (A) the well known Alcon Legacy 20,000. (B) Allergan’s Sovereign, that is now their “top of the line” and most efficient equipment. (C) Storz Millennium, which delivers all the advances described in this Chapter.
In the past three years, there have been dramatic improvements in the technology of phacoemulsification, involving every aspect of phaco systems. These range from the phaco probes and tips all the way down to the foot pedal. Improvements in the generation and control of ultrasonic power, fluidics, handpieces and tips have been made which are extremely advantageous to the cataract surgeon. We are all indebted to the manufacturers of our instruments and equipments who have invested heavily in financing this research and have attracted the best designers and engineers to carry on these developments. 150
These systems are able to provide much more reproduceable energy at each power setting regardless of the mass and density of the nuclear material at the phaco tip. Since this load is continually changing, the system must be able to adjust. If not, the efficiency of the equipment is immediately affected. The main systems available today for phacoemulsification are provided by the major players in industry and have very advanced technology. These systems are the well known Alcon Surgical LEGACY 20,000 equipment (Fig. 85-A), the AMO (Allergan) Sovereign (Fig. 85-B) and the Bausch & Lomb - Storz
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Millennium (Fig. 85-C). Allergan's Sovereign is the top of the line at Allergan. The equipment known as Diplomax made available for several years by Allergan is still a useful machine, more portable and of lower price than the Sovereign.
How to Select the Right Equipment for You In answer to the many questions that we receive from colleagues throughout the world as to which machine or equipment to purchase, we strongly recommend that the first priority should be to select one of these three, but based on the quality and availability of service and technical support that you will be able to obtain in your community. It is useless to have a superb phaco machine if that particular manufacturer provides inadequate technical support in the area where you practice. Each one of these three major systems makes available power modulations and advantages such
as auto pulse phaco, burst mode phaco and occlusion mode phaco which are most important in modern phacoemulsification surgery.
The Pulse and Burst Modes Differences Between Them This is one of the most important technological advances in phaco systems, as emphasized by I. Howard Fine, M.D., in the U.S. as well as by Edgardo Carreño, M.D., one of South America’s top phaco surgeons. When you contemplate acquiring a new machine, be certain that it offers these two modalities. What is the difference between them? In Pulse Mode we have linear power for a fixed interval of the application of that power (Fig. 86). In Burst Mode, we have fixed power with a variable interval in the application of that power (Fig. 87). Therefore, Pulse is a fixed short interval, Burst is a variable interval.
Figure 86: Concept of Pulse Mode in Phacoemulsification Pulse mode provides a great advantage in mobilizing and removing tissue. In pulse mode, the ultrasonic energy can be increased while the pulse rate or application rate of the energy remains constant. One chooses a certain number of pulses per second (P), say 2 pulses per second, which remains fixed during the surgeon's ability to increase the ultrasonic energy level as the foot pedal (F) is depressed in position 3. Note the constant pulse rate (P) as depicted by two pulses shown in front of each tip. Note increasing energy which can be applied, as represented by the enlarging size of the phaco tip and arrow (E), as the foot pedal (F) is depressed. Graph A (Pulse Rate - P/S) shows that pulse rate remains constant (horizontal line) during increased depression of the foot pedal. Graph B (Energy Level) shows that energy application (E) increases in a linear fashion, to a preset maximum, with depression of the foot pedal. Burst Mode, as displayed in the next illustration, is the reverse of Pulse Mode.
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Figure 87: Concept of Burst Mode in Phacoemulsification Burst Mode provides more control of the ultrasonic energy level, which is advantageous during certain maneuvers. In burst mode, one chooses the ultrasonic energy level desired on the control panel, and it remains fixed. As you depress the foot pedal in position 3, the pause between bursts of the fixed energy decreases from intermittent bursts to more frequent bursts, toward ultimately continuous phaco. Note the constant energy level (E) as represented by the constant size of the phaco tip and arrow. Note increasing burst rate (P) as depicted by the increasing number of bursts shown in front of each tip, as the pedal (F) is depressed. Graph A (Pulse Rate - P/S ) shows that burst rate increases during increased depression of the foot pedal. Graph B (Energy Level) shows that energy level (E) remains constant (horizontal line), with depression of the foot pedal.
Clinical Applications of the Pulse Mode Pulse mode provides a great advantage in mobilizing and removing tissue (Fig. 86). In the chopping techniques (Chapter 9), at a fixed pulse rate of 2 pulses per second, the surgeon chops by stabilizing the nucleus with the chop instrument in the golden ring. Fine likes to pull to the side of the phaco needle rather than to the top of the needle so that after the second chop, the initial tissue segment is already lolipopped. (Editor's Note: lolipopped refers to securely engulfing the tip of the phaco into the nucleus, like a lollipop or candy sucker on a stick. The phaco tip is analogous to the stick and the nucleus is the round candy portion Fig. 88) He does not have to search for the nucleus, or manipulate it: it’s already engaged
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on the phaco tip. The vacuum provides substantial control for holding the tissue between applications of phaco power, with almost no potential for chattering. (Editor's Note: chattering refers to when the nucleus bounces against the phaco tip at a high rate of speed without emulsifying it as desired, like when one’s teeth chatter when cold - Fig. 89). When using the LEGACY 20,000 equipment, for instance, Fine can specifically customize the application of the parameters of phaco power based on differences in the density and type of cataract tissue he is removing. This technological advance is also available in the other outstanding equipment already mentioned, particularly Allergan's Sovereign and Storz (Bausch & Lomb) Millennium. The power levels used by Fine are very low -- very frequently in the low teens. It is rare
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Figure 88 (right): Concept of "Lollipopping" the Nucleus Lollipopping the nucleus refers to securely engulfing the tip of the phaco into the nucleus, like a candy sucker on a stick. The phaco tip (P) is analogous to the stick and the nucleus (N) is the round candy portion. This technique provides a secure, controlled hold on the nucleus during the chopping and other maneuvers.
Figure 89 (left): Concept of "Chattering" during Application of Phaco Power (Top) An undesirable condition during phacoemulsification is when the phaco tip bounces (arrows) against the nucleus or lens piece when attempting to emulsify it. This condition wastes time and presents unneeded ultrasonic energy into the eye with no resulting emulsification and extraction. The chattering effect is represented by a bouncing ball against the ground. (Below) Increased vacuum can provide the additional control for holding the tissue between applications of phaco power, so that chattering does not occur. Here the tissue is efficiently extracted (arrow) as represented by the smoothly rolling ball.
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for him to have an effective phaco time greater than 20 seconds and an average phaco power of more than 20 percent. Meanwhile, the vacuum is high, 340 mmHg. He minimizes power and allows high vacuum to do the job.
Clinical Applications of the Burst Mode Its Role in Transition to Chopping Fine believes the easiest way for surgeons to make the transition to chopping (Chapter 9) is to use the burst mode set for singlebursts with the panel control (Fig. 87). He prefers a burst of 150 ms with vacuum of 400 mmHg. Also, by using Burst mode and a BiModal sub-mode, Fine can use a higher aspiration flow rate to attract the epinuclear ring out of the capsular fornix.
Advances with the Sovereign Phaco System Just as there are significant advances and technological contributions with the prestigious LEGACY 20,000 machine manufactured by Alcon Surgical, Allergan has recently brought into the market its Sovereign. This is really the top of the line for Allergan in this type of surgery. It takes into consideration and actually participates in what all surgeons want which is better and more predictable surgical dynamics for their cataract patients. This equipment has superb fluidics and capacity for programming and provides increasing ease of cataract removal. The Sovereign utilizes very effectively the micro-processor controls and an on-board computer regulation of all the components,
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such as fluidics, ultrasonics, footpedal, and bottle height. With respect to fluidics, the Sovereign has a digital peristaltic pump that, because of its sophistication, is capable of mimicking every other pump system. Its highly developed responsive fluidics monitoring system, called the Intellesis, monitors the fluidics 50 times per second. There is a sensitive control of what is happening to the vacuum in the anterior chamber. It also has the ability to respond rapidly because the pump can reverse, in addition to move forward, slow, and stop. An inordinately stable anterior chamber can be achieved, with a reduced tendency for vaulting of the capsule or fluctuations in chamber depth (See Chapter 7 - Figs. 62, 63, 65). This new level of control offers optimum safety. The foot pedal has an on-board computer and is capable of multiple functions (Figs. 52, 53, 55, Chapter 7). The foot pedal can be used with either the toe or heel depending on the surgeon's height. Using the foot pedal, even remote parameters such as bottle height, can be changed. Another important feature is the ultrasonics which has expanded from a two-crystal to a four-crystal handpiece. This four-crystal handpiece is adaptable to technology from manufacturers other than Allergan. Many machines are not designed to use tips from companies other than the parent company. Fine likes to use a Kelman bent tip for certain cases and he can use it with the Sovereign (Figs. 83-B and 84-E.) The ophthalmologist acquiring a new unit is naturally concerned whether the Sovereign can be programmed and used without extensive study and training in the system. Of course, every surgeon must understand the fundamentals of how phaco machines in general work, as presented in Chapter 7. Accord-
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ing to Fine, extensive study is not required because there is a sensor that monitors the delivery of ultrasound energy. It is difficult to keep a system that has a changing mass, shape, and density of material at the tip at its resonance frequency. But this system monitors, through its microprocessors, 50 different functions that are impacting resonance frequency, 500 times a second, and changes and corrects them automatically.
Pulse and Burst Modes on the Sovereign We have already outlined the great significance and importance of the Pulse and Burst Modes applicable with Alcon's LEGACY 20,000 equipment, which is a superb machine (Figs. 86, 87). Fine often combines Pulse and Burst modes also when using the Sovereign. Because the power is intermittent and the
vacuum is constant, one advantage of power modulation is that nuclear material tends to be kept at the tip. Nuclear material seldom chatters (Fig. 89) and almost never shoots into the anterior chamber, where it can threaten the endothelium. Fine feels that the Sovereign represents a new level of finesse and control that leads to safety and ease of operation. Fine’s Phacoemulsification Parameters including the Pulse and Burst Modes for Alcon’s Legacy 20,000, Allergan’s Sovereign and Storz Millennium, are presented in specially designed Tables in pages 202-203. Edgardo Carreño’s Adjustable Burst Mode Parameters using Alcon’s Legacy 20,000 are presented in this page. In essence, we have a wonderful new menu of remarkably sophisticated, helpful phaco instrument choices. Each surgeon will need to make his or her own decision, remembering to consider local service and support.
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RECOMMENDED READINGS
Buratto, L: Phacoemulsification: Principles and Techniques, 1998.
Seibel, B.: New phaco tips. Phacodynamics Mastering the Tools & Techniques of Phacoemulsification Surgery, Third Edition, Section One:104111.
Mendicute, J., Cadarso, L., Lorente, R., Orbegozo, J., Soler, JR: Facoemulsificación, 1999.
Technical advances in phacoemulsification systems, Ocular Surgery News, Feb. 2000.
Seibel, BS: Phacodynamics: Mastering the Tools and Techniques of Phacoemulsification Surgery, Third Edition, 1999.
BIBLIOGRAPHY Davidson J.: A comparison of technologically advanced ultrasonic tips. Advances in Technique & Technology, Alcon Surgical - April 1999, Part 2 of 2. Fine, IH., Lewis JS, Hoffman, RS: New techniques and instruments for lens implantation, Current Opinion in Ophthalmology 1998, 9:20-25. Fine, IH., Lewis JS, Hoffman, RS: Recent advances in phacoemulsification systems. Cataract Surgery: The State of the Art, Edited by Gills, H., Slack, 1998. Fine, IH.: Total control phaco chop. Advances in Technique & Technology - Alcon Surgical, Part 2 of 2, April 1999. Koch, PS.:Blades. Simplifying Phacoemulsification, Fifth Edition, Slack, 1997, 3:21-26. Piovella M., Camesasca, F.: New phaco tips and handpieces. Atlas of Cataract Surgery, Masket & Crandall, 1999, 5:42-47.
Salvitti, E.R: Flared tip technology. Advances in Technique & Technology, Alcon Surgical - April 1999, Part 2 of 2.
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C h a p t e r 9:
Mastering Phacoemulsification - The Advanced, Late Breaking Techniques
MASTERING PHACOEMULSIFICATION The Advanced, Late Breaking Techniques General Considerations We have presented the step-by-step technique of phaco during the transition including the fundamental understanding of how the phaco machine works (Chapter 7). The specific instrumentation, equipments and best systems used for phacoemulsification are discussed in Chapter 8. Regarding instruments and use of equipment, it is essential to keep in mind that we should first train in order to thoroughly understand and command the subtleties of our phacoemulsifier before its clinical use. As frequently emphasized by Centurion, we will not be able to improvise or try to master it in the surgical suite.
Advantages of Phaco It is also generally accepted that the main reasons why phacoemulsification has stimulated so much interest is because of the following advantages, all of which improve results: 1. Less ocular trauma induced. 2. Less postoperative inflammation. 3. Astigmatism induced is minimal or nil. 4. Postoperative refraction is more promptly stabilized. 5. Less risk of endophthalmitis. 6. Topical anesthesia can be effectively used. 7. Immediate physical and visual rehabilitation is attained.
Now let us consider fundamental concepts, measures, methods and techniques necessary to follow in order to master phacoemulsification.
Trauma-Free Phacoemulsification Considering that this procedure is very much device-dependent, Centurion establishes a tripod: physician-technician-machine. By individually organizing and interrelating the physician's role, his/her technician's important input and coordination, the functioning of the machine and the technique, we are able to perform the procedure free of trauma to our patients and less stress to the surgeon. This may be accomplished without changing the Operating Center's routine. In this "trauma-free phaco," it is also important to achieve the following: 1) no delays of patients, anesthesiologists or the surgical team. 2) Perform a limited number of daily procedures with predictable results more days in the week which is preferable to a schedule of longer but less frequent operating days with a much larger volume of operations in one single day. Perform 4 (four) cataract surgeries in one hour is as much as we should aim for. The objective is not to operate quickly but to take advantage of the results of a well-trained team that has adapted well to this system.
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Faster Operations Do They Sacrifice Patient Care? If the operating team is really efficient, speed should not necessarily lead to lesser results. The key lies in the adroitness and perfect coordination among Centurion's "tripod: surgeon-technician-machine". Making an operation safe and effective should be our primary goal. It is important to balance time, speed and safety, because in the end we all should aim for safe operations.
Readiness and Know-How to Become Efficient Stephen Lane, M.D., has very positively emphasized that if you want to go faster, ignore what is happening inside the eye and concentrate on what is happening in the operating room (OR). Make sure that the OR staff is proficiently getting the cases in and out and moving the patients with readiness. If the surgeon is only working in one room, there is more time wasted moving a patient from one room to another, getting a room cleaned up, and getting the next patient in, than during the
cataract operation itself. There are a series of steps to make the process flow efficiently. I. Howard Fine, M.D., has pointed out that there is an emphasis today of cataract surgery being likened to a foot race. Some surgeons show videos with stopwatches. Just looking at their hands reflects how they rush rather than doing maneuvers that are appropriate for working inside the eye. Racing the clock is definitely not good for the patient. In our teaching, it is important to convey that endothelial cell loss, iris trauma, incisions that do not heal, or broken capsules, may result because of a desire to do faster procedures. As a matter of fact, complications should be less because of the advanced technology we currently possess. If you have one or two operating rooms, efficiency is more connected to the turnover, not necessarily the individual case. The most practical method to obtain speed with efficiency is the one recommended by Centurion: use two operating rooms with exactly the same equipment disposition -- they are cloned rooms. This saves time because it is not necessary to change equipment; provides savings in maintenance and, most important: operating room staff can concentrate on the needs of the patient and the surgical team.
THE ADVANCED, LATE-BREAKING TECHNIQUES Anesthesia Advanced or experienced phaco surgeons may use topical anesthesia alone or combined with intracameral irrigation anesthesia (Figs. 35, 36). You may find as in-depth discussion of this subject in Chapter 5. The other alternative, of course, is to have the assistant or anesthesiologist use peribulbar anesthesia, generally Xylocaine 2% + Marcaine 0.50%. This 160
type of anesthesia has the great advantage of enabling the surgeon to operate without any intense emotional involvement or requiring the more active cooperation needed with topical anesthesia. It is very comfortable to arrive at the operating room where two or three patients are already anesthetized and ready to begin surgery. The advantages of topical combined with intracameral vs peribulbar are amply discussed
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in Chapter 5. For experienced surgeons, the combined topical-intracameral approach is much preferred because of immediate visual recovery.
Fixation of the Globe The experienced surgeon does not need to fixate the globe with sutures. Fixation by grasping the superior rectus muscle with forceps and placing a 6-0 silk suture through it, repeating the same maneuver with the inferior rectus, is completely outmoded for phacoemulsification. Besides, it leads to postoperative ptosis in a good number of cases. Many surgeons utilize the Fine-Thornton fixation ring (Fig. 75 - Chapter 8), particularly during the construction of the limbal or the clear cornea tunnel incision. Other surgeons prefer to fixate the globe with a forceps.
THE INCISIONS Phacoemulsification is a two-handed procedure in most cases. Consequently there are two incisions done: 1) The Primary Incision. 2) The Ancillary Incision.
The Primary Incision For experienced surgeons, the procedure of choice is a self-sealing clear corneal, stepped valvulated incision, performed temporally (Figs. 90-95). This incision is self-sealing and heals without sutures. It is shown in Figs. 90 and 91 (surgeon's view). Most surgeons do a two-step clear corneal tunnel incision as shown in Fig. 92, cross section view. Others prefer the three step corneal tunnel incision because they feel i t may add a factor of safety (shown in
Figure 90: Initial Stages of Self-Sealing, Corneal, Stepped, Valvulated Tunnel Incision - Surgeon's View This surgeon's view shows the Crescent knife blade (K) entering the first incision (1) just at the limbus. The blade is advanced (red arrow) for some distance in the plane of the cornea, and a tunnel (blue arrows) is created. This forms the second step (2) in the three-step incision. The knife does not enter the anterior chamber at this stage.
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Fig. 93, cross section view). When performing a two-step incision, the length of the tunnel is slightly larger to ensure that the incision will be self-sealing. A short tunnel may not self-seal (Fig. 92).
Essential Requirements for a SelfSealing Corneal Incision To be safely performed, the clear cornea tunnel incision must be done with a sharp diamond knife (Figs. 77, 90, 91, 92, 93) although the presently available stainless steel disposable knives are also very sharp and useful (Fig. 76, Chapter 8). Sergio Benchimol, M.D., in Brazil, who was one of the first surgeons to popularize this incision in South America, starts the surgery with a selfsealing, small, 1 mm paracentesis side port incision (Fig. 41) and pressurizes the eye with
viscoelastic or saline solution through this side incision. Then he proceeds to perform the primary self-sealing corneal incision, as shown in Figs. 90-93. The two-incision process, the sharpness and precision of the diamond knife and even the stainless steel blades, and the presence of viscoelastic in the pressurized eye make it possible for a valve-like self-sealing incision to be made in the cornea without damaging its structure.
Position of the Clear Cornea Tunnel Incision The trend today is to make the clear cornea incision on the temporal side as introduced by I. Howard Fine and Kimiya Shimizu, although Shimizu is inclined to perform a single plane incision, which is not generally accepted but he was a pioneer in the introduction of the clear cornea incision.
Figure 91: Final Step of Self-Sealing, Corneal, Stepped, Valvulated Tunnel Incision Performed with the Diamond Knife - Surgeon's View A diamond knife blade (D) enters the first incision (1), the second tunnel incision (2), and is then directed in a slightly oblique direction to the iris plane and advanced into the anterior chamber (arrow). This forms the internal aspect of the incision into the chamber (A). This is the third step (3) in a three-step self-sealing incision.
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Figure 92 (above left): The Two Step Clear Cornea Tunnel Incision - Cross Section View This cross section shows the location, direction and length of the two step clear cornea tunnel incision. (1) The incision is started in clear cornea just inside the limbus. (2) It extends through the stroma for 1.75 to 2.0 mm before entering the anterior chamber. This length of tunnel is important to ensure that the incision will be self-sealing. A short tunnel, by comparison (dotted line), may not self seal.
Figure 93 (below right): The Three Step Corneal Tunnel Incision - Cross Section View The three step corneal tunnel incision begins (1) with a perpendicular corneal incision 1 mm inside the corneo-scleral limbus (L). This 3.0 mm long first pass incision is made to a depth of about 300 microns. (2) The second pass consists of an incision made parallel to the cornea which tunnels for 1.75 mm to 2.00 mm. (3) The third step enters into the anterior chamber. This will form the internal lip of the incision just like the internal valve lip of a traditional cornealscleral tunnel incision.
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Reservations About the Clear Corneal Incision Some surgeons have reservations about the clear-cornea incision, particularly because of postoperative astigmatism and endophthalmitis. These used to be two major complications of clear cornea incisions. These problems have been almost solved by making the wound as small as 3.2 mm or less at the temporal site and by using intracameral antibiotics as discussed in Chapter 4.
Advantages to the Temporal Approach 1) The approach to the anterior chamber is easier, especially in patients with a narrow palpebral fissure (Fig. 94). 2) As inferior duction of the eyeball is not required with the temporal approach, the iris plane is always kept at right angles to the microscope to provide good visibility. 3) As pointed out by Kimiya Shimizu, the cornea is oval and the optical center of the cornea deviates to the nasal area from the
Figure 94: Advantages of the Temporal Approach Corneal Incision There are several advantages to the temporal approach. First, the optic center (C) is slightly further away from the temporal limbus (distance E) as compared to the 12 o'clock limbus (distance D). Therefore, a temporal cataract incision is farther away from the optic center of the eye, and any resulting post-op corneal edema around the incision is less likely to affect the immediate visual rehabilitation. Second, by utilizing a temporal approach there is no restriction of instrument movement caused by the speculum, as does exist with the 12 o'clock approach. Note portion of speculum (S) at 12, and none temporally (T). Third, the eyebrow and somewhat more protruding supraorbital rim can restrict instrument movement using the 12 o'clock approach. Compare posteriorly directed arrow at 12 (representing instrument approach) to temporal arrow (T), (representing unrestricted instrument approach in the plane of the iris). Therefore, more easeof access to the anterior chamber structures, along with the unrestricted movement of instruments, is gained using the temporal approach.
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anatomic center. Therefore, in the temporal approach, the incision's, the distance is about 1 mm more from the optical center as compared with a superior incision (Fig. 94). Thus, the operative invasion to the corneal center is minimal in the temporal incision. As a result, surgically induced astigmatism is small and recovery of visual acuity is fast. In addition, when working on clear cornea at the 12 o'clock position (closer to the optical axis than the temporal position) if there is a small amount of edema near the edge of the incision, being closer to the optic center of the cornea, may temporarily interfere with the immediate visual recovery aimed at with topical anesthesia and clear corneal incision. 4) The wound will not separate when blinking. The temporal incision, therefore, facilitates good adaptation of the wound. 5) In addition, there is more space for the surgeon's hands. The temporal approach makes the phacoemulsification itself easier because the eyebrow is not a barrier, and freer movements are possible.
Additional Patient's Comfort with Corneal Incision Jack Dodick definitely prefers to do a clear cornea incision rather than the scleral tunnel procedure. Although he considers that both incisions are excellent and lead to the same outcome, patients tend to be more comfortable and satisfied with the clear cornea incision. Using the scleral tunnel procedure, the surgeon cuts into the sclera, conjunctiva, Tenon's membrane, and some blood vessels, which takes perhaps 1 to 2 weeks to heal.
Although patients do not report having much pain, they do report a greater sense of awareness or discomfort for at least a week or so after the scleral tunnel procedure. With the clear cornea incision, on the other hand, the epithelium regenerates within 24 hours, much like it does after a corneal abrasion. Those patients who undergo a clear cornea incision report awareness of a sandy sensation which is virtually gone within 24 hours as the corneal epithelium is reepithelialized. In many cases Dodick and many surgeons have done a scleral tunnel operation that turns out perfectly with 20/20 vision, and the patient still complains months and maybe even years later of an awareness or irritation in that eye. Creating a scleral tunnel wound leaves a scar at or near the limbus (Fig. 40), which Dodick believes interferes with tear film distribution. Eventhough it heals beautifully, the interference with tear flow leaves patients with a vague awareness or irritation in the eye. With a clear cornea incision, the limbus is never invaded, and a vascular scar is never created. Therefore, tear film distribution is never disturbed. The final reason Dodick chooses the clear corneal tunnel is that it is a much more cosmetic procedure. With the scleral tunnel incision, patients often have a red eye. No change is apparent in patients who have had the clear cornea incision just a few hours after the operation. A postoperative photograph showing the barely visible scar of the corneal tunnel incision on the temporal side is shown in Fig. 95. In Edgardo Carreño's experience, phaco through clear cornea is less traumatic, considering that there is no need for conjunctival dissection nor the use of cautery related to scleral tunnel dissection. There is also no possibility of hyphema and there is less postop-
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Figure 95: Minimal Scar Following Clear Corneal Temporal Incision With slit lamp retroillumination we can see the very fine scar in the postoperative stage after performing phacoemulsification utilizing a clear corneal incision done on the temporal side of the left eye. With daylight or even a pen light frontal illumination, this scar is barely seen. Please also observe that the scar is very regular, almost like drawn on paper. This, of course, leads to practically no astigmatism postopertaively. (Courtesy of Edgardo Carreño, M.D.)
erative inflammation because there is less trauma. The postoperative cosmetic appearance of the globe is better, the eye looks as if never touched (Fig. 95). The patient feels more comfortable because there are no sutures, no cautery has been done and there is no pain. The intraoperative time is less because several traditional stages of the operation have been eliminated. Therefore, the cost is reduced.
Importance of the Length of the Tunnel Ideally, the part of the corneal tunnel itself should be about 1.75 mm (Fig. 93). A shorter tunnel (dotted line in Fig. 92) decreases the self-sealing rate, although the surgeon's visibility becomes better. Too long of a tunnel increases the self-sealing, but corneal folds sometimes disturb surgeon's visibility. Corneal endothelial damage also becomes greater as the distance between the phaco tip and
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corneal endothelium becomes shorter. Thus, when the surgeon performs a corneal incision for the first time, it is recommended to make a rather shorter tunnel and to place 11-0 nylon single knot without being concerned with selfsealing.
Placing and Making the Primary Incision As emphasized by Kimiya Shimizu, the proper placement of the incision is important. If it is too anterior, the corneal tunnel becomes shorter, and the self-sealing effect is decreased. In contrast, if it is too posterior, conjunctival bleeding and/or chemosis sometimes occur. So, before incising the cornea, dry the incision site, make the vertical first step just anterior to the terminal conjunctival vessels, then insert and advance the keratome straight about 1.75 mm into the corneal stroma. Next, direct the keratome slightly downwards in the iris plane to perforate Descemet's membrane.
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When the tip of the keratome appears in the anterior chamber, remove the Merocel sponge and release the counterpressure. After that, advance the keratome, swinging it to both right and left sides. By doing this, the incision may be conducted safely without causing the collapse of the anterior chamber. The length of the corneal tunnel is usually 1.75 mm, but if it is a complicated or hard nucleus case, it should be shorter. On the other hand, when the patient has good mydriasis or a shallow anterior chamber, the incision site should be a little anterior, and the corneal tunnel should be longer to prevent iris damage and/or iris prolapse.
Surgeon's Position When the operator is right-handed and he/she is operating the right eye, sit at the 10.30 position. When operating on the left eye, sit at 4:00.
Controversy Over the Strength and Safety of the Wound One of the most controversial criticisms of clear corneal incisions has been their relative strength compared to limbal or scleral incisions. Mackool has demonstrated that once the incision width is 3.5 mm or less and the length of the tunnel 1.75 to 2 mm, there is an equal resistance to external deformation in clear corneal incisions as compared to scleral tunnel incisions. Ernest work as well has revealed that as incision sizes get increasingly smaller, 3mm or less, the force required to cause failure of these incisions becomes very similar for limbal and clear corneal incisions. This further documents the safety of corneal incisions. The real issue for these various incisions is not healing but sealing. Fine feels that as long as an incision is sealed at the
conclusion of surgery and remains sealed, the time before complete healing of the incision is accomplished is almost irrelevant, especially since there is still a 6-day period in which limbal incisions are not healed. An analogy can be drawn to the sealing that takes place during LASIK, in which there is no fibrovascular healing of the clear corneal interface, which has little effect on the strength, effectiveness, or safety of the wound, and, in fact, is an advantage by limiting scarring and an inflammatory healing response. Clear corneal cataract incisions are becoming a more popular option for cataract extraction and IOL implantation throughout the world. Through the use of clear corneal incisions and topical and intracameral anesthesia, we have achieved surgery that is the least invasive of any kind in the history of cataract surgery with visual rehabilitation that is almost immediate. Clear corneal incisions have had a proven record of safety with relative astigmatic neutrality utilizing the smaller incision sizes. In addition, corneal incisions result in an excellent cosmetic outcome.
Testing the Wound for Leakage There are several methods to test the seal of the incision. For the most practical one, we refer you to Fig. 73, Chapter 7, and the explanatory text in the same page under this title.
Closing a Leaking Wound Without Sutures Professor Juan Murube, M.D. (Madrid), has demonstrated the effectiveness of a very comfortable maneuver in order to close-shut a leaking wound instead of having to suture it. Although a self-sealing, stepped valvulated corneal tunnel incision, 3.0 mm or 167
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less in size, is very unlikely to leak, there is always the possibility for this to occur. The main causes are related to making the corneal incision larger than 3.0 mm and excessive trauma to the lips of the wound during surgery particularly with the phaco probe. These factors may give rise to a continuous loss of aqueous humor. This may be detected the following day by means of a positive Seidel test in which several drops of fluorescein are instilled over the wound and examination is performed with ultraviolet light. Because the aqueous humor escapes through the wound continuously, the wound is kept open. Unless this is corrected immediately, the surgeon may have to suture the wound. The very comfortable and effective maneuver recommended by Professor Murube in order to close-shut a leaking wound is to place
a Honan balloon over the eye for 30 minutes at 35 mm Hg pressure. At the same time, the patient is administered orally one tablet of 250 mg of Acetazolamide (Diamox). The way this works is that the significant intraocular hypotony produced by the combined use of the Honan balloon and Diamox results in the production of a significantly reduced amount of aqueous humor that is produced with sufficient continuity to reform the anterior chamber but not in sufficient quantity to seep through the wound. After a few minutes, the walls of the wound have had a chance to adhere to each other, thereby sealing the wound. No further positive Seidel test is observed even though the normal intraocular pressure is reestablished. This maneuver is innocuous and simple as well as highly effective (Fig. 96).
Figure 96: Murube's Method of Sealing a Leaking Wound with Honan's Balloon The combined use of Honan Balloon’s compression for 30 minutes at 35 mg Hg pressure and one 250 mg tablet orally of Acetazolamide lead to sealing of the leaking wound.
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THE ANCILLARY INCISION This is an important step in performing phacoemulsification. Although there are techniques to perform phaco with only one hand, phacoemulsification is fundamentally a twohanded procedure. The ancillary or side-port incision is made before the main incision. It serves as an entry for a second instrument which is necessary for maneuvers to remove the nucleus, either nuclear manipulators (fig. 79) or choppers (Fig. 80). The location and technique of making the ancillary incision is shown in Fig. 41 A. In addition to serving as the mode of entry for the essential second instrument the ancillary incision is utilized in irrigation of the anterior chamber with intracameral local anesthetic as presented in Chapter 6 and illustrated in Fig. 36. It is also the route for the insertion of viscoelastic previous to making the primary incision. At the end of surgery, the ancillary incision is used to inject fluid into the anterior chamber to test for leaks in the wound, as shown in Fig. 73.
Making the Ancillary Incision The steps involved in performing the ancillary incision are: 1) First, mark the corneal location where the clear corneal stepped main incision would be made, which is always between 9 and 12, as shown in Figs. 41 B and 42. This measure serves the surgeon for orientation as to exactly where to place the two incisions. 2) Make the ancillary incision at 3 o'clock. This is performed with a special 15 degrees blade designed for paracentesis (Figs. 76 and 77).
ANTERIOR CAPSULORHEXIS Key Role This procedure is also presented in Chapter 7 for the transition period and illustrated in Figs. 43, 44 and 45. It is generally agreed that a well performed anterior continuous capsulorhexis is an essential step for the success of phacoemulsification. The key reasons for being so important is that capsulorhexis prevents IOL decentration. In cotrast with the extracapsular extraction and can opener capsulotomy, even when the surgeon was sure that he/she placed the IOL within the bag during surgery, sometimes 30 to 40% of cases after two or three months would have one of the lens loops protruding out of the capsular bag and reaching to the sulcus, thereby leading to decentration. On the other hand, by performing the continuous circular capsulorhexis followed by implantation of the lens within the bag, the IOL will permanently remain well centered within the capsular bag. This has been emphasized time and again by Everardo Barojas, M.D., one of Mexico's most prestigious cataract surgeons and a good number of other experts on the subject.
The Role of Viscoelastic in CCC One of the key steps in achieving a first class capsulorhexis is to do it with viscoelastic in the anterior chamber rather than with BSS. The high density viscoelastic is used not only to protect the endothelium and other surrounding tissues but also serves as a third hand that amplifies the working space and facilitates the maneuvers of the surgeon's manuevers. It also
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helps to flatten the anterior capsule. This last measure facilitates the correct performance of the procedure.
Technique for Performing a First Class CCC Beginning surgeons should be encouraged to use forceps as shown in Figs. 44 and 45. All cases should be performed with injection of viscoelastic material in the anterior chamber. The experienced surgeon may perform the procedure with a cystotome-needle which is a No. 26 needle with the tip bent into a square angle as shown in Fig. 97. The CCC utilizing the cystotome needle and viscoelastic is more safely and effectively performed using the central punch technique. This makes the first incision in the center, as shown in Fig. 98 and not in the periphery, as was the tendency when the procedure was developed (shown in Fig. 43). Using the central punch technique, there are fewer possibilities that a tear will spread to the periphery. The continuation of the capsulorhexis tear, once the central punch is done, may be done clockwise or counter clockwise, as is more comfortable for the surgeon. Usually, it is continued in a circular fashion in a counter clockwise direction as shown in Fig. 99, carefully completing a circle from outwards inward obtaining a completely closes rhexis (Fig. 100). It is fundamental to advance the capsular tear in a well controlled manner. This is achieved by placing the cystotome-needle against the surface of the anterior capsule and re-grasping the tear as many times as necessary to continue the circular teaar until completing the circle. A very important part of the first step in CCC is to be able to obtain the flipping of the resultant capsular flap once the cystotomeneedle engages the anterior capsule centrally.
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It is important for the surgeon to see the underside surface of the anterior capsular flap as shown in Fig. 98. Some surgeons find that in order to perform the procedure more safely, upon finishing each one of the circular tears with the Uttrata forceps and before completing the circle, instead of leaving the capsulorhexis folded, take it back to the way it was, that is, unfolded. This makes the next step easier to perform, that is the anterior capsule, easier to grasp in order to engage and disengage to provide the best control for creation of a circular opening (Figs. 99, 100).
Size of the Capsulorhexis For experienced surgeons mastering phacoemulsification, it is generally advisable to use a 5.5 mm central and completely enclosed rhexis. This is close to the ideal phacoemulsification technique performed safely within the capsular bag. The size of the capsulorhexis, however, may be better determined by the type of intraocular lens model to be implanted. Carreño emphasizes that upon using Alcon's foldable acrylic implant with a 5.5 mm optic, he prefers a 4.5 mm or 5.0 mm rhexis so that the edge of the optic is completely covered by the anterior capsule. This helps in preventing fibrosis which may be produced when both capsules come into contact. It is also helpful in reducing glare especially in younger patients who have more of a tendency for pupillary dilation at night or in the darkness. On the other hand, upon using the silicone foldable lenses, Carreño prefers a 5.0 mm to 5.5 mm rhexis to prevent contraction of the capsular sac, which may accompany this type of implant when the diameter of the capsulorhexis is smaller.
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Figure 97 (above left): Cystotome - Needle Adjusted for CCC The experienced surgeon often prefers to perform CCC with a cystotome-needle. Many surgeons use a 26 gauge needle with the tip bent into a square angle. Others use a 23 gauge needle. The needle is prepared with two separate bending motions as follows: 1) the tip of a straight 26 or 23 gauge needle (N) is grasped with a needle bender (B). 2) The tip of the needle is bent downward 90º in a vertical motion (arrow).
Figure 98 (center): Continuous Curvilinear Anterior Capsulorhexis Performed with the Cystotome-Needle (Step 1) The first step is to engage the cystotome-needle into the central region of the anterior capsule superiorly at the X and flip the resultant capsular flap over. Please observe that the surgeon can see the underside of the capsular flap (C). The cystotome-needle (N) engages the underside of the capsular flap (C) and moves it in the direction of the blue arrow which in this case is counter clockwise in order to produce a circular tear in the capsule (red arrows). A fixation forceps provides stability which is essential during the performance of the CCC.
Figure 99 (below left): Continuous Curvilinear Anterior Capsulorhexis Performed with the Cystotome-Needle (Step 2) After injection of viscoelastic, the surgeon starts with the puncture of the capsule and proceeds to make the first small flap. When this first flap is turned over, the tint is clearly seen because the color is detected in the internal face of the capsule and not in the epithelium.
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Figure 100: Continuous Curvilinear Anterior Capsulorhexis Performed with the Cystotome-Needle (Step 3) The cystotome needle continues to be engaged on the underside of the flipped anterior capsular flap and is moved in a direction (blue arrow) to complete the circular tear (red arrow). The capsular flap is then removed from the eye.
Another factor which influences the size of the capsulorhexis, is the degree of hardness of the cataract. In cases where the nucleus is too hard, Carreño feels that it is more prudent to perform a rhexis which is not too small, certainly no less than 5.0 mm in diameter, to ease performing the phaco chop techniques, which are the most highly recommended for treating hard nucleus.
STAINING THE ANTERIOR CAPSULE IN WHITE CATARACTS As shown in Figs. 98, 99 and 100, a well performed CCC allows the coaxial light of the
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microscope to provide the red reflex of the fundus. Over this red reflex the anterior capsule and the border of the progressively performed continuous circular capsulorhexis can be very well visualized. This allows the completion of the circle (Fig. 100) under adequate visual control. On the other hand, when the surgeon is dealing with white, hypermature cataracts that have either been allowed to get into that advanced stage or have been produced by trauma, the details and border of the CCC cannot be well visualized because this white cataract interferes with fundus reflex . Consequently, the step by step progress in the performance of the CCC is not well visualized. Accidentally, the edge of the anterior capsule
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flap could be displaced toward the periphery and the lens equator. From here, upon performing the maneuvers inherent to phacoemulsification, damage to the posterior capsule could be inflicted thereby allowing passage of the vitreous to the anterior chamber or a luxation of the nucleus into the vitreous or a displacement of the intraocular lens once inserted. These important considerations have led to the devel-
opment of a very effective technique to control the performance of the CCC in white cataracts. It consists in staining the anterior capsule of the lens in order to adequately visualize the details during the performance of the CCC (Fig. 101). Without the dye it is nearly impossible to see the anterior capsule. These cataracts are risky. It is very difficult to distinguish the anterior capsule from the underlined cortex.
Figure 101 (above right): Murube's Technique of Staining the Anterior Capsule in White Cataracts to Perform Adequate CCC White cataracts (L) present a problem because the red reflex is not present making the capsulorhexis quite difficult and risky. A viscoelastic is first injected into the anterior chamber immediately followed by the injection of a bubble of air which partially displaces the viscoelastic from the anterior chamber. This leaves the corneal endothelium lubricated with the viscoelastic. A hydrodissection cannula (H) is introduced through the corneal incision over the anterior capsule (C). Two drops of Trypan Blue are instilled. Wait for ten seconds.
Figure 102 (below left): Anterior Capsule Stained with Trypan Blue in White Cataracts to Facilitate Performance of Adequate CCC Murube's Technique After waiting for ten seconds, the anterior capsule in the white cataract is fully stained. Viscoelastic is then injected into the anterior chamber to remove the air (air exchange). The anterior capsule is a little blue. The surgeon can now proceed with the capsulorhexis now that he/ she sees the capsule clearly.
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Staining Substances and Methods There is a variety of staining substances and methods of how to perform the staining. They have been presented by prestigious ophthalmologists since 1998: in Japan through Nagoya University School of Medicine; in Spain, Oscar Asis, M.D.; in Holland, Jerritm Melles, M.D.; in the U.S., Thomas Oetting and Rick Nearhing. The most practical and effective method now being popularized is the one presented by Prof. Juan Murube (Madrid). The different staining substances analyzed by Murube are the following: 1) Fluorescein 2%. This is obtained by mixing 1 ml of 10% fluorescein for intravenous use with 2 ml of BSS. 2) Indocyanine Green (ICG): This is obtained by mixing 25 mg of ICG in 0.5 ml of an aqueous solvent which might be obtained from Akorn in Buffalo Grove, Illinois. This mixture is then diluted in 4.5 ml of BSS. 3) Trypan Blue: Prepared by mixing 1 ml of trypan blue 0.4% (obtained from Life Technology, Grand Island, New York) in 3 ml of BSS. 4) Gentian Violet: solution at 0.01 concentration diluted with BSS. 5) Methylene Blue: solution at 0.01 mixed with BSS. Murube's research has led him to select Trypan Blue as the staining solution of choice. This has been confirmed through the clinical research of Carlos Nicoli, M.D., in Argentina, one of South America's top phacoemulsification surgeons. Nicoli emphasizes that Methylene Blue and Gentian Violet are very difficult to prepare because they must have very specific concentrations. It is fundamental that the stain used not be toxic to the corneal endothelium. Therefore, it should be prepared at exactly the right concentration. For instance, 174
Methylene Blue, if used, should be a 1% solution while Gentian Violet should be at one part per thousand. The new research by the Japanese in Nagoya refers to the use of 0.05% Indocyanine Green solution. The problem with the latter is that it is very costly. The Trypan Blue solution is being currently marketed as a nontoxic stain.
Technique for Injection of Staining Solutions Murube first irrigates a viscoelastic into the anterior chamber. This is immediately and partially displaced by an air bubble in the anterior chamber in order to leave the corneal endothelium slightly lubricated and protected by the viscoelastic. A cannula is inserted through the corneal incision as shown in Fig. 101 and two drops of Trypan Blue are deposited over the anterior capsule. The surgeon waits ten seconds. This is followed by injection again of viscoelastic in order to eliminate the air bubble from the anterior chamber, the so-called "air exchange". At this time tinting is not yet detected until the first flap of the rhexis is done because the tissue absorbing the tint is not the capsular epithelium but the internal face of the capsule, visible enough for the surgeon to see the capsule very clearly and to proceed to perform the capsulorhexis adequately. Utilizing this technique, when performing the capsulorhexis (Figs. 98, 99, 100) the surgeon can see that the epithelium behind the anterior capsule is selectively stained. It is important to keep in mind that the epithelium is behind the anterior capsule. When the surgeon lifts the flap gently, he/she can see the epithelium perfectly stained so he/she may safely proceed to complete the capsulorhexis. This technique is considered of great value, a breakthrough in this step of phacoemulsification.
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HYDRODISSECTION HYDRODELAMINATION This next step is of great importance. Its objective is to separate the capsule from the cortex and the cortex from the nucleus (Figs. 46, 47, 48). Its significance is related to the liberation of the adherences which attach the nucleus to the cortex or the cortex to the capsule, facilitating aspiration (Figs. 1, 46, 47, 48). The hydric chamber created with hydrodissection also plays a role in the protection of the posterior chamber and the posterior capsule during the phacoemulsification maneuvers.
Technique of Hydrodissection Using a 3 ml syringe with a maximum of 1.5 ml infusion fluid, a 25 G flat tip cannula is introduced underneath the capsulorhexis (Fig. 78-A). Following Fine and Centurion's recommendations, the anterior capsule is raised and BSS is infused with light pressure. The fluid will distribute itself along the posterior capsule and will drain through the opposite side. The liquid wave can be seen in the center of the red reflex (Fig. 46, 47). This process is repeated at 6, 3 and 9 o'clock keeping in mind that after infusing, we should press the cataract against the capsule to avoid elevation of pressure within the capsular bag. After the liquid wave reaches the area of the pupillary opening, the syringe is withdrawn and the center of the nucleus is compressed in an attempt to release the adherences of the cortex to the capsule on the side opposite
to where hydrodissection was begun. After this maneuver, the surgeon attempts to rotate the nucleus. If the nucleus was released by complete hydrodissection, it will rotate freely. If there is no rotation, try a new hydrodissection located opposite the site of the initial one. Centurion recommends that after the nucleus is released, it be rotated four or five times 360º. This releases possible cortex or epinucleus or capsule adherence. Thus, at the end of nucleus emulsification there is practically no need to aspirate cortical remains. Following hydrodissection, it is essential to confirm that the nucleus is completely separated from the cortex before proceeding with the next step, which is management of the nucleus with the different phaco techniques. (For the do's and particularly don'ts related to hydrodissection, it is important to read the text on this subject in Chapter 7, next to Figs. 46, 47, 48).
Hydrodelamination Hydrodelamination is the separation of the nucleus from the soft epinucleus (Fig. 48). This technique is done after completing hydrodissection. The same needle (Fig. 78-A) is introduced beneath the cortex and into the lens stroma while infusing BSS, which will delaminate sheets of cataracts, isolating the nucleus from the epinucleus, forming the golden ring (Fig. 48 GR). With present techniques, many surgeons do not used to perform hydrodelamination following a very well done hydrodissectgion. They remove the epinucleus usually during the emulsification of the nucleus.
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MANAGEMENT OF THE NUCLEUS General Considerations At this stage, we proceed with the culminating phase of the operation. The previous methods of emulsification of the nucleus first within the anterior chamber and later in the iris plane are somewhat outmoded with the exception of the supracapsular otherwise known as the “tilt and tumble” iris plane technique, which is still Lindstrom’s first choice. It is less demanding. At present, though, the most often used phacoemulsification techniques in handling the nucleus are performed in the posterior chamber within the capsular bag. These are all identified as endocapsular techniques. They have the advantage of reduced risk of damaging the endothelium. They also enable the surgeon to work with a larger opening in the capsulorhexis which is definitely useful in patients whose pupillary dilatation is not adequate. These methods have the disadvantage that nucleus manipulation is done closer to the posterior capsule and more stress is placed on the zonular fibers, to their consequent risk. The almost universal use of endocapsular phacoemulsification has been made possible because of innovations in technique and equipment.
Concepts Fundamental to All Techniques Surgical Principles Almost every contemporary cataract surgeon uses some form of chopping, and all surgeons who perform chopping use some form of ultrasound to facilitate the chop. Whether it be a groove-and-chop, divide and conquer, or a technique like Fine's quick chop (the choo176
choo chop and flip technique presented in Figs. 122- 126), some form of ultrasound is used for chopping. All modern techniques are oriented toward breaking up or disassembling the nucleus to facilitate its removal from the eye. These techniques, which rely on mechanical energy, have been developed to reduce the amount of ultrasound energy necessary to break up the hard part of the lens nucleus. In addition, disassembling the nucleus removes it from the capsular recesses of the bag, thereby facilitating its removal with the phaco probe. Nuclear disassembling techniques use some ultrasound at the beginning of the procedure to create multiple troughs or grooves. A second instrument such as a spatula or chopper can then be used to crack or break the nucleus. In this chapter we present the three groups of techniques mostly used in advanced phacoemulsification methods for nucleus removal. You will find the fundamental concepts which are applicable to all methods and a description of the principles that make these methods highly successful, all of which have been developed by highly prestigious cataract surgeons. It is by understanding these concepts that the surgeon will be able to develop one or two essential techniques and use them as the methods of choice adapting his/her chosen procedure to virtually any situation and the different types of cataract encountered, either soft, standard or medium-density and the very hard cataract. The surgeon will find in this Volume precisely what he needs to understand and to adopt the method which he feels more comfortable with and most suitable for his patients. If a more complete description of the techniques
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available is desired, we suggest that you refer to the carefully selected, short list of recommended books and bibliography presented at the end of the chapter for the method's originators and proponents.
The Essential Principles 1) A general principle for all techniques to remove the nucleus in phacoemulsification, either the original four quadrants divide and conquer and its derivative divide and conquer (D & C) methods, and the relatively recent chopping techniques is that it is first essential to debilitate the core of the nucleus so that the nucleus can be split into halves, sometimes fourths (Figs. 67, 103 through 106) and occasionally into eighths. This allows emulsification and aspiration of nucleus segments (Fig. 105) instead of attempting to carve the entire nucleus without a planned strategy. This splitting of the nucleus is safer for the endothelium because it is easier to keep smaller par-
ticles away from the endothelium without having to push them against the posterior capsule. These essential principles are illustrated in Fig. 103 (The Cracking Effect), Fig. 104 (The Dividing Effect through Opposing Forces), Fig. 105 (The Slicing Process) and Fig. 106 (the Dividing Process). 2) Smooth sculpting which avoids nuclear movement and zonular stress is critical to all methods. Well-controlled deep and central sculpting facilitates cracking in segmentation methods and rim removal in one and two-handed methods. By using just enough ultrasound power to embed the phaco tip and then backing off to the I/A position (standard pedal position 2), the nucleus can be positively engaged for rotation and manipulation. This versatility of the phaco tip is especially important for one-handed techniques as well as chopping techniques. The principles of mechanical advantage apply to all methods; safety is maximized by using the minimum force and movement required to accomplish a given task.
THE ENDOCAPSULAR TECHNIQUES THE HIGH ULTRASOUND ENERGY AND LOW VACUUM GROUP THE GROOVING AND CRACKING METHODS
The Divide and Conquer Four Quadrant Nucleofractis Technique The first group of endocapsular operations was based on the principle of utilizing large amounts of phaco energy and low vacuum.
The classical and less complicated technique of this first group is the Four Quadrants "Divide and Conquer" described in 1987 by Howard Gimbel. The principles of this method are presented and described in figures 56 and 67 in Chapter 7. In order to debilitate and remove the nucleus, a linear vertical sulcus or groove is done in the nucleus from 6:00 to 12:00 o'clock and a second groove perpendicular to the first is done, both using the phacoemulsifier probe. The carving of these furrows results in the nucleus being seen with a cross as shown in Figs. 56 and 67. A second 177
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instrument known as the "manipulator" which is introduced through the ancillary or side port incision engages the opposite side of the groove inferiorly (Figs. 67 and 79). The phaco tip is impaled on one side of the already deep groove and the manipulator on the opposite side of the
sulcus (Figs. 103 and 104) Both must be positioned beyond half the depth of the groove. The sulcus should have been carved with a width equal to 1.5 diameters of the phaco sleeve. The depth at which the phaco tip is impaled is 1.5 times the width of the phaco tip (Fig. 103).
Figure 103 (above right): Phacoemulsification - Cracking Effect Once the desired thinning of the nucleus core is done (a furrow or a crater), a second instrument, a chopper or a manipulator is used to divide (arrows) the nucleus in half pulling the instrument from periphery to the center. The phaco tip is impaled on one side of the already deep groove and the manipulator in the equator of the nucleus, adjacent to the tip. The depth at which the phaco tip is impaled is 1.5 times the width of the phaco tip.
Figure 104 (below left): Phacoemulsification - Dividing Effect Opposing force (arrows) is applied to both sides of the cracking with the phaco probe and the help of the chopper. Dividing the nucleus in small pieces will facilitate its removal with the phacoemulsifier employing less ultrasound and higher vacuum.
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Cracking the Nucleus Force is applied with the instruments in opposing directions in order to crack the nucleus along the length of the groove (Figs. 103, 104, 106 below). Additional manipulations of this type further lengthen and deepen the cracks. The lens is rotated 90º within the capsular bag and a crack is made in the second groove in the same manner. The need to rotate the lens 90º, which is done in all techniques of phaco, is because the maneuvering by the surgeon is always done in the lower half of the field. Doing such maneuvering in the upper half is technically very difficult and cumbersome. In the Divide and Conquer technique, the maneuver of rotating the nucleus 90º is repeated three times until the nucleus becomes divided in four sections (Figs. 67 and 105). After this is done, the lens fragments are emulsified as shown in Fig. 67. The apex of each of
the four loose quadrants is lifted with the manipulator and the ultrasound phaco tip is embedded into the posterior edge of each segment (Fig. 105). By means of aspiration the surgeon centralizes each quadrant into the phaco tip and proceeds to emulsify each piece, which requires the use of a somewhat high amount of ultrasound power. When operating on a softer cataract, these fractured pieces are reasonably large, perhaps several clock hours in diameter, and as they are broken free they are emulsified immediately. In very dense cataracts, the pieces should be much smaller. These pieces are left in place until the surgeon has worked all the way around the nucleus, so that as the rim is manipulated and spun around, the capsular bag will stay fully expanded as the nuclear rim is manipulated and spun around. Only after the last piece is broken are they removed by emulsification.
Figure 105: Phacoemulsification - Slicing Process This cross section view shows the phacoemulsification probe removing the nucleus fragments within the capsular bag. Note the apex of one of the fragments created in the nucleus being lifted with the second instrument (arrow) and the ultrasound tip embedded into the posterior edge of each segment ready for emulsification. The epinucleus and cortex will then be removed during the phaco process. If we operate on a softer cataract, the freed fractured pieces are emulsified immediately.
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Relation Between Divide and Conquer and the Continuous Circular Capsulorhexis As pointed out by Paul Koch, M.D., the nuclear fracturing divide and conquer techniques developed initially by Gimbel and all the phacoemulsification techniques that are designed to move the nucleus through the capsulorhexis are in part possible because of the development of the continuous circular capsulorhexis that Gimbel and Neuhann originated individually (Figs. 43-45, 98, 99, 100). The CCC made nearly obsolete all the existing phacoemulsification procedures, because each of them required that the nucleus be prolapsed out of the capsular bag for each removal, either in the iris plane or in the anterior chamber (although the iris-plane tilt and tumble technique is still used by Lindstrom with significant success - Editor). Now that the capsular bag could be kept intact with a very strong form of capsulotomy, new techniques were needed to get the nucleus out of the bag. The mechanical fracturing of the lens causes extra physical stress within the capsule and cannot be done without great risk of tears of the anterior capsule extending around posteriorly unless we have a proper CCC. There is an interdependence of these techniques.
Principles of the Divide and Conquer Techniques Gimbel developed the Divide & Conquer techniques to meet the challenge and the opportunity created by the CCC: to operate
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within the capsular bag. There are actually two subdivisions: the trench Divide & Conquer and the crater Divide & Conquer, but they both follow two very simple principles: 1) Weaken the radii of the nucleus. This creates a space in the middle of the cataract in which other instruments can be introduced to force (crack) apart the sections of the nucleus (Figs. 56, 67, 103, 104, 106). 2) Break apart the nuclear parts including the rim of the nucleus (Figs. 104, 105, 106). Koch has pointed out that the distinction between a trench and a crater is not clear-cut. There is actually a continuum extending from true trench to true crater.
The Role of D & C Techniques in Cataracts of Different Nucleus Consistency Softer Cataracts (Trench D & C) Softer cataracts need preservation of firm tissue so that the cataract can be manipulated. If we remove much of the central nucleus, all of the firm tissue would be removed, and any attempt to manipulate it would be difficult. The instruments we use would go like through cheese in the remaining soft tissue. Some of the relatively hard central core is necessary to resist the instruments, give them something to press against, and, ultimately, something to manipulate. Recognizing this, Gimbel recommended the creation of a trench that is really a narrow pass down the middle of the cataract. This freed up a little space, but preserved walls of central nucleus for manipulation. The trench D & C is indicated for softer cataracts.
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Dense Cataracts (Crater D & C) In these cases the strategy is entirely different. We want to remove as much of the hard center core of the cataract as possible during this sculpting phase, leaving only a thin and soft nuclear rim for later removal. For these cataracts, a crater Divide and Conquer is recommended when using D & C techniques. The nucleus is held in place firmly in the bag. We can sculpt into the cataract with the ultrasound energy and remove all of the hard, dense nuclear core without the cataract moving. That keeps the phaco tip and all of the debris far away from the endothelium and allows safe and extensive nucleus removal. It also allows us to stay away from the posterior capsule. As pointed out by Paul Koch, M.D., we can judge the depth of the sculpting from fairly distinctive changes in the red reflex. The first clue to depth is the color of the cataract. We normally begin with a red reflex, but as soon as we start emulsifying the epinucleus, the reflex changes and becomes either burgundy or gray. As we sculpt down toward the middle of the cataract, we reach the gray center, and as we get through that, the reflex starts turning burgundy again (Fig. 69). Once we reach the posterior epinucleus, the color is back to red. If we monitor the color changes as we sculpt, we can work our way very deep into the catarac t without the risk of cutting the posterior capsule. We slow down as the color brightens. The primary goal of crater creation is to remove the very dense nuclear core, leaving only a much softer nuclear rim, thereby converting the cataract from a dense one into a soft one. The secondary goal is to create a space
below the level of the anterior capsule into which the rim tissue can be pulled for emulsification. (Editor’s Note: this technique is not to be confused with the original crater-bowl procedure used years ago).
Steps Following the Trench or the Crater D & C Once the nucleus is prepared with either the trench or the crater, the nuclear rim is broken apart using a unique and clever method of fracturing it. The phacoemulsification tip is driven into the remaining broad nuclear rim and held there with aspiration. A Barraquer spatula or manipulator (Fig. 79) is placed next to the phaco tip and poked into the rim right next to it (Fig. 67). The two instruments are separated, breaking the rim apart (Fig. 104). The nucleus is rotated around a bit, reengaged with th e phaco tip and the Barraquer spatula, and broken again (Fig. 106 below).
Present Role of Original Four Quadrant Divide and Conquer The original, four quadrant "Divide and Conquer Technique" illustrated in Figs. 56 and 67, 103, 104 and 106 below is now the technique of choice for those surgeons who are less experienced and are converting from planned extracapsular surgery to phacoemulsification. It is the easiest method. The debilitation of the nucleus is achieved by high doses of ultrasound energy and the "eating" or emulsification of the quadrants also requires high ultrasound energy. For this reason we included this technique as the one of choice in Chapter 7 that covers the stage of Transition.
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The original four quadrant divide and conquer technique has the significant importance of having served as the basis for the proliferation of many variations of the divide and conquer. Many of them are still useful. It also provided the insight needed for the
Figure 106: Phacoemulsification - Dividing Process Chopping vs Divide and Conquer (Top) The opposing forces in the chopping techniques are shown in vertical arrows. Please observe the chopper (Fig. 80) biting the nucleus fibers from the periphery towards the center, with phaco tip deeply impaled creating fixation and steadiness of the nucleus. This is sincronized move of the phaco probe and the chopper. (Below) Shows the opposing forces (arrows) cracking the nucleus after the deep groove has been made with the ultrasound (D & C technique). In this stage, the movement is from the center to the periphery (arrows).
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development of the chopping techniques, beginning with Nagahara's Phaco Chop. The latter, though, are based on different principles and constitute the group of low ultrasound energy - high vacuum procedures which at present are the techniques of choice.
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THE LOW ULTRASOUND ENERGY AND HIGH VACUUM GROUP The techniques described in the first group are known as the grooving and cracking methods. Now it is important for the surgeon to evolve into the second group, which are the chopping methods, because chopping enables you to reduce ultrasound energy in the eye by using greater mechanical forces - mechanical forces that will not harm the eye. I. Howard Fine, M.D., emphasizes that the easier we can make it to help surgeons transition to chopping, the better we will be serving our patients. Innovations in technique have undergone a rapid and important evolution driven by advances in technology. At the time when the initial four quadrant technique was introduced by Gimbel in 1987, the early phacoemulsification machines vibrated at a constant power with constant aspiration requiring the use of a large amount of ultrasound power in order to obtain rapid sculpting of the nucleus using
sharp needles to engage and cut nuclear material. The aspiration mode played a secondary role, after the material had been emulsified. The trend now is the opposite, that is, to use low ultrasound power and high vacuum. These chopping techniques emphasize the aspiration aspect while the ultrasound power is utilized as an aid to fragment the hard portions of the nucleus and to facilitate aspiration of the nuclear material. This is a significant advance which allows much more control by the surgeon. In all modern techniques, the surgeon uses only sufficient but very small amounts of ultrasound power to fragment the nuclear material that is occluding the tip of the phaco needle. The advances in technology that have made this possible are presented in Chapter 8, under “Emulsification System,” and illustrated in Fig. 85.
THE CHOPPING TECHNIQUES They are all based on the concept of the Phaco Chop technique initially devised by Nagahara in 1993. Since then a multiplicity of techniques that stem from the principles of the phaco chop have been developed but are less complex than the original Phaco Chop. The lens substance, including the nucleus, has a concentric lamellar and radial structure. It can be fractured along the direction of the lens fibers that run from one side of the equator towards the opposite side, passing through the center of the nucleus (Fig. 106 above).
Main Instruments Used In the chopping techniques, two instruments are utilized: 1) the phaco chopper introduced through the ancillary or side port incision, which serves as an ax (Fig. 80). The phaco tip serves as a chopping block (Fig. 106 above). The nucleus is easily fractured with the phaco chop technique. The latter is more effective for standard to moderately hard nuclei than a soft one.
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Surgical Principles of the Original Phaco Chop
Chopping Techniques Presented in this Volume
The surgical principle of the original phaco chop technique is first, after hydrodissection, the phaco tip is placed into the eye and touches the nucleus as far superiorly as possible, inside the limits of the capsulotomy. Using a quick burst of phaco energy the tip is buried securely into the nucleus. The chopper is inserted through the sideport incision, and placed on the nucleus as far inferiorly as possible, again right inside the capsulotomy. It is buried right into the cataract and then pulled up toward the phaco tip, dividing the cataract . This technique, which was the basis for all chopping techniques that later developed, presented two problems: unlike previous experiences with Divide & Conquer and In-Situ Fracture, there was no space in the middle of the cataract for manipulation. When the surgeon finished chopping the four quarters and was ready to emulsify one of them, he had no room to allow it to slide toward the phaco tip. It was wedged in place in the capsular bag and did not move easily. The surgeon had to engage the fragment and pull it into the anterior chamber for removal, converting the case from one that was purely endocapsular, to one that was threequarters endocapsular and one-quarter anterior chamber phaco. The surgeon had divided the nucleus into fragments, but had no space for maneuverability in order to remove them. Even though the Phaco-Chop technique of Nagahara initiated a new era in phacoemulsification, the original procedure had to be modified in order to overcome the problems here outlined.
From the large variety of chopping techniques now available, we have chosen five for presentation in Chapters 9 and 10. They were all originated by highly prestigious, experienced phacoemulsification experts and represent the direction in which this surgery is oriented. These procedures are: 1) The Stop and Chop (Paul Koch); 2) The Crater Phaco Chop (MacKool); 3) The Null Phaco Chop also referred to as Pre-Slice (Jack Dodick); 4) The Choo-Choo Chop and Flip (I. Howard Fine). 5) The Stop and Karate Chop Technique as advocated by Edgardo Carreño, one of the top phaco surgeons in South America. His insights are somewhat different than the top surgeons in North America.
THE STOP AND CHOP TECHNIQUE Surgical Principles This is the main variation of the phaco chop technique. It is widely used, and was popularized by Paul Koch. Its most important contribution is that it facilitates one of the significant difficulties encountered with the original phaco chop which is the fragmenting of the first half of the nucleus and removal of the first fragment. A superior quality CCC and a good hydrodissection are fundamental before managing the nucleus, as in all other phaco operations. After the hydrodissection is completed (Figs. 46-48, 78-A), Koch usually does not perform hydrodelineation for this procedure,
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Figure 107: Stop and Chop Technique Stage 1 - Sculpting the One Central Groove After instillation of viscoelastic, the phaco probe is introduced through the primary incision size (3.2 mm) at 10.30 o'clock and the chopper at 3 o'clock. This side view shows how the phato tip is impaled in the lens substance, sculpting a central groove as if we were doing the classical nucleofractures but only one groove is done and not the classical cross. This creates a space in the center which is essential for nucleus manipulation. The groove (G) is extended toward the periphery of the nucleus with the phaco probe (P). This maneuver debilitates the central core of the lens permitting its easier fracturing with the chopper.
because he is able to chop the nucleus into bitesized pieces. Because he constantly pulls pieces into the middle of the capsular bag, he does not need the cushion of epinucleus. All he would be doing if he created one would be adding one more step at the end -- removal of epinucleus. Koch's method is to sculpt a central groove as if we were doing the classical Nucleofractis or divide and conquer technique but only one groove is done and not the classical cross. This creates a space in the center (Figs. 107, 108) which is essential for nucleus manipulation. In softer cataracts, the surgeon does a lighter furrow or trench while in the standard two to three plus or even four plus
cataracts, a center crater is done instead of a furrow. The deep nuclear sculpting is performed from 12 o'clock to 6 o'clock, creating a vertical trough (Fig. 107). A second instrument designed for phaco chop (chopper) is inserted through the ancillary incision (Figs. 108, 80). The chopper is inserted underneath the anterior capsular edge in the lower right quadrant (Fig. 108), advanced out to the periphery of the capsule (Fig. 109), embedded in the peripheral nucleus (Fig. 110), and pulled back to the central groove. This creates a small free wedges of nucleus, which are easily emulsified and aspirated (Fig. 111).
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Figure 108 (above right): Stop and Chop Technique - Stage 2 - Insertion and Role of Second Instrument Once the groove has been sculpted deep enough (half the diameter of the phaco probe) in the 12 o'clock to 6 o'clock direction, the second instrument (chopper) is inserted through the ancillary incision and placed underneath the anterior capsular edge in the right lower quadrant. It is then advanced out to the periphery of the capsule, embedded in the peripheral nucleus and pulled back to the central groove, creating small free wedges of nucleus which are emulsified.
Figure 109 (center): Stop and Chop Technique - Stage 3 - Rotation of the Nucleus A space had been produced for the ultrasound tip and the ancillary chopper to fracture the nucleus. The surgeon stops, rotates the nucleus through 90 degrees, fixates the lower half of the nucleus with the ultrasound tip and creates a crack with the hook exherting traction in the opposite direction.
Figure 110 (above right): Stop and Chop Technique - Stage 4 - Creating Free Wedges of Nucleus The same piece of nucleus is again stabilized with the phaco tip while the chopper is advanced out to the periphery and pulled centrally. The surgeon uses the chopper (C) to crack the rotated nucleus in small pieces starting at the periphery. Observe how the chopper is pulled from the 6 o'clock position under the capsulorhexis towards the center while the phaco probe (P) maintains the nucleus in a fixed position for firm support.
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Fracturing of the Nucleus The ultrasound tip and the ancillary chopper fracture the nucleus into two parts by exerting force toward each other. The surgeon holds the ultrasound tip steady, which serves as the firm block holding the nucleus and the chopper slices the nucleus from the periphery towards the center of the nucleus. Numerous bites are performed with the choopper creating small free wedges to be emulsified (Fig. 111).
Fixating, Rotating and Creating Small Free Wedges of Nucleus for Emulsification and Aspiration At this point, the surgeon stops, rotates the nucleus through 90 degrees (Figs. 108, 109, 110). He fixates the lower half of the nucleus with the ultrasound tip and cracks it with a
hook, exerting force toward the ultrasound tip (Figs. 111, 106 above). The same piece of nucleus is again stabilized with the phaco tip, while the phaco chop instrument is advanced out to the periphery and pulled centrally (Figs. 110, 111), creating another small free wedge of nucleus for emulsification and aspiration. The process is repeated until the entire first nuclear half is removed. The other nuclear half is rotated into the inferior capsular bag, and the entire process is repeated (Figs. 108 through 111). From these four initial fragments, which can be easily mobilized from the capsular bag, each piece is further divided into smaller pieces and eaten with the ultrasound. Thereby, the importance of the burst action in the phaco machine, because the surgeon cuts small pieces and emulsifies, again cuts small pieces and emulsifies them (See Chapter 8 for Burst Mode and Pulse Mode). The whole procedure occurs with no sculpting .
Figure 111: Stop and Chop Technique - Stage 5 - Chopping and Emulsification At this point the inferior half of the nucleus has been cracked and begins to be emulsified. With the chopper the surgeon pulls from the periphery toward the center to divide and create additional small free wedges of nucleus which are then emulsified and aspirated. The process is repeated until the entire remaining nuclear half is removed.
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This is the essence of the stop and chop, one of the most important of the advanced techniques.
Absolute Requirements to Perform the Stop and Chop Although this technique is much less complex than the original phaco chop, in order for it to be successful, the following principles must be attained: 1) Hydrodissection: this stage of the procedure must be very well done (Figs. 46-48, 78-A). A great deal of the success of this technique depends on the ability to easily mobilize the nucleus (Figs. 108-110). We must be sure that the nucleus can be completely rotated before beginning its phacoemulsification. The ease with which the nucleus can be rorated depends on a very well done hydrodissection. Before beginning phacoemulsification of the nucleus, the surgeon should rotate the nucleus two or three times inside the bag. If the rotation is not easy, then there was a failure in the hydrodissection maneuver. The surgeon must not attempt to mobilize the nucleus mechanically or by force. 2) The Initial Groove: done to create the space inside the nucleus for it to be fractured (Figs. 107 - 108). This groove must be well done to be useful. It allows the surgeon to free the two sectors easily (Fig. 106 above). 3) Fracturing the Nucleus: when the surgeon has reached a good depth with the two instruments, that is, the phaco tip and the ma-
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nipulator or chopper, he should attempt to fracture the nucleus (Figs. 103, 104, 106 above). It is easy to split the nucleus into two parts because the chopper or manipulator does a better job separating the nucleus halves than the olive tip spatula previously used for this purpose. If there are difficulties and the fracture line is not seen, the initial groove in the center of the nucleus can be deepened but the surgeon must pay great attention to the color of the red reflex to be sure he/she is not too close to the posterior capsule. The fracture of the nucleus into two parts first is the key to the success of the operation. Only after this will the surgeon be allowed to proceed making smaller free segments or wedges by additionally fracturing with the chopper (Fig. 111). Fracturing with the chopper depends largely on the instrument insertion depth. Normally, the phaco probe and tip as well as the chopper should be inserted at a depth about 2/3 the diameter of the phaco tip. Once the nuclear fragments have been made, the procedure is continued with the usual maneuvers (Figs. 105 - 111). At the end of nuclear removal, there is a small quantity of residual material which is then aspirated.
Importance of the Phaco Chopper This ancillary instrument is absolutely essential to perform the chopping technique. There is a large variety of these phaco choppers. They all look like a golf club and the most
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effective ones have a somewhat sharp point 1.5 mm in length (Fig. 80). In figures 103 through 121 you may observe the chopper being used in different techniques. The chopper is inserted through the side port or ancillary incision. The hook or chopper is positioned at 6:00 o'clock underneath the anterior capsule as far peripheral and deep as possible (Figs. 105, 110, 111). The shape of the point is most important. We can chop a soft nucleus using a sharp point; a wedge shaped tip facilitates chopping of a hard nucleus.
Highlights of the Stop and Chop Technique 1) It provides excellent stabilization of the nucleus by fixation with the phaco tip and slicing and biting with the chopper. The latter has more of an active role in the procedure than the ancillary instruments in other endocapsular techniques. The surgeon uses the two hands in harmony during the entire phaco nuclear removal. This also means that the surgeon should pay very close attention to the chopper, which needs as much control as the ultrasound tip. 2) Throughout the entire procedure, the ultrasound energy transmitted to the nucleus is not transmitted to the epinucleus and the cortex. Therefore, it is not passed on to the posterior capsule and the zonules because it is
absorbed by the external cortex and the separation induced through hydrodissection 3) How useful is this procedure is in cataracts of different nuclear consistency depends on the ability of the surgeon to adapt his technique to the type of cataract he/she is operating. The size of the nuclear wedges created can vary based on nuclear consistency. This technique is even useful in hard nuclei using less ultrasound and more aspiration. Hard nuclei require smaller wedges while softer nuclei can yield with larger wedges. The stop and chop technique is useful in most cataracts with different consistency: in hard nuclei, in soft and in cataracts with nuclei of standard consistency. It is a method that lends itself to wide use. There is greater ease in dealing with very hard nuclei as compared with most other techniques. 4) The advantages of this procedure over the conventional divide and conquer methods include reduced stress on the capsular bag and zonular fibers because the use of the chopper simplifies the fracture. 5) The operation decreases phaco time. 6) It creates less turbulence and consequent complications. 7) Any remaining epinucleus and cortex is removed in standard fashion. 8) By dividing the nucleus in two halves, the stop and chop technique facilitates the more difficult maneuvering encountered by the surgeon in phaco chop.
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FUNDAMENTAL DIFFERENCES BETWEEN CHOPPING TECHNIQUES AND DIVIDE AND CONQUER (D & C) TECHNIQUES
The two main groups of techniques utilized in modern, endosacular advanced methods for managing of the nucleus in phacoemulsification are the chopping techniques and its derivatives and the cracking techniques (divide and conquer and its derivatives). There are fundamental differences in regards to their surgical principles. Chopping tends to stabilize the nucleus between the phaco tip and the chopping instrument. Furthermore, mechanical force is directed centripetally as the chopping instrument cleaves the nucleus (Fig. 106 above). Therefore, minimal force is directed outward against the capsule periphery. This is in contrast to cracking methods, during which the nuclear periphery is pushed outward against the capsule by the cracking instruments (Figs. 104, 106 below). As a consequence, any defect in the capsulorhexis is at greater risk and may have a tendency to extend to the periphery and posteriorly with cracking as opposed to chopping. Chopping is also a more productive method than cracking with respect to the need to use ultrasound power because chopping uses mechanical force for nuclear segmentation as opposed to sculpting grooves which are done with ultrasound, even though modified D & C techniques do allow the use of low total ultrasound energy because it is not used continuously. Ultrasound is used more efficiently during chopping because it is applied in the more effective occlusion mode.
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Finally, chopping is a more time productive method than cracking in that a segmenting chop can be made with a single instrument movement (Figs. 104 above, 111) as opposed to multiple ultrasonic sculpting passes required for a groove (Figs. 56, 67). Also, the smaller chopped fragments are more readily emulsified with less repositioning required as compared to larger quadrants. In the chopping techniques, the chopping direction is from the equator to the center (Fig. 104 above). In the divide and conquer procedures, the cracking is from the center toward the equator (Fig. 104 below). Therefore, in the divide and conquer procedures, the surgeon must begin sculpting the center of the nucleus and debilitating the nucleus at that stage, making a trench or a crater with ultrasound to start the cracking from the center, as shown in Figs. 106 below, and 104. In the chopping techniques, the surgeon sticks the phaco tip into the nucleus and insert the phaco chopper into the space between the equator and the capsule at the 6 o'clock position (Figs. 105, 110, 111). Then the phaco chopper is drawn to the phaco tip to crack the nucleus. There is no need of sculpting during this stage of the procedure which is the reason why the phaco energy can be significantly reduced. Sculpting with the ultrasound energy is the easiest and safest step of the operation and that is why we recommend the divide and conquer original four quadrant technique for the transition. There is no ultrasound sculpting in the stop and chop.
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THE CRATER PROCEDURES The Crater Divide and Conquer (Mackool) This procedure is based on Gimbel's Divide and Conquer surgical principles. It is a modification of the original four quadrant divide and conquer. Because it is used mostly for hard nuclei, the center of the nucleus is weakened in the shape of a small crater by applying ultrasound energy and proceeding to crack the nucleus in two halves. This is followed by further cracking into four pieces using the ultrasound energy with the help of the ancillary instrument. The pieces are then emulsified.
The Crater Phaco Chop for Dense, Hard Nuclei The crater phaco chop is essentially used in harder, more dense and brunescent cataracts (Fig. 2) in which a trench or trough or groove cannot be used because it does not weaken the entire lens nucleus sufficiently to easily fracture the nucleus. The resulting segments would be too large to manage safely. This is because the epinucleus of a hard nucleus is thin and a hard nucleus has a dual structure consisting of an outer soft and inner hard nucleus or core. Also, a hard nucleus is thicker than a soft nucleus and the posterior part is harder and more elastic. In these lenses, the phaco chop of Nagahara or even the stop and chop of Koch may not be sufficient.
Instead, a small, central crater is sculpted with controlled amounts of ultrasound energy, leaving a dense peripheral rim (Fig. 112). After the central core of the nucleus is removed, the maneuvering of fracturing can be accomplished by first placing the chopping instrument under the anterior capsule at the 6 o'clock position (Fig. 113). Keeping the phaco tip placed into the bulkhead of the nuclear rim (Fig. 113), the vacuum of the tip is used to stimulate division of the nucleus. No ultrasound is used. The chopping instrument which has been introduced through the ancillary incision pulls toward the incision (arrow), slightly away from the phaco tip and gently towards the posterior capsule. This results in a fracture through the nuclear rim and any remaining thin nuclear plate (Figs. 114). The nucleus is then rotated in order to accomplish additional fracturing of small segments (Figs. 114, 115). Fracturing is done with much less ultrasound energy than in the D & C Crater Procedure. In the Crater Chop technique, again we initially debilitate the nuclear core with ultrasound energy. When weakened, the phaco tip is impaled or firmly buried in the central nucleus (Figs. 113, 114). Multiple wedges are created by the continuous process of biting tissue using the chopper. These small pieces are then emulsified (Fig. 116). This Crater Chop technique is not to be identified as the Crater-Bowl procedure described previously in which a substantial amount of ultrasound energy was used to debilitate the central tissue.
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Figure 112 (above left): Crater Chop Technique - Stage 1 - Creation of the Small Crater The central epinucleus and anterior cortex are removed. The phaco tip (P) is used for sculpting at the center. A small central crater is sculpted with controlled amounts of ultrasound energy, leaving a dense peripheral rim. This creates a thin central nucleus suitable to easier fracturing with the chopper.
Figure 113 (center): Crater Chop Technique - Stage 2 - Fracturing the Nucleus With coordinated movements the phaco probe (P) is impaled and buried through the thickness of the dense periphery. At that time the chopoper (C) is employed to start the fracture deeply and vertically from the periphery to the center toward the phaco tip in the direction of the primary incision.
Figure 114 (below left): Crater Chop Technique - Stage 3 - Slicing the Nucleus into Small Wedges Small, controlled and smooth movements are required to slice portions of the nucleus into wedges without tearing the posterior capsule. Portions of the nucleus are attracted and rotated toward the center with the phaco probe (P) in ultrasound mode, fracturing the wedges into small pieces with the help of the chopper (C) and rendering them for emulsifiction and aspiration.
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When to Remove Nuclear Segments Immediately vs When Leave them in Place The entire lens is fractured before any pieces are removed, maintaining the distention of the capsule which helps to prevent an inadvertent capsule rupture, as shown in Fig. 115). With a dense or brunescent nucleus, it is safer to leave the segments in place to maintain the shape of the bag, without the potential for collapse. The segments are easier to fracture if they are held loosely in place by the rest of the segments still in the bag.
Figure 115 (above ): Crater Chop Technique - Stage 4 - Fracturing and Chopping Process During the fracturing process, the phaco tip is buried in the dense nuclear periphery while the continuous action of the chopper bites the nucleus into pieces bringing them to the center. Here we may observe this combined maneuver using the chopper (C) and the phaco probe (P) for rotation and cutting of fragments.
Figure 116 (below): Crater Chop Technique - Stage 5 - Attacking the Final Quadrant The phaco tip is brought in contact with the last fragment. Tip occlusion is maintained using short bursts of low energy ultrasound. While keeping the tip occluded the fragment is advanced toward the center of the capsular bag with the help of the chopper (C) for complete aspiration with the phaco probe (P).
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THE NUCLEAR PRE-SLICE OR NULL PHACO CHOP TECHNIQUE This technique has been devised by Jack Dodick, M.D., from New York, one of the world's experts in cataract surgery. Almost every contemporary cataract surgeon uses some form of chopping, and all surgeons who perform chopping use some form of ultrasound to facilitate the chop. Whether it be a groove-andchop, divide and conquer, or a technique like Howard Fine's quick chop (the choo-choo chop and flip technique presented later in this chapter), some form of ultrasound is used for chopping.
Disassembling the Nucleus Importance in Modern Techniques All modern techniques are oriented toward breaking up or disassembling the nucleus to facilitate its removal from the eye. These techniques, which rely on mechanical energy, have been developed to reduce the amount of ultrasound energy necessary to break up the hard part of the lens nucleus. In addition, disassembling the nucleus removes it from the capsular recesses of the bag, thereby facilitating its removal with the phaco probe. Nuclear disassembling techniques use some ultrasound at the beginning of the procedure to create multiple troughs or grooves. A second instrument such as a spatula or chopper can then be used to crack or break the nucleus. Dodick now routinely uses the nuclear preslice or null-phaco chop technique except in hardened, black cataracts. This procedure reduces the amount of ultrasound needed to remove cataracts by phacoemulsification. The
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actual breaking up of the lens uses no ultrasound at all. In this technique, Dodick sections the nucleus into four parts with no ultrasound using two specially designed hooks (Figs. 117 - 121). It is as safe as any phaco chop, and takes an equal amount of time.
How Is the Null-Phaco Chop Done The procedure uses two elongated Sinskey hooks, which have a 2 mm bend with a round polished ball at the end neatly shown in Figs. 119 and 120. The anterior cortex is vacuumed, and viscoelastic is placed in the eye. The first hook is introduced through the paracentesis incision parallel to the lens until it is in the capsular bag. Dodick always does the phacoemulsification at the 11:00 position, which means the paracentesis incision is at about 2:30 (Fig. 117). The hook enters the capsular bag and is rotated 90 degrees so that it engages the equator of the nucleus. The first hook is now in place and is pointing toward the optic nerve. Then the second hook is introduced through the phacoemulsification incision, again parallel to the lens (Fig. 117). It engages the capsular bag and enters it. The surgeon then rotates the hook 90 degrees so that the tip faces the optic nerve and engages the equator of the nucleus below. The hooks should be about 180 degrees apart. Taking great care, the surgeon moves the hooks to bring the tips together (Fig. 118). This process will not tear the posterior capsule, but it is important not to place the hooks in the sulcus. As the two hooks are brought together, they bisect the nucleus (Fig. 118).
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Figure 117: Dodick’s Null-Phaco Chop Technique - Stage 1 - Insertion and Placement of Hooks Two identical elongated hooks (H) which have a 2 mm bend with a round polished ball at the end serve as the choppers. The first hook is introduced through the ancillary incision at 2 - 3 o'clock and the other one through the primary incision. The hooks are positioned opposite one another. They enter the capsular bag and are rotated 90 degrees so that they engage the equator of the lens. The hooks are 180 degrees apart.
Figure 118: Dodick’s Null-Phaco Chop Technique - Stage 2 - Bissecting the Nucleus Thesurgeon pulls on the hooks to bring them together and bisect the nucleus.
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Figure 119 (above): Dodick’s NullPhaco Chop Technique - Stage 3 - Fracturing the Inferior Half of the Cataract The 11 o’clock hook is moved toward 6 o’clock and placed in the capsular bag. The second hook is left in the groove. The two hooks are brought together resulting in a trisection (this part of lens is cut into three parts).
Figure 120 (below): Dodick’s NullPhaco Chop Technique - Stage 4 Fracturing the Superior Half of the Cataract Once the inferior half is divided, the surgeon proceeds with the superior half in a similar manner. The hooks or choppers are placed at 11 o’clock and centrally and drawn together toward the visual axis to complete the disassembling of the entire cataract.
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After the first crack a second crack of each half is easily made. The 11:00 hook is moved toward 6:00, and placed in the capsular bag while the second hook is left in the trough or groove (Fig. 119). The two hooks are brought together resulting in a trisection. At this point the lens has been cut into three parts (Fig. 119). The procedure can be repeated by splitting the next half in a similar fashion (Fig. 120). Upto this point no ultrasound has been used. Once the quadrants are each broken up into three or four parts, they are removed with bevel down phaco, with high vacuum of 300 mm Hg to 500 mm Hg. This is in a peristaltic system, with a high flow rate of 30cc to 40 cc per minute. The amount of energy needed is extremely low.
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Dodick disassembles some 1+ 2+ lenses with little or no ultrasound, because this maneuver not only sections the nucleus into four parts, it actually dislodges these parts quite well from the recesses of the capsular bag (Figs. 120, 121). He brings the last two quadrants into the pupillary plane and is able to break them up further with the aid of a Sinskey hook through the paracentesis incision. When he needs ultrasound in 3+ or 4+ cataracts, he rarely goes above 30 % ultrasound because the lens is already broken into four parts (Fig. 121).
Learning and Adjustment Performing this technique does require some learning and adjustment. The learning curve required for this technique is to master the placement of the two hooks nd to prevent rotation of the nucleus while it is being divided. Great care must be exercised in the placement of the hooks into the capsular bag. There is a tendency for the nucleus to rotate, but you soon develop a proprioceptive-like sense of placing those hooks. If you see or feel internal rotation of the nucleus about to begin, you simply adjust the hooks.
Figure 121: Dodick’s Null-Phaco Chop Technique - Stage 5 - Cataract Fractured in Four Fragments Once fractured, the four fragments of the cataract are removed using mainly vacuum and aspiration. Once mastered, this technique is highly reproducible and takes no longer than any other chop technique and reduces the amount of ultrasound energy introduced into the eye.
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Once mastered, this technique is highly reproducible, it takes no longer than any other chop technique, and reduces the amount of ultrasound energy introduced into the eye. It may be a very good alternative procedure for experienced phaco surgeons.
amount of energy necessary to evacuate the lens. The technique Dodick describes is one method of nuclear disassembly. These methods in general dramatically reduce the amount of energy to break up the nucleus, leading to clearer corneas and quicker rehabilitation of the patient after surgery.
Potential Complications To critics, this technique appears dangerous. The belief is that the capsular bag can be dislocated. However, Dodick has not found this to be a problem if the recesses of the capsular bag are identified by vacuuming of the anterior cortical material and the hooks are carefully placed in the capsular bag and not in the sulcus. Critics may point out that the tip is back toward the posterior capsule, and the two hooks brought across the nucleus might rip the posterior capsule. This, according to Dodick, does not happen. On the contrary, he thinks that this can actually be a safer procedure, especially in eyes with weak zonules and pseudoexfoliation. Rather than sculpting and applying pressure toward the zonules, the vector forces from the special hooks pull toward the center, reducing stress on the zonules. For more dense cataracts (e.g. 3+), he does use low ultrasound, perhaps 15%, maximum 30%, and again high vacuum, 300 to 400 mmHg, and a high flow rate. To minimize the effect of surge, he uses the MAXVAC high vacuum tubing and the aspiration bypass ABS tip.
Contributions of this Technique Dodick's procedure shows that using mechanical energy to break up the lens in place of ultrasound is helpful in reducing the
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THE CHOO-CHOO CHOP AND FLIP PHACOEMULSIFICATION TECHNIQUE This special technique devised by I. Howard Fine, M.D., head of the Oregon Eye Institute in Eugene, Oregon and Clinical Professor at the Oregon Health Science University in Portland, is a chopping technique that uses power modulations and high vacuum along with specific maneuvers to minimize the amount of ultrasound energy in the eye and maximize safety and control. It is effective in all types of cataracts and allows hardened nuclei to be removed safely in the presence of a compromised endothelium. This procedure facilitates the achievement of two goals: minimally invasive cataract surgery and maximally rapid visual rehabilitation. It is designed to take maximum advantage of various new technologies available, mainly the Alcon 20,000 Legacy, the AMO Sovereign (Allergan) and the Storz Millennium phacoemulsification systems (Fig. 85). These technologies include high vacuum cassettes and tubing, multiple programmable features on all systems, as well as the Mackool Micro Tip (Fig. 84) with the Legacy and burst mode and occlusion mode capabilities with the Sovereign (Figs. 86, 87). The result is enhanced efficiency, control, and safety. The procedure is done as shown and described in Figs. 122, 123, 124, 125, and 126.
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Origin of the Name “Choo-Choo” Fine uses high vacuum and short bursts, or pulses, of phaco ultrasonic power. The name “choo-choo” arises from the resulting sound of the pulse mode (Fig. 125). The nucleus is continually rotated so that pieshaped segments can be scored and chopped, and then removed by high vacuum assisted by short bursts or pulses of phaco. (Editor’s Note: scoring the nucleus in this instance means using the wedge-shaped edge of the chopper instrument to groove and then cut the nucleus in half against the countering resistance of the phaco tip which has been securely engulfed in the opposite side of the nucleus.)
The short bursts or pulses of ultrasound energy continuously reshape the pie-shaped segments which are kept at the tip, allowing for occlusion and extraction by the vacuum. The size of the pie-shaped segments is customized to the density of the nucleus with smaller segments for denser nuclei. Phaco in burst mode (Fig. 125) or at this low pulse rate (Fig. 86) sounds like “choo-choo-choochoo”; this is the reason behind the name of this technique. (Editor’s Note: for a precise description and illustration of the pulse and burst modes, and their clinical applications, see pages 151-156, and Figs. 86, 87). The term “flip” refers to management of the epinucleus (Fig. 126). Fine considers it important not to remove the epinucleus too
Figure 122: Choo-Choo Chop Technique Stage 1 Following instillation of high density, cohesive viscoelastic, cortico cleaving, circular capsulorhexis (C), hydrodissection and hydrodelineation of the nucleus are performed. The exposed epinucleus (E) exposed by the CCC is aspirated. To chop the nucleus into two hemispheres, a Fine/Nagahara chopper (F) introduced through a side port incision engages the distal nuclear margin at the golden ring (G) and stabilizes the endonucleus. Simultaneously, the 30 degree bevel-down phaco tip (P) introduced through a clear corneal incision “lollipops” the proximal nucleus. The nucleus is scored by bringing the chopper proximally (red arrow) to the side of the phaco tip, which provides a countering force (blue arrow).
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Figure 123 (above): Choo-Choo Chop Technique - Stage 2 This figure shows the resting positions of the instruments just following completion of the nuclear chop (arrow). The chopper (F) has been brought proximally and slightly to the side of the phaco tip and the phaco (P) has been held stationary. The hands are then separated - the chop instrument moving to the left and slightly down (1), and the phaco tip to the right and slightly up (2).
Figure 124 (below): Choo-Choo Chop Technique - Subsequent Chopping of Nucleus In a similar manner to the first chop, the phaco (P) and chopper (F) are used in combination to score and chop the heminuclei. First the nucleus is rotated into position as shown. Here the chopper is directed from position 1 to position 2 toward the side of the bevel-down phaco tip to score (3 - arrow) the hemisphere. These smaller pieces can then more easily be extracted from the eye with reduced use of ultrasonic power by using power modulations. The second nuclear hemisphere (H) is dealt with in the same fashion.
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Figure 125 (above left): Choo-Choo Chop Technique - Use of Burst Mode Ultrasonic Power The chopper (F) is used to assist in holding the nuclear pie-shaped segments against (arrow) the phaco (P) aspiration port. Using high vacuum and short bursts, or pulses, of phaco ultrasonic power (thus the name “choo-choo” from the resulting sound of the pulse mode), the nuclear material is fragmented and aspirated with minimal or no chattering of the piece against the phaco tip. This makes for a more efficient and timely removal of the nucleus.
Figure 126 (below right): The Epinuclear Flip Technique Following removal of the endonucleus, the rim of the distal epinucleus (E) is engaged with the phaco tip (P) in the bevel-up position. The chopper (F) is used to assist in flipping (arrow) the epinucleus. In this more centrally located position, the entire epinuclear rim and floor can be evacuated from the eye safely and completely. This is followed by foldable IOL implantation and removal of viscoelastic and any residual cortex.
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early, to avoid leaving a large amount of residual cortex after evacuation of the epinucleus. The epinuclear rim of the fourth quadrant is utilized as a handle to flip the remaining epinucleus.
ultrasound energy (grooving) to further disassemble the nucleus. High vacuum is utilized to remove nuclear material rather than utilizing ultrasound energy to convert the nucleus to an emulsate that is evacuated by aspiration.
Comparison With Other Techniques Fine's Parameters The choo-choo chop and flip technique utilizes the same hydro forces to disassemble of the nucleus as in cracking techniques, but substitutes mechanical forces (chopping) for
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The parameters used by Fine for this technique and applied to the three main phacoemulsification equipments are the following:
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These Parameters are adjusted depending on the hardness of the nucleus. They can be programmed in the corresponding “Memory” of the equipment.
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THE TRANSITION TO CHOPPING TECHNIQUES In the transition to chopping, Fine recommends the following steps: Impale the nucleus on the phaco tip superiorly. If you have not lollipoped the probe tip deep enough (Fig. 88), return to position 2 and then go back into position 3. (Editor’s Note: lollipoping refers to securely engulfing the tip of the phaco into the nucleus, like a lollipop or candy sucker on a stick. The phaco tip is analogous to the stick and the nucleus is the round candy portion.) A burst takes place each time you enter position 3. When you have lollipoped deeply enough (Fig. 88), score the nucleus. (Editor’s Note: scoring the nucleus means using the wedge-shaped edge of the chopper instrument to groove the nucleus deeply, against the countering resistance from the lollipoped phaco on the opposite side of the nucleus.) Place the chop instrument in the golden ring (Fig. 75), go from foot position 2 into foot position 3 and floor it (Editor’s Note: pushing the pedal fully all the way to the bottom setting, as when applying full gas pedal pressure in a car). You can chop the nucleus without having to worry about what your foot is doing because your foot is on the floor — the vacuum will hold the nucleus as you manipulate the chop instrument. Then break the nucleus in half by separating the two instruments while depressing the chopper and slightly elevating the phaco needle. You will not have to worry about what your foot is doing because you are already in control of the nucleus — you will not have to manipulate your foot at all. This technique will allow you a much easier transi-
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tion with fewer factors to worry about. For mobilizing the nuclear tissue, Fine likes a burst width of 80 milliseconds in surgeon control (Fig. 87). Once again, you can customize your options to control what happens at the tip. If things are moving along rapidly, you can depress the foot pedal to foot position 3 and decrease the interval between bursts. Or if you feel like things are a little precarious or there is a very hard piece of nucleus and you want to avoid chattering, you can back off a little bit. (Editor’s Note: chattering is when the nucleus bounces against the phaco tip at a high rate of speed without being emulsified as desired, like when ones teeth chatter when cold - Fig. 89) The material will be held very firmly at the tip with no chatter, and will not emerge into the anterior chamber. This affords a much greater level of safety when dealing with a hard cataract in the presence of endothelial disease. Once you have taken care of the endonucleus, you can employ the Bimodal feature using the pedal to vary your aspiration flow rate in foot position 2. This helps you to mobilize and bring the epinuclear roof out of the capsular fornix and position it in such a way that you can trim it. Fine trims the rim of the epinucleus in three different quadrants and uses the rim in the remaining quadrant to flip the rest of the epinucleus (Fig. 126). He brings the handpiece central and then trims the epinucleus. Once he goes into foot position 3 the tip clears. As the rim of the epinuclear shell is removed, the aspiration flow rate causes the residual cortex to flow over the floor of the epinuclear plate. Fine does not usually have to remove the cortex as a separate step of phacoemulsification. In 70 percent of these cases, he has no cortex remaining.
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These types of maneuvers can be done because there is a stable anterior chamber with a very low tendency for surge. The new technology in these advanced machines and new software allows the surgeon to put into effect the important advance in performing phacoemulsification, which is fundamentally cutting power. The surgeon really has little worry about cutting power himself because the new software provides him/her so many more options. With these recent advances in phacoemulsification systems, the surgeon has indeed a total control phaco chop. The new type of software described in Chapter 8, Fig. 85, will advance phacoemulsification in regions of the world where there is a preponderance of hard cataract with diseased endothelium.
REMOVAL OF RESIDUAL CORTEX AND EPINUCLEUS The surgeon who is learning this technique usually has more cortex to aspirate and needs to follow a specific technique for removal of the epinucleus. This is discussed in depth and illustrated in Figs. 69, 70 and 71, Chapter 7. If not cautiously done, there is a higher incidence of rupture of the posterior capsule. The situation differs for the experienced surgeon. Due to the importance attributed to a well-performed hydrodissection and rotation of the nucleus at the end of it, generally the epinucleus and the residual cortex are
Figure 127: Irrigation/Aspiration of Residual Cortex Inferiorly Following emulsification of the nucleus, the ultrasound tip is replaced by the irrigation/aspiration tip (A). The tip is placed into the anterior chamber through the primary incision and inserted under the anterior capsule in the inferior sector to remove the small amounts of residual cortex. It is important not to be aggressive nor attempt to vacuum clean. This is risky and may result in posterior capsule rupture.
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Figure 128: Irrigation/Aspiration of Residual Cortex Superiorly In superior areas where it is difficult to maneuver with the irrigation/aspiration tip (ghost view - A), particularly at 12 o’clock, we may remove the residual cortex located superiorly using a manual aspiration technique with a curved irrigation/aspiration cannula or a standard Simcoe cannula (S). Here the Simcoe cannula is inserted inferiorly through an additional paracentesis (P) which is a third incision performed between 6 and 7 o’clock. It is moved superiorly to remove the residual cortex under the anterior capsule leaves. Manual technique allows more accurate control. Another method to attain this is following the procedure shown in figure 71. Again, it is important not to be aggressive.
aspirated together with the nucleus segments. The aspiration of cortical remains becomes unnecessary because they were partially or totally eliminated during nucleus emulsification. If this does not happen, the tip of the phaco emulsifier aspirates the free epinucleus with the pedal on position 2, with the help of the nucleus manipulator (Figs. 69 and 126). Once the nucleus has been removed and the surgeon proceeds to irrigate/aspirate whatever cortex remains, he/she may become over-confident thinking that the operation is practically finished. It is, if the cortex and epinucleus are then removed with special care. Always be certain to check the tip of the I/A phaco tip preoperatively to detect any
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little barbs or sharp spots that could rupture or tear the posterior capsule. The Chip and Flip technique advocated by Fine may be very useful in this phase (Fig. 126). The entire epinuclear rim and floor can be evacuated safely and completely. If some cortical material remains, particularly in the hard-to-reach superior capsular bag underneath the anterior capsule leaves, the surgeon proceeds to remove this residual cortex as shown in Figs. 127 and 128. It is very important not to be aggressive. Do not attempt to clear the very last bit of cortex remaining because this could lead to accidental rupture of the posterior capsule.
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INTRAOCULAR LENS IMPLANTATION The Increased Interest in Foldable IOL's Present trends point to an increasing use of foldable IOL's for the following reasons: 1) Small incision cataract surgery continues to be on the rise. Patients who are in the financial, social, business and professional levels to afford phacoemulsification look forward to a very prompt visual rehabilitation. This can be made possible only by a successful phaco with a small, valvulated, self-sealing 3 mm average incision which requires a first class foldable IOL (Figs. 90, 91). Surgeons, therefore, no longer accept the previous methods of performing a cataract extraction through a small incision followed by an enlargement of the wound in order to insert a 6.0 mm optic PMMA lens. As a consequence, industry rose to this challenge and has developed high quality foldable IOL's . 2) Through the significant clinical and laboratory research made by R. Lindstrom, I.H. Fine, Ernest and Neuhann, Langernman and other prestigious colleagues, refractive cataract surgery was developed as a standard procedure by: a) placing the corneal cataract incision in the right place. b) developing the right architectural design of a small self-sealing, valvulated, corneal tunnel incision that can result in 1.00 D or less of postoperative astigmatism (Figs. 92, 93). This has stimulated the use of foldable monofocal and multifocal IOL's.
3) Foldable IOL technology has significantly improved associated with the use of non-toxic, highly biocompatible chemicals and polymers of which the foldable IOL`s are made. This is particularly important with the development of second generation silicone lenses which have been proven to be non-toxic, non-inflammatory, non-sensitizing, inert and available at lower costs.
The Most Frequently Used IOL's Even though there is a distinct trent towards foldable lenses, PMMA IOL's continue to be the most frequently implanted intraocular lenses throughout the world, (except in the U.S). PMMA IOL’s are used more commonly even in Europe, although to an ever-decreasing extent, as has been pointed out by Tobias Neuhann, M.D., of Germany, in a classic study he made of new foldable IOL's (see bibliography). The still preponderant use of PMMA lenses is related to the unquestionable reality that, for a variety of reasons, extracapsular surgery is still the cataract operation mostly used throughout the globe. More than 60% of very good ophthalmic surgeons perform ECCE in the majority of patients even though they may recognize that phacoemulsification is a better operation especially for of very prompt visual rehabilitation.
Special Indications for PMMA Lenses Richard Lindstrom, M.D. uses foldable lens implants in most cataract operations.
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Figure 129: Insertion of PMMA Anterior Chamber Lens in Aphakia - Gonioscopic View A gonioscopic mirror is used to check the position of the proximal footplates, and to ensure that there is no iris tuck. The distal footplates are also checked again with the gonio prism to ensure that they have not been displaced during placement of the proximal haptics.
Nevertheless, he considers that there still are indications for the standard PMMA lenses, for example the secondary anterior chamber lens implant (Fig. 129). He also uses standard PMMA intraocular lenses when performing a triple procedure that includes a penetrating keratoplasty. In these patients there is no reason to use a foldable lens. He may use a 7 mm optic modified C loop PMMA lens.
The most widely accepted, major groups of foldable lenses are made of either acrylic or second generation silicone (PDMDPS). Each group has advantages and disadvantages. Other monofocal lenses creating interest are the Memory lens, the hydrogel lenses and the toric lens made by STAAR.
MONOFOCAL FOLDABLE LENSES
These lenses have a very high refractive index providing crystal clear vision. Chemically they are closely related to the still generally favored PMMA. Mechanically they are best described as pliable rather than elastic. This is clinically important because acrylic lenses are comsidered by many surgeons as somewhat bulky when folded and, consequently, difficult to implant through an inci-
An extensive variety of excellent monofocal foldable lenses are produced by manufacturers in the US, Germany, France, Belgium, Switzerland and other countries. They use the finest technology and front-line engineers, biochemists and designers. 208
THE FOLDABLE ACRYLIC IOL'S
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sion less than 3.5 mm. We have presented Carreño's technique in which he describes how to insert the AcrySof lens through a 2.8 mm incision in Chapter 8. The most widely used foldable acrylic lenses are the popular Alcon AcrySof lens model MA30BA, which has a 5.5 mm optic and PMMA haptics and the Allergan Sensar AR40 with a 6.0 mm optic. They both come with very practical folding and injector systems, the "Acrypack" for Alcon's AcrySof and the "Unfolder Saphire" for Allergan's Sensar.
Specific Advantages of Acrylic Foldables In addition to providing a very high refractive index, they are also the first choice lenses to use in higher risk cases such as patients with diabetic retinopathy (Figs. 8-17), chronic uveitis or any candidates for future vitrectomy with silicone oil. Another advantage seems to be that acrylic lenses have a "tacky" surface. According to Tobias Neuhann, M.D., a positive consequence of this tackiness is a mechanical adhesiveness between lens capsule and IOL, which, in turn, may lead to reduction of secondary cataract (posterior capsule opacification). A disadvantage of this tackiness, however, is that a multitude of small particles may stick to the lens surface and be pressed into the material with the implantation instruments, where they remain forever, since they are not absorbed. For these reasons, injector implantation or disposable implantation forceps are gaining increasing importance in handling these lenses (Fig. 82 B and C).
Disadvantages Foldables
of
Acrylic
Foldable acrylic lenses come in a 5.5 and a 6 mm optic size. Lindstrom and some other surgeons prefer the 6 mm optic because the 5.5 mm optic lenses may have problems with edge glare and unwanted visual images. Another limitation with acrylic lenses, according to Lindstrom, is that none of the foldable acrylic lenses will go through an incision smaller than 3.5 mm. (they are pliable but not elastic Editor) In his experience, you have to make one of two compromises if you use an acrylic lens. Either you make the incision larger or make the optic smaller. 3.5 mm instead of 3.2 or 3.0 mm is not a large difference but still, with a clear corneal incision, Lindstrom thinks the smaller the incision the safer it is as far as sealing of the wound. And if you go to a smaller optics then you get more symptoms of edge glare, particularly with younger patients who have larger pupils. Edgardo Carreño, M.D., on the other hand, has developed a technique by which he implants the foldable acrylic Alcon AcrySof lens 5.5 mm optic through a 2.75 mm incision. Carreño's technique is described in this book in Chapter 8.
THE FOLDABLE MONOFOCAL SILICONE IOL's Second generation silicones are gaining in popularity because they are inert and do not give rise to inflammatory reactions. This second generation silicone polymer is identified as the PDMDPS.
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There was a time when the silicone lenses caused more inflammation or capsular fibroses but the newer silicones do not do that at least based on the studies made by Lindstrom and others. Many surgeons like silicone lenses because they go through an incision smaller than other lenses thereby allowing a larger optic. The favorite lenses are those with 6.0 mm optic or larger. There are now two companies that have a 6.3 mm optic silicone lens. One of them is Staar and the other is Bausch & Lomb. Most other companies have 6 mm optic silicone lenses. The most popular monofocal foldable silicone lenses are Allergan's SI 40 NV and Bausch & Lomb's LI 61 both of which have a 6 mm optic. The Bausch & Lomb LI 63 silicone lens has a 6.3 mm optic. Silicone lenses have more elasticity. When the lens is implanted through an injector, it stretches. So it can go through a smaller incision. The Allergan SI 40 NV that has a 6.00 mm optic and the Bausch & Lomb LI 63 with a 6.3 mm optic will go through a 3 mm incision with the proper injector nd cartridge made available by the manufacturer for those spe cific lenses (Fig. 132). This gives you a 6.3 mm or 6.0 mm optic through a 3 mm incision. The open modified C loop silicone lenses are better accepted by the surgeon than the plate haptic lenses because of less decentration.
The Importance of Cost An additional advantage of the silicone lenses is that because many companies make them, they tend to be less expensive. And so, if you are in an environment where cost is an issue, which is just about anywhere in the world, the new second generation, high quality silicone lenses on the average can be purchased for maybe half the price of foldable lenses of other materials. 210
OTHER MONOFOCAL LENSES The Hydrogel, Foldable Monofocal IOL These lenses swell in water. Their mechanical properties are pliable rather than elastic. Their properties are close to PMMA but have a hydrophilic surface and may be folded and inserted through small incisions.
The Foldable Toric Lens The STAAR toric IOL (AA4203T) combines recent toric technology with a flexible optic. The toric optic offers three cylindrical powers (2.5 D, 3.5 D, 4.0 D) as well as spherical (+14D to +26 D) values, and the plate haptic possesses large fenestrations designed for lens fixation in the capsular bag. The results of this product are encouraging and appear to be stable. This implant extends the range of refractive lens surgery, especially in cases where high ametropia is combined with astigmatism.
Bitoric Lens But Not Foldable Although we here emphasize essentially the trends towards the increasing use of foldable lenses, it is important to bring out the development of the bitoric IOL although it is not foldable. This lens has been developed by H.R. Koch and manufactured by Dr. Schmidt Intraokularlinsen in Germany. The diskshaped PMMA implant consists of two toric lenses of the same power, both with one planar and one toric side, which counter-rotate to produce a variable degree of astigmatic power. The direction of the haptic defines the position of the cylindrical axis, and two additional lines in the optical periphery allow an
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exact intraocular positioning. The range of this 6 mm toric IOL is outstanding: spherical power between -3.0 D and +30 D combined with cylindrical power from +1.0 D to +12.0 D. It is 12.5 or 13.4 mm in diameter;
THE FOLDABLE MULTIFOCAL IOL The Array Multifocal Silicone Lens This is one of the most important developments in rehabilitation of sight and improv-
ing the quality of life following cataract surgery. I. Howard Fine, M.D., and Richard Hoffman, Javitt and colleagues in the U.S. and Virgilio Centurion, M.D. in Brazil have done extensive clinical research on the performance of this foldable multifocal lens and the benefits of high quality multifocal vision in their patients. Having used different kinds of multifocal IOLs in the past, Centurion is familiar with the complications in their design. This new multifocal lens, however, is a refractive molded lens instead of a diffractive lens (Figs. 130, 131). Its use is recommended by Centurion for surgeons who are confident with phacoemulsification and small incision techniques. Figure 130 (left): How the Multifocal Array Intraocular Lens Works - Frontal View The new multifocal Array intraocular lens has five refractive zones on the anterior surface. Between each of them there is a narrow aspheric transition zone. Zones 1, 3 and 5 (red) dominate for distance vision, and zones 2 and 4 (yellow) dominate for near vision. The optical mechanism of these zones is shown in Fig. 131.
Figure 131 (right): How the Multifocal Array Intraocular Lens Works - Cross Section View This cross section shows how the steeper areas of the lens (yellow zones 2 and 4) are of higher power and focus on near objects (N). The flatter areas of the lens (red zones 1, 3, and 5) are of lower power and focus far objects (F). Light rays from a distant object (O) which refract through zones 2 and 4 (yellow rays) focus at (N). Light rays from a distant object which refract through zones 1, 3 and 5 (red rays) focus at (F). Zones 2 and 4 have smooth transitions to adjacent zones, and focus light at intermediate distances. These aspheric transitions between the optical zones greatly reduce the halo effect which was sometimes bothersome using older diffractive designs.
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How Does the Array Foldable Multifocal Lens Work?
Quality of Vision with Array Multifocal
The lens is manufactured by Allergan Medical Optics. It has a foldable silicone optic that is 6.0 mm in diameter with haptics made of polymethylmethacrylate and a haptic diameter of 13 mm (Fig. 130). The lens can be inserted through a clear corneal or scleral tunnel incision that is 2.8 mm wide, using the Unfolder injector system manufactured by AMO (Allergan) (Fig. 82 A). There are five zones on the anterior surface. Between each of them there is a narrow aspheric transition zone. The 5 dominant zones provide the following: 1) a clear image for distance (2 zones); 2) one zone for intermediate distance, and 3) two zones for near. The Allergan Array Lens differs from the older diffractive lens designs not only in having classical optics for the definitive zones, but in having aspheric transition zones which, according to Centurion, provide the patient with a smooth transition between the images for distance, intermediate, and near vision, greatly reducing the halo effect which was sometimes so bothersome with older designs. Even those patients who may complain of some halos after surgery seldom report them 2 or 3 months later. Fine and Hoffman describe the lens as having an aspherical component and thus each zone repeats the entire refractive sequence corresponding to distance, intermediate, and near foci. This results in vision over a range of distances. The lens uses 100% of the incoming available light and is weighted for optimum light distribution. With typical pupil sizes, approximately half of the light is distributed for distance, one-third for near vision, and the remainder for intermediate vision.
Refractive multifocal IOLs, such as the Array, have been found to be superior to diffractive multifocal IOLs by demonstrating better contrast sensitivity and less glare disability. The Array does produce a small amount of contrast sensitivity loss equivalent to the loss of 1 line of visual acuity at the 11% contrast level using Regan contrast sensitivity charts. This loss of contrast sensitivity at low levels is present only when the Array is placed monocularly. This has not been demonstrated with bilateral placement and binocular testing. In addition to relatively normal contrast sensitivity, good random-dot stereopsis and less distance and near aniseikonia were present in patients with bilaterally placed implants as compared to those with unilateral implants. In a study by Javitt and colleagues, 41% of bilateral Array subjects were found never to require spectacles, as compared to 11.7% of monofocal controls. Overall, subjects with bilateral Array IOLs reported better overall vision, less limitation in visual function, and less use of spectacles than did monofocal controls. Studies in different parts of the world report that more than 85% of patients have 20/40 or better vision without correction after implantation with this lens. All of the 456 patients in the US Clinical Study have J3 or better, and more than 60% are J2 or J1 without correction. About half are 20/20 without correction.
Patient Selection and Results Fine and Hoffman emphasize that the advantages of astigmatically neutral clear
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corneal cataract surgery have allowed for increased utilization of multifocal technology in both cataract and clear lens replacement surgery. Careful attention to patient selection, preoperative lens power calculations, in addition to meticulous surgical technique, will allow surgeons to offer multifocal technology to their patients with great success. Researchers working with this lens have the clinical impression that depth of focus and quality of vision are improved if the surgeon does a bilateral implantation and implants the second eye within 4 weeks of the first implantation. The results seem to be improved if there is a very short interval between the first and second eye. (If the cataract merits removal in both eyes. This is usually the case when modern small incision cataract surgery is performed. - Editor). Of the 350 multifocal lens implantations Centurion has done, about half were bilateral, and half were monocular. The monocular implantations involved traumatic or inflammatory cataracts rather than senile cataracts . He has not yet used multifocal IOLs in patients with congenital cataracts, but they work well for monocular implantation when a patient has one normal eye. Generally patients do not depend upon glasses much for near vision after the implantation. With bilateral implantation, the quality of vision and quality of life of patients improve considerably. Sometimes they only need glasses to drive at night and to read very small print. Fine and Hoffman point out that the most important assessment for successful multifocal lens use, other than patient selection, involves precise preoperative measurements of axial length in addition to accurate lens power calculations. They have found applanation techniques in combination with
the Holladay II formula and the Holladay II back-calculation to yield accurate and consistent results.
Specific Guidelines for Implanting the Array Lens Fine and Hoffman have used the Array multifocal IOL over the last 2.5 years extensively, in approximately 30% of their cataract patients and in the majority of their clear lens replacement refractive surgery patients. As a result of their experience, they have developed specific guidelines with respect to the selection of candidates and surgical strategies that enhance outcomes with this IOL. AMO recommends using the Array multifocal IOL for bilateral cataract patients whose surgery is uncomplicated and whose personality is such that they are not likely to fixate on the presence of minor visual aberrations such as halos around lights. Obviously, a broad range of patients would be acceptable candidates. Relative or absolute contraindications include the presence of ocular pathological processes (other than cataracts) that may degrade image formation or may be associated with less than adequate visual function postoperatively despite visual improvement after surgery. Contraindications are age-related macular degeneration, uncontrolled diabetes or diabetic retinopathy, uncontrolled glaucoma, recurrent inflammatory eye disease, retinal detachment risk, and corneal disease or previous refractive surgery in the form of radial keratotomy, photorefractive keratectomy, or laserassisted in situ keratomileusis. Fine and Hoffman also avoid the use of these lenses in patients who complain excessively, are highly introspective and fussy, or obsessed over body image and symptoms.
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They are conservative when evaluating patients with occupations that involve frequent night driving or that put high demands on vision and near work (e.g., engineers and architects). Such patients need to demonstrate a strong desire for relative spectable independence in order to be considered for Array implantation. In their practice, they have reduced patient selection to a very rapid process. Once they determine that someone is a candidate for either cataract extraction or clear lens replacement, they ask the patient two questions: First, "If we could put an implant in your eye that would allow you to see both distance and near without eyeglasses, under most circumstances, would that be an advantage?" Approximately 50% of their patients say no directly or indirectly. Negative responses may include, "I don't mind wearing glasses," "My grandchildren wouldn't recognize me without glasses," "I look terrible without glasses," or "I've worn glasses all mylife." These patients receive monofocal IOls. Of the 50% who say it would be an advantage, they ask a second question: "If the lens is associated with halos around lights at night, would its placement still be an advantage?" Approximately 60% of this group of patients say that they do not think they would be bothered by these symptoms, and they receive a multifocal IOL. Centurion also emphasizes that these lenses should not be used in patients with a basic astigmatism of more than 1.50 diopters. Prof. Luis Fernandez Vega in Spain recommends a series of important guidelines in order to be successful with advanced technology multifocals: 1) Do only bilateral multifocal implantations in adults. Do not place a monofocal IOL in one eye and a multifocal in the other. Otherwise, patients
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compare the vision between the two eyes and refer to the differences existing, even though they may have good visual acuity in both. 2) Yes, the multifocal IOL does fullfil its optical purpose both for distance and near. Although it does not completely prevent the wearing of spectacles, it does diminish the dependency on glasses. Clarify this to the patient preoperatively. 3) Select the patient according to his/her visual needs. 4) Do a very precise preoperative biometry; 5) Perfect your cataract surgery to end up with less than 1.00 D astigmatism.
Special Circumstances for Array Implantation There are special circumstances in which implantation of a multifocal IOL should be strongly considered. Alzheimer's patients frequently lose or misplace their spectacles, and thus they might benefit from the full range of view that a multifocal IOL provides without spectacles. Patients with arthritis of the neck or other conditions with limited range of motion of the neck may benefit from a multifocal IOL rather than multifocal spectacles, which require changes in head position. Patients with a monocular cataract who have successfully worn monovision contact lenses should be considered possible candidates for monocular implantation. The same is true for certain professionals such as photographers who want to alternate focusing through the camera and adjusting imaging parameters on the camera without spectacles. In these patients, the focusing eye could have a monofocal IOL and the nondominant eye a multifocal IOL. Fine and Hoffman almost always use the Array for traumatic cataracts in young adults in order to facilitate binocularity at near,
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especially if the fellow eye has no refractive error or is corrected by contact lenses.
Need for Spectacle Wear PostOp Prior to implanting an Array lens, they inform all candidates of the lens's statistics to ensure that they understand that spectacle independence is not guaranteed. Approximately 41% of patients implanted with bilateral Array IOLs will never need to wear eyeglasses, 50% wear glasses on a limited basis (such as driving at night or during prolonged reading), 12% will always need to wear glasses for near work, and approximately 8% will need to wear spectacles on a full-time basis for distance and near correction.
Halos at Night and Glare
geographical and cultural regions. They have provided HIGHLIGHTS with the pearls of the methods that lead them to successful implantation. They are: Jack Dodick, M.D., from New York, I. Howard Fine, M.D., from Oregon, and Richard Lindstrom, M.D., from Minnesotta, three different areas of the United States. And Edgardo Carreño, M.D., from South America (Chile). First, you will find the present status of the preferred methods of lens implantation, forceps vs injectors, their pros and cons. Second, the techniques of implantation of 1) the Array Multifocal Foldable Lens (Allergan). 2) The acrylic monofocal lens, in this case the AcrySof Lens (Alcon). 3) The silicone monofocal foldable lens (STAAR).
PREFERRED METHODS OF IOL IMPLANTATION
15% of patients were found to have difficulty with halos at night, and 11% had difficulty with glare, as compared to 6% and 1%, respectively, in monofocal patients.
Use of Forceps vs Injectors
SURGICAL PRINCIPLES AND GUIDELINES FOR IOL IMPLANTATION
Many surgeons like to use forceps to implant the foldable lens, others use injectors. Lindstrom reminds us that the original instruments available for foldable lenses were all forceps. Consequently, those surgeons that used foldable lenses early on got used to the forceps insertion method (Figs. 133, 134). But there is a disadvantage to the forceps approach. It adds some mass to the amount of material you are putting into the eye (Fig. 132) thereby requiring a slightly larger incision. Another disadvantage of using forceps is that you may touch the lens to the conjuntiva or sclera before placing it into the incision. Several studies have shown that the lens picks up bacteria and mucus and
Just as there are a large number of methods to disassemble the nucleus there is a wide variety of techniques to implant the IOL's, particularly the foldable lenses. What counts is the results and the feasibility to achieve a successful implantation. We present here the surgical principles and guidelines for implantation of the most commonly used types of foldable lenses. We have chosen the principles followed by highly respected, skilled phaco surgeons who do a great deal of teaching in addition to having a large, solid practice in different
Advantages and Disadvantages
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other debris from the surface of the eye when you use the typical cross action forceps (Fig. 133). This may increase the risk of postoperative inflammation or infection. For these reasons, Lindstrom now prefers the injectors, because you take a sterile lens out of a sterile package, put it into a sterile injector and place the lens directly inside the eye. With the injector you also have less bulk, thereby requiring a slightly smaller incision (Fig. 132-A). The reason a good number of surgeons do not like the injectors is: 1) they got used to folding with forceps, (Figs. 132-B, 133) which are convenient and they are used to them. 2) All the injectors have a small failure rate. It is very annoying when you load a lens into the injector and then after placing it inside the eye, the optic is torn or one of the lens loops is bent or damaged. Some surgeons do not use injectors because they do not like the lens failures that occassionally occur with them. The newer injectors of the better companies, however, are performing very well now.
New Trends for Folding and Insertion of IOL's The majority of lenses are still folded and inserted with forceps (Figs. 132-B, 133). Nevertheless, there is a definite trend toward the development of separate instruments for folding and inserting IOL’s rather than using the insertion device to fold the IOL. The combination of instruments designed by the manufacturers to facilitate folding and insertion is known as cartridge injector systems which are then used to implant the IOL.
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Cartridge Injector Systems Fine, Lewis and Hoffman believe that there are many perceived advantages of implanting foldable IOLs with injector systems, as compared with folding forceps. These advantages include the possibility of greater sterility, ease of folding and insertion, and implantation through smaller incisions as emphasized by Lindstrom (Fig. 132). Greater sterility with injector systems is believed to occur because the IOL is brought directly from its sterile package to its sterile cartridge and inserted into the capsular bag without ever touching the external surface of the eye, as is the case for lenses in folding forceps. Although this advantage would suggest a lower rate of endophthalmitis with injector systems, recent clinical studies have shown no significantly different rate of bacterial contamination of the anterior chamber after implantation of silicone lenses with a forceps versus an injector. Perhaps the most appealing advantage of injector systems is that the lens can be loaded by a nurse or technician without the use of an operating microscope, further streamlining the procedure. In addition, inserting foldable lenses with a cartridge device is generally felt to be easier than insertion with forceps. There are no irregular surfaces as may occur between the surface of the forceps and the lens. The IOL is lodged inside the cartridge and injector system. Allergan's foldable three piece silicone lens (monofocal or multifocal - AMO Array) with PMMA haptics may be implanted with AMO's Unfolder Phacoflex injector system. Allergan's acrylic foldable IOL (Sensar and Clariflex lenses) may be implanted with a new
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Figure 132: Insertion of Foldable IOL - Forceps vs Injector - Comparative Incision Size The insertion of a foldable intraocular lens may well be done either with forceps or with injectors. There is a difference between the two regarding the size and architecture of the incision. When injectors are used (A) we may maintain the small size primary incision of 2.8 mm (red arrow). On the contrary, when we use forceps for the insertion of the IOL (B), the diamond blade needs to be extended fully (yellow arrow) in order to enlarge the incision from 2.8 mm to 3.0 mm to accommodate the silicone IOL insertion and 3.4 mm with acrylic IOL’s . This is due to the added bulk relation of lens and forceps. With the injector, there is no additional bulk.
injector now available and known as the Unfolder Sapphire, as described by Centurion (Fig. 82-A). These injectors are resterelizable (as are the forceps, of course). Alcon’s popular 5.5 mm AcrySof IOL may be implanted with one of its injectors such as the Monarch (Fig. 82) or with a standard cartridge through a 3.4 mm incision. Carreño reports injecting this lens through a 2.8 mm incision (Fig. 132). Many surgeons use Alcon’s Acrypack (Fig. 82) when implanting the AcrySof lenses. The Acrypack serves to first fold the IOL. The surgeon then uses a forceps (Fig. 81) to implant the already folded IOL. The Alcon AcrySof lens, which requires 3.5 to 4.0 mm incisions for 6.0 mm optics and
3.2 to 3.5 mm incisions for 5.5 mm optics, when implanted with forceps is now packaged in a wagon wheel dispenser. The easiest folding instrument to use for these lenses is the Rhein folder, as recommended by Fine because the tips have been extended to make it easier to remove the lens from its wagon wheel packaging. The forceps can be turned with the tips down in the nondominant hand. The tips go into the slots on both sides of the optics, so that the lens can be picked up and placed on a drop of viscoelastic. The forceps are then turned so that the tabs are down. The lens is grasped and folded, and then the insertion device is used to insert the lens using the surgeon’s dominant hand.
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Guidelines for Insertion of Different Types of Lenses Surgical Technique with Array Lens Fine and Hoffman consider it very important that incision construction be appropriate with respect to size and location because the multifocal Array works best when the final postoperative refraction has less than 1 D of astigmatism. They favor a clear corneal incision at the temporal periphery that is 3 mm or less in width and 2 mm long (Fig. 91). Each surgeon should be aware of his or her usual amount of surgically induced astigmatism by vector analysis. The surgeon must also consider the best meridian in the cornea to place the incision considering the existing preoperative astigmatism in order to end up with minimum postop astigmatism. We discuss this subject under "Refractive Cataract Surgery" in Chapter 12 (Complex Cases). In preparation for phacoemulsifiction, the capsulorhexis must be round (Figs. 44, 45) and its size should be sufficient so that there is a small margin of anterior capsule overlapping the optic circumferentially. This is important in order to guarantee in-the-bag placement of the IOL and prevent anteroposterior alterations in location that would affect the final refractive status. Hydrodelineation and cortical-cleaving hydrodissection are crucial in all patients because they facilitatelens disassembly and complete cortical cleanup. Taking the time and care to perform a careful and effective cortical cleanup as shown in Figs. 127 and 128, without being aggressive, may reduce the incidence of posterior capsule opacification, the presence of which, even in very small amounts, will inordi-
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nately degrade visual acuity in Array patients. Because of these phenomena, patients implanted with Array lenses will require YAG laser posterior capsulotomies earlier than will patients with monofocal IOLs. Minimally invasive surgery is key. Techniques that utilize effective phacoemulsification powers of 10% or less are highly advantageous and can best be achieved with power modulations (burst mode or two pulses per second) rather than continuous phacoemulsification modes (Figs. 86-89, Chapter 8). The Management of Complications with the Array Lens is discussed in Chapter 11 (Complications).
Carreño's Technique of Acrylic IOL Implantation Through a 2.75 mm Incision Because it is generally considered that acrylic lenses require a somewhat larger incision (3.4 mm) to be introduced into the anterior chamber without harming the lips of the wound, we present Carreño's technique by which he implants the AcrySof lens (acrylic, Alcon) through a 2.75 mm incision. This is one stage of the Phaco Sub 3 method which he advocates. Carreño from Chile, is a highly skilled cataract surgeon. Carreño emphasizes that in order to introduce the acrylic intraocular lens through very small incisions, as is the case in Phaco Sub 3, using adequate technique and equipment is imperative. Otherwise, the implantation could cause severe trauma to the corneal margins of the wound and the endothelium as well as leading to an undesired increase in the size of the incision. Before implantation, a generous amount of viscoelastic should be injected into the capsular bag and the anterior chamber.
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Foldable Acrylic Lens of Choice Carreño's experience is based on the use of Alcon's AcrySof lens model MA30BA (5.5mm optic, total length 12.5mm, PMMA haptics).
Implantation Technique The lens is folded with forceps (paddle), placed parallel to the haptics (longitudinal implantation technique). The implantation forceps (Buratto) are used to grasp the lens so that the haptics are perfectly parallel to the fold, going through the center line of the optic, and reaching the edge. Correctly grasping the Buratto forceps is critical to penetration with the AcrySof through a 2.75mm incision. If the lens fold is not completely symmetrically, an edge is produced that impedes its introduction. If the jaws of the forceps are at an angle to the lens fold, a separation is created between the faces, which may make the lens impossible to introduce through a small incision. The surgeon proceeds with the Buratto forceps placed in such a way that the lens fold stays on the left. It is very important that the first haptic enters the anterior chamber before the optic. Otherwise, the lens may be damaged if the haptic is trapped with the optic inside the corneal tunnel. Then the surgeon inserts the optic by exerting pressure and using slight lateral movements along the corneal tunnel. The spatula, introduced through the lateral paracentesis, exerts firm and constant counterpressure. (In order to exert adequate counterpressure, the lateral paracentesis must be placed 60 degrees from the main incision.) This pressure and counterpressure maneuver is another key aspect of successful implantation
of the AcrySof MA30BA through a 2.75mm corneal incision without complications. Before completing the insertion of the optic, which should be very controlled so as not to penetrate abruptly into the anterior chamber and risking the integrity of the posterior capsule, the surgeon puts the haptic under the edge of the capsulorhexis so it can be placed in the capsular bag. Once the optic is in the anterior chamber, the Buratto forceps are rotated 90 degrees in this position, and they are released so the lens unfolds (Fig. 133). Due to the thin incision, the lens tends to be trapped in the claws of the forceps. To release it, the surgeon pushes gently downward with the spatula. Now the forceps may be withdrawn, and the lens continues to gradually unfold (Fig. 133). The second haptic is immediately grasped with KelmanMcPherson forceps to introduce it into the anterior chamber. Aided by the spatula, using a bimanual maneuver, the implantation is completed by placing the lens optic first and then the second haptic into the capsular bag (Fig. 134). Implantation of the AcrySof MA30BA lens through a 2.75mm corneal incision is not easy, but Carreño emphasizes that if the described technique is followed step by step, the surgeon can perform it without injuring corneal tissues. However, when dealing with AcrySof MA30BA lenses stronger than 24 diopters, Dr. Carreño prefers to use a slightly larger incision (3.0mm) because the greater thickness of these lenses may make them difficult or impossible to implant through a 2.75mm incision. (Editor's Note: as pointed out at the beginning when describing the acrylic IOL's implantation, most expert surgeons find it very difficult or unfeasible to implant an acrylic lens through a 3.0 mm incision using forceps without harming the lips of the wound - Fig. 132).
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Once the implantation is complete, the viscoelastic is carefully removed from the anterior chamber and from the capsular bag. The surgeon must take care not to leave viscoelastic material behind the intraocular lens. (It is necessary to push the implant optic gently backward with the cannula to force the evacuation of the viscoelastic through the capsulorhexis opening.) Finally, balanced saline solution is injected through the lateral paracentesis to ensure that the incision is perfectly self-sealing.
Dodick's AcrySof's Implantation Technique Special Features AcrySof´s Implantation
About
could conceivably interfere with visual acuity. A second measure taken by Dodick to facilitate this lens' entry into the wound after folding and holding it with forceps is to pinch the lead edge of the lens with a second forceps, to make the "nose" conform into a bullet or missile shape. This facilitates entry into the eye. Once the nose enters into the eye, the rest of the lens follows with great facility (Fig. 133). Dodick uses folding and insertion forceps to insert the lens. They must be very fine folding forceps so as to add very little bulk to the combination of lens and forceps that have to enter through the small wound (Fig. 132).
Dodick's Three Stage Implantation
When handling the lens, it is important to keep in mind that especially in high powers up to 30 diopters, this is a thick lens. This makes folding more difficult. Jack Dodick, M.D., has found that pre-warming the lens dramatically facilitates the ease of the fold. This is done at his institution (Manhattan Eye and Ear Hospital) by placing it in a warm environment such as on top of a sterilizer that has an ambient temperature between 100 and 105 degrees. This seems to soften the material and facilitates the gentle folding of the lens, making it much easier to implant especially for high diopter lenses which are more difficult to fold. It is also important to keep in mind that if the surgeon performs rapid folding of a cold lens, this may leave striae in the lens that
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Dodick likes to divide the implantation of the lens into three stages once it is in the anterior chamber. First, when the lead haptic is in the capsular bag, the lens is allowed to unfold. Stage two is the implantation only of the optic. Stage three, once the optic is implanted the surgeon inserts the superior haptic by rotating it in with the Lester hook or placing it with a Kelman-McPherson forceps. Dodick considers that a common mistake when implanting any soft foldable IOL, is to implant it in only two stages. Once the inferior haptic is placed into the capsular bag, some surgeons proceed immediately to try to place the optic and the superior haptic in one second stage. His experience has taught him that implantation becomes simpler and more controlled by dividing it into the three stages described.
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Fig. 133 (right): Foldable Intraocular Lens Implantation Through a Corneal Incision Using Forceps - Final Unfolded Position The lens holding forceps are slowly opened and the lens is gently unfolded (arrows) inside the capsular bag as shown. Widely used cross-action forceps presented in this figure (Buratto’s forceps not shown).
Figure 134 (left): Foldable Intraocular Lens Implantation Through a Corneal Incision Using Forceps - Final Unfolded Position This view shows the final unfolded position of the foldable intraocular lens and its haptics within the capsular bag. Please observe the final appearance of the corneal incision (C).
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Implantation Technique for Silicone Foldable IOL's Using Cartridge-Injector System Lindstrom prefers to implant these lenses with a cartridge injector system. Since the second generation silicone lenses are very flexible, they stretch when implanted through a cartridge-injector system, providing the surgeon with the advantage of inserting the lens through a smaller incision (Fig. 132-A). Carreño's technique for implantation of silicone foldable lenses starts with the injection of viscoelastic in the anterior chamber, the capsular bag and into the cartridge. Once viscoelastic has been injected into the cartridge, the lens is loaded carefully so that both sides are inserted into the lateral channels. The car-
tridge is then closed and placed in the injector. In order not to enlarge the incision, Carreño considers that it is essential to introduce the tip of the cartridge a few millimeters into the anterior chamber, as its thickness increases towards the back (Fig. 132-A). With the injector in place, the lens is advanced through the cartridge. Once it begins to unfold in the anterior chamber, it is guided with the first haptic under the edge of the capsulorhexis and placed in the capsular bag. Once it is unfolded, the empty cartridge is removed. Using a spatula introduced through the lateral paracentesis, the second haptic is gently pushed downward and backward to be placed in the capsular bag as well. For you to have a mental picture of the concept of foldable lens implantation, we refer you to Fig. 135.
Figure 135: Concept of Foldable Intraocular Lens Implantation This cross section view shows the movement of the foldable intraocular lens during insertion. Folding forceps removed for clarity. (1) Folded lens outside the eye. (2) Folded lens passing through small incision. (3) Folded lens placed posteriorly into the capsular bag through anterior capsule opening and then rotated 90 degrees. (4) Lens slowly unfolded in the bag. (5) Final unfolded position of lens within the capsular bag.
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TESTING THE WOUND FOR LEAKAGE If the corneal incision has been performed adequately, following the principles outlined in Figs. 90, 91, 92, 93, the surgeon should have a self-sealing stepped valvulated corneal tunnel incision. These incisions should not leak but there is always the possibility that this may occur. Consequently, we must test the wound for leakage as shown in Fig. 73 and explained its accompanying text. Following the removal of viscoelastic from the anterior chamber and capsular bag, BSS is injected through the paracentesis. If the surgeon finds that there is a leak (Fig. 73) there are two ways to seal the incision without having to suture it: 1) Inject BSS into the lips of the incision to hydrate the tissues and seal the wound. 2) Use Professor Juan Murube's maneuver for the combined placing of a Honan balloon over the eye for 30 minutes at 35 mm Hg pressure and administering orally one tablet of 250 mg Acetazolamide (Diamox). The way Murube's clever maneuver works is explained in Fig. 96 and accompanying text. In the remote case that the corneal incision leaks and, even more remote, that the two methods for sealing described here do not work and there is a need to suture the incision, it is recommended that the surgeon place one single radial suture.
BIBLIOGRAPHY Basic and Clinical Science Course: Lens and Cataract. American Academy of Ophthalmology, Sect. 11, 1998-99;8:108-109. Barret, GD: New hydrogel lenses: current styles and future trends. Atlas of Cataract Surgery, Edited by Masket Crandal, published by Martin Dunitz, 1999, 22:182-193. Barojas, E.: How to make a safe capsulorhexis. Guest Expert, The Art and the Science of Cataract Surgery, Highlights of Ophthalmology, 2001. Carreño, E.: From can opener to capsulorhexis: The crucial step in the phaco transition, 1999. Centurion, V: Phacoemulsification: Mastering the technique. Guest Expert, The Art and the Science of Cataract Surgery, Highlights of Ophthalmology, 2001. Christensen1 GD., Simpson WA., Younger JJ et al: Adherence of coagulase-negative staphylococci to plastic tissue culture plates: a quantitative model for the adherence of staphylococci to medical devices. J Clin Microbiol 1985; 22:996-1006. Davison JA: Free-hand clear corneal incision with Legacy 20,000 aspiration bypass system. Atlas of Cataract Surgery, Edited by Masket Crandal, published by Martin Dunitz, 1999, 16:115-127. Dillman, DM: Techniques, thoughts, challenges. Clear Corneal Lens Surgery, Slack, 1999, 11;131155. Dodick J.: Null phaco chop. Advances in Technique and Technology, Alcon Surgical, Part 2 of 2, April 1999. Ernest PH, Fenzel R., Lavery KT, Sensoli A: Relative stability of clear corneal incisions in a cadaver eye model. J. Cataract Refractr Surg. 1995;21:3942.
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Ernest PH, Tipperman R., Eagle R, et al: Is there a difference in incision healing based on location? J Cataract Refract Surg, 1998;24:482-486.
Hoffer, KJ: Clear corneal implant surgical techniques. Clear Corneal Lens Surgery, by IH Fine, Slack,, 16:251-261.
Rosen, E: Clear corneal incisions and astigmatism. Clear Corneal Lens Surgery, by IH, Fine, Slack, 1999, 3:21-42.
Hoffman RS: Making the transition to temporal clear corneal cataract surgery under topical anesthesia. Clear Corneal Lens Surgery, by IH Fine, Slack,, 4:43-57.
Fine, IH.: The choo choo chop and flip phacoemulsification technique. Operative Techniques in Cataract and Refractive Surgery, 1998;1(2):61-65. Fine, IH.: The choo choo chop and flip phacoemulsification technique. Clear Corneal Lens Surgery, 6:72-79. Fine, IH., Hoffman, RS.: Controversies regarding clear corneal incisions. Clear Corneal Lens Surgery, Slack, 1999;1:1-5. Fine, IH., Hoffman, RS.: Controversies regarding clear corneal incisions. Clear Corneal Lens Surgery, Slack, 1999;2:9-20. Fine, IH, Hoffman, RS: The AMO Array Foldable Silicone Multifocal Intraocular Lens. International Ophthalmology Clinics, Edited by Davis EA, Hardten, DR., Lindstrom RL, Vol. 40 Nº3, Summer 2000.
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Hunkeler, JD.: Personal clear corneal cataract technique. Clear Corneal Lens Surgery, Slack, 1999, 8;95-97. Javitt JC, Want F, Trentacost DJ, et al: Outcomes of cataract extraction with multifocal intraocular lens implantation - functional status and quality of life. Ophthalmology, 1997:104:589-599. Kelman, C: Problem-free cortex removal. Advances in Technique & Technology, Alcon Surgical, April 1999, Part 2 of 2. Kimiya Shimizu: Clear-cornea cataract incision: astigmatic consequences. Chapter 17, ;Atlas of Cataract Surgery, Edited by Masket Crandal, published by Martin Dunitz, 1999 Koch, PS:Scleral incisions. Simplifying Phacoemulsification, Fifth Edition, Slack, 1997, 4:27-50.
Fine, IH., Lewis, JS., Hoffman, RS: New techniques and instruments for lens implantation. Current Opinion in Ophthalmol., Vol. 9 Nº 1, Feb.1998.
Koch, PS:Dense cataract phacoemulsification. Simplifying Phacoemulsification, Fifth Edition, Slack, 1997, 16:177-189.
Gimbel, HV.: Advanced capsulotomy. Cataract Surgery: The State of the Art. Slack, 1998, 6:69-74.
Koch, PS.: Divide and conquer. Simplifying Phacoemulsification, Fifth Edition, Slack, 1997.
Gimbel, HV., Brown, D., Fine HI., Fakasaku, H., Maloney W., Singer, JA., Thornton SP., Gills JP: Advanced phacoemulsification technique. Cataract Surgery: The State of the Art, Slack 1998, 9:101-124.
Koch, PS.: Phaco chop. Simplifying Phacoemulsification, Fifth Edition, Slack, 1997.
Grabow, HB, Gills, JP, Fish, JR, Van Der Karr, M: Advanced cataract incisions. Cataract Surgery: The State of the Art by J. Gills, Slack, 1998; 4:2951.
Kohnen T., Magnowski G., Koch DD: Scanning electron microscopy surface analysis of foldable acrylic and hydrogel intraocular lenses. J Cataract Refract Surg 1996;22(suppl. 2):1342-50.
Koch, PS.: Stop and chop. Simplifying Phacoemulsification, Fifth Edition, Slack, 1997.
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Lacava, AC., Centurion V: Cataract surgery after refractive surgery. Faco Total by V. Centurion. Langerman DW: Architectural design of a selfsealing corneal tunnel, single-hinge incision. J Cataract Refract Surg 1994;20:84-8. Langerman, DW: Deep groove corneal incision. Clear Corneal Lens Surgery, by IH Fine, Slack,, 7:85-93. Leaming DV. 1996 Practice Styles and Preferences of ASCRS Members Survey Results. Ocul Surg News Int 1997; 8:66. Mackool RJ, Russell RS: Strength of clear corneal incisions in cadaver eyes. J Cataract Refract Surg. 1996;22:721-725. Masket S.: Clear corneal incision: A personal method. Clear Corneal Lens Surgery, Slack, 1999, 10;121-130. Murube J.: Cerrando Heridas Fistulizadas - Tincion Capsula Anterior . Guest Expert, The Art and the Science of Cataract Surgery, Highlights of Ophthalmology, 2001. Murube J.: Using a Honnan balloom to treat ocular aqueous fistulas. Ophthalmic Surgery 1994;25:745. Neuhann TH: Intraocular folding of an acrylic lens for explantation through a small incision cataract wound. J Cataract Refract Surg 1996; 22(suppl 2): 1383-6. Neuhann TH: New foldable intraocular lenses. ;Atlas of Cataract Surgery, Edited by Masket Crandal, published by Martin Dunitz, 1999, 21:171172.
Oshika T., Shiokawa Y: Effect of the folding on the optical qualilty of soft acrylic intraocular lenses. J Cataract Refract Surg 1996; 22(suppl 2):1360-4. Osher, RH: Personal phacoemulsification technique. Phacoemulsification: Principles and Techniques by L. Buratto, 1998; 31:447-449. Seibel, B.: Capsulorhexis with shearing and ripping. Phacodynamics - Mastering the Tools & Techniques of Phacoemulsification Surgery, Third Edition. Seibel, B.: Nucleus removal technique. Phacodynamics - Mastering the Tools & Techniques of Phacoemulsification Surgery, Third Edition, Slack, 1999. Seibel, B.: Physics of capsulorhexis. Phacodynamics - Mastering the Tools & Techniques of Phacoemulsification Surgery, Third Edition, Slack, 1999. Snyder, RW: Updates in surgical techniques & therapeutics. Ocular Surgery News, Slack, June 1, 2000. Sugimoto Y., Takayanagi K., Tsuzuki, S., Takahashi Y., Akagi, Y.: Postoperative changes over time in size of anterior capsulorrhexis in phacoemulsification/aspiration. Jpn. J. Ophthalmol, 1998, 42:495498. Vaquero-Ruano M, Encinas JL, Millan I, et al: AMO Array multifocal versus monofocal intraocular lenses: log-term follow-up. J Cataract Refract Surg. 1998;24:118-123. Zacharias W: Biometry: its importance. Faco Total by V. Centurion.
Nicoli, C.: Capsulorhexis on a completely opaque cataract. Guest Expert, The Art and the Science of Cataract Surgery, Highlights of Ophthalmology, 2001.
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FOCUSING PHACO TECHNIQUES ON THE HARDNESS OF THE NUCLEUS
MULTIPLICITY OF TECHNIQUES Visiting prestigious eye centers and through personal communications with a number of expert consultants throughout the world, it is interesting to observe how many different techniques and modifications of the basic phacoemulsification procedures have been developed. They all work well, if used in skilled hands. In addition, watching videos of phaco procedures performed by outstanding cataract surgeons from different regions, cultures, races and economic status of their countries, surgeons who perform a thousand or more cataract operations a year, we find them using techniques that are quite different from each other. Some use low vacuum, others use high vacuum, one uses a 60º phaco tip while the next one uses a 0 (zero) degree tip for the same type of cataract. One would do a supracapsular while the other emphasizes the need to do all cataracts using an endocapsular technique. Some are cracking, some are chopping.
The Essential Criteria for Success The revealing experience is that the great majority of their cases have very good results and the operated eyes look very well. What we learn from this experience is that each
surgeon has developed a technique with which he/she feels comfortable, that works best for him/her and that fills the essential criteria of not damaging the posterior capsule, the iris and/or the corneal endothelium.
DIFFERENT NUCLEUS CONSISTENCY TECHNIQUES OF CHOICE In Chapter 9, in discussing the Management of Disassembling the Nucleus, we presented the surgical principles of the major, late-breaking techniques mostly used now, showing how they work and how they are performed. These can be classified as: 1) Divide and Conquer (D & C) techniques and 2) the chopping procedures based on modifications of the Phaco Chop of Nagahara (Japan). Most of the now extensively used techniques that we present in Chapter 9 have been developed by pioneers and distinguished surgeons from North America (Gimbel from Canada; and Paul Koch, MacKool, Dodick, and I. Howard Fine, from the U.S.). Many other prestigious surgeons from all continents have made substantial contributions to render this step of the operation more effective and less risky. Now let us try to get into the crucial subject that most ophthalmic surgeons want
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to know: What are the procedures of choice when we need to remove nuclei of different consistencies? The answer is that this is not a mathematical formula whereupon the techniques can be categorized based exclusively on how hard a nucleus we are going to operate. But the subject is sufficiently clear to allow us to present highly useful guidelines, based on the extensive experience of highly recognized surgeons. This is what we are providing you here. In Chapter 9, you can find the guidelines and surgical principles of the techniques most surgeons use now and what consistency of cataracts do better in general with the major techniques such as D & C operations, the Stop and Chop, the Crater Chop, the Null-Phaco Chop and the Choo-Choo Chop and Flip. A variety of other procedures not described in Chapter 9 are modifications of the fundamental techniques and carry the name of the surgeon who sponsors the procedure.
Representative Experts Confronting Nuclei of Different Hardness Now let us focus more specifically on the procedures of choice of some highly representative experts from different regions of the world regarding the operation they use when confronting nuclei of different consistencies. These surgeons are: Richard Lindstrom, M.D., from the U.S.; Lucio Buratto, M.D., from Europe (Italy); Okihiro Nishi, M.D., from Japan, Edgardo Carreño, M.D., (Chile) and Virgilio Centurion, M.D., (Brazil) the latter two representing different regions and cultures of South America. Each one of these surgeons
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has performed many thousand phacoemulsification procedures. They are highly successful and their concepts are solid. What we present in this Chapter is how each one of these five (5) prestigious surgeons perform phaco, with emphasis on nucleus removal when faced with the five types of cataracts that we are all familiar with, based on different nucleus consistency. You may observe that each one of them has a different procedure of choice. I will confirm that they are all successful. This experience may serve the ophthalmic surgeon as guidelines within which to select the technique he/she feels more comfortable with and that may serve the patients best. A great deal depends on where you practice, what equipment and facilities you have and the type of cataracts you mostly do.
LINDSTROM'S OF CHOICE
PROCEDURES
1) For Soft and Medium Density (standard) Cataract: the supracapsular iris-plane procedure (Figs. 136-139). The supracapsular operation is popularly known as the "tilt and tumble" technique. It is performed on the iris plane and is not endocapsular. 2) Posterior capsular cataract or the cataract in a young patient with relatively soft nucleus without much ultrasound power needed: the supracapsular iris plane technique. 3) For Very Hard Nuclei: the Stop and Chop (an endocapsular technique) described in Figs. 107-111). Lindstrom considers that a clear cornea incision is not indicated when doing the stop and chop in very hard nuclei. He uses a corneo-scleral incision and larger amounts of
C h a p t e r 10: Focusing Phaco Techniques on the Hardness of the Nucleus
viscoelastic. More ultrasound energy is needed to disassemble these very hard nuclei with more danger of wound burn and endothelial damage. The sclera is more resistant to the heating up of the wound than is the cornea. In addition, by moving back to the sclera you are farther away from the corneal endothelium with less risk of damage, particularly in patients with borderline corneas.
Advantages of the Supracapsular Lindstrom notes that supracapsular techniques enjoy increasing popularity. A slightly larger anterior capsulorhexis (5.5 to 6.0 mm), is necessary. This allows the sur-
geon to bring a part of the nucleus or the whole nucleus in front of the anterior capsular ridge (Figs. 136-137). In addition, Lindstrom considers that with the endocapsular techniques the number of posterior capsular tears with or without vitreous loss is higher for most surgeons because they are working inside the capsular bag. With a supracapsular technique the nucleus is up closer to the anterior chamber so the incidence of posterior capsule tears is reduced. It is also a very easy technique to learn. For a beginning surgeon the endocapsular techniques are more difficult to teach and need a longer learning curve and more time to perform (see Chapters 7 and 9).
Figure 136: Lindstrom’s Supracapsular (“Tilt and Tumble”) Technique Following clear corneal temporal incision (T), superior limbal counterpuncture for secondary instrumentation (S), and 5.5 or 6.0 mm circular capsulorhexis (C), a Pearce hydrodissection cannula (H) is introduced between the nucleus (N) and capsule. Slow continuous hydrodissection is performed with BSS (blue arrow) beneath the anterior capsular rim until a fluid wave (W) is seen. Irrigation is continued until the nucleus tilts up on one side (red arrow), out of the capsular bag. This is the “tilt” portion of the “Tilt and Tumble Phaco Technique.” Viscoelastic is introduced beneath the nucleus and into the chamber (not shown).
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Figure 137: Phacoemulsification of the First Half of the Nucleus - Lindstrom’s Supracapsular (“Tilt and Tumble”) With the nucleus (N) tilted toward the main incision, the phaco probe (P) emulsifies and removes one half of the nucleus using an outside-in approach. During this removal, the nucleus is supported by a second instrument, such as a nucleus rotator (R) introduced through the secondary counterpuncture (S).
Disadvantages of the Supracapsular The disadvantage of the supracapsular technique is that you are working much closer to the corneal endothelium. The surgeon must be very careful in his technique and should not perform it on a very hard nucleus. With the modern technology available in the phaco machines (Chapter 8) and the adequate use of viscoelastic we have another margin of security to protect the endothelium. Another measure that helps a good deal to protect the endothelium is to do the phacoemulsification with the bevel of the tip down or to the side. You have the alternative of placing the phaco instrument in the eye with the
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bevel anterior, bevel to the side, bevel down or bevel close to you. There is a little spray that comes out of the phaco tip when you are doing the surgery. We want that spray to go away from the corneal endothelium so it is important to place the bevel to the side or the bevel down technique in using supracapsular technique.
Contraindications of Supracapsular Lindstrom performs the supracapsular technique in all cataracts except: 1) Patients who have cornea guttata, Fuchs' dystrophy or low endothelial counts. 2) Very hard cataracts.
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HIGHLIGHTS OF THE SUPRACAPSULAR IRIS PLANE TECHNIQUE The main steps are illustrated and explained in Figs. 136-139. The surgeon needs to become quite adept at hydrodissecting until the nucleus is lifted, which is the first step
prior to tumbling the nucleus in a supracapsular approach. Rather than completing the tumbling of the entire nucleus, Lindstrom supports the nucleus in the plane of the iris and anterior capsular leaflet and then emulsifies half of it (Figs. 136-137). With a much smaller nuclear remnant, he tumbles the remaining one half upside down and completes the emulsification (Figs. 138-139). Figure 138 (left): Tumbling the Remaining Half of the Nucleus - Lindstrom’s Supracapsular (“Tilt and Tumble”) One half of the nucleus has been removed, the remaining half is tumbled upside down (arrow) with the secondary instrument (R). This brings the nucleus into a position to be attacked from the opposite pole with the phaco probe (P).
Figure 139 (right): Phacoemulsification of the Second Half of the Nucleus Lindstrom’s Supracapsular (“Tilt and Tumble”) The remaining nuclear half is emulsified and removed with the phaco from an outside edge-in direction. Again, the nucleus is supported in the iris plane by the secondary instrument (R) during phacoemulsification.
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In this operation, it is important to make a slightly larger anterior CCC (5.5 to 6.0 mm). If a small anterior capsulorhexis is done, the hydrodissection step where the nucleus is tilted can be dangerous and rupture the posterior capsule during hydrodissection could be possible. If a small anterior capsulectomy is inadvertently created, Lindstrom favors converting to an endocapsular phacoemulsification technique or enlarging the capsulorhexis. If he is unable to tilt the nucleus with either hydrodissection or manual technique, he will also convert to an endocapsular approach. Occasionally the entire nucleus will subluxate into the anterior chamber. In this setting, if the cornea is healthy, the anterior chamber roomy, and the nucleus soft, he will often complete the phacoemulsification in the anterior chamber keeping the nucleus away from the corneal endothelium. The nucleus can also be pushed back inferiorly over the capsular bag to allow the iris plane tilt and tumble technique to be completed.
CENTURION'S TECHNIQUES RELATED TO NUCLEUS CONSISTENCY 1) For soft nucleus (+) Centurion's procedure of choice is the flip and chip (Fine - see Figs. 122-126). 2) For intermediate nucleus (++) (those not hard enough to be chopped), Centurion performs the classical divide and conquer (Figs. 56, 67, 103, 104, 206 below). Because Centurion does not perform hydrodelamination, he usually removes the epinucleus during emulsification of the nucleus. If the hydrodissection was well done, usually irrigation-aspiration (I/A) will not be necessary.
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3) For hard nucleus (+ + + and above) Centurion's favorite technique is the Phaco Quick Chop, as developed by Pfeifer. The parameters he prefers are based on the different machines that he uses and are presented. The main difference between this technique and other phaco chop procedures are: 1) The placement of the chopper is in the center of the lens, and not under the anterior capsule. 2) The movement of the chopper is vertical, instead of horizontal as in other phaco chop techniques.
Highlights of Other Steps in Centurion's Technique Anesthesia: For routine cases he recommends topical anesthesia. Peribulbar is used for special situations, such as subluxated lens, white cataract, combined cataract- glaucoma surgery and so on. The Ancillary Incision: Usually, he sits at the head of the patient, performing first the ancillary incision and injecting a viscoelastic substance. This incision is placed 80º away from the primary incision, which is usually located between 10 and 11 o’clock (Fig. 41). The Primary Incision: Is a one step incision between 10 and 11 o'clock performed with the 3.0 mm clear path (Asico) diamond knife (Figs. 41, 42). Capsulorhexis: He refills the anterior chamber with more viscoelastic and performs a 5.5 mm capsulorhexis, with a cystotome. Hydrodissection: The next step is the cortical cleaving hydrodissection, as described by Fine. The nucleus must be totally or completely free inside the capsular bag. At this time, he rotates the nucleus once or twice clockwise or anti-clockwise.
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IOL Implantation: he injects viscoelastic. For routine cases Centurion uses foldable IOLs. He has been working with silicone IOL's for many years and is very confident with the implantation technique using the unfolder through 3.0 mm incision.
It is not necessary to enlarge the incision during the implantation. In his experience, with the acrylic lens it is necessary to enlarge to 3.5 mm to implant the Sensar (Allergan) and 3.75 mm with the AcrySof (Alcon).
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CARREÑO'S NUCLEAR EMULSIFICATION TECHNIQUE OF CHOICE (PHACO SUB 3) For the latest concepts on surgery related to density of cataracts, I also refer you to page 7. Carreño's Phaco Sub 3 is a phacoemulsification procedure performed through an incision of 3 mm or less. There are other modifications of the phaco technique also identified as "Phaco Sub 3." His goal is to make it as uninvasive as possible. He follows all the parameters appropriate for the entire spectrum of nuclear density that have proven to be efficient, safe, and replicable by other surgeons. Obviously, in order to achieve good surgical results, it is imperative that the phaco machine settings are perfectly adjusted to the needs of each type of nucleus and to the requirements of each step of the technique. Carreño uses the Legacy 20,000 equipment (Alcon).
Adjusting the Equipment Parameters to Remove Cataracts of Various Nuclear Density It is important to keep in mind that the basic parameters of the phacoemulsifier are the ultrasound power, the vacuum, and the aspiration flow. These are amply discussed and beautifully illustrated in pages 112-114, 119-122 and Figs. 83, 84, 61-65.
Three Sets of Values Programmed Into Memory Carreño uses the following criteria: three sets of values programmed into the memory in the Legacy 20,000. These parameters are set according to the degree of hardness of the cataract. They are: • Memory 1: Use high ultrasound power to enable a quick (continuous mode) nuclear sculpt or chisel and lower levels of vacuum and aspiration flow (Fig. 56). There is no need for great grasping or fixation power, or power of attraction in this stage of the technique. • Memory 2: For capture, mobilization and emulsification of nuclear fragments (pulse mode) (Figs. 67, 68) it is necessary to have high vacuum levels and aspiration flow in order to achieve considerable grasp and fixation power. It is also necessary to have little ultrasound power so that the nuclear fragments that are free are not propelled from the phaco tip by excessive vibration. • Memory 3: Is intended for the removal of soft material like the epinucleus, and uses much lower values in all settings, in pulse mode (Fig. 69). Height of the bottle (infusion): 75 cm to 85 cm. Phaco tip: Kelman type (curved) ABS Micro Tip with a 30-degree tip (Fig. 84). If a good hydrodissection is performed with the cortical cleaving technique, it is possible to remove the epinucleus along with
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the nuclear material in the majority of medium hard cataracts and in virtually all hard cataracts.
of the phaco tip and to provide protection to the corneal endothelium.
Working with well-programmed memories is a great advantage when using the Phaco Sub 3 Technique. By eliminating filtration through the surgical wound, the smaller incision directs the flow of liquid and nuclear fragments towards the micro tip for aspiration, making the phacoemulsification procedure more efficient. That is, there is no competition between the flow of liquid toward the surgical incision and the flow toward the phaco tip, which can occur with larger, leaking incisions. Also, the more hermetic incision of Phaco Sub 3 reduces the amount of liquid circulating in the eye during surgery and maintains a deeper and more stable anterior chamber. This helps preserve the integrity of the corneal endothelium and the posterior capsule, which, undoubtedly, confers greater safety to the technique. (Editor’s Note: see Chapter 7 for a very well illustrated presentation of the fluidics of phacoemulsification). While performing Phaco Sub 3 it is very important to keep in mind that a lateral movement of the micro tip must be avoided so as not to enlarge the incision during surgery. It is therefore necessary to always keep the micro tip working from 12 o’clock to 6 o’clock without lateral movement. This explains the great importance of a second instrument (manipulator or chopper), introduced through the lateral paracentesis to facilitate rotation, mobilization maneuvers, and nuclear fracture. Before beginning nuclear emulsification, regardless of the technique used, the surgeon should always inject viscoelastic in the anterior chamber to ease the penetration
Technique of Choice and Consistency of Cataract SOFT CATARACTS (grade 1 - 2 nucleus) Carreño recommends Fine’s Chip and Flip because the nuclei are not very hard and generally cannot be fractured (Figs. 122-126). With this technique, it is important to use hydrodissection and hydrodelamination maneuvers. Hydrodissection makes free nuclear rotation within the capsular sac easier, and hydrodelamination clearly outlines the separation between the harder inner nucleus and the softer epinucleus that surrounds it. The gold hydrodelamination ring denotes the limit to which it is possible to emulsify the nucleus without risking capsular damage (Fig. 48). First Step (“memory 1”: vacuum 0 to 10 mm Hg, aspiration flow 18 cc/min, U/S power 60%). With a manipulator introduced through the lateral paracentesis, the nucleus is gently moved toward 12 o’clock to allow the micro tip, maintained in a central position, to emulsify the inner nucleus ring at 6 o’clock without the risk of reaching the capsular fornix. Then, with the manipulator, the nucleus is rotated in order to place other nuclear fragments in position to be emulsified. The microtip must not be advanced past the gold hydrodelamination ring. This maneuver is repeated until the entire inner nuclear ring is completely removed.
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Second Step (“memory 2”: vacuum 200 mm Hg, aspiration flow 25 cc/min, U/S power 40%, 6 - 8 pulses/sec). The manipulator is inserted into the cleavage plane obtained through hydrodelamination and is passed behind the residual nuclear fragment (chip). The chip is lifted and taken to the center of the capsular sac. It is here that the chip may be emulsified with greater safety. Third Step (“memory 3”: vacuum 100 mm Hg, aspiration flow 20 cc/min, U/S power 30%, 6 - 8 pulses/sec). The center of the epinucleus is pushed toward 6 o’clock with the manipulator. Sliding the epinucleus out of the upper capsular fornix, the microtip can pull the epinucleus up toward the main incision using aspiration only (phaco pedal in position 2). The epinucleus is then folded over itself top-down (flip), using the spatula and the microtip. This moves the nucleus away from the posterior capsule. Once the flip maneuver is completed, the epinucleus is removed safely by simple aspiration or using low power ultrasound (Figs. 122 – 126). MEDIUM DENSITY CATARACTS (grade 2 - 3 nucleus) For cataracts with a medium-hard nucleus, Carreño prefers to use Shepherd’s Quadrant Nuclear Fracture technique, which is a variation of Gimbel’s original “Divide and Conquer” procedure (Fig. 67) which is a grooving and cracking method. Carreño considers that Shepherd’s technique has become the nuclear fracture technique most widely used by phaco surgeons because of its simplicity and the high
level of safety it provides. The nucleus is soft enough to allow quick sculpting with low ultrasound. At the same time it is hard enough for the surgeon to create fractures without difficulty (keep in mind that soft grade 1 (+) cataracts cannot be fractured). Furthermore, with grade 2-3 nuclei, no excessive pull is exerted on the zonule while the fragments are sculpted, which can occur with harder nuclei. In general, all of the nuclear fracture techniques (Fig. 106) aim to divide the nucleus in multiple fragments to allow their removal through the small circular aperture of the capsulorhexis and also to make phacoemulsification more efficient inside the capsular bag (Fig. 105). Phacoemulsification of small fragments of nuclear material is faster than emulsification of an entire nucleus. The procedure is therefore quicker, and the ultrasound time is reduced. The fragments are mobilized more easily within the capsular bag and it is possible to take them to the center without much difficulty (Fig.111). This allows them to be removed in a safe zone, eliminating the risk of injury to the posterior capsule or the corneal endothelium. In Quadrant Nuclear Fracture, the nucleus is divided into four parts, which are then moved individually toward the central safe zone to be emulsified (Fig. 105). First Step (“memory 1”: vacuum 10 to 20 mm Hg, aspiration flow 25 cc/min, U/S power 70%): A manipulator is introduced through the side port incision to rotate the nucleus (Figs. 56 and 67). Moving the microtip from 12 o’clock to 6 o’clock, thin and deep grooves are carved until a cross is formed (Fig. 67). Ideally, these grooves should
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extend almost to the edge of the capsulorhexis (to avoid the peripheral capsule), and should be deeper in the middle than in the periphery (to respect the curve of the posterior capsule) (Figs. 103, 104). They should also be slightly thicker than the ultrasound tip (including the silicone sheath) and should be 80%-90% of the depth of the nucleus (Fig. 103). The visualization of the red reflex at the bottom of the groove indicates adequate depth to the surgeon.
Second Step: Once the cross is formed (Fig. 67), the nucleus is divided into four quadrants. The phaco tip and the manipulator are placed at the bottom of the groove at 6 o’clock and are pushed in opposite directions (with a direct or crossed maneuver) (Fig. 104). The separation results in a fracture line, which extends from the periphery to the center of the posterior nuclear wall (Fig. 104). After the nucleus is rotated 90 degrees, fractures are performed until the nucleus is divided into four fragments (Fig. 105). The fracture should include all the nuclear material; all the fragments must be separated in order to ensure a good result. Before continuing to the next step, the surgeon should mobilize the quadrants with the spatula in the capsular bag to ensure that there are no connections between them (Fig. 105). Third Step (“memory 2”: vacuum 300 mm Hg, aspiration flow 35 cc/min, U/S power 50%, 6 - 8 pulses/sec) (Fig. 67) The microtip is directed toward 6 o’clock, and the phaco pedal is in position 2 (irrigation/aspiration without ultrasound). The first quadrant is captured by placing the tip in contact with nuclear material to generate occlusion (Figs. 59, 60). For greater
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safety, the surgeon may first lift the corner of the quadrant with the spatula to distance it from the posterior capsule. With harder cataracts, sometimes simple aspiration is not enough to occlude the opening of the microtip. Apply a few ultrasound bursts (phaco pedal in position 3) to grasp the nuclear material and generate occlusion (Figs. 52, 53). Once occlusion is achieved and the phaco pedal is again in position 2, the surgeon should wait until the vacuum reaches the aspiration line. This makes it possible to hold the quadrant firmly on the opening of the tip. At this precise moment, relying on good grasping force, the surgeon can pull the quadrant toward the central safe zone. The quadrant should be completely controlled by the manipulator in order to avoid turbulence and contact. Then the quadrant is emulsified with the machine in pulse mode (Fig. 86). With large and hard fragments, it is useful to use chop maneuvers (with the same chopper or secondary instrument) in order to divide the quadrant into smaller fragments, to make the surgery quicker and easier (Figs. 105, 106). The procedure described is repeated for the other quadrants until the entire nucleus is emulsified. HARD CATARACTS (grade 3-4 nucleus) With hard cataracts, Carreño prefers to use chopping techniques. They offer clear advantages over the divide and conquer procedures in the management of this type of nucleus (See pages 177-182). As a method of nuclear fragmentation, the chopping techniques derived from Nagahara’s original “Phaco Chop” considerably reduce
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the power and total time of phacoemulsification, thereby reducing the tension on the zonules and the posterior capsule and confining the entire phacoemulsification procedure to the central 3 mm of the pupil (Fig. 183). Three important features of the chopping techniques are important to emphasize: 1. Chopping is a completely different method than nuclear fracture. It basically consists of making cuts following the natural cleavage of the lens ( similar to cutting a log with ax blows) (see page 183). 2. In order to lend itself well to the chop maneuver, the nucleus must have a firm consistency. 3. The conservation of energy gained by not carving grooves (D & C) makes chopping particularly indicated for the management of hard nuclei.
The Stop and Karate Chop Carreño’s preferred chopping technique is the “Stop and Karate Chop”, which is a combination of Koch’s “Stop and Chop and Nagahara’s “Karate Chop.” He finds it is a very safe procedure combining the advantages of both techniques. Without a doubt, Koch’s “Stop and Chop” noticeably simplifies Nagahara’s original “Phaco Chop” technique by creating an initial groove (Fig. 107) which, in turn, creates a space in the nucleus, making the chopping maneuvers, mobilization, and nuclear fragment emulsification much easier. This explains its great popularity as a chop technique (page 184). At the same time, “Karate Chop,” which corresponds to a modification introduced by Nagahara to his
original “Phaco Chop,” offers a greater advantage by confining the chop to the central region within the limits of the capsulorhexis. This means the surgeon avoids the need to reach dangerously with the chopper under the anterior capsule, toward the lens equator, to create the fracture. The “Stop and Karate Chop” technique basically consists of three steps, which are the sculpting or chiseling of the central sulcus (Fig. 107, page 185) in order to fracture the nucleus in two halves, the chopping of the two hemi-nuclei, (Fig. 106, page 182) and the mobilization and ulterior emulsification of the nuclear fragments (Fig. 111). (Editor's Note: from the practical point of view, these are the same principles of the Stop and Chop (pages. 184-188), except that the direction of the cut in the “Phaco Chop” technique goes from the equator towards the center of the nucleus, while the “Karate Chop” goes from the anterior pole to the posterior pole). First Step (“memory 1”: vacuum 20 mm Hg to 30 mm Hg, aspiration flow 30 cc/min, U/S power 80%): The procedure is initiated by chiseling a central sulcus with the microtip toward 6 o’clock (as if it were nuclear fracture in four quadrants) (Fig. 107). The chiseling is completed toward the other extreme after rotating the nucleus 180 degrees aided by the chopper introduced through the side port incision (Fig. 109). Once the desired depth is obtained, the nucleus is divided into two halves. It is fractured with the phaco tip, and the chopper is placed in the bottom of the sulcus. The surgeon must ensure that the halves are completely separated (Fig. 106). From this time on, no more sculpting or cracking is
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done, and the chopping maneuvers are initiated. (Hence, the “Stop and Chop” designation by Paul Koch). Second Step (“memory 2”: vacuum 400 mm Hg, aspiration flow 40 cc/min, U/S power 60%, 6 to 8 pulses/sec): The nucleus is rotated 90 degrees so that it is in a horizontal position to ease the grasp of the distal hemi-nucleus with the microtip. The phaco pedal is in position 2 (irrigation-aspiration), the microtip is placed against the wall of the sulcus in its central portion while ultrasonic pulses (phaco pedal in position 3) are applied, and the nuclear material is grasped. Once occlusion is reached, the pedal is returned to pedal position 2 in order to increase the vacuum and obtain good fixation at the microtip. Now the choopper is sunk into the nuclear material slightly in front of the microtip. By pulling the instruments in opposite directions (the chopper towards the left and the microtip toward the right), the surgeon fractures the distal hemi-nucleus into two halves (Fig. 111, page. 189). The nucleus is then rotated 180 degrees, and the procedure is repeated so as to fracture the other heminucleus in two halves as well. The nucleus ends up divided into four quadrants. Carreño prefers not to remove the quadrants immediately. Keeping all the pieces within the capsular bag stabilizes the second hemi-nucleus at the moment the chop is performed, making the maneuver easier. It is very important to ensure that all four quadrants are completely independent of each other. Introducing the chopper directly into the nucleus, without having to reach the periphery to carry out the fracture, as with
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the “Phaco Chop,” is what prompted Nagahara to call this modification of his technique the “Karate Chop.” Third Step (“memory 2” is maintained: vacuum 400 mm Hg, aspiration flow 40 cc/min, U/S power 60%, 6 to 8 pulses/ sec): Once the nuclear division is complete, the quadrants are mobilized. They are captured with the microtip and pulled to the central safety zone, where they are emulsified. In order to capture the quadrants, the surgeon grasps the nuclear material by applying some ultrasonic pulses (Fig. 105) (phaco pedal in position 3). Once occlusion is achieved, the vacuum is increased (phaco pedal in position 2) to ensure grasp at the microtip. The maneuver is repeated until all fragments are removed. As with Shepherd’s “Quadrant Nuclear Fracture,” any large nuclear fragments present should be divided using chopping maneuvers to speed the procedure. The presence of a central sulcus plays a fundamental part in the development of the “Stop and Karate Chop” technique, as space is created within the nucleus (Fig. 107). With the occlusion of the tip, it is easier to perform the chop, to move the nucleus posteriorly, and to remove the fragments.
VERY HARD CATARACTS (4-5 grade nucleus): In these extremely hard nuclei (rubra and nigra cataracts), that represent a great challenge for the phaco surgeon, Carreño’s technique of choice is “Crater and Karate Chop,” which is a combination of Gimbel’s
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“Crater Divide and Conquer” with Nagahara’s previously mentioned “Karate Chop.” The key to success with these very hard nuclei lies in reducing the nuclear volume as much as possible while maintaining a peripheral nuclear ring firm enough to perform chopping maneuvers geared to creating the fractures (See pages. 191-193 for reference of the very similar Crater Phaco Chop Technique - Editor). The basic steps for the “Crater and Karate Chop” technique are the sculpting of a very deep central crater, the chopping of the peripheral nuclear ring to create multiple fragments, and finally, the mobilization and emulsification of these fragments (Fig. 112116 for reference). First Step (“memory 1”: vacuum 20 mm to 30 mm Hg, aspiration flow 30 cc/min, U/S power 90%): Directing the microtip always towards 6 o’clock, the surgeon sculpts a crater in the central nuclear zone, using rotation maneuvers to facilitate and deepen it. (The use of ultrasound for a prolonged amount of time during this step of the technique is not risky because the nuclear sculpting is performed inside the capsular sac, far away from the corneal endothelium.) In order to fracture, it is necessary to centrally sculpt very deeply (until the red reflex appears in the bottom) while maintaining enough dense material in the nuclear periphery. Second Step (“memory 2”: vacuum 400 mm Hg, aspiration flow 40 cc/min, U/S power 70%, 6 to 8 pulses/sec): The microtip is placed against the wall of the central crater at 6 o’clock, and ultrasound pulses are applied (phaco pedal in
position 3). The nuclear material is impaled. Once occlusion is reached, the pedal is placed in position 2 to increase the vacuum in the aspiration line and firmly attach the nucleus to the opening of the microtip. The chopper is then introduced into the nuclear edge in front of the microtip (“Karate Chop” technique, without taking the chopper to the equator underneath the anterior capsule.) The instruments are pulled apart to complete the first fracture. The nucleus is rotated, and the maneuver is repeated in order to make the second fracture, creating the first fragment. The process continues until the nucleus is divided into multiple fragments (five or more). The surgeon must ensure that there are no connections between them. The harder the nucleus, the smaller and more numerous the fragments must be in order to make them more manageable. While making subsequent chopping maneuvers, it is useful to leave the fragments in place to keep the capsular bag well-distended. This reduces the possibility of an inadvertent cut into the posterior capsule with the phaco tip. Third Step (uses “memory 2”: vacuum 400 mm Hg, aspiration flow 40 cc/min, U/S power 70%, 6 to 8 pulses/ sec): Once the nucleus is fragmented, Carreño proceeds to move each individual fragment toward the center to emulsify it. (Because very hard fragments are involved, it is advisable to inject viscoelastic to protect the corneal endothelium). The tip is placed against the nuclear fragment at 6 o’clock, and ultrasonic pulses are applied (phaco pedal in position 3) to capture the fragment. Then the vacuum is allowed to increase
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(phaco pedal in position 2) to reach a firm grasp at the microtip opening. The fragment is then pulled toward the center, into the safety zone, to be emulsified. The nucleus
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is then rotated in order to place another fragment at 6 o’clock. The procedure is repeated until all the fragments are completely removed.
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NISHI'S TECHNIQUES OF CHOICE FOR NUCLEI OF DIFFERENT CONSISTENCIES Nishi uses two different techniques depending on nucleus consistency.
1) Soft (+), Standard (++): In these groups, Nishi uses a modification of the Divide and Conquer procedure (Figs. 56 and 67) and sometimes Fine's Choo-Choo Chop and Flip technique (Figs. 122-126) using high vacuum and low ultrasound energy from the very beginning (vacuum 170 mm Hg, energy up to 60% using Allergan's Diplomax phaco machine). High energy is not necessary for those nuclei, and it is cumbersome for the surgeon to switch on from high vacuum-low energy to low vacuum-high energy.
2) Moderately Hard to Hard Nucleus (+++): In cases with moderately hard and hard nucleus, higher energy up to 80% (even 100%) is used for rock-hard nucleus, taking care not to burn the wound. This high energy is combined with low vacuum for making a groove or a cross. For making a groove, the tip is never occluded and high vacuum is not needed. After the nucleus is divided into 2 or 4 parts, the next step is emulsification. The machine is switched to high vacuum low energy, unless higher energy is needed for emulsifying the fractured quadrants. High vacuum is now needed, because the nucleus fragments must be pulled towards the center by occluding the tip opening.
BIBLIOGRAPHY Buratto, L: Buratto's elective techniques for phacoemulsification according to grades of hardness of nuclei. Phacoemulsification: Principles and Techniques by Lucio Buratto, 1998; 6:166-170. Carreño, E.: Nuclear emulsification technique of choice (Phaco Sub 3). Guest Expert The Art and the Science of Cataract Surgery of HIGHLIGHTS, 2001. Centurion, V.: Centurion's technique related to nucleus consistency. Guest Expert The Art and the Science of Cataract Surgery of HIGHLIGHTS, 2001. Lindstrom, R.: Lindstrom's procedures of choice. Guest Expert The Art and the Science of Cataract Surgery of HIGHLIGHTS, 2001. Lindstrom, R: Tilt and tumble phacoemulsification. Clear Cornea Lens Surgery, edited by I. Howard Fine, Slack, 1999;9:99-119. Lindstrom, R: Tilt and tumble phacoemulsification. Operative Techniques in Cataract and Refractive Surgery. Vol. 1, Nº 2 (June), 1998: pp. 95-102. Nishi, O: Nishi's technique of choice related to nucleus of different consistency. Guest Expert The Art and the Science of Cataract Surgery of HIGHLIGHTS, 2001.
3) Hard (++++) or Very Hard Nuclei (+++++): Nishi uses a chopping technique (Figs. 103, 106, 107-111). Care is taken to stay away from the corneal endothelium. 245
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C h a p t e r 11:
Complications of Phacoemulsification - Intraoperative and Postoperative
INTRAOPERATIVE COMPLICATIONS General Considerations Even in the most experienced hands complications occur. The best management of complications is to avoid them. When unpreventable, a well thought out, carefully executed plan can give very good visual results. When using topical anesthesia, the patient is an active participant in the procedure. Complications can occur when patients move their head, body, or eye, cough, or squeeze their eyelids. Consequently, they should be fully educated and carefully selected. We should provide proper education in advance about what will be experienced so that the level of anxiety will be low. When speaking with the patient, the surgeon should sound calm and in control. If patients sense the surgeon's anxiety they may become more anxious, further limiting their ability to cooperate. When patients become over sedated they may fall asleep and might awake disoriented. The best way to keep patients from waking up suddenly is to keep them from falling asleep. In cases under topical anesthesia, excessive globe movement can impair the safe completion of the operation. If the patient is unable to hold the eye steady, or if they are perceiving discomfort from the surgery, augmenting the anesthesia with a subtenon, peribulbar, or retrobulbar block may be helpful. This can be accomplished quite safely when a selfsealing wound is done.
Main Intraoperative Complications The main complications are related to the following phases of the operation: 1) complications related to the incision. 2) Those associated with anterior capsulorhexis. 3) Complications consequent upon rupture of the posterior capsule. 4) Complications related to emulsification and removal of the nucleus through different techniques. We also need to confront the complications related to hydrodissection and/or hydrodelineation, those that occur during the process of aspiration of the cortex, intraocular lens implantation and the difficulties of the operation when the pupil is small.
Incidence As pointed out by Howard Gimbel, M.D., the incidence of intraoperative complications will vary to some degree with the surgeon’s experience and the type of procedure performed as, for instance, when a sclero corneal tunnel is performed versus a clear corneal incision. It will also vary depending on the anatomic characteristics of the individual eye as in small pupils and hypermature cataracts. Intraoperative complications are also related to the type of anesthesia utilized but this has been significantly diminished by combining topical and intracameral local anesthesia which is used in most cases, or using this combination with sub-Tenon’s anesthe-
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sia when desired (Chapter 5). Since retrobulbar or peribulbar anesthesia are practically no longer used in phacoemulsification, even by those who are starting in the transition period, the risks of globe perforation or retrobulbar hemorrhage have practically disappeared.
Facing the Challenges Virgilio Centurion, M.D. from Sao Paulo, Brazil, one of Latin America’s most experienced and didactic anterior segment surgeons, has dedicated years of research and teaching on how to master phacoemulsification. This includes being prepared for the challenges of the intraoperative complications, which are different than those we were accustomed to face with planned extracapsular. Centurion emphasizes that each cataract operation presents its own challenges, and that even though we have reached a very advanced level of safety and predictability with phacoemulsification, it is important that we keep in mind the complications that may arise so as to minimize situations that may bring the level of stress to a peak in the operating room.
COMPLICATIONS WITH THE INCISION Too Short and Shallow or Too Large Lindstrom points out that the most frequent complication he has with the clear corneal incision is that he either makes the width of the incision a little bit too short, or the dissection too shallow or too beveled
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(Fig. 140). Or else, he makes the incision a little bit too large. If it is too shallow or beveled, it will become a non self-sealing, nonvalvulated wound. If it is too large, a persistent iris prolapse may occur. You may try to ignore it but it keeps coming back. With a superficial, shallow incision, you may manage it as shown in Fig. 140. Simply abort the superficial tunnel, go back to the first or initial vertical groove of the incision (300 microns depth) corresponding to 1/2 the corneal thickness and place the blade deeper, forming a second tunnel with the correct depth located below the first or superficial tunnel (Fig. 140). If you are having a very difficult time with an incision, the best thing to do is to close that incision with one or two vicryl sutures which will eventually dissolve and move over to another nearby spot and start over. With a clear corneal incision, starting over only takes a short additional time (Fig. 141).
Problems from Incorrect Placement and Performance of Incision In Fig. 142 you may see a summary of the problems in creating the sclero corneal, limbal and corneal tunnel incisions. The correct placement and structure of each incision is presented in Fig. 40. A key element in the success of phacoemulsification is to obtain a good internal valve incision. As Centurion has emphasized, it is only by experience and extreme care that we develop a sense of «feeling» of the ideal depth, that is, the one which will not endanger the intraocular tissues and will ensure a good tunnel protection.
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Complications of Phacoemulsification - Intraoperative and Postoperative
Figure 140 (left): Complications while Making a Clear Corneal Incision - Too Shallow and Short The corneal tunnel incision should be self-sealing and valvulated, at about 300 microns depth. That is approximately half the corneal thickness. Here we observe that the first incision was too superficial (red) not permitting a proper valve to function. Thereby, the wound is not self-sealing. One solution for this is to abort this tunnel and start again from the initial incision, go deeper forming a second tunnel (arrows) below the first superficial tunnel.
Figure 141 (right): Problems From Incorrect Placement of Tunnel Incisions The correct placement and performance of the sclero corneal tunnel, limbal or corneal incision is extremely important. In case of the sclero-corneal, a 5 mm external incision (E) is made 1-3 mm from the limbus to a depth corresponding to 1/2 to 2/3 thickness of the sclera. A scleral tunnel (T) between 2 to 3 mm in length is made. With blade directed toward and in a parallel path to the pupil, the internal valve (V) opening is created. Common placement errors are shown by blue lines. Also shown is a detachment of Descemet’s membrane (D), another common error that can be avoided by use of abundant viscoelastic. (Original illustration by HIGHLIGHTS, based on principles from Virgilio Centurion's book titled "Complicações Durante a Facoemulsificação".)
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Figure 142: Complications during Incision - Closing of the Improper Incision and Making a New One If the elected incision site is too superficial and short or too large (A) so that it may not provide correct sealing, it is advisable to close the first incision with vicryl sutures and perform a new and correct incision next to the first one (B). The surgeon may choose the horizontal (S) or radial sutures according to his/her experience.
Detachment of Descemet's Membrane An occasional but important complication is detachment of Descemet’s membrane, as shown in Fig. 143. The main causes are: 1) ocular hypotension while dissecting the tunnel or while constructing the internal part of the tunnel to make the valve-like incision. The injection of viscoelastic through the side port of the incision before performing the primary incision can prevent this from happening. 2) The introduction of the blade in the wrong direction when constructing the internal part of the incision (Figs. 140, 142 and 143). 3) The forced introduction of the phaco tip or foldable lenses in a tight incision. This may be avoided by being very careful during entry of the tip, by 252
lubricating the tunnel with viscoelastic and by very careful folding of the IOL and lubrication either of forceps or the injector, in order to attain a non-traumatic introduction and implantation of the IOL. Important: During the dissection of the internal step of the incision which leads to the formation of the internal valve (V), the intraocular pressure must be either normal or slightly high and the tip of the blade must be directed towards the pupil and follow a parallel path toward the pupil as shown in Figs. 140, 142 and 143. Use abundant viscoelastic in order to keep Descemet’s membrane where it belongs until the conclusion of the surgery. A detachment of Descemet’s membrane discovered postop, is an important complica-
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tion when it occurs because it may be followed by corneal edema and even inflammation. If it occurs, topical antiinflammatory medications are sometimes useful. If the detachment is significant, however, (Fig. 143) there may be corneal decompensation progressing to bullous keratopathy which may eventually require a penetrating graft.
Precautions with Closure of the Incision Upon Conversion Conversion to extracapsular is not infrequent when you start in the transition period and may be necessary even in the hands of a more experienced surgeon upon the development of complications. If the incision is corneal, move to the limbus. Other surgeons prefer the scleral tunnel incision or the tunnel starting at the limbus or about 1 to 1.5 mm from the limbus. When converting, enlarge the
incision for the extracapsular at the limbus. The nucleus and cortex are removed and the IOL implanted. When suturing, it is important to close the wound by placing the interrupted sutures radially. When you get to the junction between the part of the incision where the tunnel was started and the limbus, suture it as shown in Fig. 144. The arrow shows conversion when the initial incision was a sclerocorneal tunnel. Unless properly sutured, the valve may leak at this site.
Heating the Wound Very occasionally, if one is not careful, you can heat the wound. It looks like you cauterized the cornea. That is not such a problem during the surgery but this wound may well leak. If that occurs, at the end of the operation, the surgeon has to close the wound by suturing but will not be able to perfectly
Figure 143: Complications with the Tunnel Incision - Detachment of Descemet's Membrane A detachment of Descemet's membrane (D) may be observed during construction of the valvulated incision, manipulation of the incision with the phaco probe in a tight incision or from insertion of the intraocular lens. This complication happens more frequently when making the incision in a hypotensive eye, or the wrong maneuver when introducing the knife.
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approximate the edges of the incision because this may induce a large astigmatism. The most practical approach is to suture the anterior edges of the tunnel to the posterior surface of the wound using a mattress suture. A little gap will remain in almost every setting but you can create a sealing incision. You should expect a small to moderate amount of astigmatism, but the good news is that it will go away with time. It is only a temporally induced astigmatism. The difficulty is to get that incision to seal.
Management of Leaking Incisions with a Positive Seidel Infrequently, a clear cornea incision or a scleral tunnel incision larger than 3 mm in width may show leaking of fluid one day postoperatively. This is either secondary to an incision larger than planned and not sutured, or by too much trauma in the lips of the wound usually by the phaco tip. When this leaking occurs, it may be immediately detected by instilling a drop of fluorescein and observing the patient under ultraviolet light. The problem with these patients is that the constant escape of aqueous humor keeps the wound open and may require suturing of the incision which certainly is a nuisance. Prof. Juan Murube, M.D., from Madrid recommends a very ingenious maneuver in order to close the leaking wound without having to re-suture the incision. He places a Honan balloon (Fig.96) over the eye for 30 minutes at a pressure of 35 mm Hg and at the same time administers 1 tablet of acetazolamide, 250 mg orally (Diamox). The hypotony produced when the Honan balloon is removed makes the aqueous humor (that is
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constantly being produced and was causing the positive Seidel) remain in the anterior chamber. The anterior chamber has the opportunity to reform. After a few minutes, when the intraocular pressure returns to normal, the walls of the incision have come together and adhered, without any further positive Seidel. This ingenious maneuver is simple and avoids having to re-suture the patient.
COMPLICATIONS RELATED TO ANTERIOR CAPSULORHEXIS It is generally agreed that this is the procedure of choice to open the anterior capsule. In most cases, it allows the phaco technique to be performed within the capsular bag and, consequently, the maneuvering and instrumentation does not affect the surrounding tissues particularly the corneal endothelium. Capsulorhexis also allows an almost perfect positioning of the intraocular lens. As emphasized by Centurion, when the surgeon dominates the technique of capsulorhexis, cases of decentration, capture and/or subluxation of the IOL are rare.
Main Complications The main complications may be related to: 1) the size of the capsulorhexis. It may be either too large or too small. This is due to a technical mistake either in the judgment of the surgeon or in performing the technique. The ideal diameter of capsulorhexis ranges from 5 to 6 mm. Centurion advises that, when there is doubt, check the diameter of the capsulotomy by holding a compass over the cornea. When the capsulorhexis is too small, less than 5 mm (Fig. 145), problems may arise during the manipulation of the nucleus and the IOL im-
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Figure 144: Precautions with Closure of the Incision Upon Conversion The wound is closed with interrupted sutures radially. When you get to the junction between the part of the incision where the tunnel was started and the limbus, you must place the suture as shown in this figure. Otherwise, the valve may leak. (Courtesy of Virgilio Centurion, M.D., from his book titled “Complicaçoes Durante a Facoemulsificaçao”.)
Figure 145: Complications Related to Anterior Capsulorhexis - Too Small When the anterior capsulorhexis (C) is rather small (less than 5 mm), the manipulation of the nucleus may present problems that might compromise the successful results of surgery, and IOL implantation may be more difficult.
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plantation may be more difficult to the extent of compromising the final result of the surgery. If it is considered to be small, perform a small lateral cut in the capsulorhexis with Vannas scissors at 10 o'clock (Fig. 146). Afterwards, perform a second and wider anterior capsulorhexis with the Uttrata forceps at 12 o'clock which will prevent or eliminate the likelihood of stenosis of the opening (Fig. 147). This is also a good option on what to do if there is some discomtinuity or small tear identified in the anterior capsulorhexis. When the capsulorhexis is too large (Fig. 148), larger than 6 mm, some difficulties may arise in stabilizing the nucleus after hydrodissection with a tendency for the nucleus to move into the anterior chamber. Thic could possibly endanger the corneal endothelium and other surrounding structures and emulsification would need to be done in the anterior chamber. Maintain sufficient viscoelastic between the lens and the endothelium. Lindstrom considers that if the capsulorhexis is really large (Fig. 148) it is not a major problem although there is a tendency to develop a higher rate of capsular opacity because the border of the capsulorhexis is not placed over the edge of the posterior capsule. Another problem that Lindstrom has commonly encountered is the chamber will shallow as you are doing the capsulorhexis, particularly in younger eyes. The way to avoid this is that as you see the chamber shallowing, put more viscoelastic in it and put it more centrally in the younger eye. Another complication is that the capsulorhexis will tear into the zonules. If
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that occurs, Lindstrom goes back to the beginning, makes a little cut with Vannas scissors at the edge of the rhexis (Fig. 146) in the other direction from where the extension into the zonules occurred and enlarges the rhexis around the opposite way (Fig. 147). In these cases, the surgeon may have to presume that there was a little radial tear to start and must be very careful with the next step, the hydrodissection, because most probably there is a weak spot in the anterior capsule. In that case you should probably not use a plate haptic lens.
Preventing Rhexis Complications by Tinting One of the major advances in performing circular continuous capsulorhexis (CCC) in hypermature cataracts which are either totally white or very dark is the tinting of the anterior capsule. In these eyes, the fundus reflex cannot be seen by the coaxial light of the microscope. When the reflex is not present, it is extremely difficult to see in order to complete the circular capsulorhexis. Tinting of the anterior capsule through various substances such as Fluorescein 2%, Indocyanine Green, Trypan Blue, Gentian Violet, or Methylene Blue is a new development to improve the visibility of the anterior capsule during CCC. Professor Juan Murube, M.D., in Madrid and Professor Carlos Nicoli, M.D., in Buenos Aires both definitely prefer the use of Trypan Blue as the best coloring substance for this purpose. They place the tinting substance over the anterior capsule when the anterior chamber is full of air as advised by Murube. The technique is shown in (Figs. 101, 102, page 173).
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Figure 146 (above): Management of Small Anterior Capsulorhexis If it is considered to be small, perform a small lateral cut in the capsulorhexis with Vannas scissors at 10 o'clock.
Figure 147 (center): Enlarging a Small Capsulorhexis Managing a Discontinuity of the Rhexis Perform a second and wider anterior capsulorhexis with the Uttrata forceps which will prevent or eliminate the likelihood of stenosis of the opening. This figure also serves to show what to do when there is a discontinuity or small tear identified in the anterior capsulorhexis (C). The best option first is the injection of viscoelastic. Next, try with the forceps (F) to perform a second anterior capsulorhexis (arrow) leaving a regular surface with no weak points in order not to alter the correct evolution of the surgery. The white arrow identifies the small discontinuity of the rhexis which is being repaired.
Figure 148 (below): Complications Related to Anterior Capsulorhexis - Too Large The ideal size ranges from 5 to 6 mm. In this surgeon's view you may observe a large capsulorhexis (C). This may induce tears of the posterior capsule during the stage of phacoemulsification or a tendency for the nucleus to move to the anterior chamber during the operation.
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COMPLICATIONS WITH HYDRODISSECTION What we try to accomplish with hydrodissection is that by irrigating with a stream of BSS immediately under the anterior capsule, we produce a separation of the rest of the lens from the anterior capsule, including the nucleus and cortex, and separation of the cortex from the epinucleus. If you are doing an endocapsular technique, sometimes it is difficult to get the nucleus loose by hydrodissection. Sometimes surgeons will stop because they find it is taking them longer than they expected and are not sure how to proceed. If the surgeon stops to the extent of discontinuing hydrodissection, this makes the rest of the operation much more difficult and risky. Lindstrom emphasizes that one should continue to hydrodissect and do so in different
areas until one is sure the nucleus is loose and will rotate. Having a loose nucleus by hydrodissection is one of the keys to success with the endocapsular technique. If the surgeon does not get the nucleus loose it leads to complications in the next step. Centurion emphasizes that if the nucleus does not spin freely within the capsular bag it is due to incomplete hydrodissection. It is important not to try to rotate the nucleus mechanically at this stage but, instead, repeat the hydrodissection maneuver and/or introduce in the anterior chamber a Sinskey hook through the main incision and another hook through an ancillary incision as shown in Fig. 149. The hooks are fixed at opposite sides of the nucleus. In Fig. 149 the arrows indicate the direction of the spin of the nucleus when a slight traction is applied but this is done after a repeat hydrodissection. For this procedure, the anterior chamber should be filled with viscoelastic.
Figure 149: Freeing a Fixed Nucleus After Ineffective Hydrodissection Under viscoelastic, a Sinskey hook (1) is introduced in the anterior chamber through the main incision and another hook (2) through the ancillary incision. The hooks are fixed at opposite sides of the nucleus (N). Arrows indicate the direction of spin of the nucleus when a slight traction is applied.
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Figure 150: Proper Depth of the Lens Groove for “Divide and Conquer” Technique As indicated, the depth of the lens groove should be 1 1/2 to 2 times the diameter of the tip of the phacoemulsifier (P). Arrows show the direction of opposing forces applied to both sides of the groove to fracture the nucleus.
Centurion emphasizes not to proceed to the next stage, which is nucleus removal through phaco, without being sure that the nucleus is free. In traumatic or congenital cataracts be particularly careful when performing hydrodissection due to the possible fragility of the posterior capsule.
COMPLICATIONS NUCLEUS REMOVAL
DURING
Before proceeding with phacoemulsification of the nucleus, it is assumed that the surgeon has performed correctly all the previous phases of the operation. Upon entering this crucial stage of the operation, the surgeon may have difficulty in fracturing the nucleus. That usually is caused by having performed
too shallow a groove within the lens, not deep enough to allow fracturing of the remaining nuclear bed. If the surgeon is using the "Divide and Conquer" technique, the reliable point of reference when performing the groove, is the tip of the phacoemulsifier as shown in Fig. 150. The tip of the phacoemulsifier should penetrate the central region of the nucleus 1 1/2 to 2 times the diameter of the tip of the phacoemulsifier (Fig. 150). The arrows in this figure show the direction of opposing forces applied to both sides of the groove in order to fracture the nucleus. As this proceeds, the red reflex becomes redder (Also see Figs. 104 page 178, and 106 page 182). The most serious complication of nucleus removal is rupture of the posterior capsule, which we address separately in this chapter.
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Surgeon's Fatigue Lindstrom points out that another preventive measure to avoid complications during nucleus removal is that in the more difficult eyes, the surgeon fatigues, or gets tired. When this happens, he stops and rests. The minute you think you do not seem totally comfortable and your movements get a little awkward he recommends stopping and put some viscoelastic in the eye. Use two instruments to rotate the nucleus into a more favorable position (Fig. 149) and then start again. In some difficult eyes Lindstrom may restart and stop even two or three times. Maybe that means the case took four minutes longer but this is not important. In those really difficult eyes it can mean the difference between success and failure. In some complications symposia, if you observe the live surgery you can see the tremors of some surgeon's hands when it is taking them a long time in difficult cases, and they get awkward and uncomfortable, they just cannot get the nucleus into the right position. In those cases Lindstrom thinks if you just stop and rest for a minute, put a little viscoelastic, take your time and be patient until being able to rotate the nucleus (or other difficult maneuvers) you can save yourself and the patient a great deal of problems.
COMPLICATIONS DURING REMOVAL OF THE CORTEX After the nucleus has been removed, it is important that the surgeon remain concentrated on proceeding with skill and attention to every detail to the end stages of the operation. It is natural for some surgeons to consider that immediately after removing the nucleus, the main steps of the operation have been con-
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cluded and it is time to relax. Not so. An unpleasant rupture of the posterior capsule may occur during the following step, which is removal of the cortex. Lindstrom emphasizes that for most people removing the cortex is "easy" but many of the series in the world literature will show that as many posterior capsules are torn during cortical removal as are during the nucleus removal. The hard part is over but do not loose concentration. Slow down, and make sure you do this step properly. The cortex usually is quite easy to remove but most of the difficulty and risk occurs when trying to vacuum clean the posterior capsule. Lindstrom is not convinced that it makes any difference to vacuum clean the posterior capsule because this is not where the source of the eventual opacification of the posterior capsule. He discourages aggressive vacuuming of the posterior capsule. If you are going to do it be very certain that there is no barb or sharp point on the tip of the I/A. He has seen many capsules torn by a little barb or sharp tip on the I/A tip particularly during the vacuum cleaning.
COMPLICATIONS DURING FOLDABLE IOL's IMPLANTATION Wrong Decentration
IOL
Power
and
To prevent complications, the key is to get the lens symmetrically into the capsular bag or symmetrically into the ciliary sulcus if for some reason the surgeon feels insecure about the capsular bag being intact. This requires being very observant that there is a good capsular rim and certain that you are placing the complete lens at the bottom of the capsule.
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Also, be sure you have the correct lens and correct lens power. Surgeons who receive many referrals from other colleagues consider that the most common reasons they have to operate in order to change an IOL are: 1) error in lens power calculation during the previous operation and 2) late decentration or subluxation.
because they are not within the central zone; and 2) others have suffered significant tears and have had to be removed during surgery, requiring that a new lens be inserted. These tears might have been due to the lack of lubrication with viscoelastic or because the surgeon did not use the proper technique of insertion.
Asymmetric Capsulorhexis
Importance of Warming Acrylic IOL's
Sometimes, a decentration of the IOL occurs because there is an asymmetric capsulorhexis. The margins of the rhexis are not over the optic on all sides. Consequently, one side gets underneath the lens, it fibroses and pushes the lens aside. If for some specific reason the haptics were placed in the sulcus, sometimes the sulcus can be very large, as in myopes, and there can be an area of disinsertion.
Upon using acrylic lenses, they should be warmed before folding and implantation. This measure provides easier folding and a slower unfolding. If we attempt to fold and implant an acrylic IOL at room temperature, the lens presents resistance to folding and a certain resistance to unfolding.
Management of Complications with Array Multifocals
Deficient Intraoperative Handling Carlos Nicoli, M.D., one of Argentina's most prestigious cataract surgeons, finds that the intraoperative complications with foldable IOL`s are not significant but we do have to be alert as to problems arising from intraoperative handling of the lenses, the instruments used to fold the lenses, the injectors and the forceps. Heavy or high density viscoelastics placed within the plastic injectors have led to breakage of the injector at the time of insertion. In addition, if the surgeon does not have enough experience with the injectors, he may scratch the lens optic. Also, if we grasp the lenses with forceps without a stop at the tip, the optics can be scratched at the time of folding. Nicoli points out that tears may occur in lenses at the time of insertion. They may be: 1) partial tears where vision is not affected
As emphasized by Fine and Hoffman, in situations in which the first eye has already received an Array lens implant, complications management must be directed toward finding the way to implant an Array IOL in the second eye. Under most circumstances, capsule rupture will still allow for implantation of an Array lens as long as there is an intact capsulorhexis. Under these circumstances, the lens haptics are implanted in the sulcus, and the optic is prolapsed posteriorly through the anterior capsulorhexis. This is facilitated by a capsulorhexis that is slightly smaller than the diameter of the optic (Fig. 145) in order to capture the optic in essentially an in-the-bag location. If full sulcus implantation is used, then an appropriate change in the IOL power will have to be made to compensate for the more anterior location of the IOL within the
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eye. When vitreous loss occurs, a meticulous vitrectomy with clearing of all vitreous strands must be performed. Iris trauma must be avoided because the pupil size and shape may affect the visual function of a multifocal IOL postoperatively. If the pupil measures less than 2.5 mm impairment of near visual acuity may ensue owing to the location of the lens rings serving near visual acuity (Figs. 130, 131). For patients with small postoperative pupil diameters affecting near vision, a mydriatic pupilloplasty may be tried successfully using the Argon laser.
COMPLICATIONS WITH POSTERIOR CAPSULE RUPTURE Maintaining the integrity of the posterior capsule is a must because the incidence of retinal complications is higher when there is posterior capsular disruption. We specifically refer to cystoid macular edema and retinal detachment. The disruption of the posterior capsule may occur at any stage of the operation, at the beginning, in the mid stage upon removing the nucleus and in the late stage when aspirating the cortex. Adequate management can provide satisfactory vision. A tear in the posterior capsule is most frequent for surgeons who are beginning in the process of transition or who are doing their first cases. It mostly occurs when finishing the nucleus and epinucleus removal and during the phase of aspiration of the residual cortex. The tear is usually located at 12 o’clock or nearby.
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Higher Risks for Posterior Capsule Tear Carlos Nicoli, M.D., points out that posterior capsular tears have an incidence of approximately 3%. This is the maximum acceptable. There is a much lower incidence with surgeons of considerable experience. Above 3%, we must investigate what we are doing wrong. Nicoli emphasizes that there are also situations which we should detect at the time of preoperative evaluation because they favor a high risk of posterior capsule tear. The most important are: 1) patients with history of trauma who may have zonular dialysis; 2) patients with pseudoexfoliation; 3) hard cataracts with large nuclei; 4) patients with larger axial length; 5) posterior subcapsular cataracts have an inherent weakness of the posterior capsule. In the latter group, one must be very careful not to perform hydrodissection and delamination techniques because they might stimulate the formation of a capsule tear not perceived by the surgeon.
Capsule Rupture Early When it occurs early, at the beginning of nucleus phacoemulsification, it does so more frequently with soft nuclei. The surgeon miscalculates his maneuvers, is very stressed, applies too much phaco power or a disproportional vacuum all of which lead to fast aspiration and emulsification of part or the whole nucleus, epinucleus and cortex. The posterior capsule comes along with all these structures. Another cause for capsule rupture early
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is that the surgeon has sculpted deeply in a soft nucleus. By and large, tears occur in the central region and in a circular or oval shape (Fig. 151). In order to manage this complication, Centurion advises to stop everything, do a so-called "dry vitrectomy" in which no infusion is used or a limited vitrectomy with very low flow system. It is also essential to use small amounts of viscoelastic under the nucleus fragments to push the vitreous and lens fragments away from the posterior capsule tear (Fig. 151). Nevertheless, if vitreous is already prolapsed, this must be solved first. The experienced surgeon may then proceed with phacoemulsification decreasing significantly the phaco power, or convert to an extracapsular (Fig. 144). If this complication happens during the transition, the wisest decision is to convert.
Capsule Rupture During More Advanced Stages of Nucleus Removal When using the «divide and conquer» or the chopping techniques, if there is a capsular tear during phacoemulsification of one of the nucleus quadrants, the tear in the posterior capsule may or may not be perceived by the surgeon. If the phacoemulsifier’s efficiency is reduced to the extent that aspiration no longer occurs, we must always be suspicious that we have a tear in the posterior capsule and vitreous blocking the port. In these cases, Centurion again recommends to stop, inject viscoelastic, by all means identify the site and the size of the tear, perform anterior vitrectomy, inject vis-
Figure 151: Complications with Posterior Capsule Rupture A disruption of the posterior capsule (H) is the most severe intraoperative complication. If no immediate action is taken, luxation of nucleus material (N) to the vitreous and retina may occur. If vitreous prolapse is present and it mixes with nucleus fragments, the vitreous should be addressed first. To solve this complication the surgeon must stop the maneuvers of nucleus removal. Proceed immediately to inject viscoelastic (V) under the nucleus fragments to push the vitreous and lens fragments away from the posterior capsule tear. In this figure, only a "trickle" of viscoelastic (V) is seen between the tear and the nucleus fragments. The rest of the viscoelastic is underneath the nucleus attempting to push it away from the tear. At this time it is indicated to perform a well controlled anterior "dry vitrectomy" in which no infusion is used or one with a very low flow system. If abundant nuclear material still remains after these measures are taken, the surgeon may choose between converting to ECCE or very carefully continuing with phacoemulsification decreasing significantly the phaco power. It depends on the surgeon's experience.
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coelastic again, and proceed to luxation of the remaining parts of the nucleus into the anterior chamber with a bimanual maneuver (Fig. 152). If the tear is fairly large and not sufficient posterior capsular support remains, an IOL may be placed in the sulcus if the anterior capsule is intact. In case the surgeon does not feel safe enough to proceed with phacoemulsification, he can always convert to extracapsular as long as the incision has been made in the limbus and not in the cornea. He may also enlarge the limbal incision to remove the rest of the nuclear pieces (Fig. 144). In the presence of a large tear of the posterior capsule, it may be unrealistic and risky to implant an IOL completely within the bag. As a matter of fact, some of the more frequent cases of tears result in partial absence of the upper half of the capsular bag. In such cases, after infusion of viscoelastic and vitrectomy and being sure that the anterior capsule is intact, you may implant a PMMA IOL by securing the superior haptic in the sulcus by a single suture as shown in Fig. 153 and utilizing the remaining inferior part of the capsular bag as a support for the inferior haptics (Fig. 153). Some surgeons prefer to implant both loops symmetrically in the sulcus in such cases.
Nuclear Fragments Dislocated Into Vitreous A non perceived or inadvertent major tear of the posterior capsule or of the zonule when beginning to manage the nucleus or half way through the nucleus removal may lead to having pieces of nucleus or the entire nucleus fall into the vitreous. The most important measure is to identify the location of the rupture and discontinue ultra-
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sound energy. Then immediately proceed to clean the anterior chamber from all nucleus fragments present. If the nucleus or fractions of it are free or connected to capsular residues and present in the anterior third of the vitreous chamber, viscoelastic may be placed behind them for support and an anterior vitrectomy performed using a vitrectomy instrument plus viscoelastic, trying to pull the nucleus into the anterior chamber and then finish the phacoemulsification. On the other hand, if the nucleus is in a deeper location within the vitreous cavity (Fig. 155), it is strongly advised to perform only an anterior vitrectomy for removal of the fragments present in the anterior third of the vitreous cavity, remove the cortex and implant an intraocular lens as shown in Figs. 152, 153, 156. Refer the patient to a posterior segment surgeon. Do not attempt to remove a nucleus which has fallen into the vitreous yourself unless you have experience with vitreoretinal surgery. The surgeon must see what he does and certainly doing attempts «in the dark» may lead to very severe and irreversible vitreoretinal lesions that definitely jeopardize the outcome.
Capsule Rupture During Cortex Removal Rupture of the posterior capsule while removing the cortex is frequently at 12 o’clock and may be due to the use of very high aspiration parameters, usually 400 to 500 mm Hg (Figs. 71 and 128). If the capsule is ruptured during the aspiration of cortex and vitreous enters the anterior chamber, the first step is to perform a "dry anterior vitrectomy" or an anterior vitrectomy with very low flow system and proceed to implant the intraocular lens which
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Figure 152 (left): Posterior Capsule Rupture - Surgeon Luxates a Lens Fragment into Anterior Chamber In the presence of a large posterior capsule rupture, an anterior vitrectomy is performed. Viscoelastic is infused in the anterior chamber. One alternative is for the lens fragments (F) to be moved or luxated by the surgeon to the anterior chamber with a bimanual maneuver. An IOL (I) is placed in the sulcus to shield the defect. Safe phacoemulsification (P) may continue with very low ultrasound energy. The surgeon may decide not to continue with the phaco technique and convert to ECCE.
Figure 153 (right): Lens Placement over Large Capsular Disruption. A large capsular disruption has occurred resulting in partial absence of the upper half of the capsular bag. One alternative is for the surgeon to implant the IOL (L) with one haptic in the sulcus (S) above, and the other haptic within the remaining part of the capsular bag (C). The haptic in the sulcus above is secured by a single suture.
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may serve as a shield protecting the posterior capsule defect (Fig. 154). Aspirating the cortical residues at 12 o’clock is technically difficult (Fig. 128), but may be more difficult if there has been an incomplete hydrodissection or a small capsulorhexis (Fig. 145). In Fig. 154, you may see that the surgeon is aspirating the cortical residues after a posterior capsule rupture with an IOL placed to protect the posterior capsule defect as a shield so that aspiration can continue. Then the cortical residues at the 12 o’clock position are aspirated with a curved cannula. In order to prevent posterior capsule rupture during the stage of cortex I/A, it is essential not to be aggressive in attempting to remove all the remaining cortex and not to do the "vacuum cleaning" process. This is risky and does not constitute the main source of posterior capsule opacification postoperatively.
Pars Plana Vitrectomy for Dislocated Nucleus Significant Factors Related to Outcome Lihteh Wu, M.D., after reviewing the world literature, reports that immediate pars plana vitrectomy offers no visual advantage over delayed vitrectomy. As a matter of fact, sometimes it is necessary to wait for the intraocular pressure to be controlled and for the corneal edema to resolve. Borne, Tasman et al in a classic paper published in "Ophthalmology" in June 1996 in a retrospective review of 121 eyes that underwent pars plana vitrectomy for removal of retained lens fragments as a result of phacoemulsification
Figure 154: Aspiration of Cortical Residue after Posterior Capsule Rupture. The IOL (L) is placed to shield the posterior capsule defect (D) so that very low flow aspiration can continue. Cortical residues (R) at the 12:00 position are being aspirated with a curved cannula (C).
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Figure 155: Complications of Posterior Capsule Rupture - Luxation of the Nucleus Into the Vitreous Cavity When the nucleus (C) or fragments are dislocated into the vitreous cavity (V), a pars plana vitrectomy is usually indicated for the extraction of lens nuclear fragments to avoid future complications. The surgical technique consists of a pars plana vitrectomy with three ports. The endoiluminator (E), the vitrectomy probe or the ultrasonic fragmentation probe (F) are inserted through pars plana sclerotomies. The infusion cannula (I) is inserted through a third sclerotomy to obtain a stable intraocular pressure during the procedure. Perfluorocarbon liquids (P) are sometimes used in the vitreous cavity to raise the nucleus for extraction.
referred to the Wills Eye Hospital concluded that the timing of vitrectomy does not have a statistically significant impact on visual outcome. Neither the type of intraocular lens nor the timing of lens implantation significantly altered the final visual acuity. Most eyes with retained lens fragments do well after vitrectomy, with the majority recovering good vi-
sion (Fig. 155). However, the risk of retinal detachment (RD) is increased, and visual outcome may be adversely affected if RD occurs. The Wills Eye Hospital team also emphasized that during cataract surgery, the surgeon must avoid aspirating (without cutting) any presenting vitreous gel. Attempts to
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Figure 156: Complications from Posterior Capsule Rupture - Implantation of the Intraocular Lens The intraocular lens may be implanted depending on the situation: 1) In the capsular bag if sufficient posterior capsule remains to serve as partial support, as long as the anterior capsule is intact. This is shown in Figs. 152, 153, 154. 2) The second alternative is to fixate the IOL in the sulcus or even sutured (S) to the sclera (IOL). In this figure, the IOL is shown sutured to the sclera at the level of the ciliary sulcus on both sides, following vitrectomy. After the vitrectomy is completed, it is recommended to keep the infusion cannula (I) in place during the fixation of the intraocular lens and remove it at the end of the entire procedure. This will reassure a stable intraocular pressure during these maneuvers. IOL implantation at the time of vitrectomy is another alternative when the IOL was not implanted after anterior vitrectomy and the anterior segment surgeon decided it was better to do it later. The IOL is sutured to the sclera at the level of the ciliary sulcus, as shown in "S".
retrieve any lens fragments that have started to dislocate posteriorly should be made only with vitrectomy handpieces. The use of lens loops, forceps, and other instruments that have the potential to engage and pull on vitreous gel should not be used. A complete limbal vitrectomy should be performed before any lens placement and the absence of vitreous to the wound or other anterior struc-
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tures should be confirmed at the time of wound closure. Last, indirect ophthalmoscopy with scleral depression should be performed at the end of the procedure or by a retinal specialist to identify any retinal tears because these will require at least laser or cryo retinopexy. Figure 156 represents an IOL fixated to the sulcus after vitrectomy.
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POSTOPERATIVE COMPLICATIONS Despite the technological advances that have made cataract surgery an operation with such a high rate of success, postoperative complications still occur although less frequently. For didactic purposes, we have divided them into medical and surgical complications.
MEDICAL Cystoid Macular Edema Incidence Professor Juan Verdaguer, M.D., from Chile points out that the incidence of this complication has decreased due to improved surgical techniques and better management of complications. Although the incidence of angiographic CME has been estimated in about 20% in pseudophakic patients, clinically significant macular edema with reduced visual acuity occurs approximately in 1% of cases undergoing uncomplicated extracapsular cataract surgery. CME is more common following complicated extracapsular and phacoemulsification procedures, particularly if the posterior capsule was ruptured, with vitreous loss and implantation of an anterior chamber lens
and related complications typical of the transition period from extracapsular to phacoemulsification. If vitreous loss occurs, the incidence of clinically significant CME increases up to 8%. CME remains a significant cause of unexpected poor visual acuity after uneventful, uncomplicated cataract surgery.
Pathogenesis Characteristically, fluorescein angiography demonstrates leakage from the parafoveal retinal capillaries and from optic nerve capillaries. If the patient is examined right after fluorescein angiography, dye leakage into the aqueous humor can be easily seen; consequently, there is evidence of a generalized increased ocular vascular permeability. Histopathological studies have demonstrated expansion of the extracellular space in the outer plexiform layer of the fovea (Henle fibers), giving rise to cystoid spaces (Fig. 175 A). There may be also some degree of subretinal fluid. The pathogenesis of aphakic and pseudophakic CME is not known. Inflammation of the iris is considered an important factor in the pathogenesis; the irritated iris releases a number of inflammatory mediators that may be involved in CME. Inflammatory mediators, such as prostaglandins, diffuse
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into the vitreous cavity and into the retina, causing the disruption of the blood-retinal barrier at the macular and optic nerve capillaries. Chronic iris irritation by entrapment of iris to the wound with a peaked pupil, vitreous adherence to the wound with iris traction, anterior chamber intraocular lenses and iris clip lenses may trigger the release of these inflammatory mediators.
Clinical Findings The patient may complain of blurred vision four to six weeks after surgery, or much later in the postoperative period. In a patient who has undergone uncomplicated cataract surgery, the surgeon will be surprised by an unexpected and uncorrectable reduced visual acuity, in the range of 20/30 20/60. Most patients will have a white eye and only a few will show some mild form of anterior segment irritation. A few patients may show some vitreous inflammatory cells. Clinically, CME may be easily overlooked, unless the macular area is carefully examined at the slit lamp with a Goldman contact lens or similar. The macula appears thickened, with intraretinal cystoid spaces, in a honeycomb pattern; the foveal reflex is lost (Figs. 157 A, B, C). A few patients show evidence of epiretinal membrane formation, with cellophane-like reflexes. Fluorescein angiography is diagnostic. Early phases demonstrate a very slow leakage from the parafoveal retinal capillaries. In the later frames, the dye fills the cystoid spaces;
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the hyperfluorescent spaces are separated by a dark hypofluorescent stellate figure. The angiographists should be aware of the probably diagnosis to avoid missing the later frames that will show this characteristic petaloid or floral pattern (Fig. 157 B). Late leakage of optic nerve capillaries is also demonstrable in the late frames; however optic nerve swelling is usually not noticeable ophthalmoscopically. Fluorescein angiography may be the only means of making the diagnosis of CME if the media is hazy.
Clinical Course Most patients will experience spontaneous recovery of visual acuity and resolution of CME during the first year after surgery (Fig. 158). Patients with persistent CME after 6 months may develop permanent loss of vision ("chronic CME"). These patients may develop a lamellar macular hole or pigment epithelial changes.
Treatment Verdaguer clarifies that current therapeutic intervention for prophylaxis and treatment of CME are based on blocking the inflammatory mediators that may be involved in CME, mainly the prostaglandins. Prostaglandins are synthesized from arachidonic acid released from cell membranes by phospholipase A 2. Cyclo-oxygenase converts arachidonic acid to cyclic intermediates and then to prostaglandins.
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Figure 157: Cystoid Macular Edema after Complicated Cataract Surgery with Rupture of the Posterior Capsule and Anterior Chamber IOL (A) Cystoid spaces at the macula and soft exudate inferonasal to the macula. (B) Late filling of cystoid spaces with fluorescein, in a petalloid pattern. Leakage from optic nerve capillaries. (C) Late frame of fluorescein angiography after 6 months of topical treatment (sodium diclofenac + prednisolone acetate 1%) shows marked improvement. (Courtesy of Prof. Juan Verdaguer, M.D.)
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Figure 158: Cystoid Macular Edema after Uncomplicated Extracapsular Cataract Surgery (A) Four months after surgery, visual acuity 20/100. (B) Three years after surgery, visual acuity 20/25. Spontaneous improvement. (Courtesy of Prof. Juan Verdaguer, M.D.)
Corticosteroids prevent the release of arachidonic acid from cell membranes, by blocking phospholipase A 2. Non steroidal antiinflammatory drugs are cyclo-oxygenase inhibitors, blocking the synthesis of prostaglandins.
Prophylactic Treatment A randomized clinical trial by Flach et al demonstrated that cyclo-oxygenase inhibitors (COI) alone used prophylactically reduced the incidence of CME after cataract surgery. Ketorolac tromethamine 0.5% ophthalmic solution was administrated three times daily beginning one day before surgery and continued for 19 days postoperatively. Given the relatively low incidence of CME in uncomplicated cataract surgery, prophylactic treatment is seldom used.
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Treatment of Chronic CME Pooled data from randomized clinical trials indicate a treatment benefit in terms of improving final visual acuity by two or more lines. These studies report the efficacy of a combination of corticosteroid and cyclooxygenase inhibitors (COI, or NSAID's). In all but one trial, COI was tested alone with good results. Since there might be a synergistic effect, the following approach is suggested: 1. Topical corticosteroids, prednisone acetate 1% four times daily + topical COI (diclofenac sodium 0.1% or flurbiprofen sodium 0.03% or ketorolac tromethamine 0.5%) four times daily. The treatment is maintained at least for two months, with careful monitoring of the intraocular pressure. If the patient has a steroid pressure response, treatment
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should be limited to topical COI. In case of favorable response, the regime is tapered very slowly. If there is no response at two months, the following interventions could be considered, without discontinuing the initial treatment. 2. Periocular steroid injections limited to a maximum of three. 3. Carbonic anhidrase inhibitors may work in a few patients but may be poorly tolerated. 4. Surgery should be considered only in patients with surgical complications that have modified the anatomy of the anterior segment and only if a well conducted pharmacological therapeutic trial has failed. In patients with vitreous incarceration in the wound, Nd:YAG vitreolysis may be tried, but is difficult. An anterior vitrectomy, with repair of vitreous adhesion to the wound or iris may be the procedure of choice in these cases. More extensive surgery may be required if there is significant lens malposition.
Diabetes Edema
and
Cystoid
Macular
Verdaguer is an authority on diabetic retinopathy. He emphasizes once again that patients with preexisting diabetic macular edema are at substantial risk for worsening of the macular edema following cataract surgery. Moreover, diabetics are probably more susceptible to pseudophakic CME. The two conditions, diabetic macular edema and postsurgical CME may, in fact, coexist in a given diabetic patient. Patients with lipidic exudates, retinal hemorrhages, perifoveal microaneurysms, diffuse or focal leakage at angiography will have a predominantly diabetic macular edema. Patients without these characteristics, a petaloid pattern of leakage
at the macula, and disc leakage, will have a predominantly postsurgical CME.
Treatment Recommendations 1. Optimize medical treatment. (metabolic control, arterial hypertension, dislipidemia, anemia). 2. Use topical steroids and COI, to treat the presumed pseudophakic CME. 3. Laser photocoagulation, focal or grid, if there are leaking microaneurysms or diffuse leakage, with lipid exudation and retinal hemorrhages.
PHOTIC MACULOPATHY The intense illumination system of modern operating microscopes may induce photochemical retinal injury. The first cases of phytotoxicity after uneventful cataract surgery were described by McDonald and Irvine (1983).
Photochemical vs Photothermal Damage Verdaguer clarifies that photochemical injury is different from photothermal damage (photocoagulation). Photocoagulation occurs after brief and intense light exposure; photochemical injuries develops after prolonged exposure at intensity too low to induce photocoagulation. Photocoagulation induces an immediate visible reaction; photochemical damage is not immediately recognizable. In photochemical injuries, light activation of cell molecules generates oxygen singlets (free oxygen radicals). These are very toxic and induce oxidation and damage of cell components.
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Shorter wavelengths carry most energy (UV and blue visible light) and are more likely to produce photochemical damage.
Incidence Juan Verdaguer points out that the incidence of photoretinal injuries during extracapsular cataract surgery has been estimated at 7 to 28% in different series. Photic retinal injury did not develop after phacoemulsification in one series, with careful limiting of coaxial exposure time and microscope irradiance.
Risk Factors The main risk factors associated with photochemical damage are duration of the exposure (longer surgery time) and intensity of the operating microscope illumination. Longer surgery times have been associated with increased incidence of retinal photochemical injuries. However, the complication has occurred in short, uneventful procedures. Therefore, the skilled, rapid, experienced surgeon, should not disregard the dangers of photoxicity.
Clinical Findings The patient may complain of a scotoma that may be central or paracentral, in correspondence to the retinal injury location. A few patients may give a history of postoperative erithropsia. In other cases the main complaint may be unexpected poor visual acuity, if the injury is near the fovea. Visible changes at the retina will be apparent 24 to 48 hours following exposure. In the early postoperative period the lesion appears a subtle creamy deep, pale oval lesion, usually just below or above or temporal
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to the center of the fovea. If the eye is infraducted by a superior rectus suture, the lesion will be located below the macula. Fluorescein angiography will show intense staining of the oval plaque. Cicatricial changes are apparent within the first week, with pigmentary mottling and athropic changes of the pigment epithelium within a sharply demarcated oval area. The lesion shows a highly characteristic leopard-skin appearance. The scotoma fades rapidly and the visual acuity may improve, unless the lesion is large and involves the macula. Fluorescein angiography will reveal changes restricted to the oval scar, with window defects and blocked fluorescence corresponding to the areas of hyperpigmentation (Fig. 159).
Preventive Measures The illuminating light should not be brighter than necessary and the cornea should be covered whenever the surgeon is not working intraocularly. A finger blocking the light may suffice. Indirect illumination, instead of coaxial illumination should be used during closure of surgical wound in extracapsular procedures, since the risk is maximal following implantation of the lens, with the light clearlu focused directly on the retina. Tilting the microscope toward the surgeon and infraduction of the globe may displace the light below the fovea. Small incision phacoemulsification technique is less likely to induce light toxicity, since the instruments remain in the visual axis most of the time and operating times are reduced in the hands of experienced surgeons. There is no treatment for this complication.
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Figure 159: Photic Maculopathy after Extracapsular Cataract Surgery - Cicatricial Stage (A) Pigmentary mottling and cicatricial changes within an oval scar. (B) Typical leopard-skin appearance at angiography. (Courtesy of Prof. Juan Verdaguer, M.D.)
Photosensitizing agents, such as hidroxchloroquine,phenotiazines, allopurinal, etc., should be discontinued before surgery, since they may potentiate photic damage to the retina.
AMINOGLYCOSIDE TOXICITY Aminoglycosides have been widely used in the prophylaxis and treatment of ocular infections. Macular infarction is a severe complication that has been mainly associated with the administration of gentamicin, but has also been reported after use of amikacin and tobramycin. Juan Verdaguer emphasizes that aminoglycoside toxicity may be related to:
1) Intravitreal injections in endophthalmitis treatment regimes. Toxicity may follow administration of gentamicin at recommended doses. Verdaguer has seen this complication after intravitreal injection of 0.15 mg of gentamicin, a dose previously considered safe. Treatment of post surgical endophthalmitis should include the intravitreous injection of an antibiotic which acts effectively against gram-positive organisms (vancomycin) and one that is effective against gram negatives, since gram-negative endophthalmitis is much more common. Given the very narrow safe therapeutic window of aminoglycosides, a good choice would be a cephalosporin such as ceftazidime. If the surgeon is confronted with an acute postsurgi-
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cal endophthalmitis and ceftazidime is not available, an aminoglycoside should be included in the intravitreous injection, at the lowest effective dose (100 mg of gentamicin or 400 mg of amikacin). Even at these doses, toxicity cannot be ruled out. 2) Prophylactic intravitreous injections in severe trauma cases. Verdaguer has seen this complication after a prophylactic intravitreous tobramycin injection. Aminoglycosides should not be used intravitreally for prophylactic purposes. Endophthalmitis is a treatable disease and aminoglycoside toxicity is not. (Campochiaro et at). 3) Following uncomplicated subconjunctival injection after routine cataract surgery. Although this has been reported in the literature, Verdaguer has never seen a case. The complication is believed to be associated with leakage of the antibiotic into the eye through the cataract wound (with or without sutures). The tunnelled, non-sutured wounds, create a one way valve, allowing subconjunctival antibiotics and access into the anterior chamber. Subconjunctival antibiotic injections, if used, should be placed in the quadrant opposite to the wound. 4) Dilution errors in intravitreal injections. 5) Inadvertent intraocular injection due to confusion with miochol or other substances. If the mistake is discovered during surgery, profuse anterior segment lavage should be done, immediately. Immediate vitrectomy has also been recommended.
Clinical Findings Vision is profoundly affected the day following surgery or the intravitreal injection. Usually, the retinal infarction affects the
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macular area. (Intravitreal aminoglycosides tend to settle on the posterior pole in the supine position). Examination reveals milky white opacification of the retina, a cherry red spot and a few blot retinal hemorrhages. The appearance is similar to that seen in central retinal artery occlusion, but limited to the posterior pole. It also differs from branch retinal arterial occlusion, since the infarction involves the retina both above and below the macula. Fluorescein angiography reveals sharply demarcated central area of occlusion of the retinal vessels and some perivascular leakage (Fig. 160).
Figure 160: Aminoglycoside Toxicity 2 Months after Intravitreous Injection of Gentamicin Vascular occlusion involving the temporal vessels (Macular infarction). (Courtesy of Prof. Juan Verdaguer, M.D.)
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The condition is untreatable and irreversible. Optic atrophy and atrophic and pigmentary retinal changes develop later.
POSTERIOR CAPSULE OPACIFICATION Overview Okihiro Nishi, M.D., is a renowned authority on this subject because of his extensive research and revealing findings. Nishi has emphasized that posterior capsule opacification (PCO) is the most frequent postoperative complication associated with decreased vision in cataract surgery. Itoccurs with an incidence of up to 50% within 5 years after surgery. Various mechanical, pharmaceutical and immunologic techniques have been applied in attempts to prevent PCO by removing or killing residual lens epithelial cells (LECs), but none has been confirmed to be satisfactorily practical, effective and safe for routine clinical practice. Nishi emphasizes that the most effective approach to reduce or delay the incidence of PCO is by inhibiting the migration of LECs and not by killing the cells.
Main Causes of PCO Recent clinical, pathological and experimental studies have emphasized that PCO is usually secondary to a proliferation and migration of residual lens epithelial cells. (LECs).
How LECs Invade the Posterior Capsule Nishi has pointed out that residual LECs proliferate at the pre-equatorial germinative zone and migrate posteriorly onto the posterior capsule postoperatively. In addition, when the anterior capsule comes into contact with the posterior capsule, the LECs underneath the anterior capsule also migrate onto the posterior capsule abundantly, before the two capsules adhere and grow together. The apposition of the anterior capsule and the posterior capsule can induce fibrotic PCO.
Role of IOL in PCO When the IOL is in the capsular bag the optic can separate both capsules, and interferes with the LEC migration from the anterior capsular edge onto the posterior capsule. The inhibition of migrating LECs and the separation of the capsules by the IOL optic are the main reasons why the incidence of PCO is significantly lower in eyes with an IOL than in those without one.
Specific Features of the AcrySof and PCO Nishi points out that the AcrySof IOL reportedly has a significant low incidence of PCO. His recent studies indicate that this effect may be due to the sharp and rectangular edge design of the AcrySof IOL. His histopathologic findings of the lens capsule con-
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taining an AcrySof IOL in rabbits disclose that the lens capsule wrapped the IOL so firmly that it conformed faithfully to the rectangular sharp optic edge of the IOL and that migrating LECs were apparently inhibited at this capsular bend or angle created by the sharp edge and posterior capsule by contact. The creation of such a bend or angle in the posterior capsule requires a well-centered CCC, smaller than the IOL optic, so that the CCC edge is in apposition to the optic. On the other hand, the role of this lens may be dependent not only on the rectangular edge design but also on the features of the IOL acrylic material, such as adhesiveness. The AcrySof IOL has triple the adhesiveness to a collagen film compared to a PMMA IOL. The adhesiveness may also help to facilitate the creation of the bend. Moreover, the acrylic material itself may have effects on the inhibition of migrating LECs. This adhesiveness property of the acrylic lens, which we described as "tackiness" in Chapter 9 under "Advantages and Properties of Acrylic Lenses" merits further investigation. This "tackiness" or adhesiveness seems to play a role in the positive effects of the AcrySof lens. If so, then this might be a factor of particular importance for the use of acrylic lenses and designs of future IOL's. From the analysis provided here, it is clear that the preventive effect on PCO of an AcrySof IOL may be both design and material dependent.
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Role of Continuous Curvilinear Capsulorhexis in PCO Nishi emphasizes that continuous curvilinear capsulorhexis (CCC) can contribute to reduce PCO because it facilitates the implantation of an IOL symmetrically in the capsular bag maintaining it there without decentration. It is extremely important to create a well-centered CCC of the correct size for the prevention of migrating LECs. The CCC edge should be smaller than the IOL optic and cover its margin (Fig. 145). A decentered, oversized CCC or incomplete CCC with a radial tear (Fig. 146) may result in the apposition of both capsules. Even though the defective area lies in a very limited circumference, the LECs migrate from the edge of the anterior capsule onto the posterior capsule, causing PCO.
Main Factors that Reduce PCO Nishi clarifies that there are three key factors that play an important role in reducing the incidence of PCO: 1) the design of the IOL, which results in the creation of a sharp bend in the capsule. The discontinuous, rectangular bend or angle in the posterior capsule interferes with the proliferation of LECs. 2) The material of the IOL, which points to the benefits of some acrylic because of its adhesive properties and biocompatibility (less fibrosis). 3) The surgical technique which emphasizes a perfectly
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centered CCC of smaller size than the IOL optic. In addition, Nishi strongly recommends a NSAID for 3 months postoperatively, in order to reduce postoperative inflammation with conversion of mononuclear cells into fibroblasts, and possibly proliferation of residual LECs.
Visual Loss from PCO Differential Diagnosis It is often a rather difficult clinical judgment to determine if the capsule opacity is in fact responsible for the patient`s decreased vision. The principal misdiagnosis is to believe that the capsule is responsible for the problem when, in fact, the patient has developed a cystoid macular edema which may be difficult to detect because of the posterior capsular opacity. When in doubt, a pre-capsulotomy fluorescein angiography is appropriate to determine if macular edema is present.
PERFORMING THE POSTERIOR CAPSULOTOMY Size of Capsulotomy Some prestigious anterior segment surgeons have advocated not dilating the pupil for performing a YAG posterior capsulotomy. Many patients' pupillary openings are not located in the exact anatomical center of the iris. Once the pupil is dilated, it can be difficult to identify where the true pupillary opening was located.
Nevertheless, there are important contraindications to making a small capsulotomy. The most important are: 1) Difficulties in the evaluation of the retinal fundus. 2) The center of the capsulotomy may be clear following treatment but the rest of the capsule remains opaque, and sometimes with a crystalloid appearance. Patients with macular degeneration, for example, may see better when the capsulotomy is wide enough to prevent contrast reducing haze from the residual hazy peripheral capsule. In those cases it is better to dilate the pupil 4-5 mm preoperatively in order perform a more effective treatment. Dodick generally makes a capsule opening the size of a normal pupil, 3-4 mm at the most.
Posterior Capsulotomy Laser Procedure Timing Alice McPherson, M.D., was one of the first retina specialists to demonstrate that retinal detachment could be precipitated by early YAG laser posterior capsulotomy. She has advised waiting approximately 4-6 months after cataract surgery to perform a YAG laser posterior capsulotomy. The prior dictum to wait one year, was done to be sure all inflammation was finished, in order to avoid cystoid macular edema. McPherson has pointed out that once a capsulotomy is performed, the pseudophakic eye is actually like an aphakic eye. Keeping the patient`s posterior lens capsule in place as
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Figure 161: Nd:YAG Laser Cruciate Pattern in Posterior Capsulotomy For laser posterior capsulotomy, leave the pupil undilated because many pupils are not in the exact anatomical center of the iris. Leaving the pupil undilated allows the surgeon to open the capsule in exactly the correct location. Use a cruciate pattern as shown here to avoid pits in the center of the intraocular lens.
long as possible can reduce the tendency for vitreous traction on the periphery. After the YAG capsulotomy is done, any predisposing factor can increase the potential for a retinal detachment or cystoid macular edema.
Technique Use the lowest level energy pulse that will open the capsule, usually 1 mJ. An
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adequate opening can be made with 10 laser applications or less, depending on how taught the capsule is. A cruciate pattern is recommended, starting in the periphery at 12 o'clock, working down across the center of the capsule toward 6 o'clock, and complete the cross from 3 to 9 o'clock (Fig. 161). The capsule will usually retract further after completing the capsulotomy.
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Complications Following Nd:YAG Posterior Capsulotomy Intraocular Pressure Elevation The most common complication is a transient pressure elevation. This must be anticipated and treated prophylactically. The most effective method is to instill one drop of brinzolamide or dorzolamide 30 minutes before and one drop following the laser procedure. Patients at higher risk of developing transient elevation of the intraocular pressure are those that have anterior chamber intraocular lenses and patients with pre-existing glaucoma.
Retinal Detachment A higher percentage of pseudophakic detachments occurs in cases with a history of fellow eye detachment, preexisting retinal disease such as lattice degeneration and retinal holes, or in eyes with axial lengths above 25 mm. Retinal detachments associated with Nd:YAG laser posterior capsulotomy occur most often within the first 6 months following capsulotomy.
Cystoid Macular Edema It is not well-known yet whether Nd:YAG laser capsulotomy can induce the formation of cystoid macular edema (CME) in a quiet eye. Anterior segment inflammation can occur after laser capsulotomy, and inflammation has been identified as an etiologic factor for CME especially if laser treatment has been more intensive than the parameters already established. In addition, prolapse of vitreous anteriorly through the capsu-
lotomy or a disruption of the anterior hyaloid might produce posterior retinal traction, another possible cause for CME. Thus, a potential relationship does exist. In suspicious cases only a fluorescein angiogram after the treatment may provide the answer.
POSTOPERATIVE ASTIGMATISM IN CATARACT PATIENTS With present advances in small incision cataract surgery, particularly with clear corneal incisions, postoperative astigmatism following phacoemulsification should be minimal. A well trained surgeon creates an astigmatically neutral incision to prevent an induced astigmatism. If astigmatism is present preoperatively, the surgeon addresses the problem at the time of cataract surgery. By placing the corneal incision in the indicated axis, preexisting astigmatism and cataract surgery are performed simultaneously. This latter subject which we term "Refractive Cataract Surgery" is addressed at the beginning of Chapter 12 (Cataract Surgery in Complex Cases).
MANAGEMENT Astigmatism, either preexisting that was not fully corrected or induced may be managed after cataract surgery either with incisional refractive surgery (astigmatic keratotomy) or with excimer laser (LASIK or PRK).
How to Proceed Wait a minimum of three months following surgery in order to deal with a stable
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astigmatism and do the adequate evaluation. The patient is examined with refraction, keratometry and corneal topography.
Techniques The surgeon may perform either an excimer laser procedures (Fig. 162 A-B) or an astigmatic keratotomy (AK) (Fig. 162-C) in order to either enhance the effects of the cataract incision on any remaining astigmatism or correct an astigmatism induced during the cataract operation, which is usually related to large incision, planned extracapsular.
How These Techniques Work LASIK or PRK may either flatten the steep meridian or steepen the flat meridian. On the other hand, AK incisions work by flattening the steep axis. Tough not as accurate as when treating spherical corrections, myopic astigmatism treatment has been increasingly successful, on the order of 80% of intended correction.
Procedure of Choice Most surgeons prefer using astigmatic keratotomy (AK) because: 1) it is highly effective; 2) costs are much lower than excimer laser procedures. If the astigmatism is larger than 1.5 D against the rule, paired with-the-rule incisions are done because they can augment the astigmatism-reducing effect (Fig. 162-C) Oshika et al in Japan reported a prospective evaluation of predictability and effectiveness of arcuate keratotomy treating corneal astigmatism after cataract surgery in
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Figure 162: Correcting Astigmatism Following Cataract Surgery Figures 162 A and B show the use of excimer laser in postoperative astigmatism. The actual surgical procedure for astigmatism, either LASIK or PRK, is the same as for spherical ametropias. In LASIK, when treating simple or compound myopic astigmatism, the excimer beam (L) also flattens the steep axis. Figure C shows the additional relaxing incisions that can be used in the postoperative period with astigmatic keratotomy (AK). The AK technique is the same as described for congenital or idiopathic astigmatism, although not as predictable.
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104 eyes. They concluded that astigmatic keratotomy in pseudophakic eyes is less predictable than that in eyes with idiopathic astigmatism, but the procedure is sufficiently effective in reducing the residual astigmatism after cataract surgery. Individual nomograms are necessary for astigmatic keratotomy in eyes with naturally occurring and postsurgical astigmatism. In figure 164 we present Richard Lindstrom's nomograms.
Key Factors in the Effects of Astigmatic Keratotomy These are related to the diameter of the optical zone utilized (Fig. 163), and the length and depth of the incisions. In correcting postoperative astigmatism a common
choice is a 7 mm optical zone to avoid visual aberrations with a smaller optical zone. The effect of these arcuate relaxing incisions is titrated by the length of the incisions (Fig. 164).
Highlights of AK Procedure Anesthetize the eye with the topical anesthetic of your choice. The center of the pupil is marked with the tip of a .12 mm forceps which has been painted with Gentian violet. A 7 mm (or the diameter selected) optical zone marker (Fig. 163) is centered over the pupil and pressed down. The axis of the steepest meridian is identified with two marks, 180º apart, over the 7 mm optical zone previously marked.
Figure 163: Marking the Central Optical Zone in Astigmatic Keratotomy Following the marking of the visual axis (V), and steep meridian, the optical zone, which will remain free of any incisions, is delineated with this optical clear zone marker. The size of the optical zone (T) is determined by the data specific to each patient's required correction (Nomogran in Fig. 164).
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Find patient age group, then move right to find a result closest to refractive cylinder. To calculate the size of the transverse incision (when indicated) as compared to the amount of degrees of the Arcuate Keratotomies outlined above, you may use the following equivalents: 30º arc= 2.0 mm
45º arc= 2.5 mm
Make one or two arcuate incisions (Fig. 162-C) in the 7 mm zone according to the nomogram (Fig. 164). The wound is inspected and irrigated.
EXPLANTATION OF FOLDABLE IOL'S RETAINING THE BENEFIT OF THE SMALL INCISION The problem arises once a flexible IOL has been implanted and there is need to remove it. How can we proceed to explant the IOL while retaining the benefits of small incision cataract surgery? Jack
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60º arc= 3.0 mm
90º arc= 3.5 mm
Dodick, M.D., and Susan Batlan, M.D., recently developed a technique to solve this situation.
The Most Common Indications for Explantation The most common indications for explantation are dislocation or improper fixation, chronic inflammation, anisometropia, improperly oriented haptics, a defective intraocular lens, and haptic breakage. Flexible intraocular lenses, which are being used with increasing frequency with small incision cataract surgery, are introduced into the eye through a 3.0 to 3.4 mm wound. Explantation without enlarging the wound is
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certainly desirable in order to retain the benefit of the small incision.
Problems Presented by Traditional Techniques Explantation has usually been a delicate problem to handle. The techniques suggested for this purpose have been technically difficult and risk compromising the corneal endothelium and posterior lens capsule. Most procedures for intraocular lens explantation have included enlarging the wound and extruding the unfolded intraocular lens in one piece or bisecting the intraocular lens under viscoelastic with Vannas scissors before removal through the wound. The need to enlarge the wound, however, defeats the
purpose of small incision cataract surgery because the original wound needs to be enlarged from 5.0 to 6.0 mm to facilitate intraocular lens removal.
Description of New Technique Because the average central anterior chamber depth is usually 3.0 mm it is difficult to invert the intraocular lens to properly reorient the haptics. Further, removal of the intraocular lens in one piece is not possible without enlarging the wound size, even if it is a flexible IOL. Dodick and Batlan first deepen the anterior chamber and expand the lens capsule with a superior quality viscoelastic. They then incise the IOL optic along its radius with Gills' capsulotomy scissors (Fig. 165). This
Figure 165: Explantation of Foldable IOL While Maintaining a Small Incision Stage 1 The small incision size can be maintained in cases where it is necessary to remove a foldable intraocular lens. First, the anterior chamber is deepened with viscoelastic. Gills capsulotomy scissors (S) are used to partially incise the intraocular lens optic (L), along its radius. This radial incision extends from the periphery of the optic to the center of the optic, as shown by the position of the scissors in the illustration. The halfbisected optic will then hinge at the center when explanted (see Fig. 166).
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maneuver allows the lens to be folded in half, and creates a lens with no part greater than 3 mm in width. The superior haptic is then grasped with Kelman-McPherson forceps and the intraocular lens, with the optic folded in half, is gently pulled through the incision. The elastic properties of the flexible IOL enable the surgeon to deform the optic and remove the intraocular lens in one piece (Fig. 166) By utilizing this technique for explantation of a foldable IOL following small incision cataract surgery, the surgeon does not compromise the integrity of the original wound, posterior lens capsule, or corneal endothelium.
RETINAL DETACHMENT Risk Factors Cataract extraction is a well-known risk factor for the development of a rhegmatogenous retinal detachment (RRD). Anywhere from 20% to 40% of RRD occur in eyes that have undergone cataract surgery (Fig. 167).
Incidence The incidence of RRD following ECCE and PCIOL implantation has been reported to be between 0.25% and 1.7%. The incidence of retinal detachment is less in patients with uncomplicated phacoemulsification because this procedure is performed through a self-sealing, watertight small incision with improved safety during the procedure. It is also significantly less invasive. The rate of RD associated with phacoemulsification greatly increases in the
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presence of rupture of the posterior capsule particularly when lens fragments are mixed with the vitreous. What to do and what not to do is addressed in this same chapter under Intraoperative Complications of Phacoemulsification - Posterior Capsule Rupture. This is an uncommon complication but it does occur in the initial stages of the learning curve during the transition from ECCE to phacoemulsification.
Clinical Course of RD Patients typically complain of photopsias, floaters, scotomas and blurry vision. Previous reports have emphasized the poorer outcome of surgery for RRD in pseudophakic eyes as compared to phakic eyes. These authors experience is that peripheral capsular opacification, lenticular remnants and the optical effects induced by the rim of the IOL impair visualization of the small peripheral retinal breaks by indirect ophthalmoscopy, thereby interfering with the vitreoretinal surgeon's best performance. In the present practice of clinical ophthalmology, repair of retinal detachment is routinely referred by the cataract surgeon to a vitreoretinal surgeon.
POSTOPERATIVE ENDOPHTHALMITIS By definition, endophthalmitis refers to the presence of an inflammatory reaction in both the anterior and posterior segments of the eye. Its etiology may be infectious or noninfectious. The infectious nature of endophthalmitis is one of major concern to ophthalmic surgeons. Fortunately, it has become a highly infrequent complication.
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Figure 166 (left): Explantation of Foldable IOL While Maintaining a Small Incision - Stage 2 The superior haptic (H) is then grasped with Kelman-McPherson forceps (F) and the incised IOL is gently pulled through (arrow) the small 3.2 mm incision. The greatest width of the half-incised 6.0 mm optic is now 3.0 mm and therefore will fit through the maintained small incision.
Figure 167 (right): Difference Between Phakic and Pseudophakic Detachments Classic pseudophakic retinal detachments differ from phakic retinal detachments in two major ways. Retinal detachments (R) with an intraocular lens (L) following cataract surgery are usually associated with more anteriorly located multiple breaks (M) along the posterior margin of the vitreous base (dotted line). Also with pseudophakos, these types of breaks tend to be in multiple quadrants. On the other hand, phakic detachments often tend to involve a single quadrant with one tear. The second major difference between phakic and pseudophakic detachments is in the reduced ability of the surgeon to see the peripheral retina in the case of pseudophakos (not shown).
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The causes of infectious endophthalmitis include bacterial and fungal organisms. Depending on its time course, endophthalmitis may be further classified as acute or chronic. The speed with which the patient develops symptoms is directly proportional to the virulence of the organism.
Relative Virulence of Organisms Highly virulent organisms that are commonly isolated include Staphylococcus aureus, Streptococci and Gram negative rods. Staphylococcus epidermidis is a little less virulent and happens to be the most common organism isolated. Propionibacterium acnes and fungi present in a more indolent manner. Noninfectious causes include retained lens fragments. According to Professor Juan Verdaguer, the most common endophthalmitis is the one produced by gram-negative organisms.
Clinical Findings and Source of Infection In acute cases, the patient often complains of progressive worsening of vision, redness, ocular discharge and increasing ocular pain. Examination often reveals eyelid edema, chemosis, corneal edema, intense cell and flare, iris hyperemia, vitritis and hypopyon. Visual loss is often secondary to the release of toxins and the inflammatory reaction. The main sources of infection are the normal bacterial flora in the lids and conjunctiva. Scrubbing the lids with povidone 5% just prior to surgery is an effective way of reducing the bacterial load.
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Management and Visual Outcome The management of acute postoperative bacterial endophthalmitis has been influenced by the results of the Endophthalmitis Vitrectomy Study. This study provides essential information for the understanding of how to proceed in the care of patients with this potentially devastating complication. Its guidelines are as follows: 1) A vitreous specimen needs to be obtained for culture and sensitivity as soon as possible (Fig. 168). 2) Intravitreal amikacin (0.4 mg / 0.1 mL) and vancomycin (1.0 mg / 0.1 mL) must be injected after the specimen is obtained (Fig. 168). 3) If the initial visual acuity was hands motion or better, study results suggest that the visual outcome is the same whether or not immediate pars plana vitrectomy is done. 4) Vitrectomy is indicated in those eyes with initial visual acuity of light perception or worse. Systemic antibiotics did not affect the visual outcome of patients in the study. 5) The visual outcome was better in those eyes with better visual acuity at presentation, underscoring the need for early diagnosis. In the cases where fungal or P. acnes endophthalmitis is suspected, a vitrectomy is usually indicated with the injection of intravitreal antibiotics or antifungals.
INTRAOCULAR LENS DISLOCATION Posterior dislocation of an IOL is an uncommon complication of cataract surgery. Its frequency appears to have increased in the
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Figure 168: Technique of Vitreous Tap in Diagnosis and Intravitreal Administration of Antibiotics A Ziegler knife (or equivalent) is inserted 3 mm posterior to the limbus to create a tract into the vitreous. The knife is directed toward the mid-vitreous cavity. The knife is removed and a 22 gauge needle attached to a small syringe is inserted through the tract made by the knife. A vitreous specimen is obtained for culture and sensitivity studies. Another syringe is attached to the needle and amikacin (0.4 mg / 0.1 mL) and vancomycin (1.0 mg / 0.1 mL) are injected intravitreally immediately after the vitreous specimen is obtained.
past few years as more surgeons enter into the inevitable steep learning curve of phacoemulsification in which posterior capsule ruptures may occur. The great emphasis given to the Transition into Phaco in Chapter 7 of this Volume is precisely oriented toward facilitating a successful and comfortable approach to this procedure.
Symptomatology The patient with intraocular lens dislocation often complains of sudden loss of vision due to the uncorrected aphakia. If complications such as retinal detachment, cystoid macular edema or vitreous hemorrhage occur, the patient may also complain of loss of vision. If the IOL is mobile in the vitreous cavity, it may be observed by the patient as a huge
floater. Posterior capsular rupture or zonular dialysis are usually present. The IOL may be freely mobile in the vitreous cavity, may be fixed to the retina, or may be seen hanging with one haptic attached to the posterior capsule, iris or ciliary body.
Management Observation can be recommended if the IOL is not mobile and there are no retinal complications, but this would defeat the purposes of the operation. We can not expect the patient to be satisfied with aphakic spectacle correction or contact lenses. Several surgical options are available. These include removal, exchange or repositioning of the IOL. Repositioning of the IOL into the ciliary sulcus or over posterior capsu-
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lar remnants with less than a total of 6 clock hours of inferior capsular support is not a stable situation. Many of those repositioned IOLs will end up dislocating again. Transcleral suturing (Fig. 156) or IOL exchange (removal of the dislocated IOL and placement of a flexible open loop anterior chamber IOL) is recommended in these cases. Current models of AC IOLs often do not result in the same types of complications as older models. Instead of risking another posterior dislocation of an IOL, these lenses should be considered if adequate capsular support is lacking. The Kelman type of anterior chamber lens has been a good option for years. The Nu-Vita aphakic IOL may be soon available. (The Nu-Vita phakic anterior chamber IOL's have highly acceptable results in phakic patients). If the IOL is fixed in position, out of the way, some surgeons leave it alone and implant a second IOL.
The Role of Silicone Plate IOL's Silicone plate lenses deserve special attention because progressive contracture of the anterior capsulorhexis opening (“purse string”) may occur more commonly when they are used. This increases the tension on the IOL and causes it to bow posteriorly. Dehiscence anywhere in the capsular bag allows release of tension through expulsion of the implant. The anterior segment surgeon should be advised to avoid implantation of a flexible silicone plate IOL if there is a break in the posterior capsule, a radial notch or a tear in the anterior capsular rim or zonular dialysis. Small capsulorhexis openings should be avoided in these cases.
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BIBLIOGRAPHY Bartz-Schmidt KU, Kirchhof B, Heimann K: Primary vitrectomy for pseudophakic retinal detachment. Br. J Ophthalmol, 1996;80:346-349. Borne, MJ., Tasman W., Regillo, C., Malecha, M., Sarin, Lou: Outcomes of vitrectomy for retained lens fragments. Ophthalmology, 1996;103:971976. Centurion V, Lacava AC, Sanchez JC, Oliveira Mode, EA: IOL explantation. Faco Total by Virgilio Centurion. Chan KC: An improved technique for management of dislocated posterior chamber implants. Ophthalmology, 1992 Jan; 99(1):51-57. Endoophthalmitis Vitrectomy Study Group. Results of the Endophthalmitis Vitrectomy Study Group. A randomized trial of immediate vitrectomy and of intravenous antibiotics for the treatment of post-operative bacterial endophthalmitis. Arch Ophthalmol 1995; 113:1479-1496. Fastenberg DM, Schwartz PL, Shakin JL, Golup BM: Management of dislocated nuclear fragments after phacoemulsification. Am J Ophthalmol 1991; 112:535-539. Gass JDM, Norton EWD: Cystoid macular edema and papilledema following cataract extraction: a fluorescein funduscopic and angiographic study. Arch Ophthalmol 1996; 79:646-661. Gonzalez GA, Irvine AR: Posterior dislocation of plate haptic silicone lenses [letter]. Arch Ophthalmol 1996 Jun; 114(6):775-776. Hayashi K, Yahashi H, Nakao F, Hayashi F: Reduction in the area of the anterior capsule opening after polymethilmethacrylate, silicone, and soft acrylic intraocular lens implantation. Am J Ophthalmol 1997; 123:441-7.
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Joo CK, Shin JA, Kim JH: Capsular opening contraction after continuous curvilinear capsulorhexis and intraocular lens implantation. J Cataract Refract Surg 1996 Jun; 22(5):585-590.
Ravalico G, Tognetto D, Palomba MA, Busatto P, Baccara F: Capsulorhexis size and posterior capsule opoacification. J Cataract Refract Surg. 1996; 22:98-103.
Learning DV: Practice styles and preferences of ASCRS members - 1994 survey. J Cataract Refract Surg 1995; 21:378-385.
Schneiderman TE, Johnson MW, Smiddy WE, et al: Surgical management of posteriorly dislocated silicone plate haptic intraocular lenses. Am J Ophthalmol 1997 May; 123(5):629-635.
Mittra RA, Connor TB, Han DP, et al: Removal of dislocated intraocular lenses using pars plana vitrectomy with placement of an open-loop, flesible anterior chamber lens. Ophthalmology 1998; 105(6):1011-1014. Nishi, O: Prevention of posterior capsule opacification after cataract surgery: theoretical and practical solutions. Atlas of Cataract Surgery, Edited by Masket S. & Crandall AS, published by Martin Dunitz Ltd., 1999, 24:205-212.
Smiddy WE: Modification of scleral suture fixation technique for dislocated posterior chamber intraocular lens implants [letter]. Arch Ophthalmol 1998 Jul; 116(7):967. Smiddy WE, Ibanez GV, Alfonso E, et al: Surgical management of dislocated intraocular lenses. J Cataract Refract Surg 1995 Jan; 21(1):64-69. Wilkinson CP: Pseudophakic retinal detachments. Retina 1985; 5:1-4.
Nishi, O: Removal of lens epithelial cells by ultrasound in endocapsular cataract surgery. Ophthalmic Surg. 1987; 18:577-80. Nishi O, Nishi K, Fujiwara T, Shirasawa E: Effects of diclofenac sodium and indomethacin on proliferation and collagen synthesis of lens epithelial cells in vitro. J Cataract Refract Surg 1995; 21:461-5. Oshika T, Shimazaki J, Yoshitomi F, Oki K, Sakabe I, Matsuda S, Shiwa T, Fukuyama M, Hara Y: Arcuate keratotomy to treat corneal astigmatism after cataract surgery: a prospective evaluation of predictability and effectiveness. Ophthalmology, 1998; 105:2012-2016. Powe NR, Schein OD, Gieser SC, et al: Synthesis of the literature on visual acuity and complications following cataract extraction with intraocular lens insertion. The Cataract Patient Outcome Research Team. Arch Ophthalmol. 1994; 112:239-252.
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CATARACT SURGERY IN COMPLEX CASES
In previous chapters we have discussed in depth how to evaluate the patient preoperatively (Chapter 2), how to calculate the correct IOL power in standard and complex cases (Chapter 3), prevent major complications such as infection (Chapter 4), and how to proceed with the operation by using adequate, modern anesthesia and to make the operating room efficient (Chapter 5). Why phacoemulsification is so important (Chapter 6), how to make the transition from ECCE to phacoemulsification with minimum risk to the patient while minimizing mental and emotional trauma to the surgeon (Chapter 7), what are the best instruments and equipments to use in phacoemulsification (Chapter 8), are all essential experiences and information for the modern cataract surgeon. In addition, you may also find the state of the art phacoemulsification techniques and facilitate your understanding of each group of procedures so that you can establish a basis for your own selection of the procedure that will lead you to master phacoemulsification (Chapters 9 and 10). Finally, a discussion of the most important complications you may encounter in phacoemulsification and in planned extracapsulars and how to manage them successfully is presented in Chapter 11.
Aims of this Chapter Based on the tools and concepts provided in Chapters 1-11, in this Chapter we carefully consider, in depth, powerful techniques available today which allow the use of phacoemulsification in the management of complex, and more challenging cases.
Broadening of Indications As emphasized by Miguel Angelo Padilha, M.D., F.B.C.S., one of Brazil’s most prestigious anterior segment surgeons, the progressive mastering of phacoemulsification (Chapter 9) by an increasing number of surgeons in various parts of the world allows indications for this procedure to broaden rapidly extending to the complex cases that were previously considered a contraindication to phaco. Patients with very hard cataracts, classified as “rock hard cataracts”, eyes with shallow anterior chamber, pseudoexfoliation, subluxated cataracts, cornea guttata, corneal dystrophies, corneal transparency alterations, as well as small pupils, were previously considered contraindications to the use of this technique.
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In this chapter, we intend to provide the cataract surgeon with practical clinical observations, strategies and surgical techniques leading to safe and efficient management of cataract surgery in special situations that we refer to as «the Complex Cases.» Although much of the focus is on phacoemulsification, many of the approaches to complex cases here presented are also applicable to manual extracapsular.
Complex Cases Already Discussed in Previous Chapters
viscoelastics years ago as his «third assistant.» Viscoelastics are very important for cataract surgery, whether in routine or complex cases. Their main uses are for maintaining the anterior chamber depth, protecting the endothelium, as aids during capsulorhexis, hydrodissection, phacoemulsification, with I/A, maintaining the capsular bag fully open a intraocular lens during insertion, unfolding, and positioning of the IOL. They have a special place in this chapter because their adequate use has become even more valuable and indispensable in the management of complex cases.
They are: 1) Cataract surgery in patients with diabetic retinopathy (pages 21-27, Figs. 8-18). 2) In age-related macular degeneration (pages 28-29, Figs. 19-20). 3) In the presence of retinal breaks (pages 28-30, Fig. 21). 4) In uveitis (pages 31,33, Fig. 22). 5) In adult strabismus with partial amblyopia (page 33). 6) Determining IOL power in complex cases (pages 48-58, Figs. 24-32).
Cohesive and Dispersive Viscoelastics
FOCUSING ON THE MAIN COMPLEX CASES
The Cohesive VES Specific Properties
THE DIFFERENT TYPES OF VISCOELASTICS Their Specific Roles For years we have generally referred to viscoelastics (VES) as highly valuable protective and space-maintaining substances. Joaquin Barraquer, M.D., referred to
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In the past few years, industry has refined viscoelastics, and made their properties more specific so that we now have available two main groups, each type better than the other for specific functions. As clarified by Buratto, these groups are: 1) cohesive, 2) dispersive.
The better known cohesives are those with high viscosity, such as Healon GV, Healon, Provisc, Amvisc Plus, Amvisc, and Biolon. They are very useful in creating space and stabilizing the tissues, increasing mydriasis, supporting the nucleus during capsulorhexis, deepening the anterior chamber, separating synechiae, opening the capsular bag and maintaining this space during implantation of the IOL. The cohesive viscoelastics maintain space really well because the molecules hold themselves together. They are also quite easy
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to remove. If you are trying to create a space such as when opening the capsular bag, or deepening the anterior chamber, then the cohesive viscoelastics are going to work better.
each particular case. Each surgeon must be sufficiently trained to choose the most appropriate substance for the individual patient and the specific technique.
The Dispersive VESSpecific Properties
PHACOEMULSIFICATION AFTER PREVIOUS REFRACTIVE SURGERY
The dispersive VES are those with lower viscosity and lower cohesiveness. They break up easily when injected into the eye and therefore disperse in small fragments. This group includes Viscoat (Alcon), Vitrax (Allergan) and the methylcellulose products. These substances form a layer that will adhere and coat the posterior surface of the cornea to protect the endothelium during phacoemulsification, or from other instrumentation during manual ECCE. They help in capturing nuclear fragments. They are also valuable if the phacoemulsification tip accidentally catches the iris, in zonular disinsertion and rupture of the posterior capsule. The dispersive viscoelastics are excellent coaters. If you aim to reduce the friction between the intraocular lens optic and the injector, so you are less likely to tear the intraocular lens, Lindstrom uses a dispersive viscoelastic. Or, if you are operating on an eye with a dry or somewhat opaque surface, placing a few drops of the dispersive viscoelastic on the surface clears the view significantly. If you tear the posterior capsule, but have not lost vitreous yet, if you again inject a dispersive viscoelastic, it can stay in the eye over the tear and the capsule, to hold vitreous back and protect the capsule while you carefully remove the nuclear remnants or a little cortex. That can be very helpful. But the dispersives are a little more difficult to remove and they do not maintain space as well. Consequently, the choice of VES varies with the surgical requirements of
The primary challenge in operating on patients who have already had radial keratotomy (RK) or excimer laser surgery is selection of the appropriate lens power. As the corneal curvature is altered, the usual predictive formulas have also been altered. Standard ultrasound A-scan technology and corneal curvature are still used to estimate the appropriate lens implant for reaching the target refraction. In addition, if the fellow eye has not had refractive surgery, that eye is also measured. We have already discussed this subject in practical and specific terms for the clinician in pages 50-54 and presented the methods and formulas most often used. Since there is no universally accepted formula to calculate these patient’s IOL power accurately, we present here the method used by a master cataract surgeon to solve this problem. Jack Dodick, M.D., has found the following procedure quite effective. He implants a specifically designated lens under topical anesthesia with sutureless clear corneal wound. Following the operation, the patient is taken to an autorefractor just minutes after surgery. If there is a high ametropia present, the patient returns to the table, the eye is again prepped, the lens is removed and replaced with one of the appropriate power. In patients with high myopia, for example, the surgeon’s best judgment about lens implant power can be considerably off target because 297
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of untoward circumstances like a staphyloma. In patients who have had RK, surgeons tend to underestimate the power of the lens implant. Removing the lens does not present a major problem. The challenge is to remove the lens without enlarging the small incision and implant another through the same small incision . If the original 6 mm or 5.5 mm optic has been implanted through a 3.2 mm incision by folding; it is important to remove the lens without sacrificing the length of the wound. This is done quite simply by bisecting the optic with Gills’ capsulotomy scissors under viscoelastic and removing the hinged two halves through the small incision. This technique for removing the foldable lens is presented in Figs. 165 and 166, Chapter 11.
PHACOEMULSIFICATION IN HIGH MYOPIA In patients with high myopia, phacoemulsification is somewhat more challenging than in other eyes. Patients with high myopia have globes that are superelongated and sclera that is thinned out. The minute the phaco probe is inserted and the infusion starts, the chamber deepens dramatically (Fig. 169). The probe must reach deep into the eye to access the nucleus because the lens iris diaphragm may have moved considerably back. Dodick has sought to overcome this problem by lowering the bottle height and reducing the flow, so that the lens is unlikely to move to such a posterior location. Even when this occurs, it is still quite possible with
Figure 169: Special Conditions of Phacoemulsification in Patients with High Myopia Phacoemulsification in patients with high myopia presents additional challenges. Patients with high myopia have globes which are elongated (green arrows) and have thinner sclera. As the phacoemulsification probe (P) is introduced into such eyes, the lens (red arrow) and iris (blue arrow) move posteriorly by a considerable amount. The probe must then reach deeper into the eye for lens extraction. High vacuum and sectioning of the nucleus into pieces can allow the surgeon to bring the nucleus more anteriorly for easier removal.
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high vacuum to bring the nucleus up into the pupillary plane earlier than with a normal or emmetropic eye. Phaco chop helps further by cutting the nucleus in several pieces and bringing these pieces up into the pupillary plane with high vacuum. The challenges in calculating the correct IOL power in high myopia are discussed on page 50.
CHALLENGES OF PHACOEMULSIFICATION IN HYPEROPIA The challenge in hyperopia is somewhat different. Dodick refers to these as crowded eyes because all of the small anatomical structures are in a smaller, confined space. Positive pressure is more likely to occur. Dodick makes two fundamental adjustments in technique when dealing with an extremely hyperopic eye. First, he dehydrates the vitreous with an osmotic agent such as Mannitol. Secondly, he tries to compress the eye and to express some of the unbound water in the vitreous with a compressive device like an Honan balloon (Fig. 96). He leaves this Honan balloon on at about 35 to 40 mm Hg for 20 to 30 minutes. These two preparatory steps help reduce the volume of the eye and soften the eye prior to nucleus removal. The challenges in calculating the correct IOL power in high hyperopia are presented on page 48. The pros and cons of piggyback lenses in very high hyperopia are discussed on page 49.
REFRACTIVE CATARACT SURGERY Why and When Do Refractive Cataract Surgery Richard Lindstrom, M.D. has become an advocate of what he calls «refractive cataract surgery», by which we mean trying to improve the patient’s astigmatism at the time of cataract surgery. In his extensive research and clinical experience, about 70% of the cataract patients that he operates have less than one diopter of astigmatism preoperatively and about 30% have more than one. He does not make any astigmatic corrections in those that have less than one diopter. That is good enough for 20/30 uncorrected visual acuity. Lindstrom becomes somewhat more aggressive with astigmatism when there are two diopters or more before the cataract operation. His goal is to reduce it to one diopter; not to try to correct it all, just to get it down into a reasonable range. He advises making the combined operation for cataract and astigmatism only when performing phacoemulsification. As a matter of fact, he advises against it if the phacoemulsification incision, is enlarged to place a 6.5 or 7 millimeter optic PMMA IOL or when a planned ECCE is performed. In such cases, he recommends, doing the cataract surgery, see what you get, and then fix it later if there is a problem. Most patients adapt to glasses. This is be-
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cause with an incision of this size, it is almost impossible to plan the refractive operation. The range of effect on astigmatism with such incisions is significant. With a planned extracapsular wound one patient might change a diopter and another might change four diopters.
TECHNIQUE FOR REFRACTIVE CATARACT SURGERY Surgical Principles Lindstrom’s surgical principles and technique are as follows: 1) Move the cataract 3 mm tunnel incision to the steeper meridian (Fig. 170). He thinks of this small wound as an astigmatic keratotomy. This will reduce the present astigmatism by 0.50 diopters. If the patient has 1 diopter of plus cylinder at axis 90, and a 3 mm cataract incision is made at axis 90, he/she will end up with only a 1/2 diopter of cylinder. If they have +1 diopter at 180 and the 3 mm cataract/IOL incision is moved over to the temporal side where the steeper meridian is located, they will end up with only +1/2 diopter of astigmatism at 180º which is good enough for 20/20 vision uncorrected. Lindstrom’s approach is to make them better, not to correct all the astigmatism. If they have 1.5 diopters, they will end up with 1 diopter cylinder and that is acceptable. But if they have 2 diopters to begin with, they will end up with 1.5 diopters and that is outside his goal. Lindstrom’s outcome goal is 1 diopter astigmatism or less. 2) If more than 1.0 diopter of astigmatism would remain, Lindstrom applies the
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principles of astigmatic keratotomy at the time of surgery. He does this very conservatively. The cataract wound becomes one astigmatic keratotomy. On the opposite side, at a 7 mm optical zone, he will make a small 2 mm corneal incision to correct 1 diopter or a 3 mm long incision to correct 2 diopters of astigmatism in the cataract age group. This becomes a second astigmatic keratotomy (Fig. 170). If the patient preoperatively has 3 diopters of astigmatism, Lindstrom places the 3 mm cataract/IOL incision again on the steeper meridian. This brings the astigmatism down to 2-1/2. If he wants the patient to end up with 1/2 diopters instead of 2 1/2 diopters of astigmatism, he makes a small 3 mm, nonperforating corneal incision with a diamond knife on the opposite side of the cataract incision at a 7 mm optical zone (Fig. 170).
Surgical Procedure Lindstrom sets the depth of the diamond blade at 600 microns. In that area on the average the cornea is about 650 microns thick so it is a very safe setting so as not to perforate the cornea. This incision can be done at the very beginning of the surgery. The first thing to do is make this little tiny cut. The other alternative is to complete the cataract operation, firm up the eye, and make that tiny cut at the end, but that may be more difficult. The exact location of this cut in the cornea is 3.5 mm from the center of the cornea. By using a 7 mm optical zone, the cut is really 3.5 mm from the center of the cornea. The diameter of the cornea is 12 mm. The limbus is 6 mm from the center.
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Why Straight Cuts Instead of Arcuate Lindstrom uses a 7 mm optical zone marker that has little marks on it for 30, 45, 60 and 90 degrees. At a 7 mm zone a 30 degree arcuate cut is equivalent to a 2 mm straight cut and a 45 degree arcuate cut is equivalent to a 3 mm straight cut (Fig. 171). Lindstrom finds that it is safer and easier
Figure 171 (below): Length of Straight Corneal Incision Related to Arcuate Incision
Figure 170 (above)): Technique for Refractive Cataract Surgery
At the 7 mm optical zone (dotted line), a 30º arcuate cut is equivalent to a 2 mm straight cut (A). At the 7 mm optical zone, a 45º arcuate cut is equivalent to a 3 mm straight cut (B). Dr. Lindstrom finds that it is safer and easier to make such small incisions straight rather than arcuate.
Dr. Lindstrom places the 3 mm cataract tunnel incision (C) in the steeper meridian to reduce pre-op astigmatism when present in a cataract patient. Further reduction of astigmatism may be obtained with a corneal incision (A) placed opposite the cataract incision in the same axis at the 7 mm optical zone (dotted line). The example shows a patient with pre-op 3 diopters of plus cylinder at axis 145º (inset). The corneal cataract incision is placed in this axis and may reduce the pre-op astigmatism by 0.50 diopters. The 3 mm straight corneal incision placed opposite the cataract incision in the same axis at the 7 mm optical zone should reduce astigmatism further by 2.0 diopters. The two together will reduce astigmatism a total of 2.5 diopters.
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just to make these small incisions straight instead of arcuate. With this technique he tries to make things safe and better for the patient, not perfect, and without doing any harm. This means trying to bring a patient from 3.5 diopters of astigmatism down to one, in order to improve the quality of his/her vision. He finds that he can enhance the results to the point now where about 85% to 90% of the patients will have 1 diopter or less of astigmatism. Lindstrom finds that these tiny incisions programmed as outlined here are a very powerful tool and seem to be very safe. He
has not observed any major complications such as poor wound healing, infection or perforation.
Full Refractive Correction of the Cataract Patient By selecting the correct IOL power even in complex cases as outlined in pages 45-54, correcting the preexisting astigmatism as discussed here and further enhancement with the use of toric foldable IOL’s if necessary (see Chapter 9), we have the means to create in our patients the truly refractive cataract operation.
CATARACT AND GLAUCOMA Age related cataract and primary open-angle glaucoma or chronic angle closure glaucoma often coexist in the older population. With increasing longevity this is becoming more prevalent. The management of such cases has been controversial because medical or surgical therapy of one condition often affects the other. Most of the concepts and techniques presented in this chapter are based on the experiences and observations of Maurice H. Luntz, M.D., Chief of the Glaucoma Service at the Manhattan Eye and Ear Hospital in New York.
Overview - Alternative Approaches When cataract and glaucoma coexist but the glaucoma is uncontrolled or poorly controlled, one approach is to give priority to control of the glaucoma either with additional medication or if this is not possible, 302
with laser trabeculoplasty or filtration surgery. Luntz believes that this approach has its drawbacks. Medical therapy for glaucoma may necessitate miotics, which tend to reduce visual acuity regardless of preexisting lens opacities, and may encourage an acceleration of cataract progression. Surgical therapy of glaucoma may be associated with increased lens opacification, especially if the surgery is complicated by inadvertent lens trauma but even in the absence of lens trauma. Subsequent cataract extraction, even if a functioning bleb and good drainage are obtained, results in loss of the bleb in approximately 10% of eyes, and inability to restore control of the glaucoma. When the indications for cataract extraction are present but the glaucoma is controlled medically, the most common approach has been to remove the cataract and continue medical management of the glaucoma. Intraocular pressure is more easily controlled in some eyes after lens extraction but a significant number of these patients will require
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glaucoma surgery as early as 3-6 months after standard cataract extraction . The patient then faces a second surgical procedure with its attendant risks soon after the first operation. An alternative approach is combined cataract and glaucoma surgery. Most surgeons are now oriented toward this approach. Excellent results are reported with extracapsular cataract extraction and trabeculectomy (Luntz and Stein, 1988; Simmons, 1992) and phacoemulsification with trabeculectomy. The combined procedure is used in those patients in whom IOP runs above the upper limit of the target IOP for that patient, or in whom good control of IOP necessitates the use of three or more different drugs. In those patients in whom IOP is well controlled using no more than two different drugs, phacoemulsification alone will generally maintain adequate postoperative control.
COMBINED CATARACT SURGERY AND TRABECULECTOMY In this chapter, we will first present the evolution of the different types of Combined Procedures for Cataract Extraction and Trabeculectomy as described by Luntz, to provide you with an instant mental picture of the different approaches to this problem, the latest being combining phacoemulsification with a tunnel incision and trabeculectomy. Considering that this Volume covers all major, widely accepted cataract surgery procedures, we present the advanced techniques in combined surgery for glaucoma with phacoemulsification as well as with planned extracapsular. The evolution of the different types of combined cataract extraction-trabeculectomy is presented in Figs. 172, 173,
174, 175, the combined extracapsular extraction with trabeculectomy step by step in Figs. 176 through 181, and phacoemulsification combined with trabeculectomy step by step in Figs. 182 through 187.
Indications The indications based on Luntz’s observations are: 1) Any eye with open angle glaucoma and cataract in which surgery is required for the cataract, even if the glaucoma can be medically controlled but requires more than two medications to do so. If combined surgery is not done, many of these eyes will require glaucoma surgery at a later date, exposing the patient to two surgical procedures where one would have sufficed. An exception to this are those patients in whom IOP with three medications runs in the very low teens (10-11mm Hg). 2) Eyes with uncontrolled glaucoma requiring glaucoma surgery and significant cataract with corrected vision of 20/40 or less, reading 6-pt. print or less or with poor glare tolerance.
Evolution of the Incision for Combined Cataract Extraction and Trabeculectomy The combined operation for cataract and glaucoma constitutes two procedures performed at the same surgical session. The technique for each procedure remains unchanged but the surgical incision needs to be modified using either separate incisions for each procedure (Fig. 172) or combining the incisions for each operation into one compound incision (Figs. 173, 174, 175).
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A. Extracapsular Cataract Extraction with Trabeculectomy 1. Separate Incisions The cataract and trabeculectomy incisions are made separately at different sites. The cataract incision is made in the cornea and is a single 11 mm chord length corneal cataract incision. A 3 mm x 3 mm lamellar scleral trabeculectomy flap is made separately in the upper nasal quadrant in the sclera under fornix or limbus based conjunctival flap (Fig. 172). This approach has the disadvantage that it necessitates a corneal cataract wound for extracapsular surgery. This type of incision is no longer popular because of its tendency toward higher levels of astigmatism in the early postoperative phase before the corneal sutures are removed. This approach is a good technique for those surgeons using a small corneal incision for phacoemulsification combined with trabeculectomy (Fig. 187).
2. Compound Incision By the term «compound incision» we mean that the surgeon combines a limbal 2-plane cataract incision of 9.5 mm or 10 mm chord length with a 3 mm x 3 mm 1/2 thickness lamellar scleral flap for the trabeculectomy (Fig. 173). Luntz prefers to place a trabeculectomy flap in the center of the cataract incision and this is a generally favored technique (Fig. 173). When the trabeculectomy flap is placed in the center of the cataract incision and the cornea-scleral trabeculectomy block measuring (2 mm x 2 mm) is removed from the scleral bed before removing the cataract, the total surface area of the cataract incision is increased at the site of maximum thickness of the lens during extraction for 304
intracapsular surgery or of a nuclear extraction for extracapsular surgery, thus facilitating their removal. This allows the use of an incision of smaller cord length - namely, 9.5 mm instead of the usual 11 mm chord length (Fig. 173). Luntz points out that a matter of great importance in the architecture of this compound incision is that the continuity of the limbal scleral incision for the cataract removal is broken in the center by the intrusion of the trabeculectomy flap with its two radial incisions which are placed 3 mm apart. By breaking the continuity of the limbal scleral incision (the cataract portion of the incision) we introduce an element of instability into the incision. Part of the incision is parallel to the limbus (the cataract incision) and part of the incision is radial to the limbus (the trabeculectomy incision). Where the two meet at each side of the trabeculectomy scleral flap the incision, when stressed postoperatively (for example by squeezing of the eyelid or distortion of the globe) they can shift horizontally, vertically or obliquely, causing postoperative oblique or against the rule astigmatism. The ability of the incision to shift vertically is magnified if the cataract and trabeculectomy incisions meet at the limbus at a 90º angle. To minimize this effect, Luntz recommends that the cataract incision should be curved into the trabeculectomy incision forming a convex curve on each side of the cataract trabeculectomy incision junction (Fig. 173). This curving of the incision reduces any tendency for vertical shift. This can be enhanced by careful attention to placement of the interrupted sutures at the time of suturing the incision. Additional stability is imparted to the incision by placing the interrupted 10-0 nylon sutures radially in the cataract portion of the incision, and by placing the sutures in the curved junction between
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Figure 172 A (left): Evolution of Types of Combined Cataract Extraction-Trabeculectomy Surgery - Type 1- Individual Surgical Sites - Surgeon’s View The first method of combined cataract extraction with trabeculectomy involves two separate surgical sites. The cataract surgery is performed through a corneal incision (C). The trabeculectomy is performed by a standard technique at the limbus. Note separate 3 mm by 3 mm scleral flap (F) and 2 mm by 2 mm trabeculectomy window (W). Iridectomy (I). Limbus based conjunctival flap.
Figure 172 B (right): Evolution of Types of Combined Cataract Extraction-Trabeculectomy Surgery - Type 1- Individual Surgical Sites - Cross Section View In this cross-section view, you can instantly identify the anatomical structures involved in the combined procedure when using two individual surgical sites. Note the scleral trabeculectomy flap (F) separate from corneal cataract incision (C). Trabeculectomy window (W). Iridectomy (I). Limbus based conjunctival flap.
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the cataract and trabeculectomy portions at 45º to the incision line (Fig. 173). Although this is a relatively stable compound incision, it is not as stable as a single unbroken incision and will induce more astigmatism, particularly oblique and against the rule astigmatism, than would be expected with a simple, unbroken cataract incision. An unbroken incision can be achieved by making the incision for the cataract surgery separate from the trabeculectomy (Fig. 172) or by using a large scleral bevel and combining both the trabeculectomy and the cataract wound within the unbroken incision (Figs. 174, 175).
Figure 173 A (above) : Evolution of Types of Combined Cataract Extraction-Trabeculectomy - Type 2- Combined Incision - Surgeon’s View A combination of the cataract extraction and trabeculectomy incisions is seen in this surgeon’s view. Note the limbus based two-plane cataract incision (C) with cord length of 9.5 mm and centrally placed 3 mm by 3 mm scleral flap (F). Note the 2 mm by 2 mm trabeculectomy window (W). The junction of the cataract incision and scleral flap is convex in shape (arrow) for a more stable wound closure. Iridectomy (I). Fornix based conjunctival flap.
Figure 173 B (below): Evolution of Types of Combined Cataract Extraction-Trabeculectomy - Type 2Combined Incision - Cross Section View This cross section view allows prompt identification of the tissues and technique involved as explained in Fig. 173 A. Compare the site of the cataract incision (limbus-based) and the combined scleral flap (F) with cataract incision in contrast with the individual surgical sites incision shown in Fig. 172 B.
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Figure 174 A (left): Evolution of Types of Combined Extracapsular Cataract Extraction-Trabeculectomy - Type 3- Single, Unbroken Tunnel Incision - Surgeon’s View Development of the scleral tunnel incision for phacoemulsification has simplified the incision for combined extracapsular cataract extraction and trabeculectomy. A 9.5 mm to 10 mm cord length, 1/2- scleral thickness groove (S) is placed 1.5 mm posterior to the surgical limbus. A scleral tunnel is dissected to the limbus, penetrating into the anterior chamber in the center of the groove incision and widened on each side over the full 10 mm length of the groove using a crescent knife and corneo-scleral scissors (C) (See Fig.178). The resulting scleral flap (F) is reflected. A trabeculectomy window (W) is performed under this scleral flap, contained within the scleral bed. Iridectomy (I) shown in Fig. 174B. Fornix based conjunctival flap.
Figure 174 B (right): Evolution of Types of Combined Extracapsular Cataract ExtractionTrabeculectomy - Type 3- Single, Unbroken Tunnel Incision - Cross Section View The angled view of the structures involved in the tunnel incision shows the difference in this surgical approach to the two previous types of incision (Figs. 172-B and 173-B). The anatomical structures and technique of incision are explained in figure legend of Fig. 174 A.
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3. Combining the cataracttrabeculectomy into a single, unbroken incision Instead of making the cataract portion of the incision at the limbus, the cataract incision is moved posteriorly to a position 1.5 mm or 2 mm posterior and parallel to the limbus. This is the preferred incision for extracapsular cataract surgery with trabeculectomy (Fig. 174). A trabeculectomy block of 2 mm x 2 mm can be excised out of this scleralcorneal bevel (Figs. 179, 180) without the necessity of cutting a separate trabeculectomy flap in the sclera (Fig. 173). The end result is a trabeculectomy block dissected within the scleral cataract incision which is a simple, unbroken incision (Fig. 180) adding significantly to the stability of the scleral incision and reducing the amount of postoperative astigmatism.
B. Phacoemulsification with Trabeculectomy This is presently the preferred technique for those with experience in phacoemulsification surgery. It results in the least level of postoperative astigmatism and rapid visual rehabilitation. The most popular incision is similar to the one shown in Fig. 177 except that the pocket incision is made to a chord length between 3.1 mm and 6 mm rather than the 10 mm chord length incision used for extracapsular extraction. The chord length of this incision will depend on the size and type of intraocular lens used. Thus, for a foldable silicone or acrylic IOL, a 3.5 or 4 mm chord length will be used; whereas, for a PMMA
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lens a 5.5 or 6 mm chord length incision would be used. The trabeculectomy block is removed from the scleral bevel within the incision as described previously in Figs. 179, 180. (For details of the surgical technique see Phacoemulsification Cataract Incision with Trabeculectomy later in this chapter, Figs. 182, 187.
Intraocular Lens Implants Luntz considers that the indications for implanting an intraocular lens are the same in glaucoma patients as in non-glaucoma patients. The posterior chamber intraocular lens is preferable. Anterior chamber lenses (Kelman-Multiflex - Editor) have been successfully used where a posterior chamber lens cannot be safely used, for example, where the anterior and posterior capsule have been extensively torn and will not support a posterior chamber intraocular lens in the bag or in the sulcus. (This subject is discussed in detail in pages 118-123 - Editor).
Preoperative Preparation Pilocarpine drops should be stopped 24-48 hours before surgery in order to facilitate pupillary dilatation at the time of surgery. If preoperative intraocular pressure is high it should be reduced prior to surgery with intravenous Mannitol (1.5 g./kg. body weight) or with oral glycerine 75 cc. Topical steroids (Prednisolone 1% q.i.d.) and topical nonsteroidal antiinflammatory drops are given 24hours before surgery and continued for 1 to 2 weeks after surgery. This reduces postoperative inflammation and may diminish the incidence of cystoid macular edema.
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Figure 175 A (right): Evolution of Types of Combined Cataract Extraction-Trabeculectomy - Type 4 - Tunnel Incision for Phacoemulsification and Trabeculectomy A 1/2- scleral thickness, 6 mm cord length groove (S) is made 1.5 mm posterior to the limbus. A scleral tunnel (T) (its margins denoted by dotted lines) is dissected to the limbus. The corneal incision for introduction of the phacoemulsification probe and trabeculectomy window (W) are located within the resulting scleral bed. Iridectomy (I). Fornix based conjunctival flap.
Figure 175 B (left): Evolution of Types of Combined Cataract Extraction-Trabeculectomy - Type 4 - Tunnel Incision for Phacoemulsification and Trabeculectomy - Section View Compare this cross section view with the one shown in Fig. 174 B. The scleral tunnel flap is much smaller. The cataract incision (C) in Fig. 174 B is much larger. This figure shows in cross section what is described in the surgeon’s view in Fig. 175 A.
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SURGICAL TECHNIQUES STEP BY STEP The following is a summary of the two main procedures step-by-step as recommended by Luntz.
ECCE and Trabeculectomy With Single, Unbroken Tunnel Incision Conjunctival - Tenon’s Flap (Fornix-based) (5x-7x Magnification) If Mitomycin is to be used Luntz prefers to apply it to the conjunctival surface before raising the conjunctival-Tenon’s flap (see section on antimetabolites further in this chapter). A superior rectus bridal suture is optional. The fornix-based conjunctival-Tenon’s flap with a 12 mm cord length is raised at the superior limbus. The flap is dissected posteriorly to further expose the sclera. Adequate hemostasis and clearing of the sclera is obtained. Luntz considers that the fornix-based conjunctival flap has many advantages compared to a limbus-based flap: 1) There is better exposure and visualization of the operative field. 2) The possibility of damaging the conjunctival flap during dissection, particularly producing a «buttonhole» is eliminated. 3) A fornix-based flap is technically easier to dissect than a limbus-based flap, especially when operating in an area of scarred conjunctiva, either from previous surgery or trauma. It also offers better exposure of the surgical area.
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4) The fornix-based conjunctiva flap adheres and scars at the limbus. As a result, the bleb forms posteriorly producing a diffuse, well-vascularized «low-profile» bleb well behind the limbus. There is less possibility of developing a thin «high-profile» avascular anterior bleb which overhangs the cornea, which has the added risk of microscopic perforations of hypoxic conjunctiva and possible intraocular infection. 5) The posteriorly situated bleb and the scar at the limbus allow safe and early contact lens fitting if a contact lens is required. 6) Tenon’s fascia is minimally traumatized.
Scleral-Corneal Incision (7x-10x Magnification) A 1/2-thickness scleral groove is cut in the exposed sclera using a diamond knife blade or a crescent knife blade 1.5 mm posterior to the surgical limbus, extending for 9.5 to 10 mm cord length parallel to the limbus (Fig. 176). At the center point of the incision (12:00 o’clock position) a crescent knife blade is used to dissect a scleral tunnel just anterior to the corneal vascular arcade which is then dissected to each side across the cord length of the incision (Fig. 176). A 3.1 mm keratome is introduced into the «tunnel» at 12 o’clock and advanced to the anterior limit of the tunnel in the cornea (Fig. 176). Pressing the point of the keratome downward toward the iris, the keratome is advanced and penetrates the cornea into the anterior chamber with the tip of the keratome 45º to the iris plane (Fig. 177). At this point, the direction of the keratome tip is changed to run parallel to the iris surface and the keratome is advanced fully into the anterior chamber to
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complete the 3.1 mm incision (Fig. 177). The keratome is removed and the anterior chamber filled with viscoelastic. Using a Superblade, a paracentesis incision is made at the 9:00 o’clock and 3:00 o’clock meridians.
Figure 177 (below): Combined Extracapsular Cataract Extraction - Trabeculectomy Procedure With Single, Unbroken Tunnel Incision - Step 3
Figure 176 (above): Combined Extracapsular Cataract Extraction - Trabeculectomy Procedure With Single, Unbroken Tunnel Incision - Steps 1 and 2
A 3.1 mm keratome (K) is introduced into the tunnel at the 12 o’clock position and advanced to the anterior limit of the tunnel in the cornea (inset - 1). The tip of the keratome is depressed and advanced into the anterior chamber. At this point, the direction of the keratome tip is changed to run parallel to the iris surface and the keratome is fully advanced into the anterior camber (inset -2 ) to complete the 3.1 mm incision. The keratome is removed and the anterior chamber is filled with viscoelastic.
A 12 mm cord length, fornix based conjunctival flap (C) is reflected. A 1/2 thickness vertical scleral groove incision (S) is made with a diamond knife or crescent knife (not shown), 1.5 mm posterior to the limbus for a cord length of 9.5 to 10 mm, parallel to the limbus. At the center the groove (12 o’clock position), a crescent knife blade (K), is used to dissect a scleral tunnel to just anterior to the corneal vascular arcade. The sclera is then dissected to each side across the length of the groove (arrows - dotted lines).
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Anterior Capsulotomy (10x Magnification)
incision into the anterior chamber with a 1.5 2 mm wide scleral-corneal bevel (Fig. 174).
A 27-gauge needle with the tip bent to 90º is introduced into the anterior chamber and a can-opener capsulotomy or preferably a large capsulorhexis, depending on the surgeon’s preference is performed.
Trabeculectomy (10x Magnification)
Completion of Sclero-Corneal Incision (10x Magnification) The scleral flap is lifted and microsurgical corneal-scleral scissors are introduced into the scleral-corneal incision cutting to the left and right, completing the incision into the anterior chamber for the entire cord length of the original scleral groove (Fig. 178). The final result is a 9.5 to 10 mm cord length
The anterior chamber is filled with viscoelastic . A 2 mm x 2 mm block of tissue is excised from the scleral-corneal bevel at the 12:00 o’clock position using a LuntzDodick microsurgical punch (Katena). The posterior limit of the excised scleral-corneal block reaches to the scleral spur (Figs. 179, 180). The trabeculectomy opening located in the center of the scleral-corneal incision reduces resistance of the scleral bevel to passage of the lens nucleus from the eye and facilitates its removal.
Figure 178: Combined Extracapsular Cataract Extraction - Trabeculectomy Procedure - Step 4 After an anterior capsulotomy or capsulorhexis has been performed, the scleral flap (F) is lifted and corneal-scleral scissors (D) are introduced into the previous 3.1 mm incision. The cataract incision is extended to the left and right (arrow) using the scissors. This produces a 9.5 to 10 mm cord length incision into the anterior chamber with a 2mm-wide scleral-corneal bevel. The anterior chamber is then filled with viscoelastic.
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Figure 179 (left): Combined Extracapsular Cataract Extraction - Trabeculectomy Procedure - Step 5 This cross section shows the scleral-corneal bevel (T). An approximately 2 by 2mm block of tissue is excised from the scleral-corneal bevel (T) at the 12 o’clock position using a Kelly Descemets punch (P) or Vannas scissors. The posterior limit of the excised block reaches to the scleral spur (arrow).
Figure 180 (right): Combined Extracapsular Cataract Extraction - Trabeculectomy Procedure - Step 6 This surgeon’s view shows the initial 1/2-thickness scleral groove incision (S), the completed 9.5 to 10mm scleral-corneal bevel incision (C), the approximately 2mm by 2mm trabeculectomy window (W) and reflected scleral flap (F). (See Figure 174 B for corresponding cross section view). The surgeon then performs an extracapsular cataract extraction and IOL insertion using his/her preferred technique. A peripheral iridectomy under the trabeculectomy is essential.
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Figure 181: Combined Extracapsular Cataract Extraction - Trabeculectomy Procedure - Step 7 This surgeon’s view shows closure of the incision with two interrupted 10-0 nylon sutures placed through the full thickness of the scleral flap at the limbus and through the posterior scleral incision on each side of the trabeculectomy opening (dotted line). A running uninterrupted 10-0 Nylon suture closes the conjunctival incision (not shown).
Removal of the Lens Nucleus and Cortex. Insertion of IOL The surgeon proceeds with extracapsular cataract extraction and insertion of an IOL using his/her preferred technique.
midway across the iris from the right side with a Vannas or DeWecker scissors, and then moving the iris to the right and completing the iridectomy cut.
Closure of the Cataract-Trabeculectomy Incision (5x Magnification)
Iridectomy (10x Magnification) Following insertion of the IOL a peripheral iridectomy is made within the trabeculectomy opening ensuring that the base of the iridectomy is wider than the trabeculectomy opening (Fig. 173-A). This is achieved by grasping the iris near its root at the center of the trabeculectomy opening, bringing it out of the eye and moving to the left, cutting 314
Closure is achieved using interrupted 10-0 nylon sutures, one interrupted suture on either side of the trabeculectomy opening leaving the trabeculectomy opening and adjacent scleral bevel unsutured (Fig. 181). The interrupted sutures are placed through the full thickness of the scleral flap at the limbus and through the posterior scleral incision (Fig. 181). The sutures are not tightly tied,
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but tied to achieve tissue apposition without «crimping» the scleral flap and are «buried» in the sclera. It is desirable to inflate the anterior chamber with balanced salt solution to achieve a good positive intraocular pressure before tying these sutures. An alternative is to use one horizontal suture through the scleral flap and scleralcorneal bevel on either side of the trabeculectomy opening.
Closure of the Conjunctivo-Tenons’ Flap (5X Magnification) An uninterrupted 10-0 nylon suture running from the limbal sclera to conjunctiva closes the conjunctival incision. These sutures should be tightly tied, particularly if an antimetabolite is used.
Phacoemulsification With Trabeculectomy This procedure is shown in Figs. 182 through 187.
Conjunctivo-Tenons’ Flap (5x-7x Magnification) A 6 mm fornix-based flap is raised in the same way as described previously for the combined extracapsular extraction and trabeculectomy. Luntz’ technique when using antimetabolites is that if mitomycin is to be
used it is applied before raising the conjunctival flap.
Scleral-Corneal Magnification)
Incision
(7x-10x
Luntz performs a 1/2-thickness vertical scleral groove, 5.5 mm or 6.0 mm cord length, depending on the diameter of the IOL to be used, or 3.5 mm cord length if a foldable IOL is used, which is cut in the exposed sclera in the superior half of the globe, 1.5 mm posterior to the limbus using a crescent blade or diamond blade (Fig.182). The crescent knife then dissects under the anterior lip of the groove to within the corneal vascular arcade extending the dissection on either side to the limits of the incision (Fig. 182). Using a Superblade, a paracentesis incision is made at the 9:00 o’clock and 3:00 o’clock meridians. A 2.5 mm keratome is inserted into the scleral-corneal incision at the 12:00 o’clock meridian advancing the keratome to the edge of the incision just anterior to the corneal vascular arcade (Fig. 183). The tip of the keratome is pushed toward the anterior chamber, it is withdrawn slightly and the anterior chamber is penetrated with the keratome tip 45º to the iris plane. At this point, the keratome tip is raised so that the keratome advances fully into the anterior chamber parallel to the iris plane producing a 2.5 mm «tunnel» incision (Figs. 183, 177 Insets).
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Figure 182 (left): Combined Phacoemulsification Cataract Extraction - Trabeculectomy Procedure - Steps 1 and 2 A 6mm cord length fornix based conjunctival flap is reflected. A 1/2 thickness vertical scleral groove incision is made with a diamond knife or crescent knife (not shown) at 1.5mm posterior and parallel to the limbus for a cord length of 6mm for a 5.5 or 6.0mm diameter IOL, or 3.5mm if a foldable IOL is used (Fig. 40 B). At the center of the groove incision (12 o’clock position), a crescent knife blade (K) is used to dissect a scleral tunnel to just anterior to the corneal vascular arcade. The sclera is then dissected to each side across the length of the groove (arrows).
Figure 183 (right): Combined Phacoemulsification Cataract Extraction - Trabeculectomy Procedure - Step 3 A 2.5mm keratome (K) is introduced into the tunnel at the 12 o’clock position and advanced to the anterior limit of the tunnel in the cornea (See Fig. 177, inset 1). The tip of the keratome is depressed and advanced into the anterior chamber. At this point, the direction of the keratome tip is changed to run parallel to the iris surface and the keratome is fully advanced into the anterior chamber (See Fig. 177, inset 2) to complete the 2.5mm incision. The keratome is removed and the anterior chamber is filled with viscoelastic. The cataract is then removed.
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Corneal «Tunnel» Incision and Separate Trabeculectomy (7x-10x Magnification) For cataract and glaucoma surgery the 3.0 - 3.5 mm tunnel intracorneal incision placed in the temporal cornea can be used with a trabeculectomy performed separately and superiorly (Fig. 187).
Capsulorhexis, Phacoemulsification, Nucleofractis, Infusion/ Aspiration and IOL Insertion (10x-15x Magnification) Using the scleral corneal tunnel incision (Fig. 184), the surgeon performs the above procedures according to his/her preferred method.
Trabeculectomy is not performed prior to lens removal in order to maintain a watertight «tunnel» incision for the phacoemulsification. The 2.5 mm tunnel incision is enlarged to a 6 mm incision for insertion of a 6 mm IOL. If a 5 mm IOL is used, a 5 mm incision is made; and if a foldable lens is used the incision can be reduced to 3.5 mm.
Trabeculectomy (10x-15x Magnification) Following insertion of the IOL the anterior chamber is filled with viscoelastic and a trabeculectomy is made within the scleral bevel of the tunnel incision using the same technique as described in Figs. 175 and 179. The next step is an iridectomy insuring that the iridectomy base is wider than the trabeculectomy opening, as previously described (Fig. 184).
Figure 184: Combined Phacoemulsification Cataract Extraction - Trabeculectomy Procedure - Step 4 This figure shows the final configuration of the combined Phacoemulsification Cataract Extraction - Trabeculectomy incision. (See Figure 175 B for the corresponding cross section view). The scleral-corneal incision has been extended for its full length. In this figure, a cord length of 6mm is illustrated. The IOL is then inserted. Trabeculectomy (W) is performed by removing an approximately 2mm by 2mm block of the scleral-corneal bevel down to the scleral spur (see Figure 179). Iridectomy is performed (I). The sclera is shown lifted here to reveal the scleral tunnel (T) (its margins denoted by dotted lines). Initial scleral groove incision (S).
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Closure of the Incision (5x Magnification) An interrupted 10-0 nylon suture is placed through the scleral incision on either side of the trabeculectomy as described in Fig. 185. The trabeculectomy and adjoining scleral-corneal bevel is left open without sutures. The knots should be buried. The scleral flap can also be left unsutured but Luntz has found a high incidence of postoperative bleeding and hyphema in these eyes. The 3.5mm incision or the 6 mm scleral flap are left unsutured only if the surgeon anticipates that freer drainage of aqueous through the trabeculectomy opening will be required early in the postoperative period. However, the disadvantage of an unsutured scleral flap, particularly the 6 mm scleral flap, is that the anterior chamber may be shallow or flat in the immediate postoperative period. To overcome this problem, one or two releasable 10-0 nylon sutures should be used (Figs. 186 A-B). These have the advantage that the anterior chamber is very unlikely to shallow postoperatively, because the scleral incision is partially sutured, and, at the same time, the sutures can be easily removed in the postoperative period if and when more drainage through the filtering procedure is required. The releasable sutures are placed as follows: the 10-0 nylon suture (Luntz prefers a CU-5 needle) is loaded backwards in the needle holder. The suture is placed through the posterior lip of the scleral incision and then through the anterior lip of the incision (posterior lip of the trabeculectomy flap) and exteriorized through the anterior lip. A second bite is taken at the limbus and into adjacent cornea in a radial direction and is exteriorized. A third bite is then taken at the point where the suture exits from the cornea, and this bite in
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the cornea is horizontal to the limbus (Fig. 186). The free end of this nylon suture entering into the posterior lip of the scleral incision is held with tying forceps. Three throws are made, and the tying forceps then engages the portion of the suture that is exteriorized between the anterior lip of the scleral incision and the limbus. This portion of the suture is then pulled through the three loops held in the other tying forceps, and a bow knot is tightened, apposing the two lips of the scleral incision. The free end of the nylon suture from the bow tie is cut, and the free end of the nylon suture on the cornea is cut. The radial and horizontal suture in the cornea eliminates a free end of nylon suture on the cornea behaving as a windshield wiper. Two such releasable nylon sutures are placed in the incision at the same locations as shown for the interrupted sutures in Fig. 185. (The above technique is the method described by Allan E. Kolker, M.D.).
Conjunctival Closure (5x Magnification) The conjunctiva is closed with an uninterrupted 10-0 nylon suture as previously described. (Editor’s Note: in patients with glaucoma and cataract, one of the most difficult problems to deal with is the management of the small pupil. This important subject is discussed separately in this same chapter.)
Antimetabolites in Combined Procedures Luntz believes that antimetabolites should be used routinely in combined cataract and trabeculectomy as the result is better.
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Figure 185 (left): Combined Phacoemulsification Cataract Extraction - Trabeculectomy Procedure - Step 5 This surgeon’s view shows closure of the 6mm incision with two interrupted 10-0 nylon sutures placed through the full thickness of the scleral flap at the limbus and through the posterior scleral incision on each side of the trabeculectomy opening (dotted line). If properly valvulated to prevent loss of the anterior chamber, the 6mm scleral flap can be left unsutured, which will result in a bigger drop in intraocular pressure. A running uninterrupted 10-0 Nylon suture closes the conjunctival incision (not shown).
Figure 186 A-B (right): Technique for Placement of Releasable Sutures (A) The 10-0 nylon suture is passed through both lips of the scleral flap, through the limbus radially into the cornea and then through the cornea parallel to the limbus (to prevent the “windshield wiper” effect of a radial suture. Figure (B) shows the technique for tying the bow. The portion of suture between the anterior lip of the scleral flap and the limbus is pulled up into a bow and tied to the free end of the suture at the posterior lip of the scleral flap. (This technique was introduced by Alan Kolker, M.D., and is reproduced with his permission).
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Choice of Antimetabolite Surgeons in general will vary in their choice of an appropriate antimetabolite depending on the age of the patient and their own personal experience. For the combined cataract and trabeculectomy procedure, Luntz uses mitomycin-C routinely, as the results of the procedures are better with the use of an antimetabolite. There is a remote possibility of teratogenesis and the development of cancer many years following application of this drug. For this reason, and particularly so in children, an informed consent is required before Mitomycin-C is applied. When using Mitomycin, Luntz’ preferred technique is to soak a Weck cell sponge into a solution of 0.4% Mitomycin-C. The soaked Weck cell sponge is placed on the conjunctival surface at the site selected for surgery. It is held on the conjunctiva for oneminute and then replaced with a freshly soaked Weck cell sponge for a further oneminute, and this is repeated a third or fourth time giving a total application time of three or four minutes. Following this, the conjunctival surface is vigorously lavaged with balanced salt solution to remove all traces of the drug. Some surgeons have used a topical application of 5-FU intraoperatively with a Weck cell sponge soaked in the drug, similar to the way Mitomycin-C is used. The effectiveness of this method is still undecided.
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Results of Combined Cataract Surgery and Trabeculectomy In Luntz’ experience, the results of combined cataract surgery and trabeculectomy have been consistently good. In a study combining extracapsular cataract extraction with posterior chamber intraocular lens implant and trabeculectomy, 38 eyes were followed for up to 46 months, with a mean of 16.4 months. The average preoperative intraocular pressure was 20.5 mm Hg and the average postoperative pressure was 14.5 mm Hg, a statistically significant change. The mean number of medications preoperatively was 2.3 and postoperatively at the end of the follow-up period this had still dropped to a mean of 1.42. There was no significant change in the visual field graded from the preoperative to the postoperative level. Visual acuity, which averaged 20/120 preoperatively, improved to an average of 20/50 postoperatively. Simmons et al (1992), have also reported good results with few complications using extracapsular cataract extraction with posterior chamber intraocular lens and trabeculectomy (as well as phacoemulsification and trabeculectomy -Editor). In Luntz’ studies, the complications associated with combined ECCE and trabeculectomy (and (phacoemulsification and trabeculectomy) were surprisingly few and of no greater severity than would have been
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expected from the cataract surgery or the glaucoma surgery alone. Intraoperative complications specific to the combined operation were not observed. The complications that were seen were similar to those associated with a trabeculectomy or extracapsular cataract extraction alone. Immediate postoperative problems consisted of corneal edema of mild degree which rapidly resolved, and iritis which caused no long-term problems. Contrary to what was anticipated, the performance of a radial iridectomy and its repair by suturing the iris when this procedure was chosen by the surgeon did not cause an increase in the
level of postoperative iritis. None of the patients had shallow or flat anterior chambers postoperatively, which can be attributed to good apposition and closure of the cataract wound. When using antimetabolites, if a significant leak from the conjunctival wound does occur this will in most cases require surgical repair. Surgical repair entails resuturing the incision. In severely affected eyes, the conjunctiva at the site of the leak becomes friable and normal conjunctiva is rotated from the fornix or moved across as a flap from the adjacent temporal or nasal conjunctiva.
Figure 187 : An Alternative Technique of Phacoemulsification Using “Tunnel” Intracorneal Incision Combined with Separate Trabeculectomy In cases of combined phako and glaucoma surgery, a 3.0 - 3.5mm “tunnel” intracorneal incision (C) is placed in the temporal cornea to perform the phacoemulsification and foldable lens implantation. Trabeculectomy is performed in the standard manner separately and superiorly with 3mm by 3mm scleral flap (F) and 2mm by 2mm trabeculectomy window (W).
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PHACOEMULSIFICATION IN DISEASED CORNEAS PHACOEMULSIFICATION AND IOL IMPLANTATION IN THE PRESENCE OF OPAQUE CORNEA Overview Most of the concepts and techniques presented on this subject are based on the extensive clinical experience and research of Professor Miguel Angel Padilha, of Brazil. For many years, a triple procedure involving a corneal transplant, cataract extraction and intraocular lens implantation regularly entailed an open sky extracapsular cataract extraction. This technique exposed the open eye for a long period of time, while the surgeon performed the anterior capsulotomy, extraction of the cataract nucleus, aspiration of the cortical material and the implantation of the intraocular lens. Only then is the donor’s cornea placed and adequately sutured. During this period, the eye is subjected to considerable risk, including the greatly feared complication of expulsive hemorrhage.
Padilha’s Timing and Technique When the cornea is opaque to the extent of preventing visualization of the anterior chamber, no other alternative is left than to proceed with the surgical timing and steps
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described above: a corneal trephining first, followed by open sky extracapsular extraction, intraocular lens implantation and suturing the donor cornea to the recipient’s cornea to complete the operation. If the cornea is reasonably transparent, allowing the surgeon to visualize the structures of the anterior chamber (Fig. 188) Padilha’s procedure of choice is removal of the cataract by phacoemulsification first which is a pressurized, much safer system, continued by IOL implantation and last, completing the penetrating graft, as first recommended by Enrique Malbran, M.D., from Argentina in 1995. Step 1: Incomplete trephining of the moderately opaque cornea reaching half depth (Fig. 188). Step 2: Viscoelastic is injected into the anterior chamber through a side port incision. A Valvulated self-sealing scleral tunnel incision 2 mm posterior to the limbus, is performed, as shown in Fig. 40-B. Step 3: CCC with a bent needle used as a cystotome and long Kelman-McPherson forceps, preceded by injection of viscoelastic (Figs. 97, 44, 45). Step 4: The remaining phases of phacoemulsification are completed in a routine way, followed by the implantation of an PMMA or foldable intraocular lens, depending on the experience of the surgeon (Fig. 189). A miotic agent is injected intracamerally. Step 5: Padilha checks the hermetic closure of the sclero-corneal tunnel. The wound may or may not be closed with a horizontal suture depending on how sure the
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Figure 188: Phacoemulsification in Opaque Corneas - Stage 1 The surgeon first proceeds to do an incomplete trephining of the affected cornea with the trephine gauged to enter only 1/2 the corneal depth (T). Next, the surgeon proceeds with the injection of viscoelastic (V) through an ancillary incision (A). Through a scleralcorneal tunnel incision, a valvulated self-sealing wound 2 mm posterior from the limbus (W), a circular capsulorhexis (C) is performed. The remaining phases of phacoemulsification are completed in a routine way.
Figure 189: Phacoemulsification in Opaque Corneas - IOL Insertion Stage 2 Following phacoemulsification, and I/A of the cortical remains, the anterior chamber is again filled with viscoelastic. The next step is the implantation of a PMMA or a foldable intraocular lens (L), depending on the preference of the surgeon. Tunnel incision (W).
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surgeon is of its complete sealing. He proceeds with the removal of the opaque corneal button using a disposable Beaver knife and Castroviejo’s scissors (Fig. 190). The surgeon completes the procedure by bringing together the edges of the donor and recipient corneas, using 16 interrupted 10.0 nylon monofilament sutures. This approach undoubtedly reduces the long period of time during which the eye remains exposed, thus making surgery much safer.
Specific Recommendations 1) Padilha strongly recommends that the phaco procedure not be done using a clear cornea incision. Complications or difficulties may arise at the time of performing the penetrating graft. Consequently, use the sclero-corneal tunnel incision shown in Fig. 40-B.
2) The technique of phacoemulsification must be endocapsular, within the capsular bag, using the surgeon’s procedure of choice for management and disassembling the nucleus. This is with the purpose of preventing additional damage to the corneal endothelium. If necessary, the nucleus may be dislocated into the anterior chamber where it can be removed or into the iris plane (using Lindstrom’s iris-plane techniques Figs. 136-139, Chapter 10). But repeatedly lubricating the cornea with dispersive viscoelastic. 3) If corneal edema deriving from the corneal disease itself is present and interferes with visualization of the intraocular maneuvers, the corneal epithelium may be completely removed to facilitate the surgeon’s adequate view of surgical maneuvers and instrumentation. (Editor’s Note: placing dispersive viscoelastic over the cornea will further facilitate the inner view by the surgeon).
Figure 190: Phacoemulsification in Opaque Corneas - Completing the Penetrating Keratoplasty - Stage 3 Following the IOL implantation (L), through the tunnel incision (W), the surgeon completes the trephining of the cornea and proceeds with the removal of the corneal button (T) with a disposable knife and Castroviejo or Barraquer scissors (S). The surgeon completes the procedure by placing 16 radial interrupted 10-0 nylon sutures in the donor recipient.
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PHACOEMULSIFICATION, IOL IMPLANTATION AND FUCHS’ DYSTROPHY Preoperative Evaluation These patients demand a meticulous preoperative evaluation before cataract surgery. This should not be limited to a good biomicroscopic examination with the slit lamp. Specular microscopy and corneal pachymetry may provide additional information of value to decide if a cataract extraction is sufficient or if a triple procedure is the most appropriate. These diagnostic examinations should be made if the equipment is available. In the majority of patients, however, a detailed biomicroscopy may be sufficient to determine the amount of guttata and the extension of the corneal edema.
Role of Specular Biomicroscopy and Pachymetry In performing specular biomicroscopy, counting the endothelial cells is not sufficient to guarantee that an eye with corneal disease will withstand surgical trauma without developing further corneal edema, or even worse, bullous keratopathy in the future. Analysis of the cell morphology provides important additional information for predicting the nature of postoperative complications after phacoemulsification or any other intraocular surgery. Pachymetry offers a dynamic evaluation of these same corneas. Repetitive measures of the thickness of the diseased cornea may demonstrate how well its fluid system functions.
If there is considerable corneal edema, with an endothelial cell count of less than 500/mm2 and a central pachymetry up to 610 micra, the procedure of choice is performing combined surgery consisting of penetrating keratoplasty, cataract extraction and IOL implantation.
Special Precautions During Phacoemulsification 1) The presence of cornea guttata or Fuchs’ dystrophy is not a contraindication to phacoemulsification, but it does require additional specific precautions. The surgeon must significantly decrease turbulence and maintain the anterior chamber with a sufficient quantity of BSS and viscoelastic to prevent contact between the nuclear fragments and the endothelium, particularly at the stage of aspiration of cortical remnants. 2) In corneas with Fuchs’ dystrophy, it is very important to use dispersive viscoelastic for better adherence to and protection of the diseased endothelium. Be attentive in case the viscoelastic comes out through the wound. This makes it necessary to reintroduce it fairly often during the surgical procedure. This should be done through the sideport incision (Fig. 191). The phaco or the I/A tip should be kept functioning within the anterior chamber avoiding its removal and reinsertion back and forth through the main incision. This could lead to additional trauma. 3) During phacoemulsification, the maneuvers should be very delicate, using techniques that reduce the time and power of the ultrasound. Padilha considers that the phaco fracture or “divide-and-conquer” techniques, are the most indicated. When
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emulsifying the last quadrant the surgeon must prevent fragments from moving into the anterior chamber and touching the endothelium (Fig. 192). The ideal procedure is to maintain a high vacuum power (150 mmHg or higher), keeping nucle-
ar fragments attached to the titanium tip and set in motion the pulse system of the equipment. If such fragments should move into the anterior chamber, dispersive viscoelastic substance should be used to prevent their touching the endothelium (Fig. 192).
Figure 191 (left): Phacoemulsification in Fuchs’ Dystrophy - Use of Viscoelastic In such altered corneas it is very important to use dispersive viscoelastics (V) for better adherence to and protection of the diseased corneal endothelium. The lateral paracentesis or sideport incision (L) should be used for the intracameral injection of viscoelastic. The phaco tip introduced through the primary incision is not to be reinserted in and out, back and forth (T) for intraocular maneuvers . This could add trauma.
Figure 192 (right): Phacoemulsification in Fuchs’ Dystrophy - Ideal Procedure During phacoemulsification, the maneuvers should be very delicate, decreasing the power of ultrasound to the minimum desirable, and using techniques that reduce the time of ultrasound. The ideal procedure is to maintain a high vacuum power (150 mmHg or more), keeping lens fragments attached to the phaco tip (P), and use the pulse system of the equipment. If such fragments should tend to move into the anterior chamber (white arrow), the dispersive viscoelastic (V) should be once more irrigated into the anterior chamber to protect the endothelium.
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Figure 193: Phacoemulsification in Fuchs’ Dystrophy IOL Implantation At the time of IOL implantation (L) the first step should be the introduction of viscoelastic in the anterior chamber and the capsular bag (C) as presented in Fig. 191 to keep the bag well distended, especially if a foldable lens is to be implanted.
4) At the time of lens implantation, the first step should be the introduction of a cohesive viscoelastic (VE) inside the capsular bag to maintain the posterior capsule well distended, especially if a foldable lens is to be implanted (Fig. 193). The next step is to lubricate the injector with dispersive viscoelastic to facilitate the delivery of the lens from inside the injector with the bag.
At the end of surgery, the aspiration of the cohesive VE will be easier and faster than the dispersive VE. In order to protect the cornea from any damage, the dispersive VE should not be removed aggressively although all VES should be removed. Administration of carbonic anhydrase inhibitors and betablockers during the immediate postoperative period is always recommended to inhibit elevation of intraocular pressure, especially in cases with some corneal disease.
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PHACOEMULSIFICATION IN SMALL PUPILS Pharmacological Mydriasis
Mechanical Strategies
Phacoemulsification requires that the pupil be well dilated. Adequate exposure of the lens and the anterior capsule is essential. Padilha first tries to obtain a pharmacological mydriasis. He uses a combination of Phenylephrine 10%, Tropicamide 1% ( Mydriacyl R ), and a prostaglandin inhibitor such as Indomethacin or Flurbiprofen 0.03% (Ocufen R ), which is administered every 15 minutes during 1 hour before surgery. Among the two inhibitors, Padilha prefers Ocufen R, for better maintenance of the mydriasis. This pharmacological combination is administered if, of course, no cardiovascular contraindications exist. If this combination of medications is not effective, unpreserved adrenaline 1:1000 diluted in 10 ml of BSS may be injected into the anterior chamber at the beginning of surgery.
In patients who have a certain degree of iris atrophy that may be related to advanced senility, post uveitis, trauma or the long term use of miotics in glaucomatous eyes, the following options are available to obtain adequate exposure of the lens and the anterior capsule.
Mechanical Dilatation Viscoelastics
with
In the presence of iris adhesions to the anterior lens capsule, Luntz mechanically separates them using a viscoelastic passed through a cannula. Once the synechiae have been separated, intracameral Epinephrine (adrenaline) is injected and in many instances the pupil will dilate adequately.
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1. Stretching the Pupil The pupil in most patients can be stretched to an adequate dilatation using two Kuglin hooks as advocated by Maurice Luntz, M.D. One Kuglin hook is inserted into a preformed temporal paracentesis and advanced to the opposite nasal pupil margin where the Kuglin hook engages the pupil margin (Fig. 194). The second Kuglin hook enters the anterior chamber through a preformed nasal paracentesis, is advanced across the anterior chamber to the opposite temporal pupillary edge, which it engages (Fig. 194). Both Kuglin hooks are now pushed toward the limbus, stretching the pupil horizontally until maximal stretching is achieved. There will inevitably be some small sphincter tears. Both Kuglin hooks are now removed from the anterior chamber and re-entered into the anterior chamber through two preformed keratome incisiona one at 12 o’clock and the other at 6 o’clock (Fig. 195). One Kuglin hook is advanced across the anterior chamber to engage the pupil margin at 6 o’clock, and
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Figure 194 (left): Stretching the Pupil Horizontally with Two Kuglin Hooks One Kuglin hook is inserted through a temporal paracentesis and advanced to the opposite nasal pupil margin and engages the pupil margin. The second Kuglin hook enters the anterior chamber through a nasal paracentesis, and is advanced across the anterior chamber to the opposite temporal pupillary edge, which it engages. Both Kuglin hooks are now pushed toward the limbus, stretching the pupil horizontally until maximal stretching is achieved.
Figure 195 (right): Stretching the Pupil Vertically with Two Kuglin Hooks Both Kuglin hooks are now re-positioned through keratome incisions at 12 and 6 o’clock. One Kuglin hook is advanced across the anterior chamber to engage the pupil margin at 6 o’clock, and the second Kuglin hook engages the pupil margin at 12 o’clock. Both Kuglin hooks are pushed toward the limbus facing each other thereby stretching the pupil vertically. Once the maximal vertical extension is achieved, the Kuglin hooks are removed.
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the second Kuglin hook engages the pupil margin at 12 o’clock. Both Kuglin hooks are again pushed toward the limbus, facing each other, at 6 and 12 o’clock, thereby stretching the pupil vertically (Fig. 195). Once the maximal vertical extension is achieved, the Kuglin hooks are retracted. Intracameral epinephrine is injected, followed by intracameral viscoelastic. In those eyes in which the pupil margin in not significantly fibrosed and not too spastic, this maneuver can achieve a sufficiently dilated pupil to proceed with phacoemulsification. The technique using Kuglin hooks has also been advocated by Miguel Padilha, M.D.
2) Mechanical Pupillary Dilators In those cases in which the pupil margin is fibrosed or very spastic, one of the following procedures may be necessary. A) Plastic Iris Hooks (AlconGrieshaber) are inserted through four paracentesis incisions in the cornea (Fig. 196) as advocated by Luntz as well as Padilha. The hooks engage the pupil margin at the 10:00 o’clock, 2:00 o’clock, 4:00 o’clock and 8:00 o’clock meridians, and the pupil is forcibly enlarged by pulling the hooks outward and fixing their positions. Metal hooks are also available but Luntz considers that plastic hooks are less traumatic to the pupil.
Figure 196: Alcon-Grieshaber Flexible Iris Retractor for Small Pupil The flexible iris retractor is a safe alternative for temporary iris fixation in cases where dilatation cannot be achieved pharmacologically and when the pupil is not fibrosed and can be stretched. The retractor is made of prolene and a flexible tab (H) made of nylon holds the hook in position once in the eye. Four self-sealing 0.5 mm stab paracentesis incisions are made in the peripheral cornea at the 10:00, 2:00, 4:00 and 8:00 o’clock meridians. The hooks (H) are inserted through the paracentesis incisions (P) and engage the iris at the pupil margin (arrow - 1). The pupil is forcibly enlarged by pulling the hooks outward (arrow - 2). The final position of the hooks is fixed by adjusting the flexible nylon tab toward the eye (arrow - 3). Inset shows surgeon’s view of the final configuration of the retractors and the resulting pupil shape.
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Figure 197: Phacoemulsification in Small Pupils Beehler’s Pupil Dilator The Beehler’s pupil dilator (B) allows dilation in three directions with only one maneuver. Three arms (A) extend from inside the instrument and exert distention on the margins of the pupil. The same instrument also stimulates a discrete retraction of the iris in the direction of the corneal or scleral tunnel incision (T).
When the pupil margins are heavily fibrosed this method will not achieve adequate pupil dilation, or the pupil margin may be severely traumatized. Padilha considers that, of all the available mechanical resources, the one that has contributed the most safety and satisfaction in the management of small pupils is the flexible iris retractor (Alcon-Grieshaber) (Fig. 196). These retractors are extremely useful, even if placing them requires extra time. After the placement of the first or the second retractor, the anterior chamber may need to be refilled
with viscoelastic to facilitate the introduction of the other two.
B) The Beehler Pupil Dilator Padilha uses this instrument when the other options outlined above have not been effective. This dilator, made by Moria, in France, allows dilatation in three directions with only one maneuver (Fig. 197). Moreover, it provokes a discrete retraction of the iris in the direction of the corneal or scleral tunnel incision. 331
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C) The Silicone Expander Ring In more severe cases, Padilha uses a silicone ring with an indentation, which fits all along the edge of the pupil. This presents some advantages. Using this technique the iris fits like a tire around the ring, which is like an iron wheel (Fig. 198). Among its disadvantages is the fact that it can loosen itself easily with intraocular maneuvers during the phaco procedure. Known as Graether’s pupil expander (EagleVision #1540) it has three components: the preloaded expander, a disposable insertor and a glide retractor of the iris. (The use of this ring is controversial - Editor).
Padilha emphasizes that stretching maneuvers using mechanical dilators may induce a certain degree of iris atony. This predisposes the iris margins to insinuate into the titanium tip, during the phaco maneuvers, leading to injury of the sphincter and the iris tissue. The same can occur with sector iridectomies, which can also predispose the iris to the development of synechiae to the anterior capsule during the postoperative period, requiring the administration of miotic drops for some time.
Figure 198: Phacoemulsification in Small Pupils Adjustment of the Silicone Expander Ring Once the silicone expander ring (E) is in position, Padilha slides out the iris retractor glide (not shown) and adjusts the final placement of the silicone expander using two Sinskey hooks (H).
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TRAUMATIC CATARACTS Overview
Highlights of Examination
The complex repair of an eye injury is best when a team which shares anterior and posterior segment skills work together in primary and secondary management. Almost all bad results following ocular trauma occur in injuries involving the posterior segment, particularly when the lens is also damaged
The ophthalmologist must examine the patient carefully. The examination should begin with an assessment of the visual function, if there is light perception or light projection. The prognosis is better if there is good light projection. Then the eye should be examined in the usual way with the direct ophthalmoscope and the slit lamp. In many cases the fundus cannot be visualized because of the presence of opaque media: cornea, lens, and vitreous hemorrhage. The presence of a foreign body must be definitely excluded. It is important to search for anatomically related trauma. Individual intraocular structures are not often damaged alone. In severe injuries, the full extent of damage is obscured by blood or opacities in the media . Special assessment is needed before planning surgery to establish the extent of damage and the visual potential. There may be no light perception in the presence of a complete vitreous hemorrhage until the hemorrhage clears. In such cases diagnostic imaging is invaluable.
Assessment of the Injured Eye The circumstances of the injury and the early clinical assessment give important information that will determine the early management and help to predict complications. As pointed out by Michael RoperHall, M.D., an accurate history is essential. This can be very helpful in indicating the nature and extent of injury. The true history is sometimes elusive, especially when children are involved, or there is potential for litigation. The injuries that cause traumatic cataract occur not only from serious penetrating trauma, but also from blunt injury. Most blunt injuries are not severe enough to cause rupture of the sclera. In evaluating and managing all blunt injuries, it is important to recognize that each ocular tissue, from the cornea to the posterior choroid, may have been damaged by the impact. Therefore, management is based on identifying the affected tissues, understanding the pathophysiology of events that can occur after a blunt injury, and anticipating possible secondary complications.
Diagnostic Imaging B-scan ultrasonography should be used to identify the presence of a foreign body and where is it precisely located, the amount of vitreous hemorrhage present and the condition of the retina. Ultrasound imaging also demonstrates changes in lens position; posterior rupture of the lens; cyclitic
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membrane; hemorrhage into the vitreous; separation of the vitreous from the retina; and retinal detachment, which are obscured to direct examination (Fig. 199).
Combined Injuries of Anterior and Posterior Segment A damaged lens mixed with blood and vitreous needs prompt and adequate surgery. Failure to remove this debris encourages fibrosis with a cyclitic membrane causing ciliary body detachment and hypotony eventually leading to retinal detachment and phthisis bulbi.
Traumatic Cataracts in the Presence of Anterior Segment Penetrating Wounds Main Objectives In anterior segment injuries the initial objectives are watertight repair of the corneal wound, restoring normal depth to the anterior chamber, intensive antibiotic treatment to prevent infection and intense antiinflammatory therapy from the very start. The further goals are to manage the cataract adequately, reduce secondary damage by minimizing excessive corneal scarring; assuring a clear, adequately sized and cosmetically and optically desirable pupillary opening; and preventing further damage to the anterior chamber angle that could result in glaucoma. Often all of these objectives can be achieved at the time of initial wound repair although in some cases further surgical procedures are needed. The traumatic injury may have caused a lens anterior capsular
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defect either from a blunt rupture or a sharp laceration.
MANAGEMENT OF TRAUMATIC CATARACT Robert Stegmann, M.D., has very extensive experience in trauma cases. He believes that the prognosis for a traumatic cataract can be the same as for a routine senile cataract if the traumatic cataract is handled properly. This excludes cases in which there is damage to the posterior segment, the vitreous has become cloudy, or the retina is damaged from the same trauma, or where infection has occurred.
Small Wounds in Anterior Capsule In many cases a penetrating wound in the cornea and lens is small, the lens material still remains within the capsule and, even though cloudy, it may not escape through the tiny capsular tear (Fig. 200). Prof. Giora Treister from Israel recommends that in such cases, the lens be left alone during the first surgical intervention. He repairs the primary wound and goes no further at this time because generally these are the worst conditions for operating on the eye. The tissues are swollen and irritated, and perhaps even infected. The trauma may have occurred at night. In case of unexpected complications, the most experienced surgeons are not on duty. If it is not absolutely necessary to go further with the initial procedure, Treister recommends that it will suffice to close the primary wound and to concentrate on proper reconstruction later.
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Figure 199 (above): Importance of Diagnostic Imaging in Traumatic Cataracts In addition to studying the cataract itself, B-scan ultrasonography demonstrates changes in lens position; posterior rupture of the lens; cyclitic membrane; hemorrhage into the vitreous; separation of the vitreous from the retina; and retinal detachment, which are obscured to direct examination. Figure 199 shows a polaroid photo of a B-scan ultrasound.
Figure 200 (below): Traumatic Cataract from Small Penetrating Wound in the Cornea and Lens This cross section of the anterior segment of the eye shows a damaged lens with an anterior capsular tear (T). The lens is cloudy but lens material has still not escaped through the capsular tear. In such cases, Dr. Treister repairs the primary corneal wound (W) at this time and goes no further (assuming that the posterior segment of the eye is not involved in the trauma). A few days later when the eye is less irritated, lens extraction and IOL insertion can be performed.
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If Anterior Capsule More Widely Damaged
Timing for Primary Lens Extraction
If the anterior capsule is more widely damaged and lens material is present in the anterior chamber, (Fig. 201) Treister removes all the lens material during the first surgical intervention and examines the posterior segment with the indirect ophthalmoscope. If the trauma is confined to the anterior segment, the vitreous is clear, the retina is attached without retinal tears and no foreign body is seen, a posterior chamber lens is implanted .
John Alpar, M.D., who has extensive experience with traumatic cataracts, considers that a primary lens extraction should occur any time the lens is so damaged that its particles are mixed with anterior chamber or vitreous material. The lens should also be removed in cases of subluxated lens following trauma. The advantages of a primary operation in these cases are that postoperative inflammation is reduced, rehabilitation time is faster, and later examinations, including the evaluation of the retina, are easier to perform.
Figure 201: Traumatic Cataract with Anterior Capsule Widely Damaged Lens material is present in the anterior chamber. Viscoelastic has been injected into the anterior chamber. The AC is irrigated (blue arrow) with BSS and the debris, pigment residues, fibrin and lens material (D) are washed out of the eye (red arrow). Lens damage shown in (L).
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The most important indications for primary operation are signs that point to the likelihood of a ruptured posterior capsule with vitreous already entering the chamber.
More Extensive Damage Affecting Posterior Capsule In case of perforation of the lens with an opening also in the posterior capsule, Treister as well as Stegmann in South Africa remove the vitreous from the anterior chamber (if present) with a vitrector together with the lens material but try to preserve the posterior lens capsule, or part of it, for sulcus-placed posterior IOL implantation.
Specific Problems with Traumatic Cataracts Paul Koch, M.D., points out that zonules are often torn and there may be significant risk of collapse of the posterior capsule as well as vitreous prolapse around the equator of the lens. Consequently, in the preoperative evaluation with the slip lamp, look carefully for evidence of zonulysis.
HIGHLIGHTS OF SURGICAL TECHNIQUE The Incision A sclero-corneal tunnel (Fig. 40-B) is definitely the incision to be used. A corneal tunnel incision is contraindicated. The conjunctiva must be treated very delicately. Some of these patients may develop second-
ary glaucoma and might need a filtering operation at a later date.
Anterior Capsulorhexis In many cases the anterior capsule has been perforated. A CCC may be quite difficult and sometimes risky. Paul Koch has advocated that a better way to open the unsupported part of the anterior capsule ruptured zonules is to use capsule scissors. A puncture can be made in the anterior capsule, scissors introduced with one blade through the puncture, and a snip capsulotomy performed. Koch points out that pulling inward to create a capsulorhexis with a needle or forceps could be dangerous, dislocating the lens beyond the point of recovery. Other parts of the capsule, where the zonules are intact, may be opened in the usual fashion. The circular anterior capsulotomy should be made large enough so that the nucleus can be floated out of the bag with hydrodissection. Typically this occurs easily because the nucleus is white, soft and fluffy. In performing the anterior capsulotomy, if the cataract is white, the use of Trypan Blue as shown in Figs. 101 and 102, page 173 may increase the possibility for performing a successful capsulotomy.
Lens Removal In the presence of traumatic cataract, phacoemulsification is done in the anterior chamber. Once the nucleus enters the anterior chamber, viscoelastic can be placed above and below it, protecting the cornea and pushing the flaccid capsule as far posteriorly as
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Figure 202: Concept of Intracapsular Tension Ring in Traumatic Cataracts and Subluxated Lenses (A) The intracapsular tension ring (R) is an open circular PMMA ring inserted (arrows) into the capsular bag (C) via an injector (I) through a 3.5 mm incision. Both ends have a small eyelet (E) for better maneuverability with a hook during implantation. The ring lies at the equator of the capsular bag and so maintains the capsular bag shape. An IOL can then be implanted into the capsular bag with the ring in place. (B) Shows an isolated view of the entire capsular bag with the ring (R) and IOL (L) in place, with haptics of the IOL (H) properly positioned within the distended bag. The intracapsular ring distributes the forces (arrows) inside the capsular bag, thereby making it possible to work safely. Asymmetrical collapse of the bag and decentration of the IOL is prevented.
possible. In a young patient the nucleus is usually very soft and is amenable to many different options. For a patient with an intact capsulorhexis, phaco-aspiration of the nucleus is safe and effective. If an anterior or posterior capsular tear is present, then manual aspiration with a Simcoe-style cannula affords greater control. «Dry» aspiration of the soft nucleus under viscoelastic material offers excellent control, especially in the most complicated cases, as advocated by Snyder and Osher.
Role of Intracapsular Tension Ring in Traumatic Cataracts This is an important advance in cataract surgery. The ring is a relatively 338
recent development, as advocated by Robert J. Cionni, M.D., in the U.S. and Okihiro Nishi, M.D., in Japan. This device maintains the shape of the bag during and following extracapsular surgery or phacoemulsification in traumatic cases or in patients with subluxation or pseudoexfoliation. It has important implications in terms of preventing IOL dislocation, decentration, tilting, further zonular dehiscence, and posterior capsule opacification. The capsular tension ring (or intracapsular ring), is an open circular PMMA haptic (Fig. 202). It can distribute the forces inside the capsular bag, thereby making it possible to perform surgery safer, and decentration of the IOL is prevented. In the management of traumatic cataracts, the ring is placed in the bag for support,
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provided that there is an intact anterior capsulotomy and posterior capsular bag. In some cases it will be easy to place it prior to emulsification of the nucleus, while in other patients it is better to place it prior to cortical aspiration. This will stabilize the capsule and support the areas lacking zonules. Once the capsule is secure, the cortex can be removed and the implant placed. If necessary the ring can be sutured transsclerally..
Removal of Cortex After nucleus removal, before proceeding with cortical aspiration, inspect the posterior capsule carefully to be sure that there are no tears as a result of the injury, particularly a blunt injury, where tears might be hidden. If the capsule is intact, proceed as usual, following the principles and techniques outlined in Figs. 127 and 128. In case of doubt about the effects of automated irrigationaspiration, you may use the manual aspiration with the Simcoe-type cannula, as shown in Fig. 128. This allows a greater degree of control.
Selection of IOL Traumatic cataracts may be associated at a late date with some vitreoretinal complications. PMMA and acrylic lenses are well tolerated by the eye and preferred by the vitreoretinal surgeons. Since traumatic cataracts are not uncommonly associated with some degree of traumatic mydriasis, a 6.0 mm or larger diameter IOL optic is a prudent choice.
IOL Implantation With the support and stability of an intracapsular tension ring, the placement of
the IOL in the capsular bag is indicated and desirable. If an intracapsular ring is not available and only a small area of zonular dehiscence is present, slowly unfolding the implant or very gently placing a rigid lens with soft loops will minimize the stress on the intact remaining zonules. Ciliary sulcus placement of a posterior chamber implant is still possible in the setting of a posterior capsular tear or zonular dialysis (Figs, 153, 154, 156). If the anterior capsulorhexis is intact, yet a severe posterior capsule break exists, the haptics should be placed in the sulcus. It may be possible to capture the lens optic posteriorly into the capsulorhexis. This will provide adequate support and will prevent the lens from subsequently dislocating. If the capsulorhexis is incompetent or larger than the implant optic, sulcus fixation with a large diameter implant can be utilized.
Selection of Viscoelastic in Traumatic Cataracts In those eye centers where the two main types of viscoelastics are available (dispersive and cohesive), the following are good choices as advocated by Snyder and Osher: 1) When the hyaloid face is partly exposed, a highly retentive (dispersive) viscoelastic agent such as Viscoat (Alcon) or Vitrax (Allergan), may tamponade the vitreous and keep it back. The dispersive agents also protect the endothelium well. This may be particularly important in cases in which the endothelial cell density has been reduced by the trauma. 2) On the other hand, the space retaining qualities and ease of removal typical of highly cohesive viscoelastic agents, such as Healon GV (Pharmacia & Upjohn), make these agents more appropriate for the lens implantation stage of the procedure. 339
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Phacoemulsification Advantages in Traumatic Cataract Traumatized eyes with potentially weakened zonules are at greater risk for suprachoroidal hemorrhage. Maintaining a closed system as provided by phacoemulsifi-
cation reduces the risk of expulsive hemorrhage. In addition, a closed system allows compartmentalization within the anterior segment. If the posterior capsule is broken or if a zonular dehiscence is present, viscoelastic tamponade of the vitreous can be best maintained in the setting of a closed system.
PHACOEMULSIFICATION IN SUBLUXATED CATARACTS Strategic Management Phacoemulsification is performed in a totally closed system, where the ultrasound tip blocks the incision, allowing the volume of aspirated masses to equal the volume of liquid injected into the anterior chamber, thus maintaining stable intraocular pressure throughout the surgery. The space available for disassembling the cataract is extremely small, limited anteriorly by the corneal endothelium and, posteriorly, by the posterior capsule. If the zonules sustaining the crystalline lens are weak, broken or nonexistent, in part or totally, or when the posterior capsule is ruptured, a delicate and risky situation may arise unless we are ready to manage it effectively.
MANAGEMENT DEPENDING ON SIZE OF ZONULAR DIALYSIS When confronted with a zonular rupture, Padilha recommends adopting the following strategies: 1) If during biomicroscopy at the office, under mydriasis and with a slit lamp, a small or moderate zonular dialysis is detected, which does not 340
extend to more than 45º of the crystalline lens circumference, and we can see an excellent red retinal reflex, it is almost certain that a phacoemulsification can be accomplished safely. The hydrodissection must separate the lens capsule from the cortex by injecting balanced salt solution (BSS) under the anterior capsule, and the hydrodelamination must attain consistent detachment of the nucleus from the epinucleus (Fig. 203). The sharp separation of these structures will significantly reduce the tension on the fragile zonules during disassembling of the nucleus and aspiration of the residual cortex. 2. a) If the damage to the zonular fibers extends to more than 45º and the cataract has a hard nucleus with a retinal reflex turning brown, or b) the dialysis extends to 180º, the insertion of an intracapsular tension ring (Fig. 202) will be extremely useful to better support the crystalline bag throughout the surgical procedure, reducing the chances of dislocation of the cataract into the vitreous. This is true even in cases of soft cataract. The use of the intracapsular tension ring is also valid for cases with pseudoexfoliation and ectopia lentis – as in the Marfan syndrome and others.
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3. On the other hand, if there is a very extensive damage to the zonular fibers with a dialysis of more than 180º, Padilha considers that phacoemulsification or even a planned extracapsular extraction may not be sufficiently safe, even with the help of the intracapsular tension ring (Fig. 202), espe-
cially in cases of hard cataracts. In these patients, Padilha advocates performing an intracapsular extraction associated with a Kelman anterior chamber implant, or a posterior chamber lens fixated to the sclera (Fig. 156). He considers this to be a more prudent solution.
Figure 203: Subluxated Cataracts - Hydrodissection The cannula (C) is positioned under the anterior capsule (A) and the BSS is injected separating the cortex from the nucleus and epinucleus. This maneuver is repeated in order to create a clear cleavage plane. Too much irrigation must be avoided. Otherwise, it may produce a dangerous blocking of the nucleus against the margins of the anterior capsulotomy. This could give rise to a sudden dislocation of the cataract into the vitreous (V) by creating a tear of the posterior capsule (P).
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Special Precautions with Subluxated Cataracts Padilha points out that some important issues should be considered when subluxated cataracts are approached.
Anterior Capsulotomy Anterior capsulotomy should be performed as a continuous curvilinear capsulorhexis (CCC). The surgeon needs to use extreme caution starting with a bent needle and completing it with this same instrument or with the Uttrata’s or similar forceps. If any problem arises at the time of the anterior capsule perforation with the cystotome (bent-needle) the surgeon may begin the capsulorhexis with a pinch-type forceps such as the Kershner capsulorhexis cystotome-forceps (Rhein Medical). The maneuvers should be executed very carefully and smoothly so as to prevent further damage to the zonules. The diameter of this capsulotomy should not be very large. Reaching the equatorial region must be avoided at all costs. (Editor’s Note: I also refer you to the discussion of Traumatic Cataracts complicated by some zonular dialysis, in which Paul Koch recommends using scissors to perform the anterior capsulotomy so as to not exhert further pressure on the weakened zonules with the maneuvers of a standard capsulorhexis.)
Characteristics of Viscoelastics Used Another important issue involves the use of viscoelastic substances. It is important to combine one viscoelastics with cohesive
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properties, with another of dispersive properties, which scatters and adheres to instruments or tissues. While the latter will protect the damaged zonular area, by adhering to adjacent tissues of that region and helping prevent an eventual escape of the vitreous, the cohesive viscoelastic will press down upon the anterior face of the crystalline lens, transforming it into a convex surface, and facilitate making the CCC. Such convexity will help channel the zonular tear in the direction of the center of the capsule and not toward the periphery because of the centrifugal force generated above the surface (Fig. 204). (Editor’s Note: A very clear definition of the qualities of the cohesive and the dispersive viscoelastics, and how they differ from one another, is presented at the beginning of this Chapter).
Additional Measures to Reduce Risks 1) Padilha recommends that the phacoemulsification incision, whether in clear cornea or a scleral tunnel, should be placed as far away (circumferentially) as possible from the damaged zonular region. This is to prevent extension of the zonular dialysis by the insertion and withdrawal of instruments in the interior of the eye precisely in the most affected area. If the zonular rupture is located in the superior quadrants a superior temporal incision will make surgery more demanding and risky. 2) To further reduce risks, Padilha advises the use of disposable plastic flexible iris retractors, which will help sustain and stabilize the crystalline bag. The flexible hooks are anchored in the borders of the CCC, in exactly the way we use them in
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Figure 204 (left): Subluxated Cataracts - Use of Dispersive Viscoelastic An important issue involves the use of viscoelastic substances. These substances should have characteristics such as viscosity, pseudoplasticity, coatability and elasticity, which will allow various maneuvers during the surgical procedure. This view shows a cannula (C) inserted under the iris (I) in the region where a zonular dialysis (ZD) is present, injecting a dispersive viscoelastic, closing the damaged zonular area and lessening the chances of an eventual vitreous escape.
Figure 205 (right): Subluxated Cataracts - Helping Support of Capsular Bag with Flexible Iris Retractors To provide more support to the capsular bag, flexible iris retractors (F) are fastened to the borders of the anterior capsulotomy (C). The retractors are inserted through four opposite ancillary incisions. Once the retractors are in position (F), the capsulorhexis (C) is carefully put on stretch, without much traction. Then the surgeon may proceed with phacoemulsification using very low parameters such as vacuum less than 150 mmHg, low irrigation and reduced ultrasound power (less than 70%). Phaco probe (P).
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order to dilate small pupils (Figs. 205 and 196) except that the retractors are placed in the margins of the anterior capsulotomy instead of the margins of the pupil. 3) During disassembling of the nucleus, maneuvers to rotate the nucleus should be reduced to a minimum. In order to prevent the need for these maneuvers, hydrodissection and hydrodelamination should done carefully but thoroughly. 4) Padilha recommends that the intracapsular tension ring be introduced after the hydrodelamination is completed and before emulsification (Fig. 202). This is another very important measure to provide support to the capsular bag. Usually the ring is held by a long Kelman-McPherson forceps and introduced clockwise. When operating on the right eye using a superior sclero- corneal tunnel incision, the ring is moved 1 hour in the direction of 3 o’clock and 6 o’clock. A spatula—preferably Koch’s spatula—is used to facilitate the insertion of the ring in the correct position inside the bag. These rings come in different sizes. They are produced by Morcher GmbH, Germany, and Corneal, France, and will be commercially available through Alcon in the near future. If an accidental cataract subluxation occurs during a conventional cataract surgery, the surgery must be interrupted and the ring should be introduced as described above. In these cases, Padilha prefers to implant a one-piece intraocular lens, all PMMA, inside the capsular bag and to make its length coincide with the meridian where the zonular rupture occurred.
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Increasing the Safety of Posterior Lens Implantation in Extensive Zonular Disinsertion In those cases where a more extensive zonular disinsertion is present, it is important to create safer conditions to implant a lens in the posterior chamber. Variations and constant improvements of this technique have been presented at various meetings and publications by many authors, especially Drs. Jorge Villar-Kuri, from Mexico, Robert Osher, from the United States, Yoshihiro Tokuda, from Japan, Charlotta Zetterstrom, from Sweden, among others. Some guidelines are basic and very important in these extreme situations, including cases of Marfan’s syndrome. The surgeon should always opt for a small capsulorhexis using a bent needle, and carry out the hydrodissection very carefully. Padilha considers there are at least three options in order to increase the safety of the posterior chamber lens implantation. The first consists in totally removing the capsular bag following removal of the cataract. This could be indicated in certain situations where the lens is too dislocated either superiorly or inferiorly, and vitreous loss is present. Following a generous anterior vitrectomy using an automated vitrector, the intraocular lens is sutured to the sclera, (Fig. 156).
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Figure 206 (above): Subluxated Cataracts - Fixation of the Anterior Capsule to the Ciliary Sulcus - Stage 1 Once the capsular bag is filled with viscoelastic, the anterior capsulotomy (C) is enlarged to the left and right using Vannas scissors (V). This allows the capsule to distend and allow more space for the insertion of the IOL.
Figure 207 (below): Subluxated Cataracts - Fixation of the Anterior Capsule to the Ciliary Sulcus - Stage 2 A prolene 10-0 suture (P) is carefully inserted in the anterior chamber and through the anterior capsule flap (C) that has been created with the scissors, in a curved “U”. Take care to ensure that the endothelium is not touched. Scleral flap in the inferior part of the globe for final fixation of sutures (F).
Fixation of the Anterior Capsule to the Ciliary Sulcus The second option to increase the safety of the posterior lens implantation and to prevent it from dislocating is to actually suture the anterior capsule to the ciliary sulcus. This is done so that when the IOL is sutured and implanted, it will remain in place.
This technique involves making two incisions in the anterior capsule, through the small CCC (Fig. 206), as in the intercapsular technique advocated some years ago by Sourdille and Galand. The borders of the free edge of the capsule should be folded and sutured to the sclera at the opposite side of the luxation, as suggested by Villar-Kuri . The step-bystep technique is shown in Figs. 206-210.
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Figure 208 (above): Subluxated Cataracts - Fixation of the Anterior Capsule to the Ciliary Sulcus Stage 3 Viscoelastic is reinjected in the anterior chamber. Through an inferior triangular scleral flap (F), 2.0 mm from the limbus, the surgeon introduces a straight, long, 25 gauge needle (N), emerging through the primary incision (M), with its bevel up. Into its bore the surgeon inserts the C7 needle (magnified inset), and slowly pulls the long needle until it goes out of the globe through the inferior scleral flap.
Figure 209 (center): Subluxated Cataracts Fixation of the Anterior Capsule to the Ciliary Sulcus - Stage 4 The suture is used to pull up the anterior capsule (C) to the inferior scleral bed (S). The knot is buried inside the sclera, closing the scleral flap (F) with a 10-0 nylon suture (N).
Figure 210 (below): Subluxated Cataracts - Fixation of the Anterior Capsule to the Ciliary Sulcus Last Stage At this point the anterior capsule (C) is fixed to the ciliary sulcus to permit more space and safety for the IOL insertion. Finally, the IOL of the surgeon’s choice (L) is implanted, placing it in a position perpendicular to the disinsertion. The primary incision is closed with a horizontal 10-0 nylon suture (N).
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CATARACT SURGERY IN CHILDHOOD Previous Controversies Now Resolved Cataract surgery in the pediatric patient and the post op management of these children is still a complex problem, but significantly less than up to five years ago. The difficult controversies previously existing regarding finding solutions for their visual recovery have been solved in most cases. These controversies are:
1) Age and Timing for Surgery Bilateral Cataracts It is now generally agreed that early cataract surgery in bilateral cataracts and immediate optical correction can prevent otherwise irreversible deprivation amblyopia in the child born with dense cataracts. Unless this is done, children with bilateral cataracts who undergo surgery later in childhood or in their teens recover only limited visual acuity, usually an average of no better than 20/60. Optimum optical correction following surgery is more effectively done today with IOL implantation. In infants with bilateral cataracts, despite an increased complication rate, surgery must be performed within the first months of age to avoid irreversible amblyopia. Cataract surgery in children over the age of 1 year is less complex with a higher success rate and with fewer complications in the postoperative period. It is best to perform surgery in both eyes at the same «sitting». Sterility must be maintained during the whole
procedure in bilateral cases. This requires changing all instruments and sterile clothing of the surgeon, nurse and patient between eyes. Patching is not indicated. General anesthesia is used in all cases.
Unilateral Cataracts Unilateral congenital cataract presents a more challenging problem, since even a mild cataract will cause irreversible deep amblyopia in one eye if not treated. Treatment is based on surgery within two months of life, prompt optical correction with intraocular lens implantation and aggressive occlusion therapy with frequent follow-up have been successful in several series.
Preconditions to be Met for Useful Vision In cases of unilateral cataracts, if cataract surgery with IOL implantation is not done very early in life, the chances of achieving good vision are slim. It is possible to achieve useful vision in some children with monocular congenital cataracts provided certain important preconditions are met. The most important is the age at which the surgery is undertaken along with equally important immediate optical correction and occlusion therapy as emphasized by Noel Rice, M.D. at Moorfields Eye Hospital in London and Eugene Helveston, M.D. in the U.S. years ago. These preconditions continue to be valid. It is essential first to provide a focused image and second, eliminate suppression. This «triumverate» or «troika» of treatment is the key to success. To a great
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extent, the ophthalmologist depends on other professionals who determine when the cataract is identified and referral takes place. If the child does not present to the ophthalmologist within the optimal period for surgery and optical rehabilitation, clearly the ophthalmic surgeon is considerably constrained in the quality of care he/she can provide. Timing is absolutely the key. If the surgeon decides to operate on a unilateral cataract, the family needs to expect the very high likelihood of only a helper eye, and not an eye that will have very good vision. It is important to acknowledge this limitation.
Role of Parents Their role is absolutely essential for achieving a good result. The surgeon would be wise to take this factor into consideration before undertaking treatment. Parents who do not understand what they and the child need to go through for pre and postoperative management to prevent and «conquer» amblyopia, become the first contraindication to surgery. This is particularly important in unilateral cataracts in which prolonged amblyopia treatment is essential.
Importance of Asymmetrical Visual Input The period of sensitivity of the visual system and its responsiveness to the development of vision through having a good visual input in humans is still not precisely determined, but we know that it is most responsive during early infancy, and it falls off rapidly during the first year of life. The clinical research made by Rice at Moorfields and Von Noorden in the U.S. determined
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that the implications of asymmetrical input into the visual system are vitally important, particularly in relation to unilateral congenital cataracts.
When Should We Not Operate? Any unilateral lenticular opacity that is moderately severe will cause amblyopia. If management as here described is not possible very early in life, it may be best if we advise against it. Very mild unilateral lenticular opacity, may be best left alone. Removing a small unilateral cataract that causes a small degree of amblyopia creates aphakia, which may lead to even more amblyopia, unless we implant the adequate IOL and undertake aggressive occlusion therapy.
Preoperative Evaluation History In the workup of a child with cataract, a detailed history is necessary. It is important to determine whether the cataract is progressive, particularly in older children. Contrary to some earlier teaching, we now know that bilateral cataracts are often progressive. Frequently, in children from ages 3 to 6 and even of high school age, vision is gradually diminished bilaterally because of progressive congenital cataracts. As pointed out by Charlotta Zetterstrom, M.D., PhD, of Stockholm, Sweden, in a clinically healthy child, an extensive preoperative evaluation to establish the cause for the cataract is not routinely necessary. Congenital cataracts are frequently inherited as an autosomal dominant trait but a recessive inheritance also occurs.
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It is important, to rule out metabolic disorders, genetically transmitted syndromes, intrauterine infections and ocular conditions with associated anomalies.
Examination The workup of the congenital cataract patient continues with the office examination. Infants with congenital cataracts generally resist having their eyes examined, and do not cooperate with the examining physician. This causes considerable stress in the family. The ophthalmologist must use special examination techniques. First, the light should be turned down to low levels of illumination, which causes the eyes to open immediately. Direct illumination is used to determine the extent of the opacity. The red reflex should first be determined by direct ophthalmoscopy with the pupil undilated. The cataract is often most dense in the central part of the lens and after dilatation it seems to be less significant. While the newborn child is awake it is also important to assess visual function, if possible, with a Teller acuity card. Watch for the ability to fix and follow with an object that attracts attention. Clarify with the parents whether they have had any visual interaction with the child. Children with significant bilateral congenital cataracts may seem to have delayed development as well as obviously impaired visual behavior. Children with monocular cataracts often present with strabismus, which however may not develop until severe irreparable visual loss has occurred. Children with monocular cataract are almost always detected much later than cases with bilateral cataract. The presence of nystagmus
at the age of 2-3 months generally indicates a poor visual prognosis. Complete examination of infants with dilated pupils often requires sedation or general anesthesia and can be performed during the same anesthesia as the surgery although, if possible, days before surgery, so that the surgeon can be better informed to enable him/her to make adequate decisions, and to inform the parents properly. Measurement of the corneal diameter, intraocular pressure using a handheld tonometer, type and density of the cataract by photography, are all part of a good examination in these patients. Zetterstrom emphasizes that when the clarity of the media permits, indirect ophthalmoscopy may reveal persistent fetal vessels or other posterior segment abnormalities that may have an impact on the visual outcome. A-scan measurement of the axial length, and keratometer readings are done. These are essential measurements for contact lens and IOL power calculation. Newborn eyes with congenital cataract are shorter and have a smaller corneal diameter compared to controls (Fig. 31 and text pages 54-56). A B-scan ultrasound is also performed in cases in which visualization of the retina is impossible, in order to determine whether there are retinal abnormalities, masses, or the presence of hypoplastic primary vitreous. Helveston considers it important to determine the intraocular pressure because there is a significant relationship between reduced corneal diameter, intraocular pressure, and the presence of glaucoma. One of the most serious problems in the management of congenital cataracts, particularly bilateral congenital cataracts, is the glaucoma that may occur 5 to 10 years after successful cataract
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surgery treatment. This glaucoma resembles chronic simple glaucoma in the adult patient. While the intraocular pressure may show only a modest increase, glaucoma in children can be extremely resistant to successful treatment. If not controlled, it can cause the same type of atrophy in the optic nerve that occurs in chronic simple glaucoma.
The Special Case of Lamellar Cataracts Saunders, the founder of Moorfield’s Eye Hospital, determined 200 years ago that lamellar cataracts often do not interfere at all or at a rather insignificant level with visual development. The lamellar cataract looks central and quite dense on retroillumination, but is revealed under slit-lamp illumination as definitely lamellar. Children with lamellar cataracts usually achieve very good vision if these cataracts are operated on much later in life, even late in childhood or the teens or twenties. Patients do not usually develop nystagmus and often achieve normal or near normal vision. The corollary is that there is no need to operate on these children in early infancy. The prognosis is better if operated when older, when visual development is complete. An accurate calculation of IOL power can be made, with a better visual result. In his clinical research, Rice observed that in many children with lamellar cataracts, if ophthalmoscopy is undertaken even with a reasonably dilated pupil, the view of the fundus is often extremely obscured; in fact, there may not even be any red reflex. If eyes are examined fully, however, it can always be seen that there is clear cortex. If there is a reasonable view of the peripheral fundus
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through the peripheral lens, there is no indication for precipitous and early surgery. Such cases can be treated very conservatively. These patients often have vision sufficiently reduced in primary and early secondary school years to benefit from cataract removal and IOL implantation between ages 5 and 15 or even a little earlier.
Rubella Cataracts These cataracts used to be an important source of blindness. Rubella cataracts tend to be bilateral and progressive and result in a membranous type of partially resolved cataract, posterior synechiae, and chronic uveitis. For the past 25 years, since rubella immunization has been available, rubella cataracts have been virtually nonexistent. The key point in managing these rubella cataracts is not to aspirate them incompletely because eventually the eyes are lost. The process of aspiration reactivates the virus.
The Need for Close Monitoring These children should be closely monitored. This includes evaluating visual development to be sure it is proceeding in a satisfactory manner. The surgeon’s responsibility is to both nurture the process of sight and to help prevent amblyopia. Otherwise, the outcome will be poor because of insufficient attention to the anti-amblyopia treatment.
Preoperative Considerations The most important relates to the calculation and selection of the type of IOL to
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be used and its correct power. The method and the considerations relating to IOL power calculation in pediatric cataracts is amply and clearly presented in pages 54, 55, 56 and Fig. 31, page 56.
The Decision to Implant IOL’s in Children with Cataract Surgery How to optically correct patients with bilateral congenital cataracts and monocular congenital cataract has been a major subject of controversy for many years. Some distinguished ophthalmic surgeons 20 years ago were strongly against performing surgery in monocular congenital cataract followed by treatment of amblyopia with a contact lens. Visual results were so bad that children with this problem must be amblyopic by nature, they thought, and the psychological damage to the children and the parents by forcing such treatment was to be condemned. Surgery of bilateral congenital cataracts at a very early age followed by correction with spectacles and sometimes with contact lenses usually ended with no better than 20/60 vision bilaterally. This was again a source for the belief that congenital cataracts either unilateral or bilateral were by nature associated with amblyopia, profound in cases of monocular cases and fairly strong in bilateral cataracts. When posterior chamber IOL implantation in adults became established as the procedure of choice, strong influences within ophthalmology were adamantly opposed to their use in children for the following reasons: 1) the eye grows in length with consequent significant change in refraction. It was considered impossible to predict such change
and consequently, the accurate IOL power adequate for each child. 2) There was opacification of the posterior capsule in most cases. This required a second operation for posterior capsulotomy and the presence of an IOL would impede proper surgical maneuvers. The situation has now significantly changed. The previous failures with spectacles and contact lenses, the new developments in technology and surgical techniques and the fresh insight of surgeons of a new generation have led us to discard the previous thinking and to consider the implantation of posterior chamber IOL’s a very positive development in children. This has been made possible by the following developments: 1) new medications that effectively prevent and/ or control inflammation. 2) The introduction of posterior capsule capsulorhexis by Gimbel in North America promptly followed by Everardo Barojas in Mexico and Latin America (Fig. 30). 3) High viscosity viscoelastics to facilitate intraocular surgery in smaller eyes. 4) New, more appropriate IOL’s for children and implantation in the capsular bag. 5) Refined technology that leads to a more precise calculation of the IOL power.
A «Major» Controversy No More The controversy as to whether to implant IOL’s or not in the management of cataract surgery in children has been almost resolved. At present, most surgeons place intraocular lenses, whether treating congenital cataracts or traumatic cataracts, following evidence that they can be safely tolerated in most children. The informed consent discussion with the parent or guardian, however, should include the fact that intraocular lenses
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have still not been approved by the FDA for use in children. This is a matter of particular importance in the U.S. The previously existing controversy of the timing of the IOL implantation in children has also been resolved as a consequence of experience. Intraocular lens implantation may be significantly easier at the time of cataract extraction than at a later date, since iridocapsular adhesions and fusion of the anterior and posterior capsular flaps make a subsequent secondary implant procedure more challenging.
Surgical Technique The Incision A sclero-corneal tunnel 3.5 to 3.8 mm wide is the procedure of choice (Fig. 40-B). Manage the conjunctiva very carefully in case the patient develops secondary glaucoma later in life. Because the sclera is soft and elastic in children, it is hard to achieve a selfsealing incision. Consequently, the incision should be sutured.
The Anterior Chamber and Pupil High-viscosity viscoelastic material is used because the anterior chamber is shallow in these small eyes. If the pupil is small, stretching the pupil with flexible iris retractors (Alcon-Grieshaber) can be very helpful (Fig. 198). They are placed before the continuous anterior capsulorhexis is performed.
Anterior Capsulorhexis This is an important step to assure in the bag placement of the IOL. Its size should be smaller than the IOL optic. Zetterstrom 352
points out that the anterior capsule is thick and elastic in children and a capsular tear can easily extend out to the equator. A central puncture is made with a cystotome and the leading edge of the capsule is grasped with forceps. Several repeated grasps are recommended to avoid extension to the equator and to assure maximal control. The capsulorhexis should be kept small because it usually enlarges due to the inherent elasticity of the capsule. (See figures 97, 98, 99, 100 for CCC with cystotome and 45, 46 with forceps).
Nucleus Removal After an appropriate hydrodissection, the removal of the nucleus and cortex in the majority of cases can be performed using an I/A probe with a 0.5 mm orifice, because for the most part the congenital cataract is usually very soft. Occasionally the cataract is hard and has to be disassembled and removed. All the lens cortical material must be aspirated in order to reduce postoperative inflammation (Fig. 128, page 206). Proliferation of cells leading to a secondary cataract formation is more aggressive in the younger child.
Posterior Capsulorhexis In children a posterior capsulorhexis combined with an anterior vitrectomy are necessary to produce a clear optical axis and reduce the need for a secondary operation. The diameter of the posterior capsulorhexis must be at least 3.5 to 4.0 mm or it will tend to close. Moreover, the anterior and posterior capsules must be separated with the use of additional viscoelastic. This maneuver will push the vitreous back and prevent its
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prolapse into the anterior chamber (Fig. 211). Posterior capsulorhexis is performed by most surgeons before IOL implantation, as presented here. Nevertheless, some surgeons do it after IOL implantation, as shown in Fig. 30, page 52. The latter procedure may be cumbersome.
Anterior Vitrectomy This important step is performed after completing posterior capsulorhexis and aims at removing 1/3 of the anterior vitreous gel before there is any vitreous presentation. It is
performed using a vitrectomy probe, as shown in Fig. 212. Special care should be given to removing any vitreous present in the anterior chamber. A so-called “dry” vitrectomy, without infusion of fluid, is safely performed between the anterior and posterior capsulorhexis. Viscoelastic is removed to avoid elevated intraocular pressure after surgery. Using this method it is possible to implant an IOL in the capsular bag during primary surgery or in the ciliary sulcus if a secondary implantation is scheduled in the future.
Figure 211: Cataract Surgery in Children - Importance of Posterior Capsulorhexis When the capsular bag is empty of all lens material, viscoelastic is injected to fill the capsular bag and a posterior continuous capsulorhexis (P) is performed, always smaller than the anterior capsulorhexis (A). A combination of cystotome first followed by forceps is the technique preferred by most surgeons. High viscosity viscoelastic (V) is injected to separate both capsules and to keep the vitreous out of the way.
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IOL Implantation Primary IOL implantation into the capsular bag is the procedure of choice. The risk of contact with vascular tissue and the possibility of inducing chronic inflammation is reduced as compared with implantation in the sulcus. For IOL implantation it is important to extend the incision to 3.5 or 3.8 mm to facilitate the implantation of a foldable acrylic IOL. Viscoelastic is injected between the anterior and posterior capsules to separate them. The acrylic lens is folded and inserted by the same technique used in the adult eye (Fig. 213). Figure 212 (above): Cataract Surgery in Children - Anterior Vitrectomy With the anterior chamber filled with viscoelastic an anterior dry (that is, without infusion) vitrectomy is performed to avoid vitreous (V) remnants in the anterior chamber. This step should help eliminate any vitreous gel in the anterior chamber and near the posterior capsule. The vitrectomy probe (B) is inserted under the anterior capsulorhexis (A) and at the margin of the posterior capsulorhexis (P), always with the tip facing up, taking care not to touch any one of both capsules. This maneuver is preferably performed before the IOL implantation.
Figure 213 (right): Cataract Surgery in Children - Intraocular Lens Implantation The anterior chamber and capsular bag are filled with viscoelastic. IOL (L) implantation within the capsular bag is the procedure of choice. It is important to use an acrylic lens. Anterior capsule (A). Posterior capsule (P).
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The Posterior Approach to Cataract Extraction in Children This has become a second option, and certainly not the procedure of choice. With significant advances in cataract removal in children through the anterior approach, the two or three port pars plana vitrectomy with removal of the posterior capsule and lens material and IOL fixation in the sulcus is left for cases in which a vitreoretinal operation is required as the primary procedure. This is the realm of the vitreoretinal surgeon. The anterior segment surgeon feels uncomfortable with this approach particularly when the technique done through the anterior segment is now so effective and the main controversies related to this surgery are almost a problem of the past.
CATARACT SURGERY IN UVEITIS This is, indeed, one of the most delicate and complex situations in cataract surgery. In this volume it is fully discussed in pages 3133 and Fig. 22 (Chapter 2).
BIBLIOGRAPHY Alio JL, Chipont E: Cataract surgery in patients with uveitis. Cataract Surgery in Complicated Cases by Buratto, 2000; 15:193-206. Belfort Jr., R: Cataract surgery in patients with uveitis. Highlights of Ophthalmology Bi-Monthly Journal, Vol. 27, Nº 4, 1999. Buzard K, Lindstrom RL: Refractive cataract surgery. Highlights of Ophthalmology Bi-Monthly Letter. 1994; Vol. 22, Nº 11-12, pp. 111-116. Centurion V, Lacava AC, De Lucca ES, Barbosa R: High myopia and cataract. Faco Total by Virgilio Centurion. Colvard DM, Kratz RP: Cataract surgery utilizing the erbium laser. In: Fine IH, ed. Phacoemulsification: New Technology and Clinical Application (Thorofare, NJ: Slack, 1996), 161-80. Dodick, JM: YAG laser phacolysis in new cataract techniques. Boyd’s World Atlas Series of Ophthalmic Surgery of HIGHLIGHTS, 1995; 5-130-131. Dodick, JM, Christian J: Experimental studies on the development and propagation of shoch waves created by the interaction of short Nd:YAG laser pulses with a titanium target: possible implications for Nd:YAG laser phacolysis of the cataractous human lens. J Cataract Refract Surg 1991; 17:794-7. Fenzl RE, Gills III JP, Gills JP: Piggyback intraocular lens implantation. Current Opinion in Ophthalmology, Feb. 2000, Vol. 11, Nº 1. Kershner RM: Refractive cataract surgery. Current Opinion in Ophthalmology, Feb. 1998, Vol. 9, Nº 1.
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Khater TT, Koch DD: Pediatric cataracts. Current Opinion in Ophthalmology, Feb. 1998, Vol. 9 Nº 1. Koch DD, Lindstrom RL: Controlling astigmatism in cataract surgery. Seminars in Ophthalmology, December 1992; Vol. 7, Nº 4 pp 224-233. Lacava AC, Sanchez JC, Centurion V: High hyperopia, cataract, polipseudophakic or piggyback, Faco Total by Virgilio Centurion. Management of aphakia in childhood. Focal Points, American Academy of Ophthalmology, nMarch 1999 (3 Sections) Vol. XVII, Nº 1. Neto Murta J, Quadrado M: Pediatric lens implantation: technique and results. Atlas of Cataract Surgery, Edited by Masket S. & Crandall AS, published by Martin Dunitz Ltd., 1999, 33:291300. Zetterstrom C.: Cataract surgery in the pediatric eye. Cataract Surgery in Complicated Cases by Buratto, 2000; 1:1-14.
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C h a p t e r 13: Manual Extracapsular Techniques of Choice - Planned ECCE - Small Incision ECCE
THE PRESENT ROLE OF MANUAL EXTRACAPSULARS Overview Although phacoemulsification followed by implantation of a foldable IOL is the “state of the art” technique and the operation of choice for many surgeons and patients, planned extracapsular extraction with an 8 mm incision and implantation of a rigid posterior chamber IOL is still used for a vast number of patients. As a matter of fact, if we consider the day-to-day practice as performed by the majority of clinical ophthalmologists worldwide, planned extracapsular technique with a 8 mm incision and posterior chamber, in-thebag implantation of a rigid PMMA lens or some other type of manual extracapsular continue to be: 1) the cataract surgical procedure performed on the largest number of patients who undergo cataract surgery; 2) the surgical technique done by the majority of clinical ophthalmologists throughout the world regardless of whether they are technically able to do phacoemulsification. There are many first class surgeons who can perform a superior quality phacoemulsification but for a large number of patients they need to do manual ECCE. This is particularly true in less economically advanced societies. A good example of this situation is the experience of Everardo Barojas, M.D., from Mexico, one of Latin America’s most respected ophthalmic surgeons and teachers. He performs a first class phacoemulsification and teaches the technique to his residents. But in his extensive work with patients in the
rural communities which he spontaneously serves, he does the “envelope extracapsular technique” initiated in the 1960’s by Baikoff and revived in 1982 by Galand. All his residents learn how to perform the planned extracapsular with 8 mm incision, the envelope extracapsular, as well as phacoemulsification. Barojas and collaborators have selected the “envelope extracapsular” procedure for rehabilitation of large numbers of patients at a time considering cost, time it takes, safety and good results.
Advances in Manual Extracapsular In the past few years, the technique of planned ECCE has progressively and substantially improved. In addition, small incision or medium-small incision manual extracapsulars have stimulated the interest of a good number of clinical ophthalmologists in different regions who have chosen to do these manual techniques instead of undergoing the learning process of phacoemulsification even though some of these “small incision” manual extracapsulars are not easy to do. These techniques are presented in this Chapter. Advances in extracapsular surgery are related to better instruments, viscoelastics, the application of nuclear fragmentation techniques, advances in IOL technology, irrigating solutions and the methods to minimize infection and postoperative inflammation as presented in Chapter 4 of this Volume. The
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application of these advances is a long step forward for manual extracapsular as well as phacoemulsification, which is a mechanical extracapsular. As a matter of fact, a good number of steps used in phacoemulsification, such as continuous circular capsulorhexis have been incorporated into the modern methods of ECCE. All of these factors make manual extracapsular a very good operation. The essential difference with phaco regarding results is that with a very well done phaco and topical anesthesia the patient has almost immediate visual rehabilitation and minimal inflammation, in contrast to a very well performed ECCE in which final visual recovery may take 6-8 weeks, although the visual acuity is practically the same at the end of this period. There may also be more inflammation with ECCE.
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Regional Predominance of Phacoemulsification Phacoemulsification is predominant essentially in the U.S. and Western Europe, where it has become the number one technique for most ophthalmic surgeons. In many instances, this is because their patients demand and expect a very rapid visual rehabilitation and have the economic means to receive the benefit of the high technology required for phaco. In other geographical regions, phacoemulsification continues to gain ground, but essentially in teaching centers and private practice. Because manual planned ECCE is still extensively used, we have selected Professor Joaquin Barraquer, M.D., from Barcelona to present his technique of a flawless planned extracapsular. There is no one better suited for this task.
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PERFORMING A FLAWLESS PLANNED EXTRACAPSULAR CATARACT EXTRACTION With an 8 mm Incision and Posterior Chamber IOL Implantation by Professor Joaquin Barraquer, M.D., F.A.C.S.
EDITOR’S NOTE: Professor Joaquin Barraquer is one of the world’s top master surgeons. He was one of the key pioneers of ophthalmic surgery under the microscope which led to the development of microsurgery. The ASCRS selected him as “one of the world`s most outstanding innovators.” The III International Congress on Advances in Ophthalmology, 2000 declared him “Ophthalmologist of the Millennium.”
ANESTHESIA At the Barraquer Ophthalmology Center in Barcelona, we continue to find general anesthesia administered by an expert anesthesiologist the procedure of choice even with ambulatory surgery. With this type of anesthesia, the surgeon does not need to depend on the cooperation of the patient. Hypotony of the eye is excellent. The surgeon can perform the complete procedure with optimum control and safety. Nevertheless, because many eye centers and clinical ophthalmologists throughout the world routinely use local anesthesia, both techniques are here described.
General Anesthesia (as Performed at the Barraquer Ophthalmology Center) Pre-induction Midazolam anxiolytic).
(1-5
mg,
intravenous,
Induction Propophyl (1-3 mg/kg, intravenous, hypnotic) Succinylcholine (1 mg/kg, intravenous, muscular relaxant for orotracheal intubation).
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Adjunct Medications Analgesics: alfentanil (0.5-1.0 mg) or pentazocine (15-30 mg) intravenous. Neuroleptics: droperidol (2.5-5.0 mg, intravenous) Vagolyptics: atropine (0.5-1.0 mg, intravenous) Curare: atracurium besylate (0.250.50 mg, intravenous as muscle relaxant) Antiemetics: ondansetron (4 mg) and/or metoclopramide (10 mg) intravenous.
Maintenance Halogenated ethers for inhalation anesthesia (sevoflurane or isoflurane), occasionally complemented by nitrogen protoxide (N2O) 50%.
Ventilation Spontaneous respiration, if possible, depending on the type of patient and surgery. Assisted or controlled ventilation if necessary.
Monitoring Electrocardiogram (EKG) Pulsioximetry (Oxygen saturation) Non-invasive blood pressure (NIBP) every 3 minutes. Capnography (expired CO2) and respiratory frequency. Muscular relaxation.
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Awakening and Recovery Oxygenation 100% and control of vital signs. Cholinesterase inhibitors (neostigmine and/or edrophonium) if curare has been used.
Local Anesthesia With this type of anesthesia very good hypotony and akinesia can be achieved. If sedation is adequate but not excessive, minimal patient cooperation will be sufficient. Barraquer believes an expert anesthesiologist should always be available to ensure that the patient is controlled, even if local anesthesia is used.
Sedation Propophyl, alfentanil, midazolam. The dosage depends upon the patient’s weight and age. The patient should be oxygenated during the anesthetic and surgical procedure because sedation causes respiratory depression.
Peribulbar Injection Two injections are administered: Ante-equator injection - Inferotemporal Site. 1. An inferotemporal injection at the intersection of the temporal lateral third and the two medial thirds of the inferior orbit, just anterior to the equator (Fig. 214). A 23 gauge needle 25 mm long is used. 2. A superonasal injection (Fig. 215). A 25 gauge needle 16 mm long is used.
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Figure 214 (right): Peribulbar Local Anesthesia Inferotemporal injection anterior to the equator. The needle is advanced just anterior to the equator of the globe, along the inferior orbit, but not into the muscle cone. The anesthetic solution is injected at this site. The beveled side of the needle tip is directed toward the globe.
Figure 215 (left): Peribulbar Post-equator Superonasal Injection. The needle is directed posteriorly behind the globe outside the muscle cone toward the area of the superior orbital fissure. The anesthetic solution is injected just past the equator.
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Technique for Peribulbar Injection First, the inferior temporal rim of the orbit is identified by palpation, and the eyeball is displaced with the finger. The needle is always introduced in the direction of the orbit until it touches bone. At this point the needle is lowered, following the rim of the bone. Three to 4 cc of local anesthesia are injected. Then the same maneuver is performed at the superior nasal point. Massage is applied to the globe for a few seconds. A Honan balloon is placed over the globe with a pressure of about 40 mm for 5 to 10 minutes (Fig. 96).
Anesthetic Medications 5 cc lidocaine 2%, plus 5 cc buvicaine 0.75%, plus hyaluronidase 100 UI plus adrenaline 1:200 000 (3 to 4 cc in the injection inferiorly and 3 to 4 cc in the injection superiorly. This combination lasts for almost 2 hours).
Monitoring Electrocardiogram (EKG) Pulsioximetry (Oxygen saturation) Non-invasive blood pressure (NIBP) every 3 minutes. Muscular relaxation
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Extracapsular Cataract Extraction with an 8 mm Incision (ECCE) At the beginning of the operation, the pupil must be adequately dilated (8mm or more. We use cyclopegics and tropicamide every 30 minutes, beginning 3 hours before surgery. Diclophenac is added to reduce the tendency for the surgical maneuvers to cause pupillary constriction. Atropine is not recommended because we want prompt recuperation of normal pupillary reaction the first day after surgery.
Incision A traction suture is applied in the superior rectus muscle. A fornix-based conjunctival flap is prepared. The conjunctiva is separated at the limbus either with a razorblade knife or with Wescott scissors. If the scissors are used, the dissection is completed with the same scissors. Light bipolar diathermy is used to coagulate the bleeding vessels, especially in the anterior part of the sclera and at the sclerocorneal limbus, where the incision will be made to extract the nucleus and to introduce the IOL. An 8 mm-groove is made approximately 0.5 mm from the limbus with a dia-
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Figure 216: Incision - Stage 1 A non-penetrating perpendicular incision is performed 0.5 mm behind the limbus with a diamond blade knife (K). The incision extends from 2 to 10 o’clock (arrow) for a length of 8 mm. This is the first plane of the two-plane incision A paracentesis is made at the limbus (A.) To simplify Figures 216 and 217, the fornix-based conjunctival flap has not been represented in these illustrations.
mond knife, a Desmarres scarifier, a disposable knife, or a razorblade knife. The depth of the groove is approximately two-thirds of the scleral thickness and represents the first step of a two-plane incision to be completed later. This two-plane incision facilitates better apposition of the wound edges, thereby improving wound closure and reducing postoperative astigmatism induced by the sutures. The surgeon should avoid overlapping the wound edges. (Fig 216).
Continuous Curvilinear Capsulorhexis A viscoelastic substance is introduced in the anterior chamber through a paracentesis (Fig. 217) to maintain adequate depth and to facilitate the deep, horizontal incision (second step) and anterior capsulorrhexis. The horizontal incision is started with a disposable knife at one of the ends of the predetermined groove and continued over approxi-
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mately 3 mm (Fig. 217). After the capsulorrhexis has been done, as shown in Fig. 219 A, B and C, the deep plane of the incision is completed with scissors (Fig. 218). Care must be taken to ensure that
Figure 217 (above): Incision - Stage 2 A viscoelastic substance is injected with a cannula through a paracentesis to fill the anterior chamber. This will maintain the anterior chamber depth and increase dilation of the pupil. At one end of the non-penetrating limbal incision, a horizontal beveled incision is made (D). This will begin the second plane of the two-plane incision. Fixation forceps (F).
Figure 218 (below): Incision - Stage 3 The two-plane horizontal beveled incision is completed (red arrow) with Barraquer’s scissors (S) in the deep layers of the groove.
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the lid speculum does not exert pressure on the eye, which might induce protrusion or rupture of the posterior capsule. The capsulorrhexis can be performed by perforating the center of the capsule with a
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Figure 219 A-C: The Continuous Curvilinear Anterior Capsulorhexis Technique - Stages 1 - 3 (A) After the tear is started in the center of the anterior capsule, traction is exerted at the 10:00 meridian (X) on the operculum that is doubled on itself. Uttrata forceps (N) are used to grasp the underside of the capsular flap (C) and the tear is extended in a counterclockwise direction (blue arrow) to produce a circumferential capsular rupture (red arrow). (B) The tear is continued with the Uttrata forceps in the same direction (blue arrow) to complete the circular tear (red arrow). (C)The capsulorrhexis is completed, and the circular operculum is removed.
needle, or cystotome, which is an insulin injection needle, conveniently bent near its base to produce adequate angulation for better maneuvering (Fig. 97). The bend close to the tip of the needle makes a little hook used to exert traction on the capsule fragment. Cystotomes are also available commercially. Another way of performing a capsulorrhexis is to tear the central part of the anterior
capsule with adequate forceps such as Uttrata forceps. We usually prefer the forceps to the cystotome (Fig. 219 A, B,C). Once the center of the capsule has been ruptured or torn, a small flap of capsular tissue is grasped and pulled in either a clockwise or counterclockwise direction to eliminate the central part of the anterior capsule (Fig. 219 A,B,C). We attempt to create a
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circular opening 5.5mm to 6 mm in diameter (Fig. 220). In cases of very large nuclei, of capsular pseudoexfoliation, or when some phacodonesis is present, we prefer to construct a capsulorrhexis with a slightly larger diameter in order to avoid traction on the zonules when the nucleus is brought into the anterior chamber. In these cases a large capsulorrhexis facilitates mobilization and rotation of the nucleus (Fig. 221).
Figure 220 (above): Continuous Curvilinear Anterior Capsulorrhexis Standard Size The regular curve of the capsular opening is less prone to radial tears than the irregular edges of the opening that result form the can-opener and envelope techniques.
Figure 221 (below): Large Continuous Curvilinear Anterior Capsulorrhexis This illustration depicts a large CCC, adequate for removing a large and/or hard nucleus.
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Hydrodissection Next is the hydrodissection. Balanced saline solution (BSS+) with epinephrine (dilution 0.06%) is injected with a thin cannula (25 G) between the anterior capsule and the lens cortex (Fig. 222) to separate the nucleus, which tends to pass through the capsulorrhexis into the anterior chamber.
Subsequently, the nucleus is rotated with the same cannula in clockwise or counterclockwise direction, depending on where the nucleus has entered the anterior chamber. The nucleus is lifted slightly during the rotation maneuver to complete the displacement into the anterior chamber (Figs. 223, 224). As the capsule is an elastic structure, even large nuclei can pass through a relatively small
Figure 222 (left): Hydrodissection of the Lens Capsule from the Cortex - Stage 1 After the continuous curvilinear anterior capsulorrhexis has been completed, a cannula (C) is inserted in the anterior chamber. The tip of the cannula is placed between the anterior capsule and the lens cortex at the locations represented. Fluid is injected (arrows) at these locations to separate the capsule from the cortex. The resulting fluid waves can be seen (W). These waves continue posteriorly to separate the posterior capsule form the cortex.
Figure 223 (right): Hydrodissection - Stage 2 A 25 gauge needle (A) is introduced parallel to the edge of the nucleus (N), and a solution of BSS+ and epinephrine is injected. This hydraulic force (arrow) produces a cleavage plane between the posterior capsule and the posterior surface of the nucleus. The nucleus passes into the anterior chamber without tearing the capsulorrhexis.
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capsulorrhexis without tearing the capsule when a continuous circular capsulotomy without notches is performed. Other methods of opening the capsule are: 1) the envelope technique, which uses a more or less straight incision between the central and superior third. 2) The can-opener technique produces small, less circular capsule ruptures. These techniques, which are based on lineal incisions, however, may result in a higher incidence of rupture or tearing of the posterior capsule during the cleaning maneuvers of the capsular bag.
Removal of Nucleus Once the nucleus has passed into the anterior chamber, gentle compression is applied 1mm to 2mm from the inferior limbus (Fig. 224) with a round-tipped or blunt instrument. The nucleus is displaced upwards (Fig. 224), resulting in some gaping of the incision. Simultaneously, the scleral lip of the incision is depressed with another instrument such as Colibri or Adson forceps to facilitate the expulsion of the nucleus (Fig. 224). Expression of the nucleus should never be attempted while the nucleus is still inside the capsular bag because zonular rupture may occur, necessitating the continuation of surgery as an unplanned intracapsular extraction.
Removal of Cortex - Irrigation and Aspiration The anterior chamber is irrigated with BSS+ and epinephrine (0.06% dilution) to remove persistent residual lens matter or epinuclear elements. A nylon 10-0 cross suture is applied in the central part of the incision to
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maintain adequate anterior chamber depth during irrigation and aspiration of the cortex that remains adherent to the capsular bag. An aspiration probe with a 0.3mm opening at the tip is used. This probe has a special cover with two lateral openings at the inferior end for irrigation to maintain the anterior chamber depth while the cortical lens matter is aspirated (Fig. 225). The height of the bottle is adjusted from 20cm to 78cm to increase or reduce the irrigation in relation to the depth of the chamber. An adequate chamber depth makes it possible to work with greater safety, although excessive irrigation may result in iris prolapse through the wound. This can be corrected by reducing the height of the bottle. For aspiration of the lens matter, a variable vacuum with an upper limit of 450mmHg is applied. Once all the lens matter has been removed, the anterior capsule is “polished” using the same probe and a low vacuum power between 20mmHg and 60mmHg to avoid capsular retraction and rupture. Careful, exhaustive cleaning of most of the posterior capsule surface is essential in order to postpone as long as possible the opacification of the capsule and the subsequent Nd: YAG laser capsulotomy. The surgeon must be careful not to be aggressive during this step of aspiration-irrigation of the cortex so as to avoid posterior capsule rupture or zonules rupture during these maneuvers. If this should occur, vitrectomy would be required, and the IOL would have to be placed in the sulcus. If irrigation-aspiration equipment is not available, the lens matter can be removed manually. A cannula and syringe are used to gently irrigate, mobilize the lens matter, and aspirate it in the four quadrants. A curved
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Figure 224 (left): Removal of Nucleus Once the nucleus is in the anterior chamber, nucleoexpression is performed. Slight compression is exerted with a blunt instrument 1 or 2mm over the inferior limbus (H). the nucleus is displaced upwards, separating the lips of the incision. Simultaneously, another instrument (F) is used to depress the scleral lip of the incision in order to facilitate the expulsion of the nucleus.
Figure 225 (right): Removal of the Residual Cortex The aspiration probe has an opening 0.3 mm in diameter at the upper end. It also has a cover or sleeve with two inferior lateral openings for irrigation to maintain the depth of the anterior chamber during aspiration of the lens matter.
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probe tip is used for the superior quadrants (Fig. 226). The posterior capsule may also be polished manually using this technique at the end of the procedure. In cases of central capsular fibrosis, posterior capsulorrhexis can be performed at the end of the procedure or at a later stage in a Nd: YAG laser capsulotomy. A viscoelastic is injected in the capsular bag and the anterior chamber. The surgeon should check carefully to ensure that the capsular bag is completely filled with viscoelastic. The preplaced cross-point suture is removed from the wound.
IOL Implantation The lens is grasped at the superior rim of the optics with straight forceps. With a slight inclination, the inferior haptic is introduced into the capsular bag (Fig. 227). The optic is centered with the capsulorrhexis and rotated using a Sinskey hook until the superior haptic is in the correct position inside the bag. The IOL should be implanted horizontally. Introduction of the superior haptic may be easier if it is grasped with thin forceps without teeth (Fig. 228). The haptic is guided
Figure 226: Irrigation/Aspiration of the Residual Cortex (modification by Malbran). The residual cortex (C) is removed from the capsular bag with a curved irrigation/ aspiration probe. A slightly curved tip is used to gently aspirate the residual cortex nasally and temporally. The residual cortex located in the difficult-to-reach areas of the superior capsular bag is removed using a curved irrigation/aspiration probe tip.
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Figure 227 (left): Intraocular Lens Implantation. After the cataract is removed and viscoelastic is injected into the anterior chamber and the capsular bag, the PMMA (L) lens is grasped with forceps (F). The inferior haptic (H) is placed in the capsular bag (C) inferiorly. Forceps are used to introduce the optic part into the capsular bag.
Figure 228 (right): IOL Implantation The superior haptic (H) is grasped with straight forceps and bent inferiorly (red arrow) so that the elbow of the haptic can be directed (blue arrow) into the capsular bag (C) superiorly.
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toward the center of the capsulorrhexis and rotated 90 degrees. The forceps are removed from the capsulorrhexis, and the IOL settles in the capsular bag. The capsulorrhexis is clearly seen in front of the optic part of the IOL (Fig. 229). Generally, PMMA lenses are used, and the preferred diameter of the optic is 6.5 mm. Acetylcholine 1% is applied to induce 4 mm of miosis. Subsequently, a peripheral iridectomy is performed.
Suturing and Aspiration of the Viscoelastic The incision is closed with 5 to 7 nylon radial sutures. The knots must be buried in the sclera (Fig. 229). The viscoelastic material is aspirated. The anterior chamber is restored to normal depth with 1% acetylcholine (lyophilized acetylcholine dissolved in BSS) The conjunctival flap is repositioned to cover the incision. The two extremities of the flap are anchored with 10-0 nylon sutures.
Figure 229: Conclusion of the Operation Cross-sectional view. The IOL occupies its normal position within the capsular bag. The incision is sutured with 10-0 nylon, preferably radial sutures, and the knots are buried in the sclera. The fornix-based conjunctival flap is repositioned to cover the wound. The flap is anchored with 10-0 nylon sutures at the two ends of the incision (not shown in this illustration).
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THE MANUAL, SMALL INCISION EXTRACAPSULARS
There is significant interest about these methods. They allow successful removal of the cataract through a small incision and manually, without the need to use mechanized equipment. We hereby present the three most widely accepted: 1) Michael Blumenthal’s Mini-Nuc (Israel); 2) David McIntyre’s Phaco Section (USA); and 3) Francisco Gutierrez C., Manual Phacofragmentation.
There is a significant learning curve, and experience is required. The proposed Mini-Nuc technique must be performed under positive intraocular pressure during all stages of surgery. The desired IOP is achieved during surgery with the use of an anterior chamber maintaining system, and controlled by the height of the BSS bottle (Anterior Chamber Mainteiner (ACM) in Fig. 230).
THE MINI-NUC TECHNIQUE
Importance of Constant Irrigation and Positive 100% IOP
This procedure caught-on in the minds of many clinical ophthalmologists since its inception, 10 years ago. Blumenthal has continuously worked at improving the method he created and its results.
Principles of the Mini-Nuc Technique The procedure requires only a small incision and no stitches. It has proven to be safe surgery. It is possible to use topical anesthesia, and rehabilitation is speedy. Moreover, it is cost-effective. There are some disadvantages, however, of manual ECCE. It is not an easy technique to learn and perform.
The principle of maintaining positive IOP during cataract surgery is gradually becoming acceptable to more surgeons, even those performing phacoemulsification. In the mini-nuc technique, positive IOP exists 100% of the operating time. Any fluid lost during intraoperative maneuvers is promptly recovered because of the large internal diameter of the ACM tubing (“A” in Figs. 230-231). The steady flow ensures a constant depth of the anterior chamber. This flow continuously washes all debris: blood, pigment, and leftover cortical material from the eye with low turbulence and low fluctuation of anterior chamber depth. Consequently, less postoperative inflammatory reaction occurs.
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The BSS bottle can be used as a reservoir of pharmacological drugs to be infused continuously into the eye. These drugs may include adrenaline 1:1,000,000, to keep the pupil dilated, antibiotics, and any other drug the surgeon wishes to use. The length of surgery is not critical as the constant positive IOP keeps the aqueous blood barrier intact; and the ciliary processes and choroidal, retinal, and iris vessels are not exposed to a hypotonic environment at any time. This helps to prevent exudate formation or a worse complication, expulsive hemorrhage. Blumenthal considers that positive IOP provides not only a safe milieu and prevents complications; it is a precondition for controlled surgery. Because the internal architecture of the eye is not disturbed, planned maneuvers can be carried out safely.
SURGICAL TECHNIQUE Anesthesia, Paracentesis, ACM Lidocaine 4% drops are instilled 15 minutes before surgery 3-4 times. At present Esrecain gel is used with each Lidocaine drop. A total of 0.2-0.3 cc of Marcaine 0.5% with adrenaline is injected subconjunctivally between 11:00 and 2:00 in the limbal area, where diathermy will be applied. During surgery, 0.2-0.3 cc of intraocular non-preserved Lidocaine is injected into the tube of the ACM. It will reach the eye in diluted form. This is very efficient, cost-effective ocular anesthesia. Two paracenteses are performed at 10:30 and 2:30 by stiletto knife (identified as “D” in Fig. 230). Moderate beveled incisions
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are made in clear cornea just at the edge of the blood vessels. The same stiletto knife is used for an incision just anterior to the limbus in the clear cornea for the purpose of inducing the ACM cannula (5149 oval Visitec) in the 6 o'clock area (identified as “A” in Fig. 230).
Paracentesis Incision and Fixation of ACM The most important aspect of the beveled tunnel paracentesis incision to introduce the ACM is its length. The incision should be at least 2 mm long before the knife penetrates the AC, and will be 1 mm wide (Fig. 230-A). The ACM is introduced into the tunnelshaped paracentesis, beveled edge up. When it reaches the AC, it is turned beveled edge down, and the ACM flow is directed towards the iris. The ACM is introduced 2.0 - 2.5 mm into the AC, and not more. The shallower the depth of the AC, the greater care the surgeon should take not to exceed these limits. (In the illustrations, the cannula is shown beveled up for clarity but at surgery it should be kept beveled down toward the iris.)
Height of BSS Bottle Normally, the BSS bottle should be located 40 to 50 cm above the eye, keeping the IOP at 30-40 mm Hg. If intraocular bleeding occurs, raising the bottle will stop the bleeding. If a posterior capsule tear occurs, the bottle should be lowered to 20 cm. The BSS bottle should be lowered even further to 10-15 cm when suturing, in order to achieve the best adaptation of the incision edges.
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Figure 230: Creation of the Special Sclero-Corneal Pocket Tunnel Incision - Stage 1 The Anterior Chamber Maintainer (A) is in place, introduced through a tunnel in clear cornea which is at least 2mm in length and 1mm wide, near and parallel to the limbus. The height of the BSS bottle, connected to the maintainer, controls the intraocular pressure. Two 1mm paracentesis incisions (D) are made at 10:30 and 2:30 just anterior to the limbus, for instrument access. The main external incision, 0.3mm in depth and 4-5mm long, 1mm behind the limbus is made. A crescent knife (C) dissects the tunnel, first 1mm in sclera, then 2-3mm forward into clear cornea (1), then extending laterally (2) to produce the pockets (P) on both sides. While performing the pockets, the crescent knife if retracted laterally and backward (3), creating the external incision extensions (E) on both sides. Inset (F) shows the cross section of a scleral tunnel incision made under low intraocular pressure which is wavy and uneven. Inset (G) shows incision quality which is smooth and even, as achieved under high intraocular pressure from anterior chamber maintaining system.
The most important concept to keep in mind is that the height of the BSS bottle can be changed depending upon the situation. It does not need to be standardized, and the surgeon can adjust it according to his/her own technique, and varying needs during surgery.
Capsulorhexis The ACM and positive IOP push the crystalline lens backward reducing the force of the zonules exerting pressure on the anterior capsule toward the periphery. This facilitates capsulorhexis performed by a cystotome, and avoids unintended tears toward the periphery of the crystalline lens. Forceps introduced through the paracentesis corneal tunnel produce outflow of BSS thus reduc-
ing the AC depth and causing the zonules to pull the anterior capsule more forcefully. Blumenthal believes that although capsulorhexis can be done successfully using forceps with viscoelastic material or even BSS only, positive IOP in the anterior chamber provides the best precondition for successful and controlled capsulorhexis performed through the paracentesis using a cystotome.
Conjunctiva A conjunctival flap is cut 1 mm from the limbus between 11:00 and 2:00. The 1 mm of conjunctiva attached to the limbus facilitates the postoperative healing process.
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Healing of conjunctiva to conjunctiva occurs quickly and is stable, unlike the healing process between conjunctiva and limbus. The attached conjunctiva also makes it possible to glue the edges of the conjunctiva by coagulation
Sclerocorneal Pocket Primary Incision and Tunnel Precondition for Utmost Controlled Dissection The main reason the ACM is introduced at the beginning of surgery is to keep the IOP between 30 and 40 mm Hg to make the eye coats taut. The importance of this precondition for the utmost controlled dissection in the sclera and cornea should not be underestimated (Fig. 230). Most unintended misdirected scleral dissection, premature entrance to the anterior chamber, or failure to achieve a full-size scleral pocket tunnel occur as complications of dissection in soft, floppy tissue. The sclerocorneal tunnel architecture of the primary incision which Blumenthal prefers for manual ECCE begins with an external straight scleral incision 4 to 6 mm long and 0.3 mm deep (Fig. 230). It should be performed 1 mm behind the limbus at the surgeon’s choice of location, either 12:00 or temporal. As the external incision is cut straight, the distance of this incision varies gradually from the limbus. It is 1 mm behind the limbus at 12:00, while on both sides the external incision is further away form the curved limbus, up to 1.5 mm to 2 mm
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At the bottom of the 0.3 mm deep external cut, dissection is extended anteriorly until it engages the limbal tissues, which resist dissection more than scleral or corneal tissues. In overcoming this extra resistance, the surgeon must take care not to press forward too forcefully, which might cause uncontrolled forward corneal dissection and premature perforation of the AC. Control of lamellar dissection at all stages is critical. Dissection continues forward for about 2 mm in clear cornea. As the dissection approaches the lateral edge of the tunnel, the knife is swept sideways 45 degrees, resulting in a funnel-shaped tunnel (identified as C 2, 3 in Fig. 230) . Thus the internal aspect of the tunnel is about 25% larger than the external incision. While the crescent knife is at the lateral edge of the straight external part of the incision, dissection should be carried obliquely backward. In this way the crescent knife forms a lateral pocket on both sides (identified as C 1, 2, 3 in Fig. 230), extending backward for 1 mm on each side. A backward incision 90 degrees to the limbus such as hereby described, does not induce astigmatic effect. With practice the result should be a well-constructed pocket sclerocorneal tunnel (Fig. 230). Now the keratome is slid into the tunnel (identified as I-K 4 in Fig. 231) with a slight side to side movement to prevent premature perforation of the anterior chamber. When the tip of the keratome reaches the end of the tunnel, the keratome is then tilted downward to enter the anterior chamber. After entering the anterior chamber, the keratome is moved laterally and forward
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Figure 231 - Creation of the Special Sclero-Corneal Pocket Tunnel Incision - Stage 2 A keratome (K) enters the anterior chamber to accomplish the internal corneal incision (I - blue dotted line) curved shape, parallel to the limbus. The keratome must be moved in a direction slightly away from the surgeon while moving it laterally (4-arrow) to produce this curved configuration of the internal corneal incision. Lateral scleral pockets (P). Anterior chamber maintainer (A). The distance from the external to internal incision is about 3.5mm to 4mm. Internal incision (I) length is about 7mm.
(Fig. 231-K-4). This combination of movements directs the internal incision in curved fashion parallel to the limbus. The procedure is repeated on the other edge of the tunnel. Thus the extreme edges of the internal incision (temporal and nasal points of entry of the AC), are 3.5 to 4.0 mm from the lateral points of the external incision. A common error in constructing this tunnel occurs when the keratome, instead of moving laterally and anteriorly, is directed laterally and backward, thereby creating a much smaller tunnel. The more funnel shaped the tunnel is, the less astigmatism induced, and the less potential there is for BSS leakage from the AC either during or after surgery. All these movements are performed while the eye is fixated with Bonn forceps, away from the tunnel incision.
Hydrodissection and Nucleus Dislocation Hydrodissection is performed through one of the two paracenteses located at 10:30 and 2:30 (Fig. 230). Professor Blumenthal uses a 1 cc syringe attached to a cannula. A 3-5 cc syringe should not be used, as a sudden surplus of BSS in the crystalline lens might burst the posterior capsule. The cannula should be introduced under the anterior capsule at the 12:00 position. No more than 0.1 cc to 0.3 cc of BSS is injected, engulfing the lens contents instantly by hydrodissection. In most cases the nucleus tilts forward into the AC at the 12:00 position, as the BSS fluid accumulates first at this
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location (Fig. 232). In cases where the nucleus is not partially dislocated anteriorly, one or two Sinskey hooks are introduced at one or both paracenteses located at 11:00 and 2:00. Uneven pressure by one hook while the nucleus is rotated causes the nucleus to tilt and gradually to dislocate anteriorly. The surgeon should make sure that the nucleus tilts up toward the wound. If it does not, the lens should be rotated further until this alignment is achieved. When the tilt is not sufficient in the surgeon’s judgment, the bent part of a cannula should be introduced under the
lens while BSS is injected. This will cause the nucleus to move gradually anteriorly completely into the AC (Fig. 232). The use of too much force during this maneuver can cause the lens to suddenly touch the endothelium. Blumenthal does not remove cortex at the center of the lens anteriorly because this cortex protects the endothelium from the rough nucleus during movements in the AC. The lens does not need to be completely dislocated to the AC before extraction can begin. When the nucleus is free after rotation, it can remain partially in the bag and partially in the AC (Fig. 232).
Figure 232: Hydrodissection of the Nucleus and Epinucleus The anterior chamber maintainer (A) connected to a BSS bottle maintains and controls intraocular pressure during the circular capsulorhexis. A hydrodissector cannula (H) is introduced through a paracentesis (D) under the anterior capsule at the 12:00 o’clock position. Injection of fluid (blue arrows) causes the superior nucleus and epinucleus to become luxated anteriorly (arrow - 1,2,3), tilting it forward into the anterior chamber. The nucleus and epinucleus are now partly in the anterior chamber and partly in the bag, ready for expression. Main sclero-corneal pocket incision (I) is shown in cross section.
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Figure 233: Technique of Nucleus Expression Using Glide and High IOP - Surgeon’s View A lens glide (G) is introduced through the incision to a position just under the superior edge of the tilted nucleus and epinucleus within the anterior chamber. High intraocular pressure from the anterior chamber maintainer causes the nucleus and epinucleus (N)(shown in ghost views) to move toward (1-arrow) the open incision. Slight pressure from a firm instrument (not shown) placed within the incision on top of the glide may be used to initiate the movement of the nucleus toward the incision as it is forced out of the opening by the high intraocular pressure. As the epinucleus and nucleus (N) enter the incision tunnel, the epinucleus (E) may strip off within the scleral pockets (P). The hard core nucleus continues to exit the incision with the flow of BSS under pressure (2-arrow). If a large nucleus will not exit the eye, chipping off a small triangular piece of nucleus will facilitate expression of the nucleus (inset below). Anterior capsulorhexis (C).
Nucleus Expression Using Glide and High IOP Before the lens glide is introduced under the nucleus, the surgeon must first assess whether viscoelastic material is needed in addition to the ACM. Blumenthal considers using viscoelastic in shallow chambers and in patients with glaucoma that may have a small pupil. The glide should not be induced forcefully as it might engage the nucleus itself rather than slide under it (Fig. 233). The glide should not move too far inferiorly or it may tear the posterior capsule. If a glide is
not used, the nucleus may not move in a controlled way towards the incision. To move the nucleus (with its epinucleus) into the wound, slight external pressure should be exerted with a closed forceps or other instrument on the glide inside the tunnel in a stroking pattern. The strokes may need to be repeated a few times until the nucleus is pushed forward by fluid from the ACM to engage the mouth of the sclerocorneal tunnel (Fig. 234). At first, BSS still leaks around both sides of the nucleus. Stroking is continued until the nucleus is well lodged in the inner aspect of the sclerocorneal pocket,
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Figure 234: Technique of Nucleus Expression Using Glide and High IOP - Cross Section View This cross section view shows lens glide (G) in place for nucleus expression. High intraocular pressure from the anterior chamber maintainer (A-arrow) causes the nucleus and epinucleus (1) to move toward (red arrow) the open incision. As the epinucleus and nucleus enter the incision tunnel, the epinucleus (E) may strip off within the scleral pockets as the hard core nucleus (N) continues to exit (2) the incision with the flow of BSS under pressure.
and no leakage is observed. Continued pressure should not be made in the tunnel when the nucleus is engaged, as pressure in the tunnel would open the tunnel and new leakage would begin, preventing nucleus expression. Now pressure is shifted out of the tunnel, posteriorly, onto the sclera. This slightly changes the position of the nucleus in the tunnel to allow expression. The nucleus rocks from side to side, and rotates slightly on its axis while finding its way out of the tunnel (Fig. 234). The amount of pressure to induce can be assessed by observing the depth of the AC,
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which should not change. If the AC collapses, stop pressing and allow it to reform. The preceding description is accurate when the tunnel is large enough to allow the nucleus to pass through the tunnel. During this move, it sheds any remnants of epinuclear material; in this way the smallest possible nucleus is delivered. The remnants of the epinucleus are observed as leftover in the AC; they are soft and easily expressed by the hydrostatic pressure itself (Fig. 235). Their progress is helped by gentle strokes in the tunnel, causing BSS to flow out of the eye. The BSS on its way out engulfs the soft epinucleus and flushes the epinucleus out.
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Figure 235: Expression of Epinucleus If the epinucleus (1) remained in the scleral tunnel pockets, it may be hydroexpressed (2-red arrow) using slight instrument strokes of a small spatula (S) placed inside the tunnel. Anterior chamber maintainer (A) provides pressure to facilitate this expression. Lens glide (G). Note remaining cortex (C) within the capsular bag.
Should the nucleus proper be too large to be expressed, the surgeon has two choices: (1) Enlarge the inside aspect of the tunnel, not the external incision; or (2) Perform chipping. Part of the nucleus is exposed in the incision. A 25 gauge needle is introduced into the nucleus, chipping off a small triangular piece. The smallest new diameter of the nucleus can be made small enough for the nucleus to be expressed.
Epinucleus and Cortex Extraction Epinucleus Continuous flow and positive IOP inflate the capsular bag after nucleus extraction. The soft epinucleus left behind in the AC is usually hydroexpressed spontaneously. To facilitate this maneuver a spatula can be introduced through the tunnel (Fig. 235). In cases where the epinucleus is left in the capsular bag, manipulation in the bag right
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and left by the spatula will release the epinucleus from its adherence to the cortex and allow it to be flushed out.
paracentesis port for aspiration allows the amount of BSS aspirated or lost to be instantaneously replaced by the anterior chamber maintainer.
The Cortex IOL Implantation Blumenthal recommends aspirating the cortex manually; aspiration is better controlled using a 5 cc syringe and cannula (Fig. 236). The cannula should be introduced from one of the paracentesis sites and not from the tunnel because introducing a cannula through the tunnel may allow BSS to escape. The resulting instability of the posterior capsule would be unfavorable for smooth aspiration of the cortex. Using the
The leading haptic is inserted into the AC and under the anterior capsule at 6:00 o'clock (Fig. 237). The anterior chamber may become shallow for a short period during this maneuver. For this reason a strong IOL holder is recommended so that the leading loop can be directed under the capsule even in the presence of a shallow AC. When the leading loop is stable under the capsule, the IOL
Figure 236: Cortex Removal and Water Jet Technique to Remove Residual Cortex A special cannula with a 0.4mm pore (J), connected to a 5cc syringe is introduced through a paracentesis (D), where it is used to aspirate the cortex (B). Next, a hydrodissector cannula (H) is introduced through the paracentesis (D) and is used to create a water jet burst of BSS (blue arrows) directed to the posterior capsule. This forces any cortical material left over to free itself from its attachments to the capsule, either in the posterior capsule or located in the equator of the lens bag. This pressure and that from the anterior chamber maintainer (A) forces these pieces out of the eye. Anterior capsulorhexis (C).
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Figure 237: Intraocular Lens Implantation Technique - Stage 1 The intraocular lens is introduced into the anterior chamber using an IOL holder, with the distal haptic directed posterior to the anterior capsule, and into the 6:00 capsular bag (arrow). When this is achieved, the IOL holder is released, not before forceps (F) grasp the trailing loop outside the eye to prevent the IOL from springing out of the bag at 6 o’clock. The anterior chamber maintainer (A) keeps the capsular bag ballooned during implantation. Anterior capsulorhexis (C).
holder is released, but not before forceps grasp the trailing loop outside the eye to prevent the IOL from springing out of the bag at 6:00. A modified Sinskey hook is inserted through one of the paracenteses, usually at 10:00 for right-handed surgeons and the lens is manipulated into the bag. The trailing loop is introduced into the AC first. Then the IOL is rotated while pushing backward (Fig. 238). Thus the trailed loop enters the bag
(Fig. 238). Blumenthal prefers to have holes in the loops and one hole in the haptic near the optic for manipulating the lens into the capsular bag. Blumenthal has seen no ill effects resulting from haptic holes.
When to Use Viscoelastic In cases where any difficulty arises during implantation, especially in young
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Figure 238: Intraocular Lens Implantation Technique - Stage 2 With the distal haptic already located within the capsular bag at 6 o’clock, the forceps (F) moves the proximal haptic laterally (1-arrow). A Sinsky hook (S) placed through the paracentesis (D) engages the haptic hole (H) in the loop. While rotating the lens (2-arrow), the proximal haptic is introduced into the anterior chamber, compressed with the hook, directed behind the anterior capsule (3-arrow) and into the bag in one motion. Anterior chamber maintainer (A). Anterior capsulorhexis (C).
people, or if the anterior chamber is shallow, the use of viscoelastic material is indicated. It is easier to introduce the IOL into the AC in the presence of viscoelastic, but manipulation of the lens into the final preferred position is more easily achieved in the presence of BSS. Viscoelastic is not contraindicated during manual small incision Mini-Nuc ECCE while using the anterior chamber maintaining system, but the BSS flow should be reduced or stopped. It is better to activate the ACM system during aspiration of the viscoelastic. This keeps turbulence and fluctuation to a minimum.
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Pupil Enlarged by Increased IOP Deepening the AC with the ACM and increasing the IOP from 10 mm Hg to 30-40 mm Hg, pushes the iris back and sideways, dilating the pupil mechanically beyond the pharmacological effect of the dilatation drugs. In certain cases the pupil stays extra dilated at the end of surgery because of a phenomenon known as reverse pupillary block. No long-term ill effects arise from this. After a few minutes the reverse pupillary block subsides, as pressure in the posterior chamber rises above that existing in the AC. The block can also be broken mechanically
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by introducing a spatula under the iris. The pupil immediately becomes smaller, and the iris moves forward.
Advantages of the Continuous Flow of BSS during Manual ECCE Removes debris: The anterior chamber is washed throughout surgery. All pigment debris is washed out, reducing to a minimum possible ill effects during the postoperative period. Stops bleeding: When bleeding occurs in the tunnel or in the anterior chamber during surgery, it can be stopped by increasing the IOP. Moreover, no blood accumulates during surgery, as it is washed out by the continuous flow. Frees cortex remnants: These remnants find their way out of the eye due to the continuous flow through the AC. The rest are aspirated by a 5 cc syringe with a cannula attached. The aspiration is usually performed at the final stage of the surgery before the ACM is pulled from the eye. Removes viscoelastic: Viscoelastic material can and sometimes must be used during the surgery. It can be flushed out by fluid from the ACM or aspirated. Leftover quantities of viscoelastic are removed from their hidden locations with short bursts of BSS produced by a 1 cc syringe and cannula. Cleans posterior capsule: A 1 cc syringe attached to the hydrodissector cannula is used to create an intermittent water jet effect on the posterior capsule to clean it from attached cortical material (Fig. 233). This
procedure is much more effective when the ACM is used. The freed cortical material is aspirated whenever it is separated form the capsule. Aspiration of cortical material directly from the posterior capsule involves much more dangerous manipulation, as most capsule tears occur during this stage of the surgery. Prevents inflow : Hypotony, even if it occurs for a very short period, can cause inflow from outside the eye into the eye. With the ACM system, its active flow prevents foreign material from washing into the AC. By the same mechanism bacteria are partially prevented from entering the eye. If an instrument does carry bacteria to the AC, the bacteria may be washed out reducing the likelihood of endophthalmitis.
Complications Posterior capsule tear: Tears in the posterior capsule are mostly caused by suction with the aspiration cannula. The presence of the AC maintaining system during unintended tear of the posterior capsule pushes the vitreous face backward. In 70% of cases of unintended tear of the posterior capsule, the vitreous face stays intact. When the vitreous face is intact, BSS does not enter the vitreous body, even if the IOP is 40 mm Hg. The hypothesis that vitreous hydrates when in contact with BSS is not true. Hydration occurs only if the vitreous face is broken. During manual ECCE there is little turbulence or fluctuation; most of the time there is no movement at all. The amount of BSS used
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throughout one modern ECCE procedure during 10 minutes of surgery is only 20 cc to 30 cc The amount of flow during each minute of the surgery is 2 cc to 3 cc. This amount produces the least possible turbulence. Controlled aspiration using a 5 cc syringe in the presence of a posterior capsule tear can be performed without vitreous engagement, and aspiration of cortical material in the presence of posterior capsule tear is continued until the capsule bag is free of cortex, without enlarging the tear. The steady condition allows the surgeon to perform the most delicate maneuver possible, aspiration of cortical material lying on the vitreous face. This maneuver can be done only if the vitreous remains still, with no fluctuation. Vitreous involvement: When vitreous enters the AC through a posterior capsule tear, vitrectomy must be performed. An existing ACM is a great advantage at this stage. Because an imbalance of inflow and outflow would aggravate the situation, Blumenthal recommends the paracentesis entrance for the vitrectome tip. Steady conditions during vitrectomy ensure the procedure can be performed in a controlled manner. Because the posterior capsule does not move in an uncontrolled fashion, enlarging the size of the tear can be avoided. Enlarging the posterior cap-
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sule tear during vitrectomy reduces the option of choosing the bag as the best fixation site for the IOL. Locating vitreous strands is another very important aspect of the art of vitrectomy. Two-handed vitrectomy, during which the surgeon has a spatula in one hand and the vitrectome in the other, enables the surgeon to search for and locate vitreous fibers. Getting rid of all the vitreous strands, whether large or small, is essential. A quiet milieu allows the surgeon to search with the spatula carefully for strands over the iris and at the opening sites of the paracenteses and the tunnel. Eyes after such vitrectomy without strands in the AC have a very low rate of CME or iris deformation. In cases where the smallest vitreous strands remain, on the other hand, the incidence of CME is much higher. Expulsive Hemorrhage Minimized by Positive IOP: This rare phenomenon can be reduced to a minimum in routine cataract surgery, and in complicated or traumatic eyes by using continuous positive IOP during surgery. No hypotony occurs to cause leakage from, or rupture of choroidal or retinal blood vessels, especially when they are arteriosclerotic. Therefore expulsive hemorrhage or partial choroidal hemorrhage is mostly prevented.
C h a p t e r 13: Manual Extracapsular Techniques of Choice - Planned ECCE - Small Incision ECCE
THE SMALL INCISION PHACO SECTION MANUAL EXTRACAPSULAR TECHNIQUE
Overview We here present the Phaco Section cataract technique as developed by David McIntyre, M.D. one of the most talented and expert cataract surgeons in the U.S. We describe the evolution of his cataract surgery technique, present highlights of the procedure he has been using for 10 years, suggest how a surgeon can make the transition to the 5.5 mm wound Phacosection, and outline his surgical procedure step by step. At present McIntyre continues to use a 5.5 mm, non-sutured self-sealing, corneoscleral tunnel incision placed temporally under a peritomy, through which extracapsular cataract surgery is performed and a posterior chamber intraocular lens (IOL) is placed in the capsular bag. The intraocular lens is a 5.5 mm round, one-piece polymethylmethacrylate (PMMA) IOL placed in the bag, presently manufactured by Surgidev. McIntyre uses an anterior chamber maintainer, capsulorhexis and the nucleus is sectioned into 2 or 3 fragments, occasionally 4, with few exceptions in ages under 50-55.
surgery, using Kelman's phacoemulsification technique. During the past 20 years he has devised a number of instruments and modified techniques, resulting in extracapsular surgery with smaller and smaller incisions. Currently the incision is self-sealing and just large enough for the IOL implantation. From the perspective of results with patients, McIntyre has found no reason to return to the emulsification of the cataract nucleus with ultrasonic energy (phacoemulsification). At the same time he has personally attempted to develop a number of mechanical devices to aid in cortex aspiration. With each device he has reaffirmed that he has greater control over the operation when he uses a completely manual technique.
Indications McIntyre strongly believes that a basic advantage of the Phaco-Section is its applicability to all degrees of hardness of nucleus, from soft (+) to moderate (++), to fairly hard (+++) and to hard (++++), with truly minimal variations.
Evolution of Technique
PHACO SECTION MOST IMPORTANT FEATURES
McIntyre’s surgical technique has had a complex evolution. In 1974, he made the transition from intracapsular to extracapsular
The three separate tissue zones of the lens are shown in Fig. 239 to enhance the understanding of how Phaco Section works.
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Figure 239: The Three Tissue Zones of the Lens This anterior globe cross section shows the three separate tissue zones of the lens. Portions of the lens are shown removed to reveal the three dimensionality of these tissue zones. The rigid nucleus (N) is in the center. The second zone is the epinucleus (E), a firm or heavy gelatin material which is difficult to aspirate. The third and outer zone is the cortex (C) which is soft gelatin that is easy to aspirate, and lies just under the capsule (D). Note the 6 mm diameter circular capsulorhexis, which is large enough to allow the management of almost all nuclei by the phacosection technique. Air (A) is used to fill the anterior chamber during capsulorhexis to maintain the chamber depth and to eliminate the magnification effect of the corneal curvature.
The following are the most important features of McIntyre’s Phaco-Section surgical procedure.
Capsulorhexis This is performed through the incomplete tunnel incision that is perforated only by the cystotome. 390
McIntyre believes capsulorhexis offers several advantages in small incision phacosection technique. First, a 6 mm capsulorhexis is large enough to allow the management of almost all nuclei by the phacosection technique (Fig. 241). Secondly, the capsulorhexis actually gives a stronger margin to the capsulectomy than any of the "canopener" techniques. Consequently, there is considerably less risk of tears of the capsulectomy margin extending around the equator and to the posterior capsule. Third, the use of air provides significant benefit in the capsulorhexis. Air is maintained in the anterior chamber very easily after the puncture incision of the cystotome needle (Fig. 241). The presence of air in the anterior chamber makes visualization and control of the fragment of anterior capsule much easier for the surgeon. Lying on the surface of the cataract as it is torn around the circle, the fragment is very easily visualized. And finally, and perhaps most importantly, when the fluid is removed from the anterior chamber and is replaced with an air bubble, the magnification effect of the cornea is almost entirely neutralized, so that it is easy to understand the actual dimensions. When the anterior chamber is filled with fluid, the cornea becomes a 15% magnifier on average, making the capsulorhexis appear much larger than it really is.
Completing the Tunnel Incision After the capsulorhexis has been completed, the surgeon must complete the tunnel primary incision into the anterior chamber. There is a paracentesis just to the
C h a p t e r 13: Manual Extracapsular Techniques of Choice - Planned ECCE - Small Incision ECCE
right end of the tunnel incision, but the tunnel has been perforated only by a needle (the cystotome) up to this point. McIntyre enlarges the primary incision by grasping the margin of the scleral lip with a colibri forceps and passing a 15-degree supersharp blade through the cystotome puncture to slightly enlarge the incision. Then, with the double-bevelled crescent knife, he enlarges the opening into the anterior chamber to the full length of the tunnel incision, which is 5.5 mm to 6 mm (Fig. 241).
concavity facing the great circle that connects the two ends of the incision does not allow any stretching or raising of the flap. This is the reason the superficial layer of dissection in a tunnel has a very firm, unyielding geometry which to resists deformity or increased pressure within the globe. As long as the incision is concave to the great circle, a satisfactory self-sealing tunnel can be created. With the exception of children, the tunnel incision is sutured only in approximately 1 of 300 cases.
The Dynamics of the Self-Sealing Incision
Anterior Chamber Maintainer
McIntyre uses an analogy to help explain the dynamics of the self-sealing incision. Shallowness of the tunnel is important in preventing frequent hyphema. Deep tunnels tend to have frequent hyphemas; superficial tunnels tend not to result in frequent hyphema. McIntyre’s analogy is a great circle, which is the shortest distance between two points on the surface of the sphere, a common concept used in navigation (Fig. 240). On the eye the ends of an incision can be connected by a great circle around the globe. If any pressures and traction occur, there is a tendency for a wrinkle to develop that connects the two ends of the incision along the great circle. Consequently, if a scleral flap is fashioned following the curve of the limbus, that scleral flap must be sutured in position because any deformity of the globe will cause the eye to wrinkle along the great circle connecting the two ends of the incision. The scleral flap would become a free, non-supporting structure. In contrast, a frown-type incision that has a
The anterior chamber maintainer that McIntyre uses is a threaded or screw-like tip of metal tubing attached to a silicone tube, which is then attached to the hub of a needle. It can be plugged into a fluid source and has a flexible connection with the eye (Fig. 241). The internal diameter of the metal tubing is 0.6 mm. The threaded outer surface of the tube is able to grasp the corneal paracentesis very firmly so that when this has been screwed into the cornea it will hold in that position even when the eye is rotated rather vigorously. At the conclusion of the procedure it must be unscrewed to be removed. During its introduction the silicone tube and the maintainer tip itself have a stylette passed into them; the resulting rigidity allows the turning process, and a rounded point at the tips allows it to easily pass through the paracentesis. The fluid source for the chamber maintainer is balanced salt solution (BSS), which contains additional antibiotics for prophylactic purposes and is supported on an electric IV (intravenous) pole
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Figure 240: Straight vs Frown Shaped Scleral Incision A "great circle" on a sphere, or in this case on an eye, is the circumferential line (L) produced by a plane (P) which passes through the center (C) of the sphere. The great circle shown on this eye is one which passes through the area of a planned incision marked by endpoints (A) and (B). The key to the concept of the great circle is that it is geometrically the shortest distance between two points which lie on that circle. If the surface incision (D - top inset) forms a concave shape that does not cross the great circle (dotted line), then the superficial flap is quite rigid. If the incision (E - bottom inset) forms a convex shape from the great circle (dotted line), then there will be no support for the flap. Note the resulting gape of the incision.
so that the static height, and thereby the gravitational force, on the fluid that is entering the anterior chamber can be easily adjusted. The infusion tubing that comes from the BSS bottle to the table also has a roller valve so that the assistant can turn the maintainer system on and off as needed throughout the procedure. 392
Aspiration of the Anterior Cortex and Epinucleus With the tunnel completely opened and with the chamber maintainer operating and its pressure somewhat elevated, the surgeon does the preliminary aspiration of the cortex and
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epinucleus overlying the anterior surface of the firm central nucleus using a 21-gauge cannula (Fig. 241). McIntyre is careful to create a gutter or furrow around the equatorial area of the nucleus, thus allowing it to more easily come up from the remaining epinuclear "bowl". This is performed without any hydrodissection. Most experienced surgeons are aware of a complication that is frequently disastrous for the patient: the combination of posterior capsule tearing or rupturing with loss of vitreous and with portions of nucleus retained in the posterior segment. McIntyre believes that this complication indicates potential loss of control by the surgeon during portions of the operation when aspiration is being used. During removal of the lens material, the cataract should be seen as being formed of three separate tissue zones (Fig. 239). Starting from the center is the nucleus, a rigid material that is too viscous to allow aspiration. The second zone is the epinucleus or, as it is often called, the epinuclear bowl. The epinucleus is a relatively firm gelatinous material with an intermediate degree of viscosity, which can be aspirated with sufficient vacuum. The third zone is the peripheral cortex, which lies just under the capsule surface. This gelatinous zone is of a very low viscosity and is freely aspirated. This perspective of the three zones of the cataract clearly reveals an important safety factor in aspiration. Whether using manual or mechanical methods, the surgeon has more control when aspirating from the less viscous cortex toward the highly viscous nucleus. On the other hand, there is a potential loss of control and an extreme danger when aspirating from the more viscous element, such as the epinucleus, toward the peripheral cortex. In this circumstance when the aspirating
Figure 241: Aspiration of Anterior Cortex and Anterior Epinucleus The following illustration depicts the surgeon's view of a left eye. Temporal (3 o'clock) is at the bottom and nasal (9 o'clock) is at the top. First, an anterior chamber maintainer (M) is inserted nasally. A 6 mm circular capsulorhexis (A) is performed. The 5.5 mm frown shaped scleral tunnel (T) incision is completed. A specially sharpened 21 gauge cannula (D) is introduced through a paracentesis made to the right of the scleral tunnel incision. Inset shows detail of the tip of the cannula. The port of the cannula is directed posteriorly to aspirate the central cortex (C), and epinucleus (E) overlying the anterior surface of the firm nucleus (N). A furrow is created around the equatorial area of the nucleus.
instrument clears a portion of the viscous epinuclear material, the cortex will then move through the aspirating system at a much greater velocity, challenging the control of the surgeon to avoid impaction and probable tearing of the posterior capsule.
Phacosection Following the preliminary aspiration of cortex and epinucleus from the front surface of 393
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Figure 242: Hydrodissection of the Nucleus A 27 gauge cannula (F) placed through the paracentesis is used to hydrodissect the nucleus (N). The cannula is rotated (arrow) under the margin of the nucleus nearest the scleral tunnel incision to tilt it forward. A small amount of viscoelastic material may be used to maintain this tilt. Note the epinuclear bowl (E) in which the nucleus sets. Chamber maintainer (M).
the nucleus, McIntyre does a hydrodissection of only the central hard nucleus using a 27gauge, slightly narrowed and slightly curved cannula (Fig. 242). With this hydrodissection he also tilts forward the margin of the nucleus nearest the incision. Then the nucleus itself can be divided into a number of fragments using the technique called Phacosection (Fig. 243). This term, which McIntyre finds very useful, originated with Peter Kansas in New York. The procedure involves dividing the nucleus into a number of fragments, the number being determined by the size and hardness of the nuclear material, usually 2 or 3, occasionally 4. Each of these fragments is then individually surrounded by a layer of heavy viscoelastic material (Fig. 244) and simply extracted from the anterior chamber with their protective viscoelastic coating using a pair of instruments designed for this purpose (Fig. 245).
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Removal of Epinucleus and Cortical Cleanup Following the removal of the divided nucleus particles, the epinucleus is then removed as a second stage. The epinucleus is hydrodissected from its attachment to the peripheral cortex (Fig. 246). In most cases the epinucleus is a continuous structure which can be hydrodissected, brought forward into the anterior chamber, and hydraulically expressed. The epinucleus is not removed by aspiration. The third stage of the cataract tissue removal is simple aspiration of the residual cortex. The only stages of the procedure performed by aspiration are the preliminary aspiration of the anterior cortex and epinucleus, and then the final cleanup of the residual peripheral cortex. In this way the process of aspirating from a more viscous to a less viscous
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medium is avoided. Thereby, the surgeon avoids losing control and destroying the continuity of the posterior capsule.
Transition from Extracapsular Extraction to Phacosection McIntyre believes it is easier for the ophthalmic surgeon who is accustomed to standard, conventional large-incision extracapsular surgery to make the transition to small-incision phacosection (5.5 mm) than to phacoemulsification. The small incision phacosection technique offers the surgeon some very distinct advantages on his/her patient’s behalf in comparison with the conventional large-incision planned extracapsular. These advantages are: more safely, a much more rapid recovery, a much more durable eye during
Figure 244 (above): Surrounding Nuclear Pieces with Viscoelastic Each fragment of nucleus is individually surrounded by a layer of heavy viscoelastic material via a cannula through the tunnel incision. The viscoelastic (V) is shown being placed between the two hard nucleqr fragments (N). This will assist in protecting intraocular structures during their removal. The anterior chamber maintainer (M) is still turned off.
Figure 243 (left): Phacosection of the Nucleus A spatula (S) is introduced through the scleral tunnel incision (T) and placed behind the nucleus (N). A single cutter (R), also introduced through the tunnel incision, is used to section (arrow) the nucleus. The anterior chamb er contains viscoelastic with the anterior chamber maintainer (M) turned off during this sectioning.
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Protocol for Phacosection Surgery The total small incision self-sealing phacosection cataract procedure with lens implantation can be summarized in the following steps: 1) A standard patient preparation with wide dilation of the pupil. Peribulbar anesthesia followed by 40 minutes of oculopression with an equivalent of 30 mm pressure. The patient is draped with isolation of the lid margins and insertion of the speculum. 2) A nasal limbal paracentesis is followed by insertion of the anterior chamber maintainer, which is then turned on (Fig. 241). 3) A temporal limbus based conjunctival flap of 3 to 4 mm width is made with mechanical dissection of the limbus and limited bipolar cautery of the episcleral vessels. 4) A 6 mm frown incision is marked with calipers on the surface of the sclera, avoiding any major scleral vessels (Fig. 240). 5) A superficial scleral tunnel is dissected with a crescent blade. A paracentesis is created to the right side of the incision tunnel. Then perforation is made through the base of the tunnel into the anterior chamber at the center of the tunnel with a hooked cystotome. 6) The anterior chamber maintainer is turned off. The anterior chamber is inflated with air through the cystotome, and a capsulorhexis of approximately 6 mm diameter is created. 7) The chamber maintainer is turned on. Perforation is made through the central tunnel puncture with a 15 degree super sharp blade, followed by the crescent blade to enlarge the internal aspect of the tunnel incision to its full dimension.
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8) Any remaining air bubbles and the capsule fragment are aspirated through the tunnel incision with a 21-gauge cannula. The chamber maintainer is elevated to increase the hydrostatic pressure. Preliminary aspiration of the anterior cortex and the epinucleus down to the face of the nucleus is done with the 21-gauge cannula through the paracentesis (Fig. 241). 9) Hydrodissection of the firm central nucleus is done with a 27-gauge cannula through the paracentesis, tilting forward the equator of the nucleus adjacent to the tunnel (Fig. 242). Hydrodissection is intended to elevate the smallest identifiable nucleus and to tilt forward only the equator that lies directly in front of the tunnel incision. 10) The anterior chamber maintainer is turned off. The anterior chamber is deepened with viscoelastic of high viscosity; a small amount is injected behind the nucleus to hold it in the tilted position if necessary. With a cutting board and a single nucleus cutter the surgeon reaches into the anterior chamber (Fig. 243). Depending on the size and hardness of the nucleus, the surgeon decides how many cuts in the nucleus will be needed. With the single cutter he then makes one, two, or three cuts as required. The two instruments are withdrawn. 11) Additional viscoelastic is injected and the cannula is used to position the first fragment of the cut nucleus that appears most readily accessible for removal (Fig. 244). 12) With the shield of viscoelastic in place, the surgeon reaches into the anterior chamber with the two nucleus extracting instruments, which look very much like a pair of spoons. The two spoons surround the fragment of nucleus and remove it from the anterior chamber (Fig. 245).
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13) Additional viscoelastic is used to isolate each individual fragment as it is removed with the extracting instruments. The average volume of viscoelastic required is .25 ml. 14) The chamber maintainer is turned on. Hydrodissection of the epinucleus is done with the 27-gauge cannula and balanced salt solution (BSS). The entire epinucleus is hydroexpressed with or without the irrigating spoon (Fig. 246).
on the introduction forceps. The IOL is introduced under an assisting 30-gauge cannula with the leading haptic placed directly into the nasal capsular bag. The lens optic is steadied with the 30-gauge cannula as the introduction forceps are removed. The trailing haptic is placed under the incision into the capsular bag with a Dusek forceps. The lens is rotated, its position is confirmed, and the haptics are placed in the horizontal position.
15) The residual peripheral cortex is aspirated with the straight and curved cannulas through the paracentesis.
18) The conjunctival incision is sealed with bipolar cautery. The corneal margins of the paracentesis are hydrated with a 30-gauge cannula. The chamber maintainer is removed. The margins of the ACM paracentesis are hydrated with BSS.
16) The posterior capsule is polished with the straight side ported aspirating cannula turned posteriorward and introduced through the tunnel incision.
19) Absence of iris incarceration is confirmed. Final re-deepening and inspection of the anterior chamber is done through the paracentesis.
17) This is followed by inspection, irrigation, and positioning of the intraocular lens
20) Finally, medications and dressing are applied.
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Figure 245 (right): Nuclear Fragment Removal A spatula (S) introduced through the tunnel incision is inserted under the viscoelasticcoated nuclear fragment (N). The extracting instrument (X), shaped somewhat like an inverted spoon, is inserted over the nuclear fragment. Then, to extract the fragment, the spatula (S) is rotated upwards (red arrow) causing the tips of the instruments to approach one another in a pincer-like fashion. Both instruments with the included nuclear fragment are then removed from the anterior chamber in a straight horizontal movement (blue arrow), thus preventing both the instrument and the nuclear fragment from contacting the corneal endothelium. Note remaining nuclear fragment (F) still within epinuclear bowl (E). Anterior chamber maintainer (M) is still off during this extraction.
Figure 246 (left): Hydrodissection and Hydroexpression of Remaining Epinucleus The remaining epinucleus (E) is hydrodissected as shown using the special 21 gauge cannula (D) introduced through the tunnel incision. BSS is being injected through the 27 gauge cannula (F) as well as the anterior chamber maintainer (M). Working through the tunnel at this point assures that leakage will control excessive anterior chamber pressure. When the epinucleus has been hydrodissected and is floating in the anterior chamber, its removal (arrow) is facilitated with the irrigating spoon (not shown). The residual peripheral cortex (C) is then aspirated via cannula through the paracentesis.
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the immediate postoperative period, and a major reduction in the astigmatism effects of the surgery. If the surgeon decides to make a transition from the traditional large incision extracapsular technique this should be done in a very orderly way with the following steps: 1)Begin using the standard incision technique with which the surgeon is already familiar. 2) After completing the large incision with pre-placed sutures if that is the surgeon's custom, begin to practice the capsulorhexis. 3) When comfortable with the capsulorhexis technique, begin to aspirate down onto the surface of the nucleus, tilt the nucleus forward, perform the phacosectioning technique, and extract the particles of the nucleus. This is still done through the full-size extracapsular incision with which the surgeon is familiar. 4) When the surgeon is completely comfortable with all these steps, then he/she can begin to change the incision technique. McIntyre suggests that the size of the incision can first be reduced to about 7.5 mm. A frown incision can be made, but closed with two simple interrupted sutures. 5) When the surgeon is confident this is performed satisfactorily, he/ she can consider moving the incision site to the temporal limbus and can progressively reduce the linear dimension of the tunnel. 6) When the tunnel is approximately 6.5 to 6 mm, the surgeon will probably continue to put one suture in the center of the tunnel just to maintain confidence. At this point, the surgeon is in fact doing the current small incision phacosection technique, and will find it is perfectly safe to eliminate the use of sutures except in special circumstances.
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THE SMALL INCISION MANUAL PHACOFRAGMENTATION
The small incision manual phacofragmentation (MPF) that we hereby present has been designed and developed by Francisco Gutierrez C., M.D., of Spain. It is performed with a 3.2 mm clear corneal incision, which is the same size as in phacoemulsification. This manual phaco fragmentation (MPF) can also be done with a 3.5 mm scleral tunnel incision, which is the same incision size for phaco when we utilize the scleral tunnel technique (Figs. 247 and 248).
Benefits of (MPF) As advocated by Dr. Gutierrez C., this technique provides several important benefits, as follows: 1) It can be performed with a small 3.2 mm incision if done in clear cornea and with a 3.5 mm incision if done with a scleral tunnel, thereby resulting in minimum astigmatism and rapid recovery (Figs. 247 and 248). 2) It functions well with hard and soft nuclei. 3) It requires a low investment in the equipment and instrumentation. 4) Presumably, it provides a very good backup when complications arise and phacoemulsification must be discontinued. This technique helps the phacoemulsification surgeon in the event of an accidental rupture of the posterior capsule. Also, the instrumentation facilitates extracting the nuclear fragments from
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the AC through the small incision, avoiding the need to enlarge it and convert the surgery to an ECCE. 5) Presumably it is a method easier to master than phaco. 6) No less important, it requires no sutures or stitches.
Experiences with Other Phaco Fragmentation Techniques In order to overcome the two main drawbacks of phaco: 1) difficult learning curve and 2) high cost of equipment, a good number and variety of techniques for manual phacofragmentation have been used in the past. The limitations of these techniques have been related to not being able to sufficiently reduce the size of the incision because: 1) the instrumentation was coarse; 2) the nuclear fragments that were to be extracted from the anterior chamber were too large, usually because the nucleus was divided into two or three pieces.
Why Use Gutierrez' Technique? Positive Features of Instrumentation The phacofragmentor designed by Gutierrez, is manufactured by the English firm of John Weiss & Son Ltd., a subsidiary of the Swiss multinational Haag-Streit. With it
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the nucleus is broken into very small 2 x 2 mm pieces that can be extracted through a 3.2 or 3.5 mm incision (Fig. 247). This results in a practically neutral postsurgical residual astigmatism. The racquet-shaped design of the fragmentor (see P and B in Fig. 247) keeps the nuclear fragments within the racquet, avoiding their dispersion as they are removed from the AC. The phacofragmentor or nucleotome has a straight ophthalmic handle, with a 45º angle at its end, which is 8 mm long and 2 mm wide and racquet-shaped. The racquet is divided in four parts by three transverse bars two millimeters apart (Fig. 247) which keep the small pieces within the racquet. Other important instruments are: • A spatula with a straight ophthalmic handle, whose end is adapted to the dimensions
and angle of the nucleotome and serves as support for phacofragmentation (see "S" in Fig. 247). • Two straight-handled, ophthalmic manipulators, left and right, with a basket end, which serve to collect the nuclear fragments during the nuclear fragmentation (Fig. 250). • Anterior chamber maintainers were pioneered years ago by Strampelli as well as Joaquin Barraquer, and their use is always emphasized by Michael Blumenthal for his Mini-Nuc cataract extraction technique. The Gutierrez AC maintainer (ACM) maintains continuous irrigation with BSS in the anterior chamber, creating positive pressure that stabilizes the AC depth. During the stages of the operation in which the maintainer is used, the amount of viscoelastic utilized is less, thereby reducing costs.
Figure 247: Manual Multiphacofragmentation Technique - Stage 1 - Fragmentation Following creation of a 3.5mm scleral tunnel (I) or 3.2mm corneal incision, continuous circular capsulorhexis, and hydrodissection of the nucleus, the nucleus is luxated into the anterior chamber. After the nucleus is luxated into the anterior chamber, a high density viscoelastic is injected into the area surrounding the nucleus to fill the anterior chamber. The spatula (S) is placed beneath the nucleus (N). The nucleotome, (or phacofragmentor) (P) is placed on top of the nucleus. With the nucleus sandwiched between the two instruments (inset), the nucleotome is pressed downward toward the spatula (arrow). This sections the nucleus into four fragments (1,2,3,4) between the cross bars (B) of the racket shaped nucleotome.
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Surgical Technique It is important to have good pharmacological mydriasis because the pupil may contract during surgery. Incision: This method can be performed through a 3.2 mm corneal incision (clear corneal) (Fig. 247) or through a 3.5 mm scleral tunnel incision (scleral tunnel) 2 mm away from the corneal-scleral limbus (Fig. 248). The preparatory incision is made without penetrating the anterior chamber (AC). Capsulotomy: A continuous circular capsulorhexis is performed with a cystotome through a superotemporal paracentesis. This capsulorhexis should be sufficiently wide (approximately 6 mm) to allow an easy luxation of the nucleus into the AC. The AC maintainer is used during this step and when aspirating the anterior cortex and epinucleus in soft and me-
dium-soft nuclei, before hydrodissection. Nucleus Hydrodissection and Luxation: After entering the AC with a 3.2 mm beveled blade, balanced salt solution (BSS) is injected with a Binkhorst cannula through the corneal or scleral incision between the anterior capsule and the cortex at 12 o'clock. The BSS must be injected slowly and continuously until the "wave" of dissection is visible on the posterior capsule. Injection of BSS is continued until luxation of the nucleus begins. If the luxation of the nucleus into the AC is partial, it may be completed by rotating the nucleus with a cannula, cystotome or spatula. Nuclear Fragmentation: Once the nucleus has been luxated into the AC, highdensity viscoelastic is injected into the surrounding area to fill the AC. The nucleus is then fragmented by placing the spatula beneath the nucleus and the nucleotome on top of it
Figure 248 - Manual Multiphacofrag-mentation Technique - Stage 2 - Extraction While the nuclear fragments (A) remain with the nucleotome (P), the spatula (S) and nucleotome are extracted (arrow) from the anterior chamber through the incision (I). Notice the remaining nucleus (N) with center removed, within the anterior chamber. This procedure is repeated until the whole nucleus is fragmented and extracted. With hard nuclei, after capturing the nuclear fragments (A) with both instruments (P) and (S), space can be gained by extracting nuclear fragments (A) using only the nucleotome (P), as hard fragments will remain within the nucleotome (P) without the support of the spatula (S), thus reducing corneal injury.
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Figure 249: Manual Multiphacofragmentation Technique - Stage 2A - Extraction This cross section shows the extraction configuration seen in the surgeon’s view of Figure 2. Notice the nuclear fragments (A) sandwiched between the nucleotome (P) and spatula (S) as they are extracted (arrow) from the chamber. Part of the nucleus (N) remains in the anterior chamber and will be extracted in the same manner.
(Fig. 247). Pressure is then created by slowly pressing the nucleotome downward toward the spatula until the part of the nucleus in it is fragmented into four pieces (Fig. 247). The pieces remain within the nucleotome, and with the help of the spatula are extracted from the AC using a "sandwich" technique (Figs. 248 and 249). This maneuver is repeated until the whole nucleus is fragmented. During nuclear fragmentation it is important to refill the AC with high-density viscoelastic as needed to protect the corneal endothelium and facilitate safe manipulation during surgery.
Manipulation of Nuclear Fragments: There are right and left manipulators to displace the remaining fragments of the nucleus to the center of the AC to facilitate their fragmentation and subsequent removal (Fig. 250). Cortex Extraction and Nucleus Removal: The lens cortex is aspirated with a twoway Simcoe irrigation-aspiration cannula (Fig. 251). If small pieces of the nucleus remain in the AC, they can be removed according to their hardness in different ways: with the nucleotome and the spatula together (sandwich - Figs. 247, 248, 249) or only with the
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Figure 250 - Manual Multiphaco-fragmentation Technique - Stage 3 - Manipulation of Nuclear Fragments Left (L) and right (R) curved manipulators (M) are used to displace (arrows) the remaining fragments of the nucleus (N) to the center of the anterior chamber. From there they will be fragmented and extracted in a similar fashion with the nucleotome and spatula.
Figure 251 - Manual Multiphacofragmentation Technique - Stage 5 - Removal of Soft Nuclear Fragments and Cortex Following removal of the nucleus, the lens cortex and any soft residual nuclear fragments (FS) can then be aspirated and extracted from the anterior chamber with a Simcoe irrigation-aspiration cannula (A). A Charleux cannula may also be used (not shown). Lens cortex beneath the hard-to-reach incision area can be aspirated with a Binkhorst cannula (B) as shown.
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nucleotome, removing the spatula from the AC once the surgeon has grasped the nuclear fragment. Removal can also be accomplished using a two-way (I/A) Simcoe or Charleux cannula (Fig. 251), or with gentle BSS irrigation of the AC aided by a fine cannula. Intraocular Lens Implant and Wound Closure: Viscoelastic is injected into the capsular bag and a foldable lens is implanted. Sutures are not usually required.
Complications In Dr. Gutierrez C. experience, complications are rare. There is always the possibility for mild corneal edema if much intraocular manipulation is done and for a small hemorrhage in the anterior chamber if the instrumental manipulation may causes small damage to the iris. Dr. Gutierrez C. recommends that ophthalmologists beginning to use this method initially practice with incisions larger than 3.5 mm, progressively reducing the size as they master the technique.
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THE NEW CATARACT SURGERY DEVELOPMENTS 3) The Phaco Tmesis System, of
Overview
Aziz Anis. At present, there are four main avenues of development for new techniques in cataract surgery. Those who advocate them consider that they might be better than phacoemulsification. They are:
1) The Laser Techniques Two groups of procedures are done with laser: a) The Dodick Laser Photolysis System: This is the only one that has been approved by the FDA in the United States and is also clinically available in Europe. This system is manufactured by Laser Corp., based in Salt Lake City, Utah. b) The Paradigm Nd:YAG Laser System, also known on the “Phantom”. This is under investigational development by Paradigm Medical Industries also of Salt Lake City.
2) The Catarex
System, being
developed by Richard Kratz et al.
4) Warm Water Jet Technology. DODICK’S TEM
PHOTOLYSIS
SYS-
Dodick et al use a Q-switched Nd:YAG laser. The pulsed laser and a specially designed probe to use this energy are utilized for removal of the cataractous crystalline lens. The probe has a quartz-clad fiber. The proximal end of the quartz fiber is connected to the laser source. The fiber enters the probe through the probe’s infusion port and the distal end terminates in front of a titanium target inside the tip of the probe. This target is an essential element of the device (Fig. 252). The titanium target acts as a transducer, causing optical breakdown and plasma formation to occur in the aspiration chamber, and sending out acoustic shock waves configured by the target’s shape to be maximized at the aspirating tip. At the aspirating tip nuclear material is shattered by the acoustic waves and evacuated out of the eye.
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Surgical Technique As described by Kanellopoulos et al a 1.4 mm clear-cornea incision is made for insertion of the Dodick photolysis laser-aspiration probe. A second, 0.9 mm corneal incision is made to provide irrigation or infusion through a second probe. The infusion and aspiration are done after a 6 mm CCC is performed. The laser delivers pulsing photic energy, which creates a shock wave that emanates from the probe tip in a focused
cone. These shock waves break down the substance of the cataract (Fig. 252). The fragmented particles of the cataract are then aspirated out of the eye. The same probe is used to aspirate the cortex. At present, the incision needs to be enlarged for insertion of a foldable IOL. Industry is working on making foldable lenses that can be introduced into the eye with incisions smaller than the 2.8 mm minimum used now.
Figure 252: Dodick’s Laser Photolysis The laser fibre (L) terminates in front of a titanium target (T) which absorbs the emitted pulsed YAG laser energy (L). The resultant optical breakdown and plasma formation create shock waves which travel to the mouth of the aspiration port shattering the lens material. Suction occurs there and the cataract is aspirated out of the eye.
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Advantages According to Dodick, photolysis has two primary advantages. One is that it will allow smaller incisions and two, it generates no heat. One of the disadvantages of classic phaco is that the wound may be damaged by heat. With laser photolysis, we will not have any wound burns. Photolysis is felt to offer more protection of the corneal endothelium and presumably it is a somewhat simpler procedure than phaco.
THE CATAREX SYSTEM This system is under investigational development under the leadership of Richard P. Kratz, Shoeila Mirhashemi, Michael Mittelstein and John Sorensen. Through the years, Kratz has made several major contributions to improve the techniques of phacoemulsification. Catarax is a different technology that may important advantages over phaco and ECCE.
Potential Advantages and Technique Lindstrom is participating in the investigational work in animals. As he describes it, it only requires a 1.0 to 1.4 mm incision. The surgeon makes a one millimeter incision in the anterior capsule with diathermy, just inside the edge of the iris where he makes the wound. Then he puts in a device that looks somewhat like a blender blade into the eye that works through a vortex action. This basically breaks up the lens, allowing aspiration. The potential advantage of Catarex seems to be that there should be no corneal
endothelial cell loss, in contrast to phaco, which even in good hands, may have a four percent endothelial cell loss or more. With Catarex, since all maneuvering is done inside the capsule with its tight seal, the endothelium should have no damage. The other potential advantage is that by working inside the capsule this procedure might decrease posterior capsular tears and eliminate iris damage. All these potential advantages should provide us a safer operation. Another potential advantage is that it is hoped Catarex may be easier than phacoemulsification, which is a difficult operation. If so, this would be a very positive advance from the perspective of public health and the availability to many people that who cannot have phaco at present. Hopefully, the cost would be less.
Aziz PhacoTmesis PhacoTmesis uses a spinning needle that also has ultrasound. It is a very powerful cutting tool.
Water Jet Technology If you heat water to the right temperature, about 55 to 60 degrees centigrade, you can appear to melt the lens. There are several companies working on a water jet type technology to remove cataracts with basically heated balanced salt solution. It appears that this can be done without damaging the surrounding tissues from the heat either by using an endocapsular method or by having short pulses of the heated material directed at the cataract with cool material circulating in the anterior chamber. The latter two methods mentioned above seem to be brilliant ideas but it is unclear whether they can be translated into practical reality. 411
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BIBLIOGRAPHY Anis, AY: PhacoTmesis. Atlas of Cataract Surgery, Edited by Masket S. & Crandall AS, published by Martin Dunitz Ltd., 1999, 12:89-96. Colvard DM, Kratz RP: Cataract surgery utilizing the erbium laser. In: Fine IH, ed. Phacoemulsification: New Technology and Clinical Application (Thorofare, NJ: Slack, 1996), 161-80. Dodick, JM: The Nd:YAG laser phacolysis technique. Boyd’s World Atlas Series of Ophthalmic Surgery of HIGHLIGHTS. 1995; 5:130-131. Dodick JM, Christian J: Experimental studies on the development and propagation of shock waves created by the interaction of short Nd:YAG laser pulses with a titanium target: possible implications for Nd:YAG laser phacolysis of the cataractous human lens. J Cataract Refract Surg 1991; 17:794-7. Kanellopoulos AJ, Dodick JM, Brauweiler P, Alzner, E: Dodick photolysis for cataract surgery. Early experience with the Q-switched neodymium:YAG laser in 100 consecutive patients. Ophthalmology, 1999;106:2197-2202. Kratz RP, Mirhashemi S, Mittelstein M, Sorensen JT: The Catarex technology. Atlas of Cataract Surgery, Edited by Masket S. & Crandall AS, published by Martin Dunitz Ltd., 1999, 11:85-88.
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