Glaucoma Surgery

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Author: Graham Trope

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Glaucoma Surgery

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Published in 2005 by Taylor & Francis Group 6000 Broken Sound Parkway NW, Suite 300 Boca Raton, FL 33487-2742 © 2005 by Taylor & Francis Group, LLC No claim to original U.S. Government works Printed in the United States of America on acid-free paper 10 9 8 7 6 5 4 3 2 1 International Standard Book Number-10: 0-8247-2743-6 (Hardcover) International Standard Book Number-13: 978-0-8247-2743-7 (Hardcover) This book contains information obtained from authentic and highly regarded sources. Reprinted material is quoted with permission, and sources are indicated. A wide variety of references are listed. Reasonable efforts have been made to publish reliable data and information, but the author and the publisher cannot assume responsibility for the validity of all materials or for the consequences of their use. No part of this book may be reprinted, reproduced, transmitted, or utilized in any form by any electronic, mechanical, or other means, now known or hereafter invented, including photocopying, microfilming, and recording, or in any information storage or retrieval system, without written permission from the publishers. For permission to photocopy or use material electronically from this work, please access www.copyright.com (http://www.copyright.com/) or contact the Copyright Clearance Center, Inc. (CCC) 222 Rosewood Drive, Danvers, MA 01923, 978-750-8400. CCC is a not-for-profit organization that provides licenses and registration for a variety of users. For organizations that have been granted a photocopy license by the CCC, a separate system of payment has been arranged. Trademark Notice: Product or corporate names may be trademarks or registered trademarks, and are used only for identification and explanation without intent to infringe. Library of Congress Cataloging-in-Publication Data Catalog record is available from the Library of Congress

Taylor & Francis Group is the Academic Division of T&F Informa plc.

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This book is dedicated to all the great teachers who made me think including Robert and Adele Trope, Wallace Foulds, Jeffery L. Jay, John Dudgeon, and William S. Lee Graham E. Trope

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Preface

Why a new Glaucoma surgery text at this time? A review of currently available texts reveals a paucity of readily available information for the Glaucoma Specialist. Although there are some excellent surgical texts for general ophthalmologists, there are few indepth texts available to help the Glaucoma specialist deal with complications seen after adult glaucoma surgery. This book is divided into two sections. A “How to” section and a section on management of complications. Topics covered in the latter section include management of the postoperative eye with high intraocular pressure with deep chamber, the flat anterior chamber with high intraocular pressure and the flat chamber with low intraocular pressure. To aid learning surgery we have also included a surgical DVD. This DVD covers a number of important topics including Peng Khaw’s method of doing a trabeculectomy, how to insert an Ahmed valve and how to manage bleb problems. I am indebted to Professor Peng Khaw, Dr. Garry Condon and especially Dr. Wai-Ching Lam for their important contributions to the DVD. I would like to thank all the surgeons who gave their valuable time to the preparation of this book. This book contains an international approach to glaucoma surgery and the management of complications. I make no apology for extensively utilizing Canadian expertise. My Canadian colleagues are expert in dealing with complications and as a result they have made substantial contributions to this new surgical text. I sincerely hope this text will help practicing glaucoma specialists decide on the most appropriate surgery for their patients and help surgeons deal rationally with complications seen postoperatively in the adult eye. Graham E. Trope, M.B., B.Ch., Ph.D., F.R.C.S.(C.), F.R.C.Ophth., F.R.C.S. (E.D.), D.O. (R.C.P.&S.)

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Contents

Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v Biography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xi Contributors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii

Section I 1.

Surgical Techniques

Indications, Pre-operative Evaluation, and Outcomes of Filtering Surgery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Arthur J. Sit and Graham E. Trope

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2.

Glaucoma: Surgical Anatomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Maurice H. Luntz and Graham E. Trope

13

3.

Modern Anesthesia for Adult Glaucoma Filtration Surgery . . . . . . . . . . . . . Monica M. Carrillo and Graham E. Trope

17

4.

Advances in the Modulation of Wound Healing Including Large Treatment Areas and Adjustable Sutures: The Moorfields Safe Surgery System . . . . . . . . . . . . . . . . . . . . . . Peng Tee Khaw and Graham E. Trope

5.

How to Do a Trabeculectomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Clive Migdal and Graham E. Trope

6.

Nonpenetrating Glaucoma Surgery: Indications, Techniques, and Complications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tarek Shaarawy, Graham E. Trope, and Andre´ Mermoud

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45

51

7.

How to Insert a Glaucoma Implant . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Jeffrey Freedman and Graham E. Trope

63

8.

Management of Glaucoma Implant Complications . . . . . . . . . . . . . . . . . . . Jeffrey Freedman, Shlomo Melamed, and Graham E. Trope

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Contents

9.

Pars Plana Insertion of Ahmed Glaucoma Valve . . . . . . . . . . . . . . . . . . . . . Roland Ling, Wai-Ching Lam, and Graham E. Trope

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10.

Full-Thickness Filtering Glaucoma Surgery . . . . . . . . . . . . . . . . . . . . . . . . Maurice H. Luntz and Graham E. Trope

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11.

How to Do a Surgical Iridectomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 101 Maurice H. Luntz and Graham E. Trope

12.

Combined Cataract and Glaucoma Surgery . . . . . . . . . . . . . . . . . . . . . . . . . 107 Ruth Lapid-Gortzak, David S. Rootman, Yvonne M. Buys, and Graham E. Trope

13.

Ultrasound Biomicroscopy in Glaucoma Surgery . . . . . . . . . . . . . . . . . . . . 119 Charles J. Pavlin and Graham E. Trope

Section II

Management of Complications

14.

Overview: An Approach to the Diagnosis of Early Postoperative Complications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135 Yvonne M. Buys and Graham E. Trope

A.

Management of High Intraocular Pressure with a Deep Chamber

15.

Massage: Techniques and Complications . . . . . . . . . . . . . . . . . . . . . . . . . . 139 Yvonne M. Buys and Graham E. Trope

16.

Glaucoma Suture Lysis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 145 Graham E. Trope

17.

Releasable Sutures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 151 Ruth Lapid-Gortzak, David S. Rootman, and Graham E. Trope

18.

The Failing Bleb: Risk Factors and Diagnosis Paul R. Healey and Graham E. Trope

19.

Encapsulated Bleb . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179 Adael S. Soares, Marcelo T. Nicolela, Paul E. Rafuse, and Graham E. Trope

20.

Needling Procedures in Postoperative Management of Glaucoma Surgery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 187 Tarek Shaarawy, Pieter Gouws, Graham E. Trope, and Andre Mermoud

B. 21.

. . . . . . . . . . . . . . . . . . . . . . 159

Management of Flat Anterior Chamber with High Intraocular Pressure Suprachoroidal Hemorrhage in Filtering Surgery and Practical Management . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 193 Ravikrishna Nrusimhadevara, R. G. Devenyi, and Graham E. Trope [email protected]

Contents

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22.

Malignant Glaucoma . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 199 Dimitrios Kourkoutas, Charles J. Pavlin, and Graham E. Trope

C.

Management of a Flat Chamber with Low Intraocular Pressure

23.

Management of the Leaking Bleb . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 217 Andrew C. Crichton, Garry P. Condon, and Graham E. Trope

24.

Remodeling the Filtration Bleb . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 225 J. E. Morgan and Graham E. Trope

25.

Management of Flat Anterior Chambers and Choroidal Effusions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 235 Ridia Lim, Ivan Goldberg, and Graham E. Trope

26.

Hypotony Maculopathy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 247 Catherine M. Birt and Graham E. Trope

D.

Management of Bleb Infection

27.

Blebitis and Bleb-Associated Endophthalmitis: Diagnosis and Treatment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 255 Fani Segev, Allan R. Slomovic, and Graham E. Trope

Index

. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 265

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Biography

Dr. Graham E. Trope is Professor of Ophthalmology at the University of Toronto. He has directed the Glaucoma Service at University Health Network since 1984. Dr. Trope is the past Chairman of Ophthalmology at the University of Toronto. He has published over 115 scientific articles, has been involved in Glaucoma Research and Treatment for over 20 years and is the Founder and Scientific Director of Glaucoma Research Society of Canada. He is incoming Editor-in-Chief of the Canadian Journal of Ophthalmology and he sits on a number of editorial boards including the Journal of Glaucoma. He has won a number of awards including The Ontario College of Physicians and Surgeons Council Award for his contributions to patient care. He has trained more than 20 glaucoma fellows from all over the world and is a past examiner for the Royal College of Physicians and Surgeons of Canada. He is a member of a number of learned societies and has published a book entitled Glaucoma, A Patient’s Guide to the Disease which is in its 3rd edition. xi

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Contributors

Catherine M. Birt, M.A., M.D., F.R.C.S.(C.) Associate Professor, Department of Ophthalmology, University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada Yvonne M. Buys, M.D., F.R.C.S.(C.) Associate Professor of Ophthalmology, University Health Network and University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada Monica M. Carrillo, M.D. Clinical and Research Fellow, Department of Ophthalmology, Dalhousie University, Halifax, Nova Scotia, Canada Garry P. Condon, M.D. Clinical Associate Professor, Drexel University College of Medicine, Allegheny General Hospital, Pittsburgh, Pennsylvania, USA Andrew C. Crichton, M.D., F.R.C.S.(C.) Calgary, Calgary, Alberta, Canada

Clinical Associate Professor, University of

R. G. Devenyi, M.D., F.R.C.S.(C.) Professor of Ophthalmology & Ophthalmologist in Chief and Director of Retinal Services, University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada Jeffrey Freedman, M.B., B.Ch., Ph.D., F.C.S.(S.A.), F.R.C.S.E. Professor of Clinical Ophthalmology, Department of Ophthalmology, S.U.N.Y. Brooklyn, Brooklyn, New York, USA Ivan Goldberg, M.B.B.S., F.R.A.N.Z.C.O., F.R.A.C.S. ates and Sydney Eye Hospital, Sydney, Australia

Ophthalmologist, Eye Associ-

Pieter Gouws, M.B., B.Ch., F.R.C.Ophth. Glaucoma Fellow, Department of Ophthalmology, University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada Paul R. Healey, M.B.B.S.(Hons.), B.Med.Sc. (Cell Biology), M.Med. (Clinical Epidemiology), F.R.A.N.Z.C.O. Ophthalmic Surgeon, Director of Glaucoma Services and Clinical Senior Lecturer, Western Sydney Eye Hospital; University of Sydney, Centre for Vision Research (Westmead Millennium Institute); and Save Sight Institute, Sydney, Australia xiii

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Contributors

Peng Tee Khaw, Ph.D., F.R.C.P., F.R.C.S., F.R.C.Ophth., F.R.C.Path., F.I.Biol., FMed.Sci. Professor of Glaucoma and Ocular Healing & Consultant Ophthalmic Surgeon, Director, Department of Glaucoma and Ocular Healing, ORB Ocular Repair and Regeneration Biology, Glaucoma, Pathology and Cell Biology, Moorfields Eye Hospital and Institute of Ophthalmology, London, UK Dimitrios Kourkoutas, M.D. Consultant in Ophthalmology, Department of Opthalmology, 401 Hellenic Army General Hospital, Athens, Greece Wai-Ching Lam, M.D., F.R.C.S.(C.) Associate Professor, University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada Ruth Lapid-Gortzak, M.D. Cornea Fellow, Department of Ophthalmology, University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada and Lecturer in Ophthalmology, Ben Gurion University of the Negev, Israel Ridia Lim, M.B.B.S., F.R.A.N.Z.C.O., M.P.H. Ophthalmologist, Eye Associates and Prince of Wales and Westmead Hospitals, Sydney, Australia Roland Ling, B.A., B.M., B.Ch., F.R.C.Ophth. Consultant Opthalmologist & Vitreoretinal Surgeon, The Royal Devon & Exeter Hospital, Exeter, UK Maurice H. Luntz, M.D., F.A.C.S., F.R.C.S. (E.D.), F.R.C.Ophth., D.O. (R.C.P.&S.), D.O.M.S. (R.C.S.I.), Diplomate A.B.O., Hon. F.C.S. (S.A.) Ophth. Attending and Director Emeritus, Glaucoma Services, Manhattan Eye, Ear and Throat Hospital, New York; Attending, New York Eye, Ear Infirmary, New York; Director Emeritus Department of Ophthalmology, Beth Israel Medical Center, New York; Clinical Professor of Ophthalmology, Mount Sinai School of Medicine, New York; Clinical Professor of Ophthalmology, New York University School of Medicine, New York, New York, USA Shlomo Melamed, M.D. Tel Hashomer, Israel

The Sam Rothberg Glaucoma Center, Sheba Medical Center,

Andre´ Mermoud Professor and Head, Glaucoma Unit, Jules Gonin Eye Hospital, University of Lausanne, Lausanne, Switzerland Clive Migdal, M.D., F.R.C.S., F.R.C.Ophth.

Western Eye Hospital, London, UK

J. E. Morgan, M.A., D.Phil., F.R.C.Ophth. Reader, Department of Ophthalmology, School of Medicine, Cardiff University, Cardiff, UK Marcelo T. Nicolela, M.D. Associate Professor in Ophthalmology, Dalhousie University, Halifax, Nova Scotia, Canada Ravikrishna Nrusimhadevara, M.B.B.S., D.N.B. (India) Retina Fellow, Department of Ophthalmology, University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada Charles J. Pavlin, M.D., F.R.C.S. Professor, Department of Ophthalmology and Visual Science, University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada Paul E. Rafuse, M.D., Ph.D. Assistant Professor in Ophthalmology, Dalhousie University, Halifax, Nova Scotia, Canada [email protected]

Contributors

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David S. Rootman, M.D., F.R.C.S.(C.) Associate Professor of Ophthalmology, University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada Fani Segev, M.D. Department of Ophthalmology, University Health Network and University of Toronto, Toronto, Ontario, Canada Arthur J. Sit, M.D., P.Eng., F.R.C.S.(C.) Glaucoma Fellow, University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada Allan R. Slomovic, M.A., M.D., F.R.C.S.(C.) Associate Professor of Ophthalmology, Department of Ophthalmology, University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada Tarek Shaarawy, M.D. Head, Glaucoma Sector, Ophthalmology Service, University of Geneva, Geneva, Switzerland Adael S. Soares, M.D. Nova Scotia, Canada

Clinical Fellow in Glaucoma, Dalhousie University, Halifax,

Graham E. Trope, M.B., B.Ch., Ph.D., F.R.C.S.(C.), F.R.C.Ophth., F.R.C.S. (E.D.), D.O. (R.C.P.&S.) Professor of Ophthalmology, Department of Ophthalmology, University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada

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Section I: Surgical Techniques

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1 Indications, Pre-operative Evaluation, and Outcomes of Filtering Surgery Arthur J. Sit and Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada

1. Indications for Surgery 1.1. Target Pressures: A Review of Recent Clinical Trials 1.2. Risk Factors for Progression 1.3. Compliance 1.4. Quality of Life and Lifestyle Factors 1.5. Diurnal Variations 1.6. The Case for Early Surgery 2. Pre-operative Evaluation 2.1. Patient Age 2.2. External Disease 2.3. General Health Status 3. Surgical Outcomes 4. Summary References

1.

3 3 5 6 6 7 8 9 9 9 9 9 10 11

INDICATIONS FOR SURGERY

Glaucoma surgery is indicated when target pressures are not achieved, or when neural tissue or visual function is progressively lost despite maximally tolerated medical and laser therapies.

1.1.

Target Pressures: A Review of Recent Clinical Trials

Target pressure is generally accepted to be the pressure at which progression of glaucomatous optic neuropathy is unlikely to continue. It is an attempt to prevent progression in a prospective manner. Target pressures need to be re-evaluated periodically and re-set at a lower level if progression continues. At the present time, the success of target pressure 3

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Sit and Trope

estimates can only be determined in a retrospective manner after many years of treatment. Recent multi-center, randomized controlled trials have demonstrated the efficacy of lowering intraocular pressure (IOP) in reducing both the risk of developing glaucoma and progression of the disease, and provide some help in choosing the initial target pressure. The Collaborative Normal-Tension Glaucoma Study (CNTGS) evaluated the efficacy of a 30% reduction of IOP on the rate of progression of open-angle glaucoma with normal IOP (,24 mmHg). Over a 5-year follow-up period, 35% of untreated eyes had evidence of progression of disease compared with 12% of treated eyes. The investigators concluded that IOP is related to the pathogenesis of normal-tension glaucoma, and lowering IOP by 30% decreases the risk of progression (1). On the basis of this study, we recommend trying to achieve an initial target reduction of IOP of 30% in all normal-tension glaucoma cases. Surgery may be indicated in cases when this target level is not reached. The Advanced Glaucoma Intervention Study (AGIS) was originally designed to compare the efficacy and prognosis of two different surgical treatment protocols in white and black patients. Although the original objective of the study has become somewhat irrelevant due to changes in surgical techniques, the data collected has provided important insights into the selection of target pressures. After 7 years of follow-up, the investigators reported a “dose –response” between IOP and visual field loss, in which the amount of visual field progression increased with IOP (2). In the “predictive” analysis, the patients were stratified into three groups based on average pressure. The group with average IOP ,14 mmHg had significantly less visual field deterioration than the group with average IOP .17.5 mmHg. In the “associative” analysis, the patients were stratified into four groups based on the proportion of IOP measurements that were ,18 mmHg. The group that was ,18 mmHg for all visits had an average IOP of 12.3 mmHg and demonstrated no visual field progression. The three groups that were ,18 mmHg for ,100% of visits demonstrated visual field progression. It is noteworthy that even in the first group, 14.4% of patients demonstrated visual field progression, which was balanced on average by 18.0% of patients who demonstrated improvement in their visual fields. On the basis of this evidence, we set initial target pressures in the low teens for all patients with advanced glaucomatous optic neuropathy. Clearly, if this is not achieved with medical and laser therapies, surgery may be indicated in such cases. The Ocular Hypertension Treatment Study (OHTS) compared the rates of progression for treatment vs. no treatment in patients with ocular hypertension, but no clinical evidence of glaucoma as indicated by normal optic discs and visual fields. In this study, 1636 patients with a mean IOP of 24 –32 mmHg were randomized to medical treatment with a target of 20% reduction, or observation. At 5 years, the mean reduction in IOP for the treatment arm was 22.5%. In this study, the probability of developing primary openangle glaucoma (POAG), as demonstrated by progression in visual fields or optic discs, was 4.4% for treated patients when compared with 9.5% of controls (3). This study supports lowering IOP in ocular hypotensives especially those at risk for progression, but clearly surgery is not indicated in these cases unless there are very unusual circumstances present. These studies clearly show the benefit of IOP reduction in the management of glaucoma and selected patients with ocular hypertension, and help us to set initial target pressures. Lower pressures 12 –15 mmHg clearly result in a lower risk of progression, but even reducing IOP by 20% has a protective effect. Advanced disease requires lower pressure when compared with early disease in order to halt or minimize the risk of progression. It is for this latter group that surgery should be considered sooner than later. The risk of progression posed by IOP must always be balanced with the risks of treatment. This is especially true when surgery is being considered. There is even some [email protected]

Indications, Pre-operative and Outcomes of Filtering Surgery

5

discussion as to whether patients are being over-treated in the zeal to reach the target pressure, particularly with early glaucoma. It is instructive to consider that the OHTS found that 90% of untreated ocular hypertensives did not progress over 5 years. Clearly, however, patients with advanced disease require aggressive therapy. However, not all glaucoma patients require an IOP of 12– 14 mmHg. For example, an 85-year-old with a 0.75 cup-to-disc ratio and an IOP of 18 mmHg will likely not go blind from progressive optic neuropathy despite this IOP level. However a 55-year-old with a 0.9 cup-to-disc ratio and the same IOP level with a life expectancy of at least another 20 years is at greater risk of blindness if IOP is not dropped into the low teens. Spaeth has suggested that the goal of treatment is not to prevent disease progression, but to prevent patients from becoming symptomatic or from becoming more symptomatic (4). 1.2.

Risk Factors for Progression

The decision to proceed with glaucoma surgery must include an evaluation of risk factors other than IOP alone. Table 1.1 lists the risk factors for glaucoma progression other than IOP that were found in the major recent randomized controlled trials of glaucoma treatment. In addition, factors that were assessed and found to be noncontributory, and factors that were found to be protective are listed. All of these factors should be considered prior to proceeding to surgery. Normal-tension glaucoma appears to have different risk factors than other types of glaucoma (5). Among the studies of elevated-pressure glaucoma, age is the only factor identified universally. Note that none of the studies found family history to be a significant factor for progression, and only the Collaborative Initial Glaucoma Treatment Study (CIGTS) identified race as a factor (6). This is likely a result of the high prevalence of the disease, but seems to contradict population surveys that clearly show race and family history to be associated with the presence of glaucoma. Race is clearly an important Table 1.1 Factors for Progression Other than IOP Protective factors

Study (Ref.)

Risk factors

CNTGS (5)

Disc hemorrhage, migraine, female, race (black)— tendency Better baseline VF (MD), male, age, less formal education, diabetes

AGIS (11)

EMGT (9)

Exfoliation, age, both eyes affected, worse baseline VF (MD), disc hemorrhages

CIGTS (6)

Age, race (nonwhite), diabetes, worse baseline VF (MD) Central corneal thickness (thin), age, cup-to-disc ratio, worse baseline VF (PSD)

OHTS (10)

Asian

Noncontributory factors Age, family history, hypertension, cup-to-disc ratio Race (black, nonblack), marital status, systemic hypertension, vascular disease, systemic beta-blockers, refractive error Sex, central corneal thickness, refractive error, family history, hypertension, vascular disease, migraine, smoker Sex, type of glaucoma

Diabetes

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Race, sex, family history, migraine, vascular disease, blood pressure, oral antihypertensives, refractive error

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factor in glaucoma, because blacks have four to five times the prevalence of disease as whites (7). Race may simply be an indicator for other risk factors. Family history as a risk factor may be more useful in glaucoma that occurs at a younger age. Central corneal thickness may also be an important independent risk factor for progression (8). Advanced disease is generally considered to be more susceptible to further glaucomatous damage than early disease. This is supported by the EMGT (9), CIGTS (6), and OHTS (10), which examined early glaucoma and ocular hypertension. However, the opposite result was found with AGIS (11) which examined advanced glaucoma and found that patients with better baseline visual fields were more likely to demonstrate progression. The investigators suggested that this might be due to greater difficulty in detecting visual field changes in advanced disease when compared with early disease.

1.3.

Compliance

Compliance with glaucoma medications, as with medications for any type of chronic diseases, is a major risk factor for progression. In the study by Kass et al. (12) using an eyedrop medication monitor, compliance with pilocarpine was found to be very poor. Fifteen percent of patients administered less than one-half of the prescribed doses. Twenty-five percent of patients missed at least 1 day per month. When interviewed, however, patients reported taking an average of 97% of prescribed doses. In general, compliance with medications decreases with the frequency of dosing and the number of medications. However, even with newer medical therapies with less frequent dosing, compliance continues to be very poor (13). This is further exacerbated by the fact that glaucoma is an asymptomatic disease until the very late stages, and therapy does not result in any subjective improvement in their condition. Other major reasons for noncompliance include medication side effects (both local and systemic) and difficulty administering the medication. In a patient where target IOP cannot be achieved consistently due to noncompliance, surgery must be seriously considered but only after patient education has been tried. The majority of the reasons sited by patients for noncompliance is not related to social or environmental factors and may be amenable to patient education or modification of medications (13). These include regimen factors (e.g., cost, complexity and side effects), patient factors (lack of knowledge/skill, forgetfulness, lack of motivation, and complexities created by co-morbidities), and medical provider factors (e.g., dissatisfaction with care and lack of communication). Some situational compliance factors may be difficult to remedy. Patients who live in parts of the world where drops are not available or are prohibitively expensive, or live alone and have difficulty in administering the drops for physical reasons require earlier glaucoma surgery in order to achieve target pressures (14,15). However, caution must be exercised since good compliance with medications is required postoperatively in order to reduce potential surgical complications and enhance the chance of successful surgery.

1.4.

Quality of Life and Lifestyle Factors

Both medical and surgical therapies have an impact on patient quality of life. Multiple medical therapy presents problems for elderly patients who often have difficulty in instilling drops, whereas, younger, active patients often have difficulty in maintaining a schedule for their medications. Surgical therapy often results in fewer medications in [email protected]

Indications, Pre-operative and Outcomes of Filtering Surgery

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the long-term, but requires intense patient participation in the postoperative period. Complications of surgery can also affect patient quality of life. In the CIGTS, quality of life factors was evaluated between initial medical and initial surgical therapies (16). Symptoms and vision specific factors were evaluated at baseline, 2 months and 6 months postrandomization, and then at 6 month intervals. Visual function symptoms included evaluation of glare disability, light/dark adaptation, acuity/spatial vision, visual search, visual processing speed, depth perception, color discrimination, and peripheral vision. The results indicated lower IOP in the surgical group (14 – 15 mmHg) vs. the medical group (17 – 18 mmHg) but visual field progression was not statistically different between the two groups. Patients in the surgical group reported being bothered by more visual function symptoms than the medical group. Systemic and local eye symptoms were also evaluated. No consistent differences were found in systemic symptoms. The most persistent differences were in the local eye symptoms, which were reported more frequently in the surgical group. However, differences in symptoms between the treatment groups did not result in differences in broader measures of quality of life. Therefore, unless further information to the contrary arises, quality of life should not be used as a major factor in the decision to postpone or proceed with glaucoma surgery. 1.5.

Diurnal Variations

IOP has long been known to undergo diurnal variations (17). As well, IOP can undergo short-term fluctuations in response to environmental factors such as food or fluid intake. Consumption of large amounts of water results in an osmotic shift into the aqueous resulting in increased IOP. The opposite effect occurs when hyperosmotic solutions are used in the treatment of glaucoma. Current evidence suggests that IOPs normally peak at the end of the sleep cycle or upon awakening, and decrease through the course of the day (18). The reason for IOP increase at night is unclear, as there are currently no studies of human 24 h IOP measurements that do not require opening the eyes of the patient and/or waking the patient. It is unlikely to be related to aqueous production, since production is actually higher during the day than at night (19,20). Diurnal IOP variation has been implicated as an independent risk factor for glaucoma progression (21). In a study by Asrani et al., patients used a self-tonometer to measure IOP five times a day for 5 days at home. The diurnal IOP range and the IOP range over multiple days were found to be significant risk factors for progression, even after adjusting baseline factors including for office IOP, age, race, gender, and visual field damage at baseline. Further studies are indicated to confirm these results. Interestingly, glaucoma patients seem to have larger diurnal/waking IOP variations, but may actually have smaller nocturnal/sleeping IOP variations when compared with normals. Twenty-four-hour IOP measurements on newly diagnosed, untreated glaucoma patients show a peak at night similar to normal patients (22). However, after taking into account the change in positioning of the patient (i.e., upright while awake and supine while asleep), the diurnal-to-nocturnal IOP change was less in glaucoma patients than in normal patients. Although the role of diurnal and nocturnal IOP variations in the pathogenesis and progression of glaucoma is still not fully elucidated, it is reasonable to target therapy towards reducing diurnal IOP variations, as well as lowering mean IOP. Although any measure to lower the IOP will decrease the pressure variations, therapy that increases outflow facility, instead of decreasing aqueous production, may result in more stable measurements (23). A recent study has suggested that trabeculectomy results in reduced IOP variations compared with medical therapy, likely due to improved outflow facility [email protected]

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(24). In the study by Asrani et al. (21), the risk of progression was 5.76 times higher in patients with a diurnal IOP range of 5.4 mmHg (75th percentile) compared with a range of 3.1 mmHg (25th percentile). Therefore, in a patient with progression of glaucoma on maximally tolerated medical therapy, surgical treatment may be indicated if there is evidence of large diurnal pressure range (.5 mmHg) even if the mean IOP is within the target range. 1.6.

The Case for Early Surgery

Early surgical intervention has been advocated by the European glaucoma community. This approach was initially supported by a study from Scotland that compared initial medical therapy with initial surgical therapy for newly diagnosed POAG (25). In this study, 116 patients were randomized to either trabeculectomy at diagnosis or initial medical therapy followed by trabeculectomy in unsuccessful cases. No difference in visual acuity was detected, but greater visual field loss was found in patients with initial medical therapy. The investigators suggested that this was due to delay of surgery, whereas medical therapy was modified in patients with minimal visual field loss at diagnosis. The Moorfields Primary Treatment Trial also evaluated medical therapy vs. surgical therapy for the primary treatment of glaucoma. This study randomized 48 patients to initial surgery and 40 patients to initial medical therapy. Surgery as primary treatment resulted in a lower mean IOP than medicine as primary treatment, although the visual fields were not statistically different (26). The investigators suggested that initial surgery is a safe and more cost-effective method for treating glaucoma. CIGTS evaluated initial medical therapy vs. initial surgical therapy for the primary treatment of glaucoma (6,16). In that study, the surgical group achieved a lower average IOP than the medical group, but there was no statistically significant difference in the visual field scores between the two groups. As well, the medical treatment group had a better average visual acuity than the surgical group, and was less likely to have a clinically substantial visual loss (15 letters or more). This was partially due to the surgical group having a cataract extraction rate almost three times higher than the medical group. However, the difference remained even after adjusting for cataracts. The investigators speculated that the differences in the results of this study compared with the European studies might be related to having patients with glaucoma earlier in the disease course, as well as the availability of newer, more effective medical treatments. They did not suggest changing current treatment protocols based on their 5 year results indicating that longer-term studies were required for a chronic diseases such as glaucoma. These studies suggest that both medical and surgical therapies as initial treatment for glaucoma are effective and safe. In general, surgery results in a slightly lower IOP than medical treatment alone. However, the importance of this additional IOP lowering in early glaucoma must be considered in relation to potential complications and effect on central vision. Since the potential for vision threatening complications is real, we feel surgical treatment should still be reserved for second- or third-line therapy until conclusive evidence becomes available to show that surgical treatment of glaucoma results in better visual function outcomes. The exception to this rule is in developing countries, where early surgical intervention is often indicated. With limited health care resources, there is often limited access to long-term follow-up care. In addition, life-long medical treatment is commonly prohibitively expensive for the patient. Under these circumstances, primary surgical treatment for glaucoma is a cost-effective solution despite the increased potential for complications (14,15). [email protected]

Indications, Pre-operative and Outcomes of Filtering Surgery

2.

9

PRE-OPERATIVE EVALUATION

Once the decision to proceed with glaucoma surgery has been made, several factors should be considered during surgical planning. 2.1.

Patient Age

Younger patients tend to have a more vigorous healing response making them more susceptible to failure. This may indicate the use of antifibrotic agents, although they should be used with caution in young myopes due to the risk of hypotonous maculopathy. By the virtue of their longer life expectancy, younger patients are more likely to have surgical failure within their lifetimes, requiring repeat surgery. We therefore advise initial surgery in one upper quadrant leaving the other quadrant for repeat surgery at a later date. It is important to remember that surgery in younger patients may result in an increased risk of blebitis and endophthalmitis due to their longer life expectancy. Older patients may have a decreased healing response and may be more susceptible to complications in the short-term. In addition, elderly patients may have difficulty with postoperative care without assistance from caregivers. 2.2.

External Disease

Evidence of ocular surface disease, including dry eye, conjunctival scarring, symblepharon, and previous ocular surgery, should be noted. These conditions make the surgical procedure more difficult, and also increase the risk of postoperative scarring, and complications. Lack of suitable conjunctiva may require an alteration in both the type and the site of surgery planned (e.g., from a trabeculectomy to a seton). The lids should always be examined for epiphora, entropion, or distachiasis. These should be dealt with prior to glaucoma surgery. Temporary measures, such as Quickert sutures for entropion or epilation for distachiasis, may be sufficient. Chronic infections, such as staphylococcal blepharitis or purulent discharge from the lacrimal sac, must be addressed prior to glaucoma surgery. 2.3.

General Health Status

Although most glaucoma surgery is performed with local anesthetic, including topical anesthetic, general health status should be known. In particular, patients with cardiovascular disease, systemic hypertension and diabetes are at increased risk of suprachoroidal hemorrhage. Surgery should be performed with caution in such cases. Patients with liver dysfunction or patients on anticoagulation therapy will have increased intraoperative bleeding. Such patients should be advised of the increased risk and be assessed by the relevant specialists before recommending discontinuation of anticoagulation therapy. Most glaucoma surgery can be successfully performed with patients on anticoagulation therapy but informed consent is important in such cases.

3.

SURGICAL OUTCOMES

Success rates for incisional glaucoma surgery depend on patient factors as discussed earlier, but are also affected by surgical techniques. The use of antimetabolites has significantly improved both the success rate and the survival rate of trabeculectomies. Two types [email protected]

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Figure 1.1 Success rates with and without 5-FU (27). [Reprinted from Ref. (27), with permission from Elsevier.]

of antimetabolites are commonly used in glaucoma surgery. 5-Fluorouracil (5-FU) inhibits DNA replication but is reversible and may be used intraoperatively, as well as multiple times postoperatively. Mitomycin-C permanently binds DNA, and can only be used once with maximal effect after 5 min. The Fluorouracil Filtering Surgery Study examined the success rates of trabeculectomies with and without the use of postoperative 5-FU. Success was defined as IOP ,21 mmHg with or without medications and no need for re-operation to control IOP. The 5 years success rate of trabeculectomies was 49% with 5-FU use, but only 26% without antimetabolite use (Fig. 1.1) (27). One of the major causes of failure in both groups was early postoperative wound leak (within 2 weeks of surgery). At 5 years, the success rate for the 5-FU group was 54% in eyes without a leak and 28% in those with a leak. The 5 year success rate in the group without antimetabolites was 24% without a wound leak and 15% with a leak (28). Risk factors for wound leaks include the use of antimetabolites, one-layer (vs. two-layer) conjunctiva-Tenon capsule closure, inferiorly located trabeculectomy, and older patients. More recent studies have demonstrated similar efficacy with intraoperative mitomycin-C without the need for postoperative injections of antimetabolites (29). With the use of any antimetabolite, caution must be exercised as these patients may be more susceptible to complications from glaucoma surgery such as wound leaks or blebrelated infections (30 – 32). 4.

SUMMARY

The decision to proceed with glaucoma surgery is usually straightforward: surgery is indicated when target pressures are not achieved or when optic disc and/or visual field loss occurs despite maximally tolerated medical and laser therapies. However, risk factors [email protected]

Indications, Pre-operative and Outcomes of Filtering Surgery

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for progression other than IOP must be evaluated as well. The presence of numerous risk factors in addition to IOP suggests the need for more aggressive target pressures and treatment. Early surgery may be indicated when compliance with medical therapy is a problem, or in developing countries where the cost of medications may be prohibitive. Large diurnal pressure variations in a patient with severe disc damage may also be an indication for earlier surgery even if the mean IOP is at target. Conversely, quality of life issues should not be used in the decision to either proceed with or delay with surgery. Once the decision to proceed with surgery has been made, careful pre-operative evaluation must be performed to determine the optimal site and type of glaucoma surgery, including the use of antifibroblastic agents. This will help to improve the success of the surgery and minimize potential complications.

REFERENCES 1.

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Collaborative Normal-Tension Glaucoma Study Group (CNTGS). The effectiveness of intraocular pressure reduction in the treatment of normal-tension glaucoma. Am J Opthalmol 1998; 126:498 – 505. The AGIS Investigators. The Advanced Glaucoma Intervention Study (AGIS): 7. The relationship between control of intraocular pressure and visual field deterioration. Am J Opthalmol 2000; 130:429 – 440. Kass MA, Heuer DK, Higginbotham EJ, Johnson CA, Keltner JL, Miller JP et al. The Ocular Hypertension Treatment Study: a randomized trial determines that topical ocular hypotensive medication delays or prevents the onset of primary open-angle glaucoma. Arch Ophthalmol 2002; 120:701 – 713. Spaeth GL. OHTS one year later: has it reduced my threshold for treatment? American Academy of Ophthalmology Subspecialty Day Glaucoma Meeting. Anaheim, CA, Nov 15, 2003. Drance S, Anderson DR, Schulzer M. Collaborative Normal-Tension Glaucoma Study Group. Risk factors for progression of visual field abnormalities in normal-tension glaucoma. Am J Ophthalmol 2001; 131:699 – 708. Lichter PR, Musch DC, Gillespie BW, Guire KE, Janz NK, Wren PA et al. Interim clinical outcomes in the Collaborative Initial Glaucoma Treatment Study comparing initial treatment randomized to medications or surgery. Ophthalmology 2001; 108:1943 – 1953. Tielsch JM, Sommer A, Katz J, Royall RM, Quigley HA, Javitt J. Racial variations in the prevalence of primary open-angle glaucoma. The Baltimore Eye Survey. JAMA 1991; 266:369 – 374. Herndon LW, Weizer JS, Stinnett SS. Central corneal thickness as a risk factor for advanced glaucoma damage. Arch Ophthalmol 2004; 122:17 – 21. Leske MC, Heijl A, Hussein M, Bengtsson B, Hyman L, Komaroff E, EMGT Group. Factors for glaucoma progression and the effect of treatment: The Early Manifest Glaucoma Trial. Arch Ophthalmol 2003; 121:48 – 56. Gordon MO, Beiser JA, Brandt JD, Heuer DK, Higginbotham EJ, Johnson CA et al. The Ocular Hypertension Treatment Study: baseline factors that predict the onset of primary open-angle glaucoma. Arch Ophthalmol 2002; 120:714 –720. The AGIS Investigators. The Advanced Glaucoma Intervention Study (AGIS): 12. Baseline risk factors for sustained loss of visual field and visual acuity in patients with advanced glaucoma. Am J Ophthalmol 2002; 134:499 – 512. Kass MA, Meltzer DW, Gordon M, Cooper D, Goldberg J. Compliance with topical pilocarpine treatment. Am J Ophthalmol 1986; 101:515 – 523. Tsai JC, McClure CA, Ramos SE, Schlundt DG, Pichert JW. Compliance barriers in glaucoma: a systematic classification. J Glaucoma 2003; 12:393 – 398. [email protected]

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Thomas R, Kumar RS. Primary open-angle glaucoma: the developing world perspective. American Academy of Ophthalmology Subspecialty Day Glaucoma Meeting. Anaheim, CA, Nov 15, 2003. Thomas R, Sekhar GC, Kumar RS. Glaucoma management in developing countries: medical, laser, and surgical options for glaucoma management in countries with limited resources. Curr Opin Ophthalmol 2004; 15(2):127 –131. Janz NK, Wren PA, Lichter PR, Musch DC, Gillespie BW, Guire KE et al. The Collaborative Initial Glaucoma Treatment Study: interim quality of life findings after initial medical or surgical treatment of glaucoma. Ophthalmology 2001; 108:1954 – 1965. Wilensky JT. The role of diurnal pressure measurements in the management of open angle glaucoma. Curr Opin Ophthalmol 2004; 15:90 – 92. Liu JHK, Bouligny RP, Kripke DF, Weinreb RN. Nocturnal elevation of intraocular pressure is detectable in the sitting position. Invest Ophthalmol Vis Sci 2003; 44:4439 – 4442. Larsson LI, Rettig ES, Brubaker RF. Aqueous flow in open-angle glaucoma. Arch Ophthalmol 1995; 113:283 – 286. Liu JHK. Diurnal measurement of intraocular pressure. J Glaucoma 2001; 10(suppl 1):S39–S41. Asrani S, Zeimer R, Wilensky J, Gieser D, Vitale S, Lindenmuth K. Large diurnal fluctuations in intraocular pressure are an independent risk factor in patients with glaucoma. J Glaucoma 2000; 9:134 – 142. Liu JH, Zhang X, Kripke DF, Weinreb RN. Twenty-four-hour intraocular pressure pattern associated with early glaucomatous changes. Invest Ophthalmol Vis Sci 2003; 44:1586 – 1590. Brubaker RF. Targeting outflow facility in glaucoma management. Surv Ophthalmol 2003; 48(suppl 1):S17 –S20. Medeiros FA, Pinheiro A, Moura FC, Leal BC, Susanna R Jr. Intraocular pressure fluctuations in medical versus surgically treated glaucomatous patients. J Ocul Pharmacol Ther 2002; 18:489 – 498. Jay JL, Allan D. The benefit of early trabeculectomy versus conventional management in primary open angle glaucoma relative to severity of disease. Eye 1989; 3:528 –535. Hitchings RA, Migdal CS, Wormald R et al. The Primary Treatment Trial: changes in the visual field analysis by computer-assisted perimetry. Eye 1994; 8:117– 120. The Fluorouracil Filtering Surgery Study Group. Five-year follow-up of the fluorouracil filtering surgery study. Am J Ophthalmol 1996; 121:349– 366. Parrish RK II, Schiffman JC, Feuer WJ, Heuer DK. Fluorouracil Filtering Surgery Study Group. Prognosis and risk factors for early postoperative wound leaks after trabeculectomy with and without 5-fluorouracil. Am J Ophthalmol 2001; 132:633 – 640. Singh K, Mehta K, Shaikh NM, Tsai JC, Moster MR, Budenz DL, Greenfield DS, Chen PP, Cohen JS, Baerveldt GS, Shaikh S. Trabeculectomy with intraoperative mitomycin C versus 5-fluorouracil. Prospective randomized clinical trial. Ophthalmology 2000; 107:2305– 2309. Lehmann OJ, Bunce C, Matheson MM, Maurino V, Khaw PT, Wormald R, Barton K. Risk factors for development of post-trabeculectomy endophthalmitis. Br J Ophthalmol 2000; 84:1349 – 1353. DeBry PW, Perkins TW, Heatley G, Kaufman P, Brumback LC. Incidence of late-onset bleb-related complications following trabeculectomy with mitomycin. Arch Ophthalmol 2002; 120:297 – 300. Mac I, Soltau JB. Glaucoma-filtering bleb infections. Curr Opin Ophthalmol 2003; 14:91– 94.

15.

16.

17. 18. 19. 20. 21.

22. 23. 24.

25. 26. 27. 28.

29.

30.

31.

32.

[email protected]

2 Glaucoma: Surgical Anatomy Maurice H. Luntz Manhattan Eye, Ear and Throat Hospital, New York; New York Eye, Ear Infirmary, New York; Beth Israel Medical Center, New York; Mount Sinai School of Medicine, New York; New York University School of Medicine, New York, New York, USA

Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada

Glaucoma filtering surgery is performed at the surgical limbus. The anatomical limbus is situated where the peripheral cornea meets the sclera externally. This is a well-demarcated zone. Conjunctiva and Tenon’s Fascia are fused and inserted here. The transition from peripheral cornea to sclera in the deeper layers is not well demarcated but is a broad area of transition 1 mm in width, has a bluish-grey appearance and constitutes the surgical limbus. The bluish-grey appearance of the surgical limbus is due to the extension of the deeper corneal lamellae beyond the external margin of the

Figure 2.1 Line drawing of dissected 1/3 thickness scleral flap. 13

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Figure 2.2 (See color insert) Photograph of dissected 1/3 thickness scleral flap with anatomical landmarks.

peripheral cornea. Viewing the scleral bed of a 1/3 thickness scleral flap at the limbus, one can note the deep corneal lamellae extending beyond the edge of the corneal periphery and this is well illustrated in Figs. 2.1 and 2.2. Figure 2.1 is a drawing and Fig. 2.2 is a photograph of the same dissection of a 1/3 thickness scleral flap which is anteriorly rotated onto the cornea. This dissection

Figure 2.3 [email protected]

Glaucoma: Surgical Anatomy

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exposes the deeper layer of the scleral bed at the surgical limbus. In the upper part of the scleral bed, there are transparent corneal lamellae through which brown iris is visible. This is also recognizable in the photograph (Fig. 2.2) which records the surgeons view. Note that the corneal tissue in the scleral flap does not reach as far as the corneal lamellae in the deeper scleral bed (Fig. 2.1). Posterior to the cornea in the scleral bed is a grey band, which is the trabecular meshwork, and at the posterior border of this grey band dense scleral tissue is visible. The junction of the posterior limit of the grey band and the sclera is the external landmark for the scleral spur and canal of Schlemm. Deeper dissection at this landmark will lead the surgeon directly to the canal of Schlemm (e.g. for trabeculotomy). The scleral spur extends slightly posterior to this junction. It is important to recognize these landmarks, particularly when performing trabeculotomy or nonpenetrating filtration surgery. The ciliary body is attached to the junction of the trabecular band and the sclera at the scleral spur. Dissection through the sclera posterior to this junction will expose the ciliary body and the pars plicata which if cut may result in significant bleeding. In planning filtration surgery, bear in mind that the extraocular rectus muscles are inserted around the limbus area. As the muscle insertions are placed well back from the limbus, for example, the superior rectus is 7.75 mm behind the limbus, the extraocular muscles do not interfere with filtration surgery which for the most part is performed within 3 –4 mm posterior to the limbus. With a limbus-based conjunctival flap, if the scleral flap is dissected further back, great care must be taken not to cut the extraocular muscles (especially superior rectus) (Fig. 2.3).

[email protected]

[email protected]

3 Modern Anesthesia for Adult Glaucoma Filtration Surgery Monica M. Carrillo Dalhousie University, Halifax, Nova Scotia, Canada

Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada

1. 2. 3. 4.

Introduction Pre-operative Evaluation General Anesthesia Local Anesthesia for Glaucoma Surgery 4.1. Monitored Anesthesia Care with Local Anesthesia 4.1.1. Intravenous Medications 4.1.2. Technique 4.1.3. Adverse Effects 4.2. Local Anesthesia 4.2.1. Advantages 4.3. Local Anesthetics 4.4. Retrobulbar Anesthesia 4.4.1. Technique 4.4.2. Complications 4.5. Subconjunctival/Sub-Tenon’s Anesthesia 4.5.1. Introduction 4.5.2. Advantages 4.5.3. Technique 4.5.4. Complications 4.5.5. Recommendation 4.6. Topical Anesthesia with Unpreserved Lidocaine 2% Jelly 4.6.1. Introduction 4.6.2. Advantages 4.6.3. Disadvantages 4.6.4. Technique of Topical Jelly Anesthesia 4.7. Topical Anesthesia with Eye Drops 4.7.1. Technique 4.7.2. Disadvantages of Local Drops

18 18 19 20 20 20 20 21 21 21 21 22 22 23 24 24 24 25 25 26 26 26 26 27 27 27 27 27 17

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5. Conclusion Acknowledgments References

1.

27 27 28

INTRODUCTION

Anesthetic techniques for filtration surgery have evolved over the years. Table 3.1 shows this evolution. Selection of the appropriate anesthetic method for glaucoma surgery depends on the pre-operative assessment of the patient, surgeon’s technique, and the complexity of the surgical procedure. Although glaucoma surgery is relatively low-risk, glaucoma patients represent a high-risk population, as they tend to be at extremes of age and to have concomitant systemic disease. Mortality for ophthalmic surgery is significantly lower than for general surgery (1 – 4). General anesthesia is more likely to cause adverse systemic effects. The incidence of anesthesia-related deaths in the operating room for all types of surgery is approximately 1 in 3000. The mortality rate associated with ophthalmic surgery is lower at 1 in 5000 or less (5). Prior to surgery, every glaucoma patient should be carefully evaluated so that potential complications can be identified and reduced to as close to zero as possible.

2.

PRE-OPERATIVE EVALUATION

The goals of pre-operative evaluation are to psychologically prepare the patient, to establish a doctor – patient relationship, to plan peri-operative management, to assess local and systemic risk, to obtain informed consent, and to meet other legal requirements. When approaching a pre-operative patient, it is important to consider the following points: .

Every patient undergoing a surgical procedure must have a comprehensive and timely medical history and physical examination and the results should be inserted in the medical record preferably by the patient’s personal physician. A thorough review of all medications should also be included. The interaction

Table 3.1 Evolution of Anesthetic Techniques for Filtration Surgery Technique

Year

Author

General anesthesia Topical cocaine Retrobulbar Posterior peribulbar Facial nerve block Anterior peribulbar Sub-Tenon’s Topical with eye drops Topical with lidocaine 2% jelly

1846 1884 1884 1985 1914 1991 1992 2002 2003

Koller Knapp Davis and Mandel van Lint, O’Brien Bloomberg Ritch R, Liebman JM Jonas et al. Trope et al.

[email protected]

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.

.

19

of glaucoma medications with general anesthetics should be considered. Complications such as tachycardia, extra systoles, hypertension, and syncope have been reported in patients on therapy with topical epinephrine (6,7). Special precautions should also be taken with patients on chronic acetazolamide therapy, as patients may be hypokalemic and hyponatremic and therefore at risk of significant arrhythmias especially under general anesthesia. Preanesthetic assessment with an anesthesiologist or a member of the anesthesia care team is advisable. This evaluation should include: a review of the patient’s medical history, a decision regarding further laboratory tests or consultations, development of an anesthetic plan, and discussion with the patient. The role of pre-operative blood tests and electrocardiogram on post-operative outcome is controversial. Evidence from a large, multi-centre trial reported no benefit of pre-operative tests on post-operative outcome (8–10). Our pre-operative testing and consultation protocol for patients scheduled for glaucoma surgery in Toronto is guided by each patient’s particular anesthetic risk provided by the patient’s medical history, that is, if under 65 with no history of heart, respiratory, or other problems, routine x-ray chest and electrocardiogram are not done. The risks associated with anesthesia and the procedure itself should be carefully discussed with the patient and detailed informed consent should be completed.

Guidelines to encourage consistency of care and to minimize disruption to patients have been published by the British Ophthalmic Anesthesia Society, specifically addressing pre-operative management of patients with cardiovascular disease (8). Adequate pre-operative evaluation is a medical, ethical, and legal duty of the ophthalmic medical care team.

3.

GENERAL ANESTHESIA

Many ophthalmic procedures including filtration surgery traditionally performed under general anesthesia (GA) are now routinely performed under topical anesthesia with monitored anesthesia care. There are, however, occasions when local anesthesia is not appropriate and GA is still the best option. Although a discussion on the details of general anesthetic technique and medications are beyond the scope of this chapter, we will briefly describe the indications, contraindications, risks, and goals of GA. Indications for GA include: .

. . . . . .

Inability of the patient to cooperate with monitored local anesthesia care (e.g., children, adults with mental or psychological deficits, nystagmus, general movement disorders, excessive anxiety or claustrophobia, tremor, inability to lie supine). Surgeons or patient preference. Surgical field not amenable to regional, local, or topical anesthesia. Regional block technically difficult or contraindicated (e.g., large globe from myopia or congenital glaucoma, coagulopathy). Allergy or sensitivity to topical anesthesia. Following intrathecal or intravascular injection of local anesthetic. Previous retrobulbar hemorrhage.

General anesthesia should be avoided in the following cases: [email protected]

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. . .

Patients with Marfan’s syndrome as they have a high prevalence of cardiovascular and pulmonary abnormalities (11). Myotonic dystrophy patients as they may develop significant bradycardia and respiratory complications (12). Patients with previous severe reactions to general anesthesia or a family history of malignant hyperthermia.

It is prudent to avoid general anesthesia in patients with severe cardiovascular or pulmonary disease, and those who are particularly prone to post-operative nausea and vomiting. Ocular complications of GA include: . . .

4.

Retinal or optic nerve ischemia from profound hypotony (rare) (13). Retinal or suprachoroidal hemorrhages due to vomiting and straining on the endotracheal tube. These are of importance in filtration surgery. Exposure keratitis in the fellow eye (incidence as high as 44%) (14).

LOCAL ANESTHESIA FOR GLAUCOMA SURGERY

4.1.

Monitored Anesthesia Care with Local Anesthesia

In Toronto, virtually all filtration surgery is done under local anesthesia with monitored anesthesia care (MAC) utilizing a respiratory therapist under the supervision of an anesthesiologist to monitor the patient. The patient should ideally be awake or rousable during the procedure and able to communicate. The level of monitoring required during local anesthesia depends on the anesthetic technique and the medical condition of the patient. Appropriate facilities for monitoring in the post-operative period must be available.

4.1.1.

Intravenous Medications

An intravenous ultra short hypnotic such as propofol and very small doses of a short-acting narcotic such as alfentanyl, remifentanyl, fentanyl, or sufentanyl can be combined to accomplish most of the goals of MAC (15). Propofol provides sedation, decreased awareness, antiemesis (counteracting the pro-emetic effects of the narcotic), and amnesia. The narcotic provides a brief period of intense analgesia. This combination yields cardiopulmonary stability during stress and painful stimuli and return to baseline mental status within 10 min. Intravenous benzodiazepines such as midazolam can be used as an alternative anesthetic providing adequate sedation for patients who require anxiolysis or a small amount of sedation after the application of topical anesthesia.

4.1.2.

Technique

At the University Health Network, Toronto, intravenous sedation is, virtually, always used in conjunction with topical anesthesia for glaucoma surgery. Our sedation protocol includes a combination of: . . .

Fentanyl 1– 2 mg/kg I.V. (1 or 2 bolus depending on each patient). Propofol 0.24 –0.40 mg/kg I.V. (one dose). Occasionally midazolam, just one dose 0.75 –0.2 mg I.V. in total is utilized along with the previous two agents. [email protected]

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Doses should be individualized. Patients generally do not need any further sedation and are ready for discharge when they leave the recovery room.

4.1.3.

Adverse Effects . . . .

4.2.

Sudden movement and restlessness. Airway obstruction. Lack of response to command and mild stimulation. Induction of anesthesia.

Local Anesthesia

Local anesthesia is the procedure of choice for most anterior segment ophthalmic surgeries. The use of local anesthesia in United Kingdom has risen from around 20% in 1991 (16,17) to 86% in 1997 (18).

4.2.1. . . . . . .

Advantages Less post-operative nausea and vomiting. Greater cardiopulmonary stability. Morbidity and mortality lower than with GA. Quick return to ambulation. Prolonged post-operative analgesia. Cost.

Local anesthesia includes: . . . . . .

Retrobulbar anesthesia. Peribulbar anesthesia. Sub-Tenon’s or subconjunctival anesthesia. Topical and peribulbar anesthesia. Topical and intraocular anesthesia. Topical anesthesia.

In this chapter, only the most frequently used anesthesia techniques for filtration and Seton surgery are described including retrobulbar, sub-Tenon’s, and topical anesthesia with lidocaine jelly. Ophthalmic regional anesthesia can be nonakinetic and akinetic. Akinetic blocks include retrobulbar, peribulbar, and combined retro/peribulbar techniques (19 – 23). Motor, sensory, and autonomic fibers are all blocked, resulting in regional motor paralysis and anesthesia.

4.3.

Local Anesthetics

Clinicians who use local anesthetics must be familiar with three different groups: short-acting local anesthetics (20 – 45 min), including procaine and chlorprocaine; intermediate-acting anesthetics (60 – 120 min, longer with epinephrine), including lidocaine (xylocaine) and mepivacaine; and long-acting anesthetics (400 – 450 min or longer), including bupivacaine, etidocaine, and ropivacaine (24,25) (Table 3.2). [email protected]

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Table 3.2 Commonly Used Local Anesthetic Drugs (24,25) Anesthetic

Concentration (%)

Lidocaine

0.5– 1

Mepivacaine Bupivacaine Ropivacaine Etidocaine Procaine Chlorprocaine

15

0.5– 1 0.25– 0.5 0.25– 1 1 1– 2 1– 2

15 – 30 1 – 15 15 2–5 ,15

Tetracaine

4.4.

Onset (min)

15 s

Duration (h) No epinephrine: 1.5 – 2.5 With epinephrine: 2 – 4 45 – 90 min 2 –4 2 –6 2 –3 1 No epinephrine: 30 – 45 min With epinephrine: 60 – 90 min 15 min

Retrobulbar Anesthesia

4.4.1. .

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.

.

.

.

Technique For retrobulbar anesthesia, light general sedation and analgesia should be started before the retrobulbar is started. It is important that the patient remains cooperative during the retrobulbar. After the retrobulbar, more sedation can be supplied. A 1:1 mixture of lidocaine (2%, 1.5 mL) without epinephrine and bupivacaine (0.5%, 1.5 mL) should be used, with or without hyaluronidase (5 U/mL). There is poor evidence that adding hyaluronidase increases the effectiveness of these blocks at producing akinesia (26). We do not use hyaluronidase in our unit. A maximum of 3 mL retrobulbar injection is administered with the globe in primary position preferably via a short blunt 25 –27-gauge (31 mm) needle on a 5 –10 mL syringe. This provides consistent tactile feedback for both insertion of the needle and injection of the anesthetic, which in turn, provides reliable and safe blocks. Several techniques for the administration of retrobulbar block have been described, however, no single method has established a striking advantage in safety or efficacy. We recommend an entry site through the lower lid at the junction of the lateral and middle third of the inferior orbital rim with the eye in the primary position with the needle initially directed parallel to the floor of the orbit aimed at the opposite mandibulary process. It is very important to feel the lower border of the globe through the lid prior to needle insertion. The globe size is determined and only then the needle inserted 1– 2 mm below the lowest edge of the globe. Once passed the equator the needle can be tilted 208 with the tip towards superior orbit to facilitate entry to the muscle cone. A slight “give” from the inferior rectus can sometimes be felt. The hub of the needle should not go beyond the inferior orbital rim. Any pain reported by the patient may signal contact with the sclera and should prompt partial withdrawal and redirection of the needle. After aspiration to rule out intravascular placement, 1 –3 mL of anesthetic solution is injected slowly (1 mL/10 s) (27). It is important not to deliver a large bolus into the muscle cone, as the increased pressure around an atrophic glaucomatous nerve can damage it. There should be little resistance to injection. Fullness and mild ptosis of the upper lid will be evident towards the end of the injection. The tension in the orbit should be monitored manually. On no account [email protected]

Modern Anesthesia for Glaucoma Surgery

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23

should pressure be applied to the glaucomatous eye to disperse the anesthetic. Pressure from a Honan’s balloon with orbital pressure from the injection bolus can cause dangerous reduction in optic nerve head perfusion possibly leading to “wipe out” of remaining field. On withdrawal, orbicularis akinesia is achieved with injection of 1.5 mL of the same anesthetic solution slowly (1 mL/s) anterior to the septum orbitale.

Supplementary injections may be needed in 10% of cases. It takes around 10 min for most retrobulbar injections to exert their maximal effect. Evaluation of the block involves: .

Paralysis in all positions of gaze and ptosis help you to decide whether there is adequate anesthesia.

If there is excessive movement or if more than two muscles are still active at 10 min, a further 1.0 mL of the anesthetic mixture should be given in the same manner. Some activity of the superior oblique persists after the recti are completely blocked, probably from incomplete spread of the anesthetic to the superonasal/posterior aspect of the orbit where cranial nerve IV supplies the superior oblique (28). 4.4.2. Complications As the retrobulbar technique involves blind insertion of a needle into a space occupied by a number of neural and vascular structures, significant complications can and do threaten the patient’s vision or life. Complications can be divided into systemic and ocular. Systemic Complications. The systemic toxicity of local anesthetics on the central nervous and cardiovascular systems are often due to inadvertent intravascular or subarachnoid injection of the drug via the sheaths of the optic nerve or via the superior orbital fissure, with immediate transit via the bloodstream to brain or heart, or due to systemic absorption of an excess dose of the drug. This can result in brainstem anesthesia (incidence as high as 0.79%), respiratory depression, apnea, and even death (25,29 – 31). The development of toxic blood levels depends, to some degree, on the total dose, location of the block, the addition of epinephrine to the anesthetic, and the skill of the physician administering the anesthetic. Within the central nervous system, toxicity is a spectrum, extending from “excitation” to convulsions. This can serve as a warning of impending local anesthetic-induced cardiovascular collapse, characterized by profound hypotension, cardiac arrhytmias, and even death (32). It is therefore crucial that resuscitation equipment be on hand when this form of anesthesia is used. Also an experienced member of the anesthetic team should be available on short notice if retrobulbar anesthesia is to be performed. It is important to remember the maximum dosage for each anesthetic when considering local anesthesia. Table 3.3 shows the maximum dosage for local anesthetics. Ocular Complications. Rare but serious complications including amaurosis, akinesia, retinal vascular occlusion, scleral perforation, sight-threatening retrobulbar hemorrhage (incidence of 1 –5%), and even “ocular explosion” (35 –37) have all been reported (38 – 40). Post-operative ptosis, diplopia, and transient loss of vision in both eyes have also been described. Although these are less serious and transient, they are disturbing to patient and physician (41,42). Methods to reduce complications include: . .

Using a short needle with a blunted tip. Aspirating the syringe prior to injection. [email protected]

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Table 3.3 Maximum Doses for Local Anesthetics (Illustrated in the Case of a 70 kg Patient) (24,33,34)

Anesthetic Long duration Bupivacaine Ropivacaine Moderate duration Lidocaine Mepivacaine Short duration Procaine Chlorprocaine

. .

Maximum adult dose

Concentration (%)

Without epinephrine (cc)

With epinephrine (cc)

0.5 0.5

35 40

45

2 1

15 28

25 50

2 2

40 40

50 50

Reducing the bolus volume. Reducing the force with which the local anesthetic is injected.

In Toronto, we never use retrobulbar blocks for trabeculectomy surgery, but we do use them in selected Seton cases.

4.5.

Subconjunctival/Sub-Tenon’s Anesthesia

4.5.1.

Introduction

Sub-Tenon’s local anesthesia, an alternate to retrobulbar anesthesia, has the advantage of being performed under direct observation potentially reducing the numerous complications associated with retrobulbar anesthesia (43 – 49). Parabulbar block, pinpoint anesthesia, single quadrant injection, episcleral block, and subconjunctival injection are different names or modifications of this technique (50 –53). A recent survey of the members of United Kingdom and Ireland Cataract and Refractive Society (UKISCRS) suggests that the sub-Tenon’s block is now practiced in 51% units (23). This suggests that large numbers of surgeons still use retrobulbar or general anesthesia, methods we stopped using many years ago.

4.5.2.

Advantages . . . . . .

.

Provides prolonged anesthesia and adequate akinesia for filtration surgery. Smaller volume of local anesthetic is required compared with retrobulbar block. No risk of retrobulbar hemorrhage and minimizing the risk of ocular perforation. Reduced surgical time. No need to wait for the retrobulbar to work. Excellent patient and surgeons acceptance of the technique. Allows the surgeons to check for conjunctival mobility in filtration and Seton surgery in cases of re-operation as the infiltration of anesthetic fluid separates Tenon’s capsule and conjunctiva from episclera. Easy and safe anesthetic technique not only for trabeculectomy (49,54) but also for cataract surgery (46,55,56). [email protected]

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4.5.3. Technique There are many variations of this block but they have similar principles. The techniques differ in access to the sub-Tenon’s space, cannula used, local anesthetic agent, volume and the use of adjuvant. Our technique (49) involves the following steps: . . .

.

.

Insertion of tetracaine eyedrops 5 min before prepping and draping and one drop before the anesthetic injection followed by insertion of the lid speculum. For virtually painless anesthesia place a tetracaine soaked cotton bud tip on the proposed injection site for 3 – 5 min prior to injecting subconjunctival lidocaine. The most commonly used agent is 2% lidocaine without epinephrine. With the patient looking down, 0.5 – 1 cc of 2% lidocaine is injected under direct vision into the sub-Tenon’s or subconjunctival space utilizing the operating microscope via a 30-gauge needle (with a length of 0.5 in.) 8 mm from the limbus to avoid buttonholing the surgical area. With a fornix-based flap insert the needle 3 –4 mm from the limbus outside the area operation site. Insert enough anesthetic to elevate the conjunctiva over the planned operation site. It is essential to ensure that the needle tip is visualized by the surgeon throughout the procedure; this avoids the possibility of scleral perforation. Excellent globe anesthesia for trabeculectomy is usually provided by 0.25– 0.5 mL, but larger volumes (using cannulae) are required if akinesia is required (4 – 5 mL). Akinesia is not a prerequisite in our hands. Prior to final conjunctival closure, a further injection of anesthetic is administered into the conjunctival wound edges. This considerably reduces closure discomfort.

Different sub-Tenon’s anesthetic techniques have been described as follows: .

.

Fukasaku reported rapid, complete anesthesia with no akinesia utilizing placement of a specially designed curved 24-gauge blunt, metal cannula through an incision in conjunctiva and Tenon’s capsule 8 – 12 mm posterior to the limbus in the superotemporal quadrant. The cannula is introduced into the subTenon’s space and advanced posteriorly along the eye wall to its fullest extent and 1 mL of 2% lidocaine is infused. As the incision is made far from the limbus, this technique is used by some during limbal-based filtration surgery (51). Another technique described by Greenbaum involves performing an incision 2 mm behind the limbus followed by sub-Tenon’s infusion of anesthetic through a specially designed, flexible cannula (50). This conjunctival limbal incision can be eventually enlarged to incorporate a fornix-based conjunctival flap.

Cannulae for sub-Tenon’s anesthesia are either made of metal or plastic. Metal cannulae come in various sizes ranging from 19 to 23 gauges. The selection of a cannula depends on the availability and the preference of the surgeon and anesthetist. SubTenon’s anesthesia with a retained polyethylene catheter has been described for surgery of long duration (57). Access to sub-Tenon’s space has been described from the superotemporal quadrant (51), medial canthus (52), and via inferonasal quadrant dissection (58). 4.5.4.

Complications . Pain during injection (reported in up to 44% of patients) (53,59). . Subconjunctival hemorrhage (incidence: 20– 100%) (49,53). [email protected]

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Carrillo and Trope

. . . . . .

Chemosis. Loss of local anesthetic volume during injection (53). Conjunctival injection buttonholes. Scleral perforation (60). Temporary muscle paresis. Trauma by metal cannula to inferior and medial rectus muscles leading to fibrosis and diplopia (61).

Other blocks not involving blind use of sharp needles include intracameral, deep fornix nerve block, and various combinations of two or more of these. These are usually performed by surgeons only and do not provide akinesia. 4.5.5. Recommendation We recommend subconjunctival placement of local anesthetic. This works well, raises the conjunctiva, is safe (as long as the needle tip is visualized), and effectively controls pain during surgery (49). 4.6.

Topical Anesthesia with Unpreserved Lidocaine 2% Jelly

4.6.1.

Introduction

Topical jelly anesthesia has been used by us for over 5 years for patients needing filtration surgery (62). Lidocaine 2% jelly is a widely used agent for topical anesthesia in urogenital, laryngotracheal, and even skin anesthesia and has recently been described in cataract, trabeculectomy, and phacotrabeculectomy surgery (63 – 65). Recent evidence suggests that topical anesthesia with lidocaine 2% jelly is a safe and effective alternative for clear cornea cataract surgery (66), trabeculectomy (62), and phacotrabeculectomy, even without systemic sedation (67). 4.6.2. . . . .

. . . . .

Advantages Pain control equal to sub-Tenon’s anesthesia (62). Provides adequate anesthesia and patient comfort (65 –68). Excellent patient and surgeon acceptance (62). Compared with regional anesthetic techniques such as peribulbar anesthesia, this topical approach does not increase vitreous pressure and there is no effect on the optic nerve perfusion. Post-operative recovery is quick and post-operative pain is minimal. No subconjunctival hemorrhage. Eye look is cosmetically better. Promotes efficient use of operating time (62). Preserved ocular motility can be used to optimize the wound access. The gel formulation has an increased contact time with the ocular surface, providing prolonged release of lidocaine, thus creating a sustained effect.

We conducted a prospective randomized clinical trial comparing lidocaine 2% jelly vs. sub-Tenon’s injection in 59 trabeculectomy patients (62). Anesthesia with lidocaine 2% jelly was not associated with any significant complications. For trabeculectomy surgery, 2% jelly was found to be as effective as sub-Tenon’s anesthesia. In addition, it may be safer as it does not involve injections. Topical jelly anesthesia is our preferred technique for filtration surgery. Topical anesthesia is the preferred technique for cataract surgeons in the USA [email protected]

Modern Anesthesia for Glaucoma Surgery

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(37%; range: 22 – 63%) according to a survey conducted by David Learning in 1998 (20). Topical anesthesia for ophthalmologic surgery has been successfully used by different authors for cataract surgery (69 – 71), trabeculectomy (62,72,73), vitrectomy (74), and phaco-trabeculectomy surgery (67,75). We find it possible to perform Seton surgery with topical jelly, but suggest addition of subconjunctival anesthesia for routine cases. A modified topical anesthesia technique has also been described for Ahmed valve placement surgery (Ayala R. Seven easy steps allow Ahmed glaucoma valve implantation under modified topical anesthesia. Ocular Surgery News 2003). 4.6.3. . . 4.6.4.

Technique of Topical Jelly Anesthesia .

. .

4.7.

Disadvantages Slightly sticky jelly covering the surgical field. Possible increased expense.

Lidocaine 2% jelly, 0.2 cc, is instilled into the conjunctival fornices 5 min before surgery. Use a 5 cc syringe with a size 20 angiocath on its end. The angiocath facilitiates application of the jelly. The Lidocaine jelly is directed over the operation site and cornea at the start of surgery and supplemented during surgery as required. Prior to final conjunctival closure, a further application of jelly must be administered to the edges of the open conjunctival wound to reduce pain.

Topical Anesthesia with Eye Drops

Topical anesthesia with eyedrops alone has been reported to be a safe and effective alternative for trabeculectomy surgery (72,73). 4.7.1.

Technique

For topical anesthesia administration with eyedrops, use preservative-free single-dose unit (minims) of tetracaine containing 0.5 mL. For each case, the entire contents of a single unit should used and administered 5 –10 min prior to surgery. One drop more should be additionally administered after draping the patient just before start of surgery and during the procedure as required (73). 4.7.2.

Disadvantages of Local Drops . . .

5.

Need for administration of several doses prior and during surgery. Short anesthetic effect without elimination of ocular movement. Potential for cumulative corneal toxicity.

CONCLUSION

Subconjunctival and, more recently, topical jelly anesthesia are rapidly replacing older forms of anesthesia for filtration surgery. ACKNOWLEDGMENTS The authors acknowledge the support of Dr. Frances Chung from the Department of Anesthesia, Toronto Western Hospital, University Health Network. [email protected]

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et al., eds. New Frontiers in Ophthalmology. Proceedings of the XXVI International Congress of Ophthalmology, Singapore, March 1990, Exerpta Medica 1991:103 –106. Hessemer V, Jacobi B, Kaufman H. Motorische blockade durch retrobulbaranesthesie title: phanomenologie and mechanismen. Ophthalmologe 1995; 92:307– 310. Javitt JC, Addiego R, Friedberg HL. Brainstem anesthesia after retrobulbar block. Ophthalmology 1987; 94:718 – 724. McGalliard JN. Respiratory arrest after two retrobulbar injections (letter). Am J Ophthalmol 1978; 96:847. Meyers EF, Ramirez RC, Boniuk I. Grand mal seizures after retrobulbar block. Arch Ophthalmol 1978; 96:847. Binnion PF. Toxic effects of lignocaine on the circulation. British Medical Journal 1968; 2:470 – 472. White PF. Outpatient Anesthesia. New York: Churchill Livingston, 1990. Duke J, Rosenberg S. Local anesthetics. Anesthesia Secrets. Philadelphia: Hanley & Belfus Inc., 1995:96 – 101. Rathi V, Basti S, Gupta S. globe rupture during massage after peribulbar anesthesia. J Cat Refract Surg 1997; 23:297 – 299. Magnate DO, Bullock JD, Green WR. Ocular explosion after peribulbar anesthesia. Ophthalmology 1997; 104:608– 615. Bullock JD, Warwar RE, Green WR. Ocular explosions from periocular anesthetic injections. Ophthalmology 1999; 106:2341– 2353. Sullivan KL, Brown GC, Forman AR et al. Retrobulbar anesthesia and retinal vascular obstruction. Ophthalmology 1983; 90:373– 377. Ramsay RC, Knobloch WH. Ocular perforation following retrobulbar anesthesia for retinal detachment surgery. Am J Ophthalmol 1978; 86:61 – 64. Morgan CM, Schatz H, Vine AK. Ocular complications associated with retrobulbar injections. Ophthalmology 1988; 95:660– 665. Kaplan LJ, Jaffe NS, Clayman HM. Ptosis and cataract surgery. Ophthalmology 1985; 92:237 – 242. Rainin EA, Carlson BM. Post-operative diplopia and ptosis. A clinical hypothesis based on the myotoxicity of local anesthetics. Arch Ophthalmol 1985; 103:1337 – 1339. Smith RJH. Editorial: Why retrobulbar anesthesia? Br J Ophthalmol 1988; 72:1. Redmond RM, Dallas NL. Extracapsular cataract extraction under local anesthesia without retrobulbar injection. Br J Ophthalmol 1990; 74:203– 204. Smith R. Cataract extraction without retrobulbar anesthetic injection. Br J Ophthalmol 1990; 74:205 – 207. Furuta M, Toriumi T, Kashiwagi K, Satoh S. Limbal anesthesia for cataract surgery. Ophthalmic Surg 1990; 21:22 – 25. Petersen WC, Yanoff M. Subconjunctival anesthesia: an alternative to retrobulbar and peribulbar techniques. Ophthalmic Surg 1991; 22:199 – 201. Ritch R, Liebman JM. Sub-Tenon’s anesthesia for trabeculectomy. Ophthalmic Surg 1992; 23:502 – 504. Buys YM, Trope GE. Prospective study of sub-Tenon’s versus retrobulbar anesthesia for inpatient and day-surgery trabeculectomy. Ophthalmology 1993; 100:1585 –1589. Greenbaum S. Parabulbar anesthesia. Am J Ophthalmol 1992; 114:776. Fukasaku H, Marron JA. Sub-Tenon’s pinpoint anesthesia. J Cataract Refrac Surg 1994; 20:468 – 471. Ripart J, Metfe L, Prat-Pradal D. Medial cantus single-injection episcleral (sub-Tenon anesthesia): computed tomography imaging. Anesth Analg 1998; 87:42 – 45. Stevens JD. A new local anesthesia technique for cataract extraction by one quadrant infiltration. Br J Ophthalmol 1992; 76:670– 674. Ritch R, Liebmann JM. Sub-Tenon’s anesthesia for trabeculectomy. Ophthalmic Surg 1992; 23:502 – 504.

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Redmond RM, Dallas NL. Extracapsular cataract extraction under local anaesthesia without retrobulbar injection. Br J Ophthalmol 1990; 74:203– 204. Smith R. Cataract extraction without retrobulbar anaesthetic injection. Br J Ophthalmol 1990; 74:204 – 207. Behndig A. Sub-Tenon’s anesthesia with a retained catheter in ocular surgery of longer duration. J Cataract Refract Surg 1998; 24:1307 – 1309. Kumar CM. An update: sub-Tenon’s block. Ophthalmic Anaesthesia News 2001; 5:13– 16. Roman SJ, Chong Sit DA, Boureau CM. Sub-Tenon’s anesthesia: an efficient and safe technique. Br J Ophthalmol 1997; 81:673 – 676. Frieman BJ, Firedberg MA. Globe perforation associated with subtenon’s anesthesia. Am J Ophthalmol 2001; 131:520 – 521. Jaycock PD, Mather CM, Ferris JD, Kirkpatrick JNP. Rectus muscle trauma complicating sub-Tenon’s local anaesthesia. Eye 2001; 15:583 – 586. Carrillo MM, Buys YM, Faingold D, Trope GE. Prospective study comparing Lidocaine 2% jelly versus sub-Tenon’s anaesthesia for trabeculectomy surgery. Br J Ophthalmol 2004; 88(8):1004– 1007. Bardocci A, Lofoco G, Perdicaro S, Ciucci F, Manna L. Lidocaine 2% gel versus Lidocaine 4% unpreserved drops for Topical anesthesia in cataract surgery. Ophthalmology 2003; 110:144 – 149. Bellucci R, Morselli S, Pucci V, Zordan R, Magnolfi G. Intraocular penetration of topical lidocaine 4%. J Cataract Refract Surg 1999; 25:643– 647. Assia EI, Pras E, Yehezkel M et al. Topical anesthesia using lidocaine gel for cataract surgery. J Cataract Refract Surg 1999; 25:635 – 639. Koch PS. Efficacy of lidocaine 2% jelly as a topical agent in cataract surgery. J Cataract Refract Surg 1999; 25:632 –634. Lai JSM, Tham CCY, Lam DSC. Topical Anesthesia in Phacotrabeculectomy. J Glaucoma 2002; 11:271 – 274. Barequet IS, Soriano ES, Green R, O’Brien TP. Provision of anesthesia with single application of lidocaine 2% gel. J Cataract Refract Surg 1999; 25:626– 631. MacLean H, Burton T, Murray A. Patient discomfort during cataract surgery with modified topical and peribulbar anesthesia. J Cataract Refract Surg 1997; 23:277 – 283. Vicary D, McLennan S, Sun XY. Topical plus subconjunctival anesthesia for phacotrabeculectomy: one year follow-up. J Cataract Refract Surg 1998; 24(9):1247– 1251. Zehetmayer M, Radax U, Skorpik C et al.Topical versus peribulbar anesthesia in clear corneal cataract surgery. J Cataract Refract Surg 1996; 22(4):480 – 484. Sauder G, Jonas JB. Topical anesthesia for penetrating trabeculectomy. Graefe’s Arch Clin Exp Ophthalmol 2002; 240:739 – 742. Zabriskie NA, Ahmed IIK, Crandall AS, Daines B et al. A comparison of topical and retrobulbar anesthesia for trabeculectomy. J Glaucoma 2002; 11(4):306 – 314. Yepez J, Cedeno de Yepez J, Arevalo JF. Topical anesthesia in posterior vitrectomy. Retina 2000; 20(1):41– 45. Ahmed IK, Zabriskie NA, Crandall AS et al. Topical versus retrobulbar anesthesia for combined phacotrabeculectomy. J Cataract Refract Surg 2002; 28:631– 638.

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63.

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4 Advances in the Modulation of Wound Healing Including Large Treatment Areas and Adjustable Sutures: The Moorfields Safe Surgery System Peng Tee Khaw Moorfields Eye Hospital and Institute of Ophthalmology, London, UK

Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada

1. Introduction 2. Which Antifibrotic Agent(s) 3. Clinically Used Agents 3.1. 5-Fluorouracil 3.2. Mitomycin-c 3.3. Other Agents 4. Application Technique 4.1. Intraoperative Application of Antimetabolite 4.1.1. Type of Incision/Dissection 4.1.2. Scleral Flap 4.1.3. Conjunctival Clamp 4.1.4. Type of Sponge 4.1.5. Antimetabolite Treatment Duration and Washout 4.1.6. Scleral Flap Sutures—New Adjustable, Releasable, and Fixed 4.1.7. Conjunctival Closure 4.2. Postoperative Application of Antimetabolites 4.2.1. Indications 4.2.2. Technique for Postoperative 5FU Injection 5. Summary Acknowledgments References

32 32 32 32 32 33 35 35 35 37 38 38 39 39 39 40 40 40 42 42 42 31

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1.

Khaw and Trope

INTRODUCTION

Agents that modulate healing such as the antimetabolites 5-fluorouracil (5FU) and mitomycin-c (MMC) have revolutionized glaucoma surgery, in patients with a high risk of surgical failure. There is increasing evidence from long-term prospective trials, that intraocular pressures in the 10–15 mmHg range best preserve long-term vision in glaucoma (1,2). However, vision threatening complications occur with the use of these agents (3,4). Changes in clinical techniques of antimetabolite application can increase the safety and considerably reduce complications while maintaining effectiveness. In this chapter, we describe how our surgical technique has been changed to make the use of antimetabolites as safe as possible—the Safe Surgery System. This technique has evolved at Moorfields on the basis of both clinical observation and experimental studies to reduce complications and to enhance success. Some changes in surgical technique are necessary to take full advantage of these improvements. The techniques and materials described are straightforward and have been designed to be easily available to ophthalmologists. 2.

WHICH ANTIFIBROTIC AGENT(S)

There are many antifibrosis agents available for use and these range from steroids used in virtually every patient, through to antimetabolites and newer experimental agents. The full details of all antiscarring agents are too extensive for this chapter and are covered elsewhere. However, the many potential agents are summarized in Table 4.1 and the risk factors, risks of antimetabolite complications, and regimen we use in Tables 4.2– 4.4. 3.

CLINICALLY USED AGENTS

The most commonly used agents are 5FU and MMC, with other agents such as betaradiation occasionally used. Newer agents currently undergoing clinical trials in humans include Trabiow human antibody to transforming growth factor beta2, photodynamic therapy and suramin. 3.1.

5-Fluorouracil

5FU is most commonly thought of as an agent preventing DNA synthesis and therefore cell proliferation, but it also has other effects including interference with RNA function. 5FU was first used after glaucoma filtration surgery in the 1980s by Parrish and the Miami group. More recently, 5FU has been used as a single intraoperative sponge application, stimulated in part by laboratory experiments suggesting that long-term effects of 5FU could be achieved from convenient single, short intraoperative applications in vitro and in vivo (7,8) and the the intraoperative use of MMC. 3.2.

Mitomycin-c

MMC is an antibiotic antimetabolite that damages DNA by alkylation and possibly crosslinking. Free radicals are also generated that can damage many nonspecific aspects of cell function including DNA, RNA, and protein synthesis. MMC is more effective than 5FU, essentially, because at the clinical doses currently used, more cell death than cell growth arrest occurs, resulting in tissues that are relatively acellular and unable to respond to healing stimuli. [email protected]

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Table 4.1 Sequence of Events in Tissue Repair and Possible Types of Modulation After Glaucoma Filtering Surgery (Events and Agents Have Overlapping Time Duration and Action) Modified from Khaw et al. (5,6) Event

Possible modulation

Activated conjunctiva “pre-activated” cells

Conjunctival/episcleral/scleral incisions Damage to connective tissue Release of plasma proteins and blood cells Activation of clotting and complement Fibrin/fibronectin/blood cell clot Release of growth factors from blood

Aqueous released from eye Breakdown of blood aqueous barrier Release of growth factors into aqueous Aqueous begins to flow through wound Migration and proliferation of polymorphonuclear neutrophil cells, macrophages, and lymphocytes

Activation, migration, and proliferation of fibroblasts

Wound contraction Fibroblast synthesis of tropocollagen glycosaminoglycans and fibronectin Collagen cross linking and modification Blood vessel endothelial migration and proliferation Resolution of healing Apoptosis Disappearance of fibroblasts Fibrous subconjunctival scar

3.3.

Stop medical therapy (especially drops causing red eye) Pre-operative steroids Minimal trauma Less invasive surgical techniques Hemostasis (blood can reverse MMC) Agents preventing/removing fibrin (e.g., heparin, tissue plasminogen activator, hirudin) Antagonists to growth factor production (e.g. antibodies to growth factors humanized antiTGF-beta2 antibody (CAT 152 Trabiow) or receptors) Anti-sense oligonucleotides, ribozymes, siRNA Less specific antagonists (tranilast, genistein, suramin) Blood aqueous barrier stabilising agents (e.g. steroids) Non-steroidal anti-inflammatory agents Anti-inflammatory agents (e.g., steroids, cyclosporine, glucosamine dendrimers) Anti-metabolites (e.g., 5FU/MMC) Antibodies to inflammatory mediators Angiotensin converting enzyme or chymase inhibitors Pre-operative steroids to reduce activation Anti-metabolites MMC 5FU Methylxanthine derivatives, Mushroom lectins Antiproliferative gene p21(WAF-1/Cip-1) Photodynamic therapy Anti-contraction agents (e.g., colchicine, taxol lectins, MMP inhibitors) Interferon alpha, MMP inhibitors, fibrostatin-c Anti-cross linking agents (e.g., beta-aminopropionitrile/penicillamine) Inhibitors of angiogenesis (e.g., fumagillin analogs, heparin analogs) MMC 5FU death receptor ligands Stimulants of apoptosis pathways

Other Agents

In photodynamic therapy, the area is sensitized with a photosensitizing dye (carboxyfluorescein) and then the bleb area to be treated exposed to appropriate wavelength of light (blue 450– 490 nm) protecting other areas (9). Beta-radiation is delivered using a [email protected]

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Table 4.2 Risk Factors for Failure Due to Scarring After Glaucoma Filtration Surgery Risk factors

Risk 1 –3þ

Ocular Neovascular glaucoma (active) Previous failed filtration surgery Previous conjunctival surgery Chronic conjunctival inflammation Previous cataract extraction (conj incision) Aphakia (intracapsular extraction) Previous intraocular surgery Uveitis (active, persistent) A red, injected eye Previous topical medications (beta-blockers þ pilocarpine) (beta-blockers þ pilocarpine þ adrenaline) New topical medications High preoperative intraocular pressure (higher with each 10 mmHg rise) Time since last surgery (especially if within last 30 days) Inferiorly located trabeculectomy Patient Afro-Caribbean origin may vary (e.g., West vs. East Africans) Indian subcontinent origin Hispanic origin Japanese origin young þ (þ) (particularly children) þþ

þþþ þþ(þ) þþ þþ(þ) þþ(þ) þþþ þþ þþ þþ þ(þ) þþþ þ(þ) þ(þ)

Comments

Uncertain

Depends on type of surgery

Particularly if they cause a red eye

þ þþ(þ) þ þþ þ (þ) (þ)

Strontium-90 probe, which is applied to the bleb area at the end of surgery. A dose of 1000 cGy is normally given—the time of exposure depends on the emission rate of the probe. Trabiow is given as a subconjunctival injection of antibody just before opening the conjunctiva, at the end of surgery, on day 1 and day 7 after surgery. Beta-irradiation has also been used effectively to inhibit wound healing after filtration surgery, principally by causing cellular growth arrest (10). A summary of the currently used intraoperative agents is shown in Table 4.5.

Table 4.3 Possible Risk Factors for Antimetabolite Related Complications † † † † †

Elderly patient Primary surgery no previous medications Poorly supportive scleral tissue prone to collapse (e.g., Myopia/buphthalmos/Ehlers Danlos) Thin conjunctiva or sclera Bleb placed in interpalpebral or inferior position

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Table 4.4 Moorfields Eye Hospital (More Flow) Intraoperative Single Dose Anti-scarring Regimen v2005 (Continuously Evolving). Lower Target Pressures Would Suggest that a Stronger Agent May be Required Low risk patients (nothing or intraoperative 5FU 50 mg/mL )a No risk factors Topical medications (beta-blockers/pilocarpine) Afro-Caribbean (elderly) Youth ,40 with no other risk factors Intermediate risk patients (intraoperative 5FU 50 mg/mL or MMC 0.2 mg/mL)a Topical medications (adrenaline) Previous cataract surgery without conjunctival incision (capsule intact) Several low-risk factors Combined glaucoma filtration surgery/cataract extraction Previous conjunctival surgery (e.g., squint surgery, detachment surgery, trabeculotomy) High risk patients (intraoperative MMC 0.5 mg/mL)a Neovascular glaucoma Chronic persistent uveitis Previous failed trabeculectomy/tubes Chronic conjunctival inflammation Multiple risk factors Aphakic glaucoma (a tube may be more appropriate in this case) Intraoperative beta-radiation 1000 cGy can also be used. CAT-152 (Trabiow) or humanized anti-TGF-beta2 antibody may be appropriate in the low and intermediate risk groups in the future on the basis of the results of current studies. These groups account for the majority of patients undergoing glaucoma surgery. a Postoperative 5FU injections can be given in addition to the intraoperative applications of antimetabolite.

4.

APPLICATION TECHNIQUE

The variations in the technique used to deliver intraoperative antimetabolites may account for some of the variations in efficacy and complications seen in the literature. It is very important for individual users to maintain a consistent technique and to build up experience with one technique. Changes in area of treatment, conjunctival and scleral flap construction, and adjustable sutures have led to a dramatic difference in terms of reducing short and long term complications (Fig. 4.1). This has led to a reduction in cystic areas within the bleb from 90% to 29%. The blebitis and endophthalmitis rate over 3– 5 years was 20% for older limbus based techniques with a smaller treatment area vs. 0% over the same period for the current technique (11). Falls in complication rate have also been seen in the USA in lower risk populations from 6% to 0.5% to date (Paul Palmberg, personal communication). If these figures were extrapolated to an approximate figure of 50,000 trabeculectomies with antimetabolite per year in the United States it is possible that bleb related complications could be avoided in many thousands of patients (Fig. 4.2). 4.1.

Intraoperative Application of Antimetabolite

4.1.1. Type of Incision/Dissection Dr. Khaw has changed to a fornix-based incision for either intraoperative 5FU or MMC. The cut length is 8 mm. He does not make a relieving incision to avoid any restricting [email protected]

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Table 4.5 Various Intraoperative Anti-scarring Agents Applied Directly to the Bleb Site 5FU (50 or 25 mg/mL)

Beta-radiation (1000 cGy)

Delivery

2 – 5 min

20 s – 3 min depending on output rate Approximately UK£3000 for probe but lasts 10þyears Special ordering and licensing required Lead shielded area

Cost

UK£1.50 (10 mL vial)

Availability

Good

Storage

Room temperature ready constituted

Duration effect on fibroblast proliferation

Several weeks Clinical effects several years

Several weeks

Primary effect Control over area treated

Growth arrest Moderate

Growth arrest Precise

MMC (0.2– 0.5 mg/mL) 2 – 5 min

UK£8 (2 mg vial makes 5 mL of 0.4 mg/mL) Good

Powder stable at room temperature Unstable once reconstituted Months/permanent cell death at higher range concentrations Growth arrest and cell death Moderate

Note: There have been reports of 5FU given intraoperatively directly into the filtration site during surgery. However, the risk of intraocular penetration is great and commercial 5FU is alkaline with a pH 9.0. Injected MMC has also been occasionally reported but one case of combined central retinal artery and vein occlusion has been reported following MMC injection. An aliquot of 50 mL of MMC (one drop) irreversibly damages the cornea.

incision. He dissects backwards with Westcott scissors to make a pocket of 10 – 15 mm posteriorly and wide for the antimetabolite sponges. When he dissects over the superior rectus tendon he lifts the conjunctiva to cut attachments avoiding the tendon itself (Fig. 4.3).

Figure 4.1 (See color insert) Changes in technique leading to improvements in outcome following the use of antimetabolites. [email protected]

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Figure 4.2 (See color insert) Patient’s left eye treated with smaller area of mitomycin-c 0.4 mg/mL showing focal cystic bleb. Left eye treated with mitomycin-c 0.5 mg/mL and large area showing diffuse noncystic bleb.

Explanation. Dr. Khaw previously used a limbus-based incision with antimetabolite as he was worried about postoperative leaks. However, his clinical observation of cystic blebs led him to the hypothesis that they had two things in common. The first was restricted posterior flow “the ring of steel.” The second was anterior aqueous flow. Even cystic blebs from preantimetabolite days have these. The restricted flow from the posterior incision resulting in more focal cystic blebs led him to change. The effects of treatment are very focal (8,12), the cells at the edge of the treatment area although growth arrested (13,14), can make scar tissue, and encapsulate the area resulting in thinning and a cystic bleb. A fornix-based incision allows a larger area of antimetabolite treatment, without a posteriorly placed restricting scar. Similar blebs can be achieved with a limbus-based flap but the incision has to be very posteriorly placed and this result is not as consistent. This does make the subsequent scleral flap and sutures more difficult. 4.1.2. Scleral Flap Dr. Khaw now cuts the scleral flap before he applies antimetabolite. He tries to cut the largest flap possible and leave the side cuts at the limbus incomplete (1 –2 mm from limbus). This forces the aqueous backwards over a wider area to get a diffuse bleb.

Figure 4.3 (See color insert) Fornix dissection to ensure large surface area of treatment. [email protected]

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Explanation. An aqueous jet at the limbus predisposes to an anterior focal cystic bleb, whereas posteriorly directed diffuse flow of aqueous from incompletely cut sides of a large scleral flap results in a more diffuse noncystic bleb. There is also evidence that treatment under the flap increases the success rate (15). Finally, if dissection occurs before the antimetabolite treatment and if there is any defect in the flap the use of intraoperative agents, particularly mitomycin can be avoided and postoperative injections used instead. 4.1.3. Conjunctival Clamp Dr. Khaw uses a special conjunctival T clamp he designed (Duckworth and Kent 2-686 Duckworth-and-Kent.com) to hold back the conjunctiva and to prevent antimetabolite touch. This clamp maintains a pocket for antimetabolite treatment. Explanation. Our experiments have shown that the antimetabolite affects mainly the area it touches (8), therefore protecting the edge prevents wound leaks and dehiscence. 4.1.4.

Type of Sponge

Dr. Khaw uses circular medical grade polyvinyl alcohol sponges used for lasik and corneal shields rather than other sponges. He cuts the sponges in half and folds them like a foldable lens. They fit through the entrance to the pocket without touching the sides (5 mm 3 and insert about 6 of these) (Fig. 4.4). He attempts to treat as large an area as he can. He also treats under the scleral flap. He has used polyvinyl alcohol sponges for many years as they maintain their integrity and do not fragment. In contrast, other sponges (e.g., Weck Cell) fragment relatively easily, with an increased chance of leaving small pieces of sponge behind in the wound. The large area of treatment results in more diffuse noncystic blebs clinically. Dr. Khaw treats under the flap as there is evidence that it improves the success rate. In addition, when he has re-explored failed surgery he has found adhesions between the scleral flap and bed in addition to episcleral fibrosis.

Figure 4.4 (See color insert) Special clamp protecting conjunctiva while folded sponges are being inserted. [email protected]

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Increasing the surface area of treatment results in a much more diffuse noncystic area clinically. A large area prevents the development of a ring of scar tissue (the “ring of Steel”), which restricts flow and promotes the development of a raised cystic avascular bleb. 4.1.5. Antimetabolite Treatment Duration and Washout Dr. Khaw treats for 3 min. If he needs to vary the effect of MMC, he varies the concentration. He uses only two concentrations (0.2 and 0.5 mg/mL). For intraoperative 5FU he always uses 50 mg/mL. He washes out with 20 mL of balanced salt solution. Explanation. Pharmacokinetic experiments we have done show a rapid uptake over 3 min after which there is a plateau when relatively little drug is added for extra minutes. In the period from 1 to 3 min there is considerable variation in the dose delivered (16). 4.1.6.

Scleral Flap Sutures—New Adjustable, Releasable, and Fixed

The sclerostomy is created and secured with a mixture of fixed and releasable sutures. Dr. Khaw has developed a new type of adjustable suture which he has evolved for about 2 years. These allow the tension to be adjusted postoperatively through the conjunctiva. Specially designed forceps with very smooth edges are used for this adjustment of pressure (Duckworth and Kent 2-502) (Fig. 4.5). Explanation. If strong antimetabolites such as MMC are used, complete suture removal can lead to a sudden drop in intraocular pressure even many months after surgery. An adjustable suture system allows a gradual titration of the intraocular pressure—more gradual than that seen with suture removal or massage (17). 4.1.7. Conjunctival Closure The main reason fornix-based flaps are not popular despite the increased speed, much better exposure, and absence of a scar in the line of aqueous flow leading to more cystic blebs is the inconvenience of aqueous leakage at the limbus in the postoperative period. To get rid of this problem and take advantage of a fornix-based bleb

Figure 4.5 (See color insert) New adjustable sutures being adjusted through the conjunctiva using special finely machined forceps. For video, see http://www.ucl.ac.uk/ioo/research/khaw.htm [email protected]

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Dr. Khaw has used several strategies . . . .

4.2.

No side cut in the conjunctiva—this minimizes manipulation and side leakage. Ensure Tenons is engaged in every stitch rather than just conjunctiva. Minimize any contact with antimetabolites, for example, with clamp. Side purse string sutures and deep attachment sutures buried in corneal grooves; 10/0 nylon is used throughout.

Postoperative Application of Antimetabolites

Postoperative injections of 5FU can be used postoperatively on their own, or even after intraoperative MMC or 5FU have been used. Subconjunctival injections of MMC have been given, but occasionally significant complications have been reported, so we do not use MMC injections routinely. 5FU was originally used as a planned regimen following surgery, but with the advent of intraoperative metabolites, the 5FU injections are now usually used according to the clinical situation at each post operative visit. 4.2.1.

Indications 1. 2. 3. 4. 5.

As part of a planned regimen in a patient with a significant risk of scarring or requiring a low postoperative intraocular pressure. In a patient showing signs of scarring and imminent bleb failure. Following a needling or re-exploration procedure. To prevent failure of an existing bleb after a healing stimulus (e.g., cataract extraction surgery). Injections may be given up to several months after surgery, if there is a persistent healing response and the intraocular pressure is rising.

4.2.2. Technique for Postoperative 5FU Injection The technique of postoperative injection is important. Laboratory experiments show that the degree of effect of antimetabolites on fibroblasts depends on either concentration or duration of exposure, hence the logic for using a very high concentration of 5FU intraoperatively in the surgical area (7,8). 1.

2.

3.

4. 5.

The eye is anaesthetized with several drops of topical amethocaine. It may also be useful to blanch the conjunctiva with a drop of adrenaline 0.01% or pheneylephrine 2.5% if there is no contraindication, as this may reduce the incidence of postinjection subconjunctival hemorrhage. Quantity and concentration. The original regime involved injections of 5 mg of 5FU diluted with 0.5 mL of saline. 5FU is now generally given in a concentration directly from the bottle, which is either 0.1 mL of a 50 mg/mL solution or 0.2 mL of a 25 mg/mL solution (i.e., injection dose ¼ 5 mg). A thin needle is advantageous as it reduces the reflux of 5FU into the tear film. For convenience we use a presterilized insulin syringe with an integral 27-gauge needle. A lid speculum is inserted to improve access. Site of injection. 5FU was originally given 1808 from the bleb to minimize the risk of intraocular entry of the 5FU solution which has an alkaline pH of 9. Dr. Khaw now gives the injection about 908 from the bleb to maximize the effect. Occasionally, the injection can be given deep in the upper fornix away from the drainage bleb if there is very good exposure. The conjunctiva is [email protected]

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Figure 4.6 (See color insert) Injection of 5FU being given through a viscoelastic wall.

6.

gently lifted with a nontoothed forceps and the needle inserted subconjunctivally. If the needle is too deep, there is a danger of scleral bleeding and direct tracking into the eye. The bleb resulting from the injection is slowly raised and watched as it advances towards the drainage bleb area, and injecting should stop just before the injection bleb meets the drainage area. Great care should be taken, particularly in a soft eye, as 5FU may enter the eye much more easily in a soft eye. The needle should be left in place for a few seconds as this helps to seal off the entry site and reduce leakage of 5FU into the tear film.

Figure 4.7 (See color insert) Example of diffuse noncystic bleb with intraocular pressure of 12 mmHg 5 years after surgery using mitomycin 0.5 mg/mL and described techniques. This result may be possible for the majority of patients having filtration surgery with improvements of current techniques, and can lead to a dramatic reduction in complications. [email protected]

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7.

8.

5.

Any remnant 5FU in the tear film should be irrigated out. If amethocaine eyedrops are used after a 5FU injection, a fine white precipitate in the tear film indicates that there is 5FU present. Washing out the fornix may reduce the incidence of corneal complications. Dr. Khaw has developed a new technique of 5FU preceded by subconjunctival Haelon GVTM. This “viscoelastic wall” prevents leakage of 5FU back into the tear film and enhances the effect of the 5FU (Fig. 4.6).

SUMMARY

Simple changes in the method of intraoperative antimetabolite application coupled with changes in surgical technique can very greatly increase the long-term safety of filtration surgery (Fig. 4.7).

ACKNOWLEDGMENTS Dr. Khaw research has been supported in part by the Medical Research Council (G9330070), the Guide Dogs for the Blind, the Wellcome Trust, Fight for Sight, the RNIB, Eranda Trust, Hayman Trust, Moorfields Trustees, the Healing Fund, and the Michael and Ilse Katz Foundation, who have supported our glaucoma and ocular repair and regeneration research program. Without them newer safer techniques for surgery would not have been developed. Mr. Alan Lacey produced the diagrams. This chapter is dedicated to Ilse Katz who inspired and helped us to help others. The author has no financial interest in any of the products listed in this review including the instruments which he has designed.

REFERENCES 1.

2.

3. 4. 5. 6. 7.

8.

The Advanced Glaucoma Intervention Study (AGIS): 7. The relationship between control of intraocular pressure and visual field deterioration.The AGIS Investigators. Am J Ophthalmol 2000; 130(4):429– 440. Collaborative Normal-Tension Glaucoma Study Group. The effectiveness of intraocular pressure reduction in the treatment of normal-tension glaucoma. Am J Ophthalmol 1998; 126(4):498– 505. Higginbotham EJ, Stevens RK, Musch DC, Karp KO, Lichter PR, Bergstrom TJ et al. Blebrelated endophthalmitis after trabeculectomy with mitomycin C. 1996; 103(4):650– 656. Greenfield DS, Suner IJ, Miller MP, Kangas TA, Palmberg PF, Flynn HW. Endophthalmitis after filtering surgery with mitomycin. Arch Ophthalmol 1996; 114(8):943 –949. Khaw PT, Chang LPY. Antifibrotic agents in glaucoma surgery. In: Duker D, Yanoff M, eds. Ophthalmology—A Practical Textbook. London: Churchill Livingston, 2003. Khaw PT, Occleston NL, Schultz GS, Grierson I, Sherwood MB, Larkin G. Activation and suppression of fibroblast activity. Eye 1994; 8:188– 195. Khaw PT, Ward S, Porter A, Grierson I, Hitchings RA, Rice NSC. The long-term effects of 5-fluorouracil and sodium butyrate on human Tenon’s fibroblasts. Invest Ophthalmol Vis Sci 1992; 33:2043 – 2052. Khaw PT, Sherwood MB, MacKay SLD, Rossi MJ, Schultz G. 5-Minute treatments with fluorouracil, floxuridine and mitomycin have long-term effects on human Tenon’s capsule fibroblasts. Arch Ophthalmol 1992; 110:1150 – 1154. [email protected]

Moorfields Safe Surgery System 9. 10.

11.

12.

13.

14. 15.

16. 17.

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Diestelhorst M, Grisanti S. Photodynamic therapy to control fibrosis in human glaucomatous eyes after trabeculectomy: a clinical pilot study. Arch Ophthalmol 2002; 120(2):130– 134. Siriwardena D, Khaw PT, King AJ, Donaldson ML, Overton BM, Migdal C et al. Human antitransforming growth factor beta(2) monoclonal antibody—a new modulator of wound healing in trabeculectomy: a randomized placebo controlled clinical study. Ophthalmology 2002; 109(3):427– 431. Wells AP, Cordeiro MF, Bunce C, Khaw PT. Cystic bleb formation and related complications in limbus versus fornix based conjunctival flaps in paediatric and young adult trabeculectomy with mitomycin C. Ophthalmology 2003; 110:2192 – 2197. Khaw PT, Doyle JW, Sherwood MB, Grierson I, Schultz G, McGorray S. Prolonged localized tissue effects from 5-minute exposures to fluorouracil and mitomycin C. Arch Ophthalmol 1993; 111(2):263 –267. Occleston NL, Daniels JT, Tarnuzzer RW, Sethi KK, Alexander RA, Bhattacharya SS et al. Single exposures to antiproliferatives: long-term effects on ocular fibroblast wound-healing behavior. Invest Ophthalmol Vis Sci 1997; 38(10):1998– 2007. Daniels JT, Occleston NL, Crowston JG, Khaw PT. Effects of antimetabolite induced cellular growth arrest on fibroblast-fibroblast interactions. Exp Eye Res 1999; 69(1):117 –127. El Sayyad F, Belmekki M, Helal M, Khalil M, El Hamzawey H, Hisham M. Simultaneous subconjunctival and subscleral mitomycin-C application in trabeculectomy. Ophthalmology 2000; 107(2):298 –301. Wilkins MR, Occleston NL, Kotecha A, Waters L, Khaw PT. Sponge delivery variables and tissue levels of 5-fluorouracil. Br J Ophthalmol 2000; 84(1):92 – 97. Wells AP, Bunce C, Khaw PT. Flap and suture manipulation after trabeculectomy with adjustable sutures: titration of flow intraocular pressure in guarded filtration surgery. J Glaucoma 2004; 13:400 – 406.

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5 How to Do a Trabeculectomy Clive Migdal Western Eye Hospital, London, UK

Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada

1. Technique 2. Postoperative Care 3. Conclusion References

45 49 50 50

Trabeculectomy is currently the most frequently performed surgical procedure for glaucoma. The modern trabeculectomy is a safe and effective procedure, with a high success rate. The chief aim is to allow aqueous to bypass the trabecular meshwork into the subconjunctival space, but at the same time, ensuring an optimum intraocular pressure (IOP) (i.e., not too high or too low) as well as maintaining the anatomy of the globe (i.e., preventing shallowing of the anterior chamber) (1,2). It is important to assess each patient individually before undertaking trabeculectomy. Aiming for a target pressure specific for each individual eye should be an important consideration. There are many different modifications of the trabeculectomy technique (3). To obtain optimum results, however, careful attention to detail at every step of the procedure is essential. In this way, outcomes can be improved and complications minimized. In general, everything possible to minimize fibroblast proliferation should be done, with as little tissue manipulation as possible.

1.

TECHNIQUE 1.

Selecting the site: All trabeculectomies should be sited superiorly (either centrally or superonasal or superotemporal). A superonasal or superotemporal quadrant site allows preservation of the adjacent superior quadrant for 45

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2.

3.

4.

subsequent filtering or cataract surgery. Avoid the interpalpebral area as this predisposes to infection. If the patient has had previous surgery that has involved the conjunctiva, choose a site where the conjunctiva is mobile, if possible. Anesthesia: We prefer doing trabeculectomy surgery utilizing topical 2% xylocaine jelly (4); however, the procedure can be performed with subtenons/ subconjunctival anesthesia. We do not recommend retrobulbar, peribulbar, or general anesthesia unless there are specific indications for these. (See chapter on anesthesia for glaucoma surgery.) Positioning the globe: A corneal traction suture allows the best positioning of the globe (Fig. 5.1). A superior rectus traction suture can also be used, but care must be taken not to put unnecessary traction on the muscle, which might cause damage, leaving the patient with a slight ptosis. Any hemorrhage in the area might also promote postoperative fibrosis, which is undesirable. Conjunctival flap: The conjunctival flap can either be fornix- or limbal-based (5,6). It is suggested that the success and safety of these two surgical approaches are similar. A fornix-based flap is currently the most popular. Advantages include better exposure (allowing better visualization and easier forward dissection of the scleral flap), technically easier (less time and less bleeding, thus reducing fibrosis), a more diffuse bleb (as there is no posterior scar line to limit the bleb), less manipulation of the conjunctiva, easier wound closure, and less chance of buttonholing the conjunctiva. The main disadvantage of the fornix-based flap is the risk of postoperative wound leak at the limbus. This can be minimized with careful closure of the conjunctiva at the end of the operation.

Figure 5.1 Conjunctival flap. [email protected]

How to Do a Trabeculectomy

5. 6.

47

The limbal incision can either be linear, or with a relieving incision [Fig. 5.1(A) and (B)]. It is usually about 2’O clock hours in length. The incision is made through both the conjunctiva and the Tenon’s capsule, entering into the plane just above the sclera, and allowing separation of the conjunctiva and Tenon’s from the sclera. A small amount of oozing from the episcleral blood vessels usually stops spontaneously. Persistent bleeders should be individually cauterized using bipolar cautery. If a limbal-based incision is used, make sure that the incision is sufficiently posterior to avoid overlying the scleral flap, as this may cause scarring/ walling off of the bleb. In addition, care must be taken not to damage the underlying superior rectus muscle. Application of antimetabolites: This subject is covered in a separate chapter and therefore will not be discussed here. Scleral flap: This can be either square, rectangular, or triangular in shape (1 in Fig. 5.2). The size of the flap can vary. Most square flaps are 4 mm 4 mm, and rectangular 4 mm 2 mm. The flap is usually half scleral thickness. After delineating the flap and performing the linear posterior incision, the flap is carefully dissected forwards, using an angled crescent blade. This is less sharp than a diamond knife, and thus avoids inadvertent perforation. It is necessary to follow a pathway parallel to the wall of the globe, thus maintaining a scleral flap of uniform thickness. As the flap is retracted, the underlying bed should have a white color similar to the surrounding sclera, although slightly grayer due to the underlying ciliary body. If it is very gray, the flap is too deep and the bed too thin. As the flap is dissected forward, a

Figure 5.2 Scleral flap, sclerostomy, and iridectomy. [email protected]

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7.

8.

9.

10.

definitive white line is encountered, marking the anterior extent of the sclera. This lies approximately over the scleral spur, or the posterior extent of the trabecular meshwork. The grayish blue zone anterior to the white line is the oblique junction between the cornea and the sclera and overlies the trabecular meshwork. About 1 mm further forward, the bluish gray area gives way to the more translucent clear cornea. This junction corresponds approximately to Schwalbe’s line. The dissection is stopped when clear cornea is encountered. Cautery should be kept to a minimum order to avoid promoting postoperative fibrosis. Tip: Avoid extending the side cuts of the scleral flap too anteriorly. This will prevent excessive leakage immediately postoperatively, which risks causing hypotony and/or a flat anterior chamber. Paracentesis: This is an essential part of the procedure and should be placed in the horizontal meridian. Tip: Avoid incising into an eye with a very high IOP. The sudden decompression risks choroidal detachment or an expulsive hemorrhage. If the IOP is .30 mm Hg preoperatively, consider administering mannitol, or other IOP reducing medications in order to reduce the IOP. Sclerostomy: The sclerostomy incision should be at least 1 mm clear of either side of the scleral flap (Fig. 5.2). After the initial linear incision into the anterior chamber, there are a number of different options for completing the sclerostomy: this can either be fashioned with a scleral punch (e.g., the Kelly Descemet’s membrane punch) (4 in Fig. 5.2), or a second parallel linear incision performed with the diamond knife, and the two then joined, enabling the removal of a block of scleral tissue (3 in Fig. 5.2). A fistula of 0.5– 1 mm in height and 1.5 –2 mm in width is created. Tip: Ensure that a full-thickness block of scleral tissue is removed, and that Descemet’s membrane, which is transparent, does not remain. Peripheral iridectomy: This is performed by grasping the peripheral iris through the sclerostomy with a fine-toothed forceps, then using a scissors (e.g., De Wecker’s) to excise a small portion of the iris (5 in Fig. 5.2). Tip: Ensure that the peripheral and not central iris is gripped. Holding the scissors blade in the horizontal meridian allows a wide v-shaped iridectomy, rather than a narrow one. The iridectomy should be visible through the clear cornea and the pupil should be round. Should bleeding from the iris occur, instilling air into the anterior chamber at this point will stop the bleeding immediately and prevent a hyphema forming (this works via a tamponade effect). The air can be withdrawn through the paracentesis at the end of the procedure. Closure of the scleral flap: This is done using various combinations of fixed and/or releasable sutures. Dr. Migdal’s preference is one fixed and one releasable suture using 10/0 monofilament nylon. Other methods include using three 10/0 nylon sutures, one at each corner of the rectangular flap (or tip of the triangle) and one on each side, 1 – 2 mm from the limbus. Tip: Always place the fixed suture first as manipulation of the flap for the second suture may loosen the first suture if this is of the releasable type. The suture is placed at 458 across the angle of the flap. The suture should be rotated to bury the knot. [email protected]

How to Do a Trabeculectomy

11.

12.

13.

2.

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See the chapter on releasable sutures for methods to close the flap utilizing this technique. Suturing the conjunctival flap: In the case of a fornix-based flap, it is very important to execute closure carefully, avoiding any conjunctival laxity and thus postoperative leakage. Two sutures are inserted in a purse-string fashion at either end of the incision, drawing the conjunctiva tightly across the limbus. The suture ends are buried, thus avoiding postoperative discomfort. If there is still laxity or retraction of the flap, a mattress suture can be used, spanning the two end sutures. Some surgeons prefer a continuous suture to close fornix-based flaps plus two wing sutures. With a limbal-based flap, it is essential to ensure that the incision is tightly sutured, making it water-tight. A useful method is to use a mattress stitch (absorbable 8.0 vicryl suture), taking bites of the conjunctiva and Tenon‘s capsule of the distal edge of the incision, followed by Tenon’s and conjunctiva of the proximal edge in turn. Each bite is locked in succession. If Mitomycin is used, we recommend closing limbal flaps in two separate layers using 8/0 vicryl sutures. Reformation of the anterior chamber: At the end of the procedure, it is important to reform the anterior chamber, using saline injected through the paracentesis, ensuring that the chamber is of good depth and the tension reasonable (tested by pressing gently on the central cornea with a blunt instrument). This avoids a shallow anterior chamber postoperatively, and possibly also helps prevent hypotony or choroidals. Antibiotics/steroids/patch: Some surgeons use subconjunctival antibiotics at the conclusion of the procedure, but we recommend a topical antibiotic/ steroid combination (Tobradex). We do not patch the eye after surgery (7). A plastic shield is used to cover the eye and the patient is instructed to start their postoperative drops (Tobradex QID and Atropine 1% BID) 4 h postsurgery. We recommend discontinuing the atropine after a few days if the chamber is deep. We discontinue the antibiotic steroid combination after 4 days and switch to a topical steroid drop (prednisone QID or more often if needed) for an additional 6 weeks or until the bleb is quiescent without active vacularization (8).

POSTOPERATIVE CARE

At the first postoperative visit, it is important to check the IOP, the state of the anterior chamber and fundus, and the morphology of the drainage bleb. If the IOP is raised on the first day, it is possible to apply gentle localized pressure with a sterile cotton bud to the edge of the scleral flap, thus separating the edges of the wound and allowing egress of aqueous into the subconjunctival space. If this fails to reduce the IOP to a satisfactory level, the releasable suture can be adjusted, or, if all else fails, fully released. A fixed suture can also be released, if necessary, by means of laser suture lysis (9,10), using the argon laser. See relevant chapters for further descriptions of these techniques. In most cases, the releasable suture is removed at the first or second postoperative week. However, if the IOP is at an optimum level, the releasable suture described earlier can be left in situ permanently, as the exposed parts of the suture usually become covered by epithelium within about 4 weeks. [email protected]

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The approach to the management of postoperative problems such as shallowing of the anterior chamber, bleb leakage, and so on is dealt with in another chapter.

3.

CONCLUSION

Trabeculectomy is an effective procedure that maintains IOP control at a satisfactory target level for a long period of time. It is essential to develop a safe and careful surgical technique, keeping in mind the aims and potential pitfalls of the procedure, in order to ensure good results and prevent complications.

REFERENCES 1. 2. 3. 4.

5. 6. 7. 8.

9.

10.

Cairns JE. Trabeculectomy: preliminary report of a new method. Am J Ophthalmol 1968; 66:673 – 679. Watson PG. Surgery of the glaucomas. Br J Ophthalmol 1972; 56:299– 305. Lerner SF. Small incision trabeculectomy avoiding Tenon’s capsule: a new procedure for glaucoma surgery. Ophthalmology 1997; 104:1237 – 1241. Carrillo M, Buys Y, Faingold D, Trope GE. Prospective randomized study comparing lidocaine 2% jelly versus subtenons anesthesia for trabeculectomy surgery. Brit J Ophthalmol 2004; 88:1004 – 1007. Shuster JN, Krupin T, Kolker AE, Becker B. Limbus- versus fornix-based conjunctival flap in trabeculectomy: a long-term randomized study. Arch Ophthalmol 1984; 102:361 – 362. Traverso CE, Tomey KF, Antonios S. Limbal- vs fornix-based conjunctival trabeculectomy flap. Am J Ophthalmol 1987; 104:28– 32. Trope GE, Buys YM, Flanagan J, Wang L. Is a tight patch necessary after trabeculectomy? Br J Ophthalmology 1999; 83:1006– 1007. Roth SM, Spaeth GL, Starita RJ et al. The effect of postopertive corticosteroids on trabeculectomy and the clinical course of glaucoma: five-year follow-up study. Ophthamic Surg 1991; 23:724 – 729. Lewis RA. Laser suture lysis and releasable sutures. In: Weinreb RN, Mills RP, eds. Glaucoma Surgery. Principles and Techniques. 2nd ed. San Francisco: American Academy of Ophthalmology, 1991:60 – 63. Macken P, Buys Y, Trope GE. Laser suture lysis. Br J Ophthalmol 1996; 8:398– 401.

[email protected]

6 Nonpenetrating Glaucoma Surgery: Indications, Techniques, and Complications Tarek Shaarawy University of Geneva, Geneva, Switzerland

Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada

Andre´ Mermoud University of Lausanne, Lausanne, Switzerland

1. Principles of Nonpenetrating Glaucoma Surgery 2. Indications for NPGS 2.1. Open-Angle Glaucoma 2.2. Glaucoma Patients with High Myopia 2.3. Pigmentary Glaucoma 2.4. Exfoliative Glaucoma 2.5. Congenital Glaucoma 3. Relative Contra-indications to NPGS 4. Absolute Contra-indications 4.1. Neovascular Glaucoma 5. Surgical Technique of NPGS 5.1. Deep Sclerectomy 5.1.1. Anesthesia 5.1.2. Technique 5.1.3. The Use of Implants 5.2. Viscocanalostomy 6. Nd:YAG Goniopuncture After NPGS 7. Complications of Nonpenetrating Surgery 7.1. Intraoperative Complications 7.1.1. Perforation of the TDM 7.2. Early Postoperative Complications 7.2.1. Wound Leak 7.2.2. Inflammation 7.2.3. Hypotony 7.3. Postoperative Increase in IOP

52 52 52 52 53 53 53 53 53 53 54 54 54 54 56 57 57 58 58 58 58 58 59 59 59 51

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7.4. Late Postoperative Complications 7.4.1. Late Rupture of the TDM 7.4.2. Descemet’s Detachment 7.4.3. Peripheral Anterior Synechia 7.4.4. Scleral Ectasia 8. Results of NPGS References

1.

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PRINCIPLES OF NONPENETRATING GLAUCOMA SURGERY

Nonpenetrating glaucoma surgery (NPGS) selectively targets the pathological structures responsible for the increase in intraocular pressure (IOP) (1,2). This is done without penetration into the eye (3). In this respect, NPGS is essentially extraocular surgery as opposed to other surgical modalities that necessitate eye penetration. The avoidance of penetration into the eye reduces the risk of hypotony and its sequelae. In primary and in some cases of secondary open-angle glaucoma, the main aqueous outflow resistance is thought to be located at the level of the juxtacanalicular trabeculum and the inner wall of Schlemm’s canal (4). These two anatomic structures are removed during NPGS. The principal behind this technique was first proposed by Zimmerman (1,2), and he used the term ab externo trabeculectomy to describe it. Kozlov (5) suggested a variation on ab externo trabeculectomy in an attempt to increase the aqueous outflow facility. He extended the dissection anteriorly into peripheral corneas for an extra 1– 2 mm removing the corneal stroma behind Descemet’s membrane (Fig. 6.1). This has been termed deep sclerectomy. Postoperatively, the main aqueous outflow occurs at the level of the anterior trabeculum and Descemet’s membrane, the so-called trabeculo-Descemet’s membrane (TDM). In viscocanalostomy, as described by Stegmann et al. (6), the aqueous filters through the TDM to the surgically created scleral space, as in deep sclerectomy, but it does not form a subconjunctival filtering bleb because the superficial scleral flap is tightly closed. From the scleral space, the aqueous reaches Schlemm’s canal ostia, which are surgically opened, and dilated with viscoelastic. 2.

INDICATIONS FOR NPGS

Most published trials have evaluated efficacy of NPGS in primary and secondary openangle glaucoma. In cases where the angle is grossly distorted or closed, NPGS should not be performed. 2.1.

Open-Angle Glaucoma

NPGS has been advocated as a safer option to trabeculectomy in open-angle glaucoma (7). Instead of excising a portion of peripheral cornea and trabecular meshwork, NPGS targets the presumed site of pathology, namely the inner wall of Schlemm’s canal and the juxtacanalicular meshwork. 2.2.

Glaucoma Patients with High Myopia

Conventional glaucoma surgery in patients with high myopia carries a higher risk of complications. One study (8) reported on the results of NPGS in highly myopic [email protected]

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Figure 6.1 (See color insert) Sclerectomy, ab externo trabeculectomy, deep sclerectomy.

glaucoma patients. Two out of 21 patients developed choroidal detachments, one of which was secondary to blunt trauma to the operated eye. This low rate of complication is attributed to the gradual intraoperative IOP reduction with NPGS. 2.3.

Pigmentary Glaucoma

NPGS is a potential therapy for pigmentary glaucoma; NPGS targets the site of the pathology, namely the pigment loaded trabecular meshwork. 2.4.

Exfoliative Glaucoma

NPGS is an option in exfoliative glaucoma. One study (9) reported 2-year acceptable IOP control rates in patients with exfoliative glaucoma. They also reported a low incidence of complication with NPGS. 2.5.

Congenital Glaucoma

Tixier and co-workers (10) were the first to report on NPGS in congenital glaucoma. Nine of 12 operated eyes were ,16 mmHg at 10 months without medications. They concluded that NPGS is at least as effective as trabeculectomy in congenital glaucoma with fewer complications.

3.

RELATIVE CONTRA-INDICATIONS TO NPGS

There are no published reports on NPGS in primary angle closure glaucoma. This is not surprising considering the principles behind NPGS and its presumed mechanisms of function. Likewise, secondary angle closure aetiological entities are a relative contraindication. The descision, though, depends on the degree of angle closure.

4. 4.1.

ABSOLUTE CONTRA-INDICATIONS Neovascular Glaucoma

Neovascular glaucoma is an absolute contra-indication to NPGS. The condition of the angle structures and the pathological state of the trabeculum provide little chance of surgical success. [email protected]

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SURGICAL TECHNIQUE OF NPGS

5.1. 5.1.1.

Deep Sclerectomy Anesthesia

Three to four milliliters of a solution of bupivacaine 0.75% and xylocaine 4% are usually sufficient for a successful retrobulbar anesthesia. A combination of topical and subconjunctival anesthesia is possible with cooperative patients.

5.1.2.

Technique

Exposure. A superior rectus muscle traction suture or a superior intracorneal suture is used to expose the upper nasal or supero-temporal surgical quadrant. The corneal suture should not be inserted too near the limbus so that the anterior dissection of the deep sclerectomy is not obscured. Optionally, two 7/0 vicryl tangential intracorneal sutures may be placed on either side of the potential surgical site in order to reduce tension on the corneal stroma during dissection. The conjunctiva is opened as either a limbalbased flap or a fornix-based flap. A fornix-based incision offers better scleral exposure, but needs careful closure, especially when antimetabolites are used. The sclera is exposed, and moderate hemostasis is performed. To facilitate the scleral dissection, all Tenon’s capsule residue should be removed with a knife (e.g., beaver 64 or 57). Sites with large aqueous drainage veins should be avoided, to preserve the aqueous-humor physiological outflow pathways. Often gentle and continuous pressure on a bleeding vessel for 1 min stops the bleeding. Scleral Dissection. A superficial scleral flap measuring 5 5 mm2 is dissected, 1/3 scleral thickness (300 mm) (Fig. 6.2).

Figure 6.2 (See color insert) Dissection of superficial scleral flap. [email protected]

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The initial scratch incision is done with a No. 11 stainless-steel blade. The horizontal dissection is done with a crescent blade. In order to later dissect the corneal stroma down to Descemet’s membrane, the scleral flap is dissected anteriorly 1 –1.5 mm into clear cornea. In patients at high risk of sclero-conjunctival scar formation (young, secondary glaucoma or African-origin), a sponge soaked in mitomycin-C 0.02% may be placed for 45 s in the scleral bed between the sclera and the conjunctiva. Deep sclero-keratectomy is done by performing a second deep scleral flap (4 4 mm2) (Fig. 6.3). The two lateral and the posterior deep scleral incisions are made using a 15-degree diamond blade or a No. 11 stainless-steel blade. The deep flap is smaller than the superficial one leaving a step of sclera on the three sides. This allows for tight closure of the superficial flap in case of intraoperative perforation of the TDM. Tip: While dissecting, the deep flap start at one corner and deepen the scratch incision till the choroid is identified, then begin the dissection in the sclera a few microns above this level. The remaining scleral layer should be as thin as possible (50 –100 mm). A second important tip involves holding the deep flap firmly so as to stretch it. Use gentle side-to-side dissection, while the flap is stretched maintaining this deep level of dissection. Maintaining a consistent straight deep level of dissection allows for successful bisection of Schlemm’s canal. As one dissects past the scleral spur (the anterior part of the dissection), Schlemm’s canal is unroofed. Schlemm’s canal is located anterior to the scleral spur where the scleral fibers are regularly oriented, parallel to the limbus. Schlemm’s canal is opened and the sclero-corneal dissection is continued anteriorly into peripheral cornea for another 1 – 1.5 mm in order to remove the roof of Schlemm’s canal and stromal tissue superficial to Descemet’s membrane. This surgical step is challenging as there is a high risk of perforation of the anterior

Figure 6.3 (See color insert) Dissection of deep flap, excision, and exposure of Schlemm’s canal. [email protected]

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chamber (AC) at this point. In patients with congenital glaucoma, Schlemm’s canal localization is more difficult to find, because it is often more posteriorly situated. Tip: The best way to perform this last part of the dissection is to make two careful radial corneal cuts without penetrating down to anterior trabecular meshwork or Descemet’s membrane. This is performed with a 15-degree diamond knife or with No. 11 stainless-steel blade with the bevel side facing up. When the anterior dissection between corneal stroma and Descemet’s membrane is completed, the deep scleral flap is cut at its anterior edge using the diamond knife. At this stage, there should be a diffuse percolation of aqueous through the remaining TDM. The juxtacanalicular trabeculum and Schlemm’s endothelium are then removed using a small blunt forceps (Fig. 6.4). Tip: Just before attempting to grasp the inner wall of Schlemm’s canal with the forceps, the area should be dried, this greatly facilitates the process of stripping. Finally, the superficial scleral flap is closed and secured with two loose 10/0 nylon sutures. Note that the procedure has evolved into a combined deep sclerectomy and ab externo trabeculectomy. 5.1.3.

The Use of Implants

The original idea (5,11) behind using implants in NPGS was to avoid collapse of the superficial flap over the TDM and the remaining sclera. The first implant was a collagen implant placed in the scleral bed and secured with a single 10/0 nylon suture (Fig. 6.5). The implant was processed from porcine scleral collagen. It increased in volume after contact with aqueous and is slowly resorbed within 6– 9 months leaving a patent scleral space for aqueous filtration. Other implants currently available are the reticulated

Figure 6.4 (See color insert) Peeling of the innerwall of Schlemm’s canal and juxtacanalicular trabeculum. [email protected]

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Figure 6.5 (See color insert) Implantation of a collagen implant.

hyaluronic (12) acid implant resorbing in 3 months or the T-shaped hydrophilic acrylic implant, which is nonabsorbable. The role of implants in nonpenetrating surgery is still controversial, but studies comparing deep sclerectomy with an implant vs. without (13) seems to show greater success rates with implant use. 5.2.

Viscocanalostomy

In the case of viscocanalostomy, high viscosity hyaluronic acid is injected into the two surgically created ostia of Schlemm’s canal, aiming at dilating both the ostia and the canal. The viscoelastic agent is also placed in the scleral bed. The superficial scleral flap is tightly sutured in order keep the viscoelastic in place and to force the aqueous percolating through the TDM into the two ostia.

6.

Nd:YAG GONIOPUNCTURE AFTER NPGS

When filtration through the TDM is insufficient, Nd:YAG goniopuncture is performed (14). Using a gonioscopy contact lens, the aiming beam is focused on the semitransparent TDM. Using the free running Q-switched mode, with a power of 4– 5 mJ, 2 – 15 shots are applied. This results in the formation of microscopic holes through the TDM allowing direct passage of aqueous from the AC to the subsuperficial flap space (also termed decompression chamber or intrascleral bleb). The success rate of Nd:YAG laser goniopuncture is 50%. The success of goniopuncture depends mainly on the thickness of the TDM, hence the importance of sufficiently deep dissection. [email protected]

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By opening the TDM, however, goniopuncture converts a nonperforating filtration procedure into a perforating one. Nevertheless, the combined complication rates of deep sclerectomy and goniopuncture are significantly lower than the complication rates associated with trabeculectomy (15). 7.

COMPLICATIONS OF NONPENETRATING SURGERY

Nonpenetrating surgery has a lower complication rate than conventional trabeculectomy (16,17), with or without antimetabolites. Complications of NPGS are considered intraoperative, early postoperative or late postoperative. Comprehensive knowledge of these complications, as well as an understanding of the best ways to deal with them, help to make appropriate management decisions. 7.1.

Intraoperative Complications

7.1.1. Perforation of the TDM The commonest intraoperative complication of nonpenetrating surgery is perforation of the TDM. Perforations occur in 30% of the first 10 – 20 cases. After the initial learning phase, surgeons can expect perforations in 2 – 3% of cases. Different types of perforations are as follows. Transverse Tear. This occurs at the junction of the anterior meshwork and Descemet’s membrane, the weakest point of the TDM corresponding to Schwalbe’s line on gonioscopy. A perforation at this level will usually lead to the formation of a long tear, followed by immediate iris prolapse. TDM Holes. Holes may occur in the TDM during the anterior deep dissection with the knife. Holes may be small with no loss of depth of the AC or large and accompanied by shallow or flat AC and/or iris prolapse. Management. The two factors that determine the management of a TDM perforation are the depth of the AC and the presence of iris prolapse. Small holes with no iris prolapse or loss of AC depth should be ignored, and the surgery continued. Perforations with shallow or flat AC and no iris prolapse should be dealt with in order to prevent subsequent iris prolapse or peripheral anterior synechia formation. Viscoelastic material should be injected through a paracentesis, into the AC under the TDM window to reform the AC and reposition the iris. The smallest possible amount of viscoelastic material should be used to avoid postoperative ocular pressure spikes. In addition, an implant can be placed on the perforation site to tamponade the hole. The superficial scleral flap should be tightly sutured with 6– 8 10/0 nylon sutures once the AC has been reformed and the iris pushed back. Iris prolapse accompanying a larger hole is an indication for a peripheral iridectomy. The superficial flap should be tightly closed after viscoelastic material has been inserted into the surgically created scleral space so as to increase the outflow resistance. Because the scleral space left after deep sclerectomy decreases the aqueous-humor outflow resistance, very tight superficial scleral-flap closure is of great importance (18). 7.2.

Early Postoperative Complications

7.2.1. Wound Leak Wound leaks or positive Seidel test occurs with the same frequency after trabeculectomy and nonpenetrating surgery and are often due to inadequate conjunctival wound closure. [email protected]

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In most cases, leaking stops after a week and after discontinuing steroid therapy. Rarely, surgical intervention is necessary to repair the wound leak. 7.2.2. Inflammation The degree of inflammatory reaction following nonpenetrating surgery is usually less than that seen with trabeculectomy. This is due to the fact that the AC is not penetrated and an iridectomy is not performed. Inflammation is treated with topical steroids for 6 weeks. 7.2.3.

Hypotony

Early hypotony without perforation is an excellent indicator of good surgical dissection. Low postoperative IOP is expected in the early postoperative period because of the surgically induced increase in outflow facility. Ideally, the TDM should always offer enough resistance to prevent anterior-chamber collapse; flat anterior chambers are not expected with successful nonpenetrating filtering surgery. On the first postoperative day, mean IOP after nonpenetrating filtering surgery usually measures 5 mmHg (19,20). IOP usually increases over the next few days without specific treatment. 7.3.

Postoperative Increase in IOP

Because the main site of postoperative aqueous-humor outflow resistance after nonpenetrating filtering surgery is located at the TDM level, this complication should not occur if the dissection of the membrane has been performed correctly. Early postoperative IOP spikes are due to the following causes. 1.

2. 3. 4.

5. 6.

Insufficient surgical dissection. In such cases, the operative site can possibly be revised. A revision though is usually difficult, many surgeons opt for a re-operation in a different site. Hemorrhage in the scleral bed. This usually spontaneously resolves without treatment within a few days. Excess viscoelastic remaining in the AC, mainly after combined surgery or AC reformation with a microperforation. This usually resolves in a few days. Postoperative rupture of the TDM with iris prolapse, secondary to increased IOP from eye rubbing, Valsalva’s maneuver, and so on. This should be managed with miotics and gonio Yag laser to the prolapsed iris. If this does not work, surgical iridectomy is indicated. Peripheral anterior synechia (PAS) formation at the site of the filtering window, often secondary to intraoperative microperforation. Steroid induced IOP increase within the first postoperative weeks.

Overall, IOP spikes are unusual postoperative complications and should be managed according to each specific cause. 7.4. 7.4.1.

Late Postoperative Complications Late Rupture of the TDM

The risk of membrane rupture decreases with time because the postmembrane outflow resistance slowly builds for several weeks. However, rupture can occur after ocular trauma or after goniopuncture. With rupture, iris prolapses into the tear leading to a [email protected]

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distorted pupil and darkening of the subconjunctival area. If the IOP remains under control, no further treatment is needed. However, if the iris prolapse blocks the aqueous-humor outflow and the IOP rises, medical or surgical therapy including gonio laser or surgical iridectomy and AC reformation should be performed. 7.4.2.

Descemet’s Detachment

Descemet’s membrane detachment is a rare complication after nonpenetrating filtering surgery. We estimate it occurs in about 1 out of 250 –300 operated eyes. With viscocanalostomy, detachment is related to misdirected viscoelastic injection. The detachment is noticed during the procedure or generally shortly afterwards. After deep sclerectomy, this complication may be explained by the passage of aqueous humor from the scleral space to the sub-Descemet space at the anterior edge of Descemet’s window, secondary to increased intrableb pressure from trauma, encysted bleb, and vigorous ocular massage. This is usually a transient complication, but if it becomes prolonged, Descemetopexy has been tried successfully in such cases. 7.4.3.

Peripheral Anterior Synechia

The iris may adhere to trabeculo-Descemet’s window and form PAS (21) in the following situations: intraoperative microperforation with microiris prolapse; iris entrapment into a goniopuncture hole, which usually occurs rapidly after laser treatment, and rupture of the TDM (e.g., blunt trauma) with subsequent iris prolapse. There may be an associated increase in IOP if there is insufficient aqueous-humor flow through the membrane. Yag laser lysis should be attempted to remove the iris from the osteum. If this fails, medical or surgical treatment should be considered. 7.4.4.

Scleral Ectasia

In the literature, there is a single reported case (22) of scleral ectasia following deep sclerectomy in a12-year-old girl with chronic arthritis complicated with glaucoma secondary to a chronic uveitis. As rare as it is, this complication should be considered in patients with high myopia and chronic uveitis, especially in association with rheumatoid or juvenile arthritis. The use of antimetabolites intra- or postoperatively may also increase the risk of this complication.

8.

RESULTS OF NPGS

Prospective nonrandomized trials of deep sclerectomy (23 – 27) and viscocanalostomy (28 –30) provide sufficient evidence that the procedure can reduce IOP to acceptable levels. Randomized controlled trials (15,31 –35) comparing NPGS with trabeculectomy have a consensus on the superior safety profile of NPGS. On efficacy, we have controversial reports. This disparity in results can be attributed to a number of factors, namely the fundamental differences between various NPGS techniques, the long-learning curves, and the use of goniopunctures to achieve target IOPs. One should keep in mind though as he browses between results that it is all about technique. Issues related to which technique is superior to which in the wide spectrum of NPGS is of paramount importance. The fact of an existing long learning curve could not be over-stated. It is neither meaningful nor scientifically sound to compare one’s last twenty cases of trabeculectomy to one’s first twenty [email protected]

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deep sclerectomies. What is valid is that with its apparent mechanisms of function that seems to target specific pathological structure in glaucoma, NPGS is quite promising. It would be prudent to remember that from the weight of evidence that we have available, it is of absolute importance to achieve proper depth of dissection, to use implants, and to perform goniopuncture whenever target IOPs are not achieved.

REFERENCES 1.

2.

3. 4. 5. 6. 7.

8. 9. 10. 11. 12. 13.

14.

15.

16.

17.

18.

Zimmerman TJ, Kooner KS, Ford VJ, Olander KW, Mandlekorn RM, Rawlings EF et al. Trabeculectomy vs. nonpenetrating trabeculectomy: a retrospective study of two procedures in phakic patients with glaucoma. Ophthalmic Surg 1984; 15:734 –740. Zimmerman TJ, Kooner KS, Ford VJ, Olander KW, Mandlekorn RM, Rawlings FE et al. Effectiveness of nonpenetrating trabeculectomy in aphakic patients with glaucoma. Ophthalmic Surg 1984; 15:44– 50. Mermoud A. Sinusotomy and deep sclerectomy. Eye 2000; 14:531– 535. Johnson DH, Johnson M. How does nonpenetrating glaucoma surgery work? Aqueous outflow resistance and glaucoma surgery. J Glaucoma 2001; 10:55– 67. Kozlov VI, Bagrov SN, Anisimova SY, Osipov AV, Mogilevtsev VV. Deep Sclerectomy with collagen. Eye Microsurg 1990; 3:44– 46. Stegmann R, Pienaar A, Miller D. Viscocanalostomy for open-angle glaucoma in black African patients [see comments]. J Cataract Refract Surg 1999; 25:316– 322. Mermoud A, Schnyder CC, Sickenberg M, Chiou AG, Hediguer SE, Faggioni R. Comparison of deep sclerectomy with collagen implant and trabeculectomy in open-angle glaucoma. J Cataract Refract Surg 1999; 25:323 – 331. Hamel M, Shaarawy T, Mermoud A. Deep sclerectomy with collagen implant in patients with glaucoma and high myopia. J Cataract Refract Surg 2001; 27:1410 – 1417. Drolsum L. Deep sclerectomy in patients with capsular glaucoma. Acta Ophthalmol Scand 2003; 81:567 – 572. Tixier J, Dureau P, Becquet F, Dufier JL. Deep sclerectomy in congenital glaucoma. Preliminary results. J Fr Ophtalmol 1999; 22:545– 548. Kozlov VI, Bagrov SN, Anisimova SY, Osipov AV, Mogilevtsev VV. Nonpenetrating deep sclerectomy with collagen. Eye Microsurg (In Russian) 1990; 3:157– 162. Detry-Morel M. Non penetrating deep sclerectomy (NPDS) with SKGEL implant and/or 5-fluorouracile (5-FU). Bull Soc Belge Ophtalmol 2001; 280:23– 32. Shaarawy T, Nguyen C, Schnyder CC, Mermoud A. Comparative study between deep sclerectomy with and without collagen implant: long-term follow up. Br J Ophthalmol 2004; 88(1):95– 98. Mermoud A, Karlen ME, Schnyder CC, Sickenberg M, Chiou AG, Hediguer SE et al. Nd:Yag goniopuncture after deep sclerectomy with collagen implant. Ophthalmic Surg Lasers 1999; 30:120 – 125. Gandolfi S, Quaranta L, Cimino L, Bettelli S. Deep sclerectomy versus trabeculectomy. Prospective Randomized Clinical trial. 4-Year interim analysis. Proceedings of the Second International Congress on Glaucoma Surgery, Luxor, Egypt, 2003. Karlen ME, Sanchez E, Schnyder CC, Sickenberg M, Mermoud A. Deep sclerectomy with collagen implant: medium term results [see comments]. Br J Ophthalmol 1999; 83:6 – 11. Mermoud A, Schnyder CC, Sickenberg M, Chiou AG, Hediguer SE, Faggioni R. Comparison of deep sclerectomy with collagen implant and trabeculectomy in open-angle glaucoma [see comments]. J Cataract Refract Surg 1999; 25:323 – 331. Sanchez E, Schnyder CC, Mermoud A. Comparative results of deep sclerectomy transformed to trabeculectomy and classical trabeculectomy. Klin Monatsbl Augenheilkd 1997; 210:261 – 264. [email protected]

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19.

Shaarawy T, Karlen M, Schnyder C, Achache F, Sanchez E, Mermoud A. Five-year results of deep sclerectomy with collagen implant. J Cataract Refract Surg 2001; 27:1770– 1778. Ambresin A, Shaarawy T, Mermoud A. Deep sclerectomy with collagen implant in one eye compared with trabeculectomy in the other eye of the same patient. J Glaucoma 2002; 11:214 – 220. Kim CY, Hong YJ, Seong GJ, Koh HJ, Kim SS. Iris synechia after laser goniopuncture in a patient having deep sclerectomy with a collagen implant. J Cataract Refract Surg 2002; 28:900 – 902. Milazzo S, Turut P, Malthieu D, Leviel MA. Scleral ectasia as a complication of deep sclerectomy. J Cataract Refract Surg 2000; 26:785– 787. Sanchez E, Schnyder CC, Sickenberg M, Chiou AG, Hediguer SE, Mermoud A. Deep sclerectomy: results with and without collagen implant. Int Ophthalmol 1996; 20:157– 162. Karlen ME, Sanchez E, Schnyder CC, Sickenberg M, Mermoud A. Deep sclerectomy with collagen implant: medium term results. Br J Ophthalmol 1999; 83:6– 11. Hamard P, Plaza L, Kopel J, Quesnot S, Hamard H. Deep nonpenetrating sclerectomy and open angle glaucoma. Intermediate results from the first operated patients. J Fr Ophtalmol 1999; 22:25 – 31. Shaarawy T, Karlen M, Schnyder C, Achache F, Sanchez E, Mermoud A. Five-year results of deep sclerectomy with collagen implant. J Cataract Refract Surg 2001; 27:1770– 1778. Yamin M, Quentin CD. Results and complications after deep sclerectomy. Ophthalmologe 2002; 99:171 – 175. Sunaric-Megevand G, Leuenberger PM. Results of viscocanalostomy for primary open-angle glaucoma. Am J Ophthalmol 2001; 132:221 – 228. Wishart MS, Shergill T, Porooshani H. Viscocanalostomy and phacoviscocanalostomy: long-term results. J Cataract Refract Surg 2002; 28:745 – 751. Shaarawy T, Nguyen C, Schnyder CC, Mermoud A. Five-year results of viscocanalostomy in Caucasians. Br J Ophthalmol 2003; 87(4):441 – 445. Carassa R. Viscocanalaostomy versus trabeculectomy: a 12 months prospective randomized study. American Society of Cataract and Refractive Surgery, Boston, USA, 2000. Netland PA. Nonpenetrating glaucoma surgery. Ophthalmology 2001; 108:416 – 421. Jonescu-Cuypers C, Jacobi P, Konen W, Krieglstein G. Primary viscocanalostomy versus trabeculectomy in white patients with open-angle glaucoma: a randomized clinical trial. Ophthalmology 2001; 108:254– 258. Luke C, Dietlein TS, Jacobi PC, Konen W, Krieglstein GK. A prospective randomized trial of viscocanalostomy versus trabeculectomy in open-angle glaucoma: a 1-year follow-up study. J Glaucoma 2002; 11:294 – 299. El Sayyad F, Helal M, El-Kholify H, Khalil M, El-Maghraby A. Nonpenetrating deep sclerectomy versus trabeculectomy in bilateral primary open-angle glaucoma. Ophthalmology 2000; 107:1671 – 1674. Dietlein TS, Luke C, Jacobi PC, Konen W, Krieglstein GK. Variability of dissection depth in deep sclerectomy: morphological analysis of the deep scleral flap. Graefes Arch Clin Exp Ophthalmol 2000; 238:405 – 409.

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22. 23. 24. 25.

26. 27. 28. 29. 30. 31. 32. 33.

34.

35.

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7 How to Insert a Glaucoma Implant Jeffrey Freedman S.U.N.Y. Brooklyn, Brooklyn, New York, USA

Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada

1. Introduction 2. Surgical Technique 2.1. Anesthesia 2.2. Conjunctival Incision 2.3. Plate Attachment 2.4. Valve Priming 2.5. Tube Preparation and Patch Graft 2.5.1. Tube Stent 2.5.2. Patch Graft 2.5.3. Tube Suture 2.5.4. Tube Trimming 2.6. Insertion of a Double Plate Molteno Implant 3. The Express Glaucoma Shunt 4. General Principles Regarding the Insertion of All Glaucoma Draining Implants References

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63 64 64 64 64 66 66 66 66 68 68 72 72 73 73

INTRODUCTION

The contemporary glaucoma implants are all modeled on the long tube Molteno implant introduced in 1973 (1). The implants most commonly used are the Molteno single and double plate devices, the Baerveldt, Ahmed, and the Krupin implants. The Ahmed and Krupin implants are valved, whereas the Baerveldt and Molteno implants are nonvalved. Insertion techniques for valved and nonvalved implants differ. In that, nonvalved implants require additional techniques to be applied on insertion to prevent hypotony. The different implants do require minimal modifications regarding their individual insertions, and these will be described. 63

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SURGICAL TECHNIQUE Anesthesia

We prefer performing glaucoma implant surgery under local anesthesia. Our preference is for retrobulbar anesthesia, but this surgery can be done utilizing subtenons and even local anesthetic jelly if required. 2.2.

Conjunctival Incision

The single plate implant may be inserted superonasally or superotemporally, between the superior rectus and the medial or lateral rectus muscles. A limbal or fornix-based incision can be utilized. We prefer fornix-based conjunctival incisions. The conjunctiva is ballooned up at the limbus by the injection of balanced salt solution (BSS). If the conjunctiva is adherent to the sclera for a distance .1 mm as a result of previous surgery, a different site needs to be chosen for the placement of the implant. The fornix-based conjunctival flap is then formed by incising the conjunctiva at the limbus for a length of 12 mm. A relieving incision of 5 mm is then made parallel to the upper border of medial or lateral rectus muscle, depending on which quadrant the implant is to be inserted. The two edges of the cut limbal conjunctiva are identified for reattachment, by placing two marker sutures at their extremities. This allows for accurate reattachment at the conclusion of the insertion of the implant. The conjunctiva is then undermined, by opening with Westcott scissors between sclera and conjunctiva. The dissection extends posteriorly for about 10 –12 mm. A pocket is thereby created for the insertion of the drainage plate. The posterior widespread dissection is to be avoided, as the space created should not be larger than the diameter of the plate. This can be achieved by pushing a Weck cell sponge into the area designated for the plate, creating a limited space, and thereby decreasing the chances for hypotony in the immediate post-operative period, particularly when using a nonvalved implant (3). If a Baerveldt implant is to be used, isolation of the medial or lateral rectus muscle, as well as the superior rectus muscle, is achieved by the use of muscle hooks. This needs to be done as the lateral and medial wings of the implant need to be placed beneath the muscles. Prior to the insertion of the implant, two 8/0 silk sutures on Alcon cu5 needles are inserted through the two anterior suture holes located on all the implants (Fig. 7.1). The steep curve of the needles enables the exit path of the needle to be very close to its entry, allowing for accurate placement of the anterior edge of the implant distance wise from the limbus. A less curved needle would exit a greater distance from the plate, moving it forward towards the limbus. 2.3.

Plate Attachment

The Ahmed and Molteno implants may be slid back into the pocket created between Tenons-conjunctiva and sclera, by using a curved Harms tying forceps placed on either side of the silicone tube, at its junction with the plate, and gently pushing the plate posteriorly into the previously created pocket (Fig. 7.2). The Baerveldt implant requires retraction of the superior and medial or lateral rectus muscles, so that the wings of the implant can be placed underneath two of these muscles, depending on which quadrant the implant is being placed. The plate is then fixed to the sclera with the preplaced 8/0 silk sutures. The anterior edge of the plate should be 8 –10 mm from the limbus (Fig. 7.3) Tip 1: If a preplaced suture is not used prior to placing the plate into the conjunctival pocket, it is still possible to suture the plate to sclera. However, in this situation, first place the plate into position. Then, place the first suture into the sclera 10 mm from the limbus in [email protected]

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Figure 7.1 (See color insert) Needles preplaced through anterior needle holes. Supramid suture inserted from plate side.

Figure 7.2 (See color insert) Harms forceps used to insert plate. [email protected]

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Figure 7.3 (See color insert) Placing sutures through sclera 8 – 10 mm from limbus.

front of one of the holes on the leading edge of the plate. Then, pass the blunt side of the suture (the side with the suture) through the lower plate hole while holding the plate to exit through the upper opening last, that is, backwards. Tie the suture and repeat the process with the second hole. This maneuver prevents inadvertent scleral perforation that can occur if the suture is passed from plate into sclera. Tip 2: If fibrosis or poor visualization prevents access to one or the other plate holes, it is still possible to firmly tie the plate by passing a suture through the anterior lip of one of the newer silicone Ahmed valves. The lip is soft enough to easily pass a sharp needle through it to facilitate plate adhesion to sclera. 2.4.

Valve Priming

Using the Ahmed implant, the implant should be examined and primed prior to implantation. Priming is accomplished by injecting 1 cc of BSS or sterile water through the drainage tube and valve using a 30 gage cannula. The BSS should be seen to flow through the valve to ensure that it is open prior to inserting the implant. The valve site should not be touched with forceps, as this may lead to damage resulting in failure of valve function. 2.5. 2.5.1.

Tube Preparation and Patch Graft Tube Stent

If a Baerveldt or Molteno implant is being used, then prior to insertion of the plate, a 3/0 supramid suture is placed into the silicone tube from its opening onto the plate (Fig. 7.1). A section of 3/0 supramid suture 15 –20 mm in length is cut, and one end is grasped with a tying forceps and gently inserted into the silicone tube from the opening on the plate side. The suture is inserted for a distance of 6 – 10 mm into the tube. This suture will be used as a temporary valve to be removed during the post-operative period (2). 2.5.2. Patch Graft Prior to the trimming and insertion of the tube, donor or preserved sclera or pericardium used to cover the tube is brought onto the operative field and cut to size, so that it will cover [email protected]

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Figure 7.4 (See color insert) Pericardium cut to cover tube from plate to limbus.

the tube from its insertion into the anterior chamber to its attachment to the plate (Fig. 7.4). The graft is sutured to the sclera prior to the insertion of the tube into the anterior chamber. This is done by suturing one side of the graft and preplacing the sutures into the other side but leaving them untied, so that the graft can be retracted to one side leaving access to the underlying tube (Fig. 7.5). Preplacing the sutures allows the graft to be fixated into place immediately after the tube is inserted into the anterior chamber. Furthermore, if hypotony occurs, as it occasionally does after tube insertion, having preplaced the sutures eliminates the need to insert sutures into an hypotonous eye, which can be difficult. The sutures used for the graft are 10/0 nylon sutures placed at the anterior and posterior corners of the graft. Tip 1: If a seton is inserted in the infero-temporal quadrant, cover the tube with half thickness donor cornea. Cornea, being clear, has a much better cosmetic appearance than

Figure 7.5 (See color insert) Pericardium retracted to side following insertion of preplaced sutures. Suture preplaced around silicone tube. [email protected]

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sclera that is cosmetically unacceptable in this potentially exposed areas because of its white color. 2.5.3.

Tube Suture

It is important to fixate the tube to the sclera. This is done by passing a 10/0 suture through sclera beneath the tube, again left untied, until the tube has been inserted, at which time this preplaced suture should be tied to fixate the tube to the sclera (Fig. 7.5). Be careful not to tie this suture too tightly as you may block aqueous flow; however, this is highly unlikely with the use of a 10/0 nylon suture. 2.5.4. Tube Trimming Prior to inserting the silicone tube into the anterior chamber, it needs to be trimmed. The length of tubing to be inserted depends on the condition being treated. Usually, the tube should be 1– 3 mm in length in the anterior chamber. However, if neovascular glaucoma is being treated, the tube needs to be longer to avoid blockage by fibrous tissue. The tube should extend almost to the pupil margin. As this measurement is done over the exterior of the cornea, one should ensure that no traction is placed on the tube when estimating the future internal length, as this will result in a shorter than desired result. The tube is then cut with a scissors, the blades facing upwards to ensure a bevel on the tube that is facing upwards and away from the iris preventing it from blocking the tube (Fig. 7.6). Prior to inserting the tube, a paracentesis should be done at the lateral aspect of the limbus with a microsharp blade (Fig. 7.7). This allows for reformation of the anterior chamber, if this become necessary during insertion of the tube, as well as possible manipulation of the tube with an iris repositor, again if this become necessary. A 22 or 23 gage needle is then used to enter the anterior chamber. The needle is inserted immediately posterior to the limbus, unless peripheral anterior synechiae are present, as seen in neovascular glaucoma, in which case the needle needs to be inserted anterior to the peripheral anterior synechiae, thus avoiding obstruction of its insertion into the anterior chamber (Fig. 7.8). The needle is inserted parallel to the iris and mid-way between iris and

Figure 7.6 (See color insert) Cutting of tube with scissor blades facing upwards to ensure bevel of tube is facing up. [email protected]

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Figure 7.7 (See color insert) Paracentesis with microsharp blade.

cornea. This creates the path through which the silicone tube will be passed. The distal cut end of the silicone tube is then grasped with a tying forceps, while at the same time the anterior lip of the entry tunnel is elevated, allowing the eye to be steadied, facilitating the entry of the tube into the anterior chamber (Fig. 7.9). A tube inserter manufactured by ASSI may also be used for this purpose. If peripheral anterior synechiae are present, the tube may have to be passed more anteriorly to avoid the peripheral iris. If this become necessary, it is imperative to ensure that the anterior edge of the graft is far enough anterior to totally cover the tube. The preplaced 10/0 suture around the tube is now tied, fixating the tube to the sclera. If a 3/0 supramid suture had been placed into the tube, then prior to inserting the tube, venting slits are made in the sides of the tube, which will lie beneath the graft. These slits may be made by passing the needle of the 10/0 suture through the tube or by slitting

Figure 7.8 (See color insert) Use of 22 or 23 gage needle to create passage for silicone tube into anterior chamber. [email protected]

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Figure 7.9 (See color insert) Inserting silicone tube into anterior chamber.

with a microsharp blade. BSS may then be injected into the tube from its distal end to test the flow of fluid through these slits that will allow drainage to occur in the immediate postoperative period, during which the tube will be temporarily tied off to prevent hypotony (Fig. 7.10). The tube is now tied down to sclera. Again, ensure that this suture is not so tight as to obstruct flow of aqueous through the tube. The preplaced graft is then sutured into place over the tube by tying the final two preplaced 10/0 sutures. Where a 3/0 supramid suture was preplaced, a 7/0 vicril suture is placed around the tube at its junction with the plate and gently tied down onto the internal suprapramid suture, thus blocking the tube (Fig. 7.11). The supramid suture can be removed at any time post-operatively, re-establishing the lumen of the silicone tube, as the vicril suture will only close the tube to the position of the supramid suture.

Figure 7.10

(See color insert) Testing patency of slits made in silicone tube by injecting BSS. [email protected]

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Figure 7.11 (See color insert) Pericardium sutured to sclera. Tube tied off with 70 Vicril at junction with plate.

The conjunctiva is then closed by suturing the free ends of the conjunctiva, located by the preplaced sutures, to their original position at the limbus (Fig. 7.12). Two wing sutures are needed for the limbal reattachment of the conjunctiva, using an episcleral insertion at the limbus, and then passing the needle through the free edge of the conjunctiva close to where the preplaced marker sutures were placed. The conjunctiva is brought forward to completely cover the scleral/pericardial patch and if this is not achieved, a further one or two sutures placed at the limbus may needed to accomplish this. The relieving incisions of the conjunctivae are also sutured. All of these suturings being done with 7/0 vicril sutures. Prior to closure of the conjunctiva, the previously placed supramid suture protruding from the plate end of the draining implant is brought forward under the conjunctiva, so that it protrudes beyond the limbus. After the conjunctiva has been

Figure 7.12 (See color insert) Suturing conjunctiva to limbus and showing availability of supramid suture for removal at a later date. [email protected]

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sutured at the limbus, the supramid suture is trimmed, so that it just protrudes beyond the limbus from under the conjunctiva (Fig. 7.12). Edema of the conjunctiva will just cover the suture and it may easily be grasped at a later date, when it needs to be removed from the tube. This allows the suture to be removed from the tube without having to disturb the conjunctiva. Tip 1: If the tube and scleral patch are bulky and apply pressure to the overlying conjunctiva, the limbal wound can retract exposing the graft. To prevent this, we recommend using half thickness scleral patch grafts. In such situations, we prefer to close the conjunctiva at the limbus with a continuous 8/0 vicryl limbal suture. If a fornix-based conjunctival flap is used, we recommend closure of tenons first (using a continuous suture) followed by a continuous conjunctival suture (i.e., closed in two layers). This is particularly important if the tube has been inserted from below, as conjunctival wound healing is often poor in the inferior quadrants. 2.6.

Insertion of a Double Plate Molteno Implant

The use of a double plate Molteno implant requires modification of the insertion technique. The device is labeled right or left side, indicating that the plate to which the tube entering the anterior chamber is attached will be placed on the nasal side. However, it is more practical to have the primary plate placed in the supero-temporal quadrant, where more space allows for easier placement of the plate, the tube, and the scleral patch. This is achieved by placing a left-labeled double plate implant in the right eye and vice-versa. In placing a double plate, a fornix-based conjunctival flap is once again fashioned from the limbus, but is now extended 1808. Relieving incisions are made parallel to the upper borders of the lateral and medial rectus muscles. The nasally placed plate is sutured to the sclera between the medial and the superior rectus muscles 7 –10 mm behind the limbus, using the same technique as described for a single plate. The superior rectus muscle is isolated with a muscle hook, and the conjunctiva is carefully dissected from the muscle sheath. This allows the second plate to be passed over the muscle and to be placed in the temporal quadrant between superior and lateral rectus muscles. The laterally placed plate is sutured to the sclera 7– 10 mm behind the limbus, in the manner described for the medial plate. The silicone tube is handled in the same manner as described for a single-plate implant. In addition, the tube connecting the two plates is tied off with a 7/0 vicril suture, which will release in about 2 –3 weeks, at which an adequate capsule over the second plate will prevent excessive hypotony. The conjunctiva is resutured to the limbus utilizing the preplaced 4/0 silk suture markers to ascertain correct anatomical placement of the conjunctiva to the limbus. The conjunctiva is sutured with two interrupted 7/0 vicril sutures, the initial placement of the suture being from the limbus through episcleral tissue. If the conjunctiva does not fit snugly to the limbus, further interrupted 7/0 vicril sutures can be inserted. The relieving incisions along the upper borders of the medial and lateral rectus muscles are sutured with a continuous 7/0 vicril suture. The previously placed supramid suture is handled as described for single-plate implants.

3.

THE EXPRESS GLAUCOMA SHUNT

Within the past few years, a new mini-glaucoma shunt has been introduced (4), labeled the Express Mini-glaucoma Shunt. The shunt is a stainless steel “tube” that measures ,3 mm in length and 400 mm in diameter. The device has a penetrating tip that is inserted into the anterior chamber. Behind the tip is a spur to prevent extrusion of the device and at the [email protected]

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proximal end, there is an external flange that prevents over-penetration. The Express is intended to reduce IOP in patients with glaucoma, where medical and conventional surgical treatments have failed, indications similar to those for other drainage implants. Originally designed for insertion as a minimally invasive procedure, more recently the insertion of the Express under a trabeculectomy flap has been described. The Express is implanted through a simple four-step procedure. 1. 2. 3.

4.

Inject viscoelastic material into the anterior chamber through a paracentesis opening. A small 1– 2 mm incision is made in the conjunctiva, 10 mm from the limbus. A 25 gage needle is inserted through the conjunctival incision and guided subconjunctivally to the limbus, where it is used to penetrate into the anterior chamber. The Express is then introduced into the anterior chamber, via the introducer, which is passed along the same subconjunctival pathway. The introducer is then withdrawn, the spur keeping the Express in position.

An alternative method of implantation, is to place the Express under a scleral flap (5). A standard trabeculectomy is performed up to the stage of entry into the anterior chamber. Instead of removing corneoscleral tissue, the Express shunt is inserted into the anterior chamber beneath the scleral flap, without the addition of a peripheral iridectomy. If so desired, an antimetabolite such as mitomycin C or 5 Fu may be used, as one might do in a standard trabeculectomy. The flap is then sutured over the mini-shunt with interrupted sutures or a releasable suture. The use of the shunt in this way is a modified nonpenetrating and penetrating glaucoma procedure. Early results with the shunt placed under a flap have been encouraging, particularly with regard to eliminating such complications as hypotony and erosion associated with the original technique of subconjunctival insertion.

4.

GENERAL PRINCIPLES REGARDING THE INSERTION OF ALL GLAUCOMA DRAINING IMPLANTS

Utilize a fornix-based flap, as this places the conjunctival incision at the furthest distance from the draining bleb eliminating the possibility of erosion and leakage through the conjunctiva. In nonvalved implants, a stent within the silicone tube needs to be placed to prevent post-operative hypotony. If deciding to place the tube via the pars plana, a total vitrectomy needs to be done to avoid blockage of the tube by vitreous (see chapter elsewhere in this book). If superior quadrants are not available, the implant may be placed inferiorly. In doing so, the patient should be warned of the possibility of diplopia where binocular vision is present. When placing the implant inferiorly instead of using sclera or pericardium, half thickness cornea should be used to cover the silicone tube as this affords a better cosmetic result. If an Ahmed valve is used inferiorly using a limbal-based flap, the conjunctiva must be and closed in two layers. REFERENCES 1.

Molteno ACB, Straughn JL, Anker E. Long tube implants in the management of glaucoma. SA Fr Med J 1976; 50:1062 –1066. [email protected]

74 2. 3. 4.

5.

Freedman and Trope Sherwood MD, Smith MF. Prevention of early hypotony associated with Molteno implants by a new occluding stent technique. Ophthalmology 1993; 6:515– 520. Freedman J. Drainage implants. In: Yanoff M, Duker J, eds. Ophthalmology. London: Mosby, Section 12, 32.1– 32.6. Kaplan-Messas A, Traverso C, Sellem E, Zagorski Z, Belkin M. The Ex-Press minature glaucoma implant in combined surgery with cataract extraction: prospective study. ARVO, Fort Lauderdale, FL, 2002. Dahan E, Carmichael T. The Ex-Press minature glaucoma implant: implantation under a scleral flap. Fourth IGS Meeting, Barcelona, Spain, March 2003.

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8 Management of Glaucoma Implant Complications Jeffrey Freedman S.U.N.Y. Brooklyn, Brooklyn, New York, USA

Shlomo Melamed The Sam Rothberg Glaucoma Center, Sheba Medical Center, Tel Hashomer, Israel

Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada

1. Introduction 2. Intraoperative Complications 2.1. Conjunctival “Button Hole” or Laceration 2.2. Tube Problems 2.2.1. Tube Misdirection 2.2.2. Vitreous Loss 2.2.3. Bleeding 3. Early Postoperative Complications 3.1. Flat Anterior Chamber 3.2. Blocked Tube 3.3. Tube-Corneal Touch 3.4. The Hypertensive Phase 3.5. Iritis 4. Late Postoperative Complications 4.1. Implant Drainage Failure 4.2. Tube Erosion 4.3. Plate Erosion 4.4. Diplopia 4.5. Corneal Decompensation 4.6. Other Complications References

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INTRODUCTION

Currently, most surgeons use glaucoma implants in cases of refractory glaucoma with scarred conjunctiva and active inflammation as well as in cases of neovascular glaucoma. 75

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Consequently, there is a higher risk for intraoperative and postoperative complications. Complications associated with glaucoma implants can be classified as intraoperative, early postoperative, and late postoperative.

2. 2.1.

INTRAOPERATIVE COMPLICATIONS Conjunctival “Button Hole” or Laceration

Manipulation of a friable conjunctiva may result in tearing or laceration of the conjunctiva, especially as these patients have often had previous surgical procedures involving conjunctival manipulation. Elevating the conjunctiva with balanced salt solution prior to cutting it allows the surgeon to delineate the areas of conjunctiva that are adherent to the underlying sclera and therefore more likely to perforate if elevated and thus can be avoided, decreasing the probability of lacerating the conjunctiva. If a tear is noted during surgery, attempts must be taken to close it with a 10/0 nylon on a BV needle. If the tear will not close, care should be taken to ensure the entrance to the anterior chamber is well covered by the patch graft under the tear and ensure there is no external aqueous leak. If there is none, it is likely that the conjunctiva will heal with vascularization of the patch. If there is an external leak, the implant may have to be removed, the wound tightly closed and the tube inserted in a new quadrant. Inability to accomplish adequate conjunctival closure at the end of the procedure can occur, especially if a thick patch graft is used such as full-thickness sclera or cornea. We recommend half-thickness cornea or sclera to cover the tube. Also, the conjunctiva has a tendency to contract, particularly in elderly patients. This problem can be minimized by marking the cut ends of the conjunctivae with sutures on disinsertion from the limbus, so that the ends can be identified at the end of the procedure and reattached to their correct anatomical area. If it still does not close, care must be taken to ensure the entrance wound is well covered by the patch graft. Then the conjunctiva is closed as close as possible to the limbus, as a small area of exposed patch graft does not pose a problem. The drainage occurs in a posterior situation so that if conjunctiva covers the plate and most of the patch graft, aqueous leakage is unlikely. 2.2.

Tube Problems

The silicone tube may be cut too short and cannot adequately enter the anterior chamber. This can be remedied by splicing on more tube, utilizing a tube extender such as the one made by Ahmed (model TE), which is commercially available. It is advisable to always have a spare tube extender in case it is needed. 2.2.1. Tube Misdirection A tube can be inserted too anteriorly or too posteriorly. If inserted too anterior, corneal endothelium will be damaged, and if inserted too posterior, iris or lens can be damaged. This complication is best avoided by correct placement of the introducing needle. The needle tract needs to be carefully planned, with the eye in the primary position with the needle track parallel to the iris plane. The needle track should start 1– 2 mm posterior to the limbus in order to position the tube away from the corneal endothelium. The tube should enter the anterior chamber parallel to, but in front of the iris and lens, 1 –2 mm behind the corneal endothelium. Careful assessment of the tube position is essential at the end of surgery and the tube should be repositioned anterior or posterior to the initial incision if it is too close to the endothelium or iris before the patient leaves the operating [email protected]

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room. In the postoperative period, if the tube is noted to touch the endothelium but this touch is localized, such as just the tip of the tube, this will not usually cause diffuse endothelial damage and may be left. If the tube touch is more extensive, that is, the whole intraocular portion of tube touches the endothelium, repositioning of the tube in the operating room should be seriously considered as extensive endothelial damage may result. If the tube is noted to touch the iris and is not blocked, it may be left alone. Misdirection of the tube into the posterior chamber is likely to happen in the presence of posterior synechiae, where the flexible tube follows the path of least resistance. This can be remedied by inserting an iris spatula through a limbal paracentesis opening to the site of entry of the tube and by guiding the tube above the spatula into the anterior chamber. 2.2.2.

Vitreous Loss

A rare complication associated with plate insertion is the very deep placement of the fixating sutures with vitreous presentation at the insertion site. Should this occur, the sutures must be removed and the plate reattached at a different site. Should the eye become hypotonous, a careful examination of the retinal area is indicated and even if nothing is seen cryoablation at the perforation site is indicated. The patient should be followed up by a vitreoretinal specialist. 2.2.3.

Bleeding

Bleeding into the anterior chamber can occur, especially on introducing the tube into the anterior chamber where rubeosis iridis is present. To avoid this complication, the hypotony associated with tube insertion needs to be avoided, and this can be accomplished by either the use of an anterior chamber maintaining cannula attached to a bottle of balanced salt solution or the insertion of a viscoelastic substance prior to the tube introduction. The rubeotic vessels bleed when the surrounding pressure is lowered, therefore maintaining the intraocular pressure by balanced salt solution through the cannula or by inserting a viscoelastic material decreases the potential for bleeding from these vessels. The complication of suprachoirodal hemorrhage is more likely to occur in neovascular glaucoma or when there is uncontrolled intraocular pressure. The hemorrhage occurs when the eye is suddenly decompressed following tube introduction into the anterior chamber. This can be avoided by lowering the intraocular pressure preoperatively with appropriate medications and decompressing the eye slowly with a paracentesis prior to tube insertion. A small amount of aqueous should be removed in a controlled fashion until the eye is no longer hard. A prophylactic posterior sclerotomy can also be done prior to insertion of the tube. Intraocular pressure should be kept constant during insertion of the tube by inserting viscoelastic prior to tube insertion or with the use of an anterior chamber maintainer.

3. 3.1.

EARLY POSTOPERATIVE COMPLICATIONS Flat Anterior Chamber

The commonest postoperative complication is the absence of the anterior chamber. This is most likely to occur with nonvalved implants, where no precaution has been taken to prevent postoperative hypotony. Nonetheless, this complication can occur with valved implants as well even with ligaturing of the tube. If the anterior chamber is shallow with iris corneal touch, it should be treated in the usual way with cycloplegics and aqueous suppressants. Transient shallow chambers usually resolve after a few days. If [email protected]

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still shallow, the anterior chamber may be reformed 7 –10 days postoperatively with air or sooner if the tube seems to be damaging the endothelium or is in contact with the lens. If the anterior chamber is flat, it may be reformed with the injection of a viscoelastic material through the paracentesis opening that was created intraoperatively. This may have to be repeated, but if the hypotony persists, the tube may have to be ligated in the operating room. Hypotony may be associated with the development of a suprachoroidal effusion. Large effusions may require the use of systemic steroids to eliminate them. Kissing choroidals will require suprachoroidal fluid drainage with the injection of gas and elimination of the cause of the hypotony, which usually means the tying off of the tube. The tube may be tied off by exposing it in its anterior position beneath the patch, which is where it is most accessible. A 5/0 vicryl suture may be used. This will dissolve at a later time. Alternatively, the tube may be removed from the anterior chamber, occluded with a prolene suture, and then reinserted. This suture can be released at an appropriate time using a YAG laser. 3.2.

Blocked Tube

The tube may become blocked resulting in elevation of the intraocular pressure. The blockage may be due to blood, iris, or fibrin. Blood usually dissolves unless there is a full hyphema that may have to be washed out. Iris plugging the tube opening may be removed with a YAG laser. Fibrin responds well to intensive use of topical steroids, and if persistent can also be removed with a YAG laser. A large fibrinous exudate in the anterior chamber will respond to topical steroid use but may need a subconjunctival injection of steroid. Occasionally, an intense vitreitis is seen, particularly in neovascular glaucoma, which may require systemic steroid use. 3.3.

Tube-Corneal Touch

Tube-corneal touch, if very localized and peripheral, can be left alone. It may produce some peripheral corneal decompensation in the region of contact without affecting the rest of the cornea. More extensive corneal touch can produce generalized corneal decompensation and the tube may need to be removed and repositioned. 3.4.

The Hypertensive Phase

The hypertensive phase seen in most but not all glaucoma implant surgeries occurs 4 –6 weeks postoperatively. The elevation of intraocular pressure may be treated with reduction of topical steroids and anti-glaucoma medications, but if very high, is best treated by draining using a 29 gage needle which is passed into the bleb under local anesthesia at the slit lamp, with the withdrawal of a quarter to a half cc of aqueous, without loss of the anterior chamber. This may have to be repeated on a weekly basis until the pressure returns to normal level. By decreasing the pressure within the bleb around the plate, ongoing fibrosis due to TGFb production is prevented, with the likelihood of a more successful outcome in bleb formation. 3.5.

Iritis

Occasionally, a recurrent uveitis is seen in association with glaucoma implants. Care should be taken to ensure the tube is not eroding the peripheral iris or angle structures. If the iritis or iris erosion is mild it can be left alone or treated with low doses of [email protected]

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topical steroids. If severe, the tube may be repositioned or replaced. However, in most postoperative cases the cause for the persistent uveitis is unknown, and the treatment is that of any anterior uveitis in a glaucoma patient.

4. 4.1.

LATE POSTOPERATIVE COMPLICATIONS Implant Drainage Failure

The most significant late complication is failure of the implant due to bleb fibrosis. Excision of the capsule with the application of an anti-metabolite such as mitomycin has been attempted but with moderate success. We do not recommend this approach. Placement of a second implant in a separate quadrant can lead to good success. J. Freedman, utilizes a supratenons position for the second implant with the view for trying to prevent fibrosis over the plate. This has been done with good success in a number of patients. Prevention of late encapsulation can be achieved by the use of fibrosis suppression medication as described by Molteno and colleagues (1,2). The medication consists of a nonsteroidal anti-inflammatory, a systemic steroid, colchicine and topical adrenaline. These medications need to be given no later than 14 days after insertion, and to be continued for 6 weeks thereafter. This systemic approach will need supervision by a rheumatologist or someone expert at dealing with the side effects of these toxic drugs. The removal and replacement of an existing implant is inadvisable, as fibrosis will occur very rapidly over the new implant. 4.2.

Tube Erosion

Erosion of the tube through the sclera or overlying patch material can occur. This complication requires recovering of the tube with patch material, such as sclera or pericardium, to prevent the possibility of endophthalmitis from occurring. If the coverings fail to prevent recurring erosion of the tube, this is an indication to remove the tube from the eye (you can leave the plate) and a new implant should be inserted at a different site. Removal of the tube can be difficult as the tube is usually encased in a sleeve of connective tissue. When removing the tube, it is important to dissect carefully over the tube so as not to cut it, open the sleeve on its surface, and extend the opening to the limbus. Before removing the tube an 8/0 suture should be placed around the tube and the sleeve. On removal of the tube, the suture must be tied tightly to prevent the fistula from leaking. It is usually not necessary to remove the plate. The tube should be cut as close to the plate as possible and the plate should be left. 4.3.

Plate Erosion

Erosion of the conjunctiva overlying the plate may occur especially if the tube is blocked purposely or accidentally. This allows the conjunctiva to constantly contact the plate, giving rise to the erosion. If there is a patent connection between the anterior chamber and the plate, in the presence of an erosion, the eye will become extremely hypotonous and the chances for endophthalmitis to develop are high. The best treatment for the erosion is to remove the implant. Erosions are more likely to occur in those cases where the conjunctiva over the implant has been treated with an anti-metabolite, particularly mitomycin C. Erosion through the conjunctiva is also more likely to occur if the original conjunctival incision is limbal based with the wound close to the plate. Erosions in such cases can be associated with epithelial down growth over the plate. This down [email protected]

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growth inhibits often repeated wound closure attempts including patch grafting necessitating removal of the plate and tube on occasion. 4.4.

Diplopia

Limitation of eye movements may occur particularly in the presence of large blebs. As the plates are usually superiorly positioned, the limitation of movement is usually in upward gaze with little effect on the patient clinically. Placement of implants inferiorly is more likely to cause restriction of down-gaze with associated diplopia and such placement should be avoided if vision is good in both eyes (5). Certain implants may produce motility problems even if placed in the superior quadrants (3). Diplopia is common in the early postoperative period, but often resolves with time. Prisms are helpful if the diplopia is troublesome. 4.5.

Corneal Decompensation

Another late complication of glaucoma implants is the development of corneal decompensation. This occurs particularly in aphakic and pseudophakic eyes. Many of these eyes have undergone previous glaucoma filtering procedures prior to the use of the glaucoma implant surgery, and these multiple surgeries invariably result in endothelial cell loss, added to by the further surgical trauma induced by the use of the glaucoma implant. It is possible that the silicone tube per se has some toxic effect on the endothelium, although this has never been proven. Extensive tube endothelial touch (direct touch or touch with eye movements) can precipitate endothelial cell decompensation in an eye with a low endothelial cell count. Corneal transplantation is needed when corneas decompensate. If it is well away from the endothelium, the tube needs to be left in situ. If the tube is close to the endothelium, a suture may be placed across the tube within the anterior chamber thus deflecting it away from the cornea (4). Alternatively, the tube may be repositioned prior to the penetrating keratoplasty. Other options include removing the tube and inserting a new valve in another quadrant, preferably before the corneal transplant (or in conjunction with the PKP). One of us (GT) has had success removing the tube from the anterior chamber repositioning it into the vitreous chamber, a maneuver requiring total vitrectomy, which potentially increases the morbidity of the procedure. Although not proven, this maneuver may prevent further corneal decompensation or allow for later corneal grafting. In postpenetrating keratoplasty, two further complications can occur. The first of these is greater difficulty in controlling the glaucoma, as corneal transplants are often associated with the development of raised intraocular pressure. This is often seen even in the presence of a previously placed glaucoma implant. The second problem often seen is the development of a fibrous membrane seen covering the iris, as well as covering the intraocular lens. A possible cause is the formation of TGFb in the bleb, which then induces an inflammatory reaction in the anterior chamber. Management often requires removal of the membrane with total iridectomy and removal of the intraocular lens as well. 4.6.

Other Complications

Although infrequent, complications that have been associated with glaucoma implants include retinal detachments (5), cataract formation, and the more serious complication of endophthalmitis. A rare form of sterile endophthalmitis is seen in glaucoma implants, [email protected]

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especially where an intratubal stent has been used to prevent postoperative hypotony (6). The cause is unknown. Attention to meticulous surgical technique as well as adequate, frequent, and continued follow up of all glaucoma implant patients will result in a diminution of complications related to glaucoma implant surgery.

REFERENCES 1. 2.

3.

4. 5. 6.

Molteno ACB, Straughn JL, Ancker E. Control of bleb fibrosis after glaucoma drainage surgery. S Afr Med J 1976; 102:91 – 97. Molteno ACB, Dempster AG. Methods of controlling bleb fibrosis around draining implants. In: Mills KB, ed. Glaucoma: Proceedings of the Fourth International Symposium of the Northern Eye Institute, Manchester, UK. Oxford: Pergamon Press, 1988:192– 211. Smith SL, Starita RJ, Fellman RL, Lynn JR. Early clinical experience with the Baerveldt 350 mm glaucoma implant and associated extraocularmuscle imbalance. Ophthalmology 1933; 100:914 – 918. Freedman J. Management of the Molteno silicone tube in corneal transplant surgery. Ophthalmic Surg Lasers 1988; 29:432– 434. Waterhouse WJ, Lloyd MAE, Dugel PU et al. Rhegmatogenous retinal detachment after Molteno glaucoma implant surgery. Ophthalmology 1994; 101:665 –671. Ball SF, Latfield K, Scharfenberg J. Molteno ripcord suture hypopyon. Ophthalmic Surg 1991; 22:82 – 86.

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9 Pars Plana Insertion of Ahmed Glaucoma Valve Roland Ling The Royal Devon & Exeter Hospital, Exeter, UK

Wai-Ching Lam and Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada

1. Introduction 2. Indications for Pars Plana Tube Placement 3. Surgical Technique 3.1. Placement of the Ahmed Glaucoma Valve Plate 3.2. Pars Plana Vitrectomy 3.2.1. The Infusion Port 3.2.2. The Superotemporal Port 3.2.3. The Superonasal Port 3.3. Placement of the Pars Plana Tube 3.4. Closure 4. Results and Complications of Pars Plana GDI References

1.

83 84 84 85 86 86 87 87 87 88 90 92

INTRODUCTION

Refractory glaucoma, defined as glaucoma not responsive to medical therapy and/or conventional filtration surgery, can be a management challenge. In addition to trabeculectomy with adjuvant antifibrotic agents (1,2) and cyclodestructive procedures (3,4), glaucoma drainage implant (GDI) surgery has emerged as a management option in these difficult cases (5 –7). Conventional GDI surgery aims to create an alternative pathway for aqueous outflow between the anterior chamber and the equatorial subconjunctival space through the artificial channel of the drainage implant (5 – 7). However, implantation of the tube in the anterior chamber may be difficult for anatomical reasons and contraindicated in certain situations. For example, extensive peripheral anterior synaechiae or new vessels 83

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of the iridocorneal angle may make placement of the tube in the anterior chamber very difficult or even impossible (8). Furthermore, tube-corneal endothelial touch has been observed in up to 23% of cases with anterior chamber tube, resulting in endothelial decompensation in as many as 35% of cases (9). Anterior chamber tube placement may therefore be contraindicated in eyes with existing corneal grafts or those with severe corneal disease awaiting penetrating keratoplasty. Because of these difficulties, placement of the tube in the vitreous cavity by combining the GDI surgery with pars plana vitrectomy has been advocated (8,10 –15). In this chapter, we aim to review the indications, surgical technique, results, and complications of GDI surgery with pars plana seton placement.

2.

INDICATIONS FOR PARS PLANA TUBE PLACEMENT

The indications for pars plana tube placement are generally limited to cases in the following categories: 1.

2.

3.

4. 5.

3.

Cases with shallow and/or extensively closed anterior chamber angle (10 –13): These include anterior cleavage syndromes (Axenfeld/Reiglers syndrome, Aniridia), iridocorneal endothelial (ICE) syndrome, epithelial downgrowth, neovascular glaucoma, chronic angle closure glaucoma with shallow anterior chamber, uveitic and traumatic glaucoma with extensive peripheral anterior synaechiae, and disorganized anterior segment secondary to trauma. Cases of previous GDI surgery and anterior chamber tube, with tube-related anterior segment complications (14): Repositioning of the implant tube from the anterior chamber into the vitreous cavity can be carried out in cases with anterior segment tube-related complications such as tube erosion, tube obstruction, or corneal decompensation. Cases of postpenetrating keratoplasty or those with severe corneal disease requiring penetrating keratoplasty (15): In eyes with refractory glaucoma and existing corneal graft or severe corneal disease awaiting penetrating keratoplasty (such as pseudophakic bullous keratopathy, aphakic bullous keratopathy, corneal scarring secondary to trauma, herpes simplex keratitis, and ulcerative keratitis), pars plana tube surgery is one option for simultaneously achieving IOP control and avoiding anterior chamber tube-related complications such as tube-corneal touch and corneal decompensation, therefore potentially enhancing the rate of corneal graft survival. Aphakic and pseudophakic cases with shallow anterior chambers and/or vitreous prolapse into the anterior chamber (8). Cases with concurrent indication for pars plana vitrectomy (13): Concurrent glaucoma and retinal indications for vitrectomy includes macular pucker, dropped nucleus, vitreous hemorrhage, and endophthalmitis.

SURGICAL TECHNIQUE

In Toronto, we use the Ahmed Glaucoma Valve with a Pars Plana Clip (Model PS2) (New World Medical, Inc. Rancho Cucamonga, CA) for pars plana tube surgery, although other GDIs such as Molteno, Schocket, and Baerveldt have also been described (8,10 – 15). [email protected]

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We recommend a combined approach, with both a vitreoretinal and a glaucoma surgeon performing the surgery together, as this is a technically complicated surgery. The following description of the surgical technique is for the pars plana insertion of the Model PS2 Ahmed Glaucoma Valve. This implant consists of a Model S2 Ahmed Glaucoma Valve with an additional Pars Plana ClipTM. The Pars Plana ClipTM imposes a smooth “bend” in the tube and provides the curvature required for insertion through the pars plana. The Pars Plana ClipTM can slide along the length of the tube, and the distance from the receptacle plate to the Pars Plana ClipTM can therefore be adjusted accordingly.

3.1.

Placement of the Ahmed Glaucoma Valve Plate Following Retrobulbar or sub-Tenon’s local or general anesthesia, a 7/0 vicryl corneal traction suture is used to expose the superotemporal or inferotemporal quadrant. Subconjunctival injection of lidocaine 2% is given in the superotemporal or inferotemporal quadrant, raising a conjunctival bleb to facilitate the creation of a conjunctival and Tenon’s flap. The conjunctival and Tenon’s capsule is then incised 5 – 7 mm posterior to the limbus, for 3 –4’O clock hours parallel to the limbus to create a limbal-based flap. The Ahmed Glaucoma Valve is primed by introducing a 23-gage cannula on a 3 cc syringe, 3 – 4 mm into the tube, and balanced salt solution (BSS) is flushed with at least 1 mL through the tube until the initial spurt of BSS is observed to flow from the valve in the receptacle plate (Fig. 9.1). The receptacle plate is tucked underneath the conjunctival flap in the relevant quadrant (Fig. 9.2). The plate is anchored to the episclera 10 mm posterior to the limbus with interrupted 8/0 silk sutures through each of the two eyelets on the receptacle plate (Fig. 9.3). Two additional 8/0 silk sutures can be passed, one through each eyelet, to further anchor down the receptacle plate, if it is not securely fixed to the sclera.

Figure 9.1 (See color insert) The Ahmed valve is primed with balanced salt solution. [email protected]

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Figure 9.2 (See color insert) The Ahmed valve is tucked underneath the limbral-based conjunctival flap.

3.2.

Pars Plana Vitrectomy Three-port pars plana vitrectomy is then performed by a vitreoretinal surgeon (Fig. 9.4).

3.2.1. The Infusion Port In an aphakic or pseudophakic eye with the seton in the superotemporal quadrant, the infusion port is made through the inferotemporal limbus with a 20-gage MVR blade. An anterior chamber maintainer is inserted and the infusion is started once the tip of the infusion is in the anterior chamber. In a phakic eye, an inferotemporal sclerotomy is made with a 20-gage MVR blade 4 mm posterior to the limbus through a separate inferotemporal peritomy. A 7/0 vicryl suture is preplaced at the sclerostomy to facilitate closure at the

Figure 9.3 (See color insert) The Ahmed valve is anchored to the episclera with interrupted 8/0 silk sutures through the eyelets on the receptacle plate. [email protected]

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Figure 9.4 (See color insert) Sclerostomy is made with MVR blade 3 mm posterior to the limbus.

end of the vitrectomy. A posterior chamber infusion line is inserted, and the infusion started following confirmation that the tip of the infusion is in the vitreous cavity. 3.2.2.

The Superotemporal Port

A superotemporal sclerostomy is made with a 20-gage MVR blade 3 mm posterior to the limbus in an apakic/pseudophakic eye or 4 mm posterior to the limbus in a phakic eye, at a location that is in line with the tube of the preplaced Ahmed Glaucoma Implant. This allows for the tube to be inserted into the pars plana through the same sclerostomy at the end of the vitrectomy. The placement of the superotemporal sclerostomy is therefore more superior than usual compared to a standard three-port pars plana vitrectomy. 3.2.3. The Superonasal Port A superonasal sclerostomy is made with a 20-gage MVR blade 3 mm posterior to the limbus in an apakic/pseudophakic eye or 4 mm posterior to the limbus in a phakic eye, through a separate superonasal peritomy. A complete vitrectomy is then performed. Particular attention must be paid to thoroughly remove the vitreous in the area of the tube insertion to prevent tube blockage by vitreous. Air – fluid exchange is then performed at the end of the vitrectomy. This is to ensure that the tube is “pneumatically stented” in the immediate postoperative period inside the vitreous cavity, preventing residual vitreous from plugging the pars plana end of the tube. With the air-pump maintaining the intraocular pressure, the superonasal port is plugged with a scleral plug. Attention is now turned to the placement of the tube into the pars plana. 3.3.

Placement of the Pars Plana Tube The Pars Plana ClipTM is slide along the tube until the “bend” is at the correct distance for insertion through the superotemporal sclerostomy (Fig. 9.5). [email protected]

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Figure 9.5 (See color insert) Set up for Pars Plana sclerostomy with Landers ring suture in place.

Excess amount of tube is trimmed so that the tube extends 5 mm into the vitreous cavity when inserted through the sclerostomy. After inserting the tube through the superotemporal sclerostomy, the sclerostomy is narrowed with an interrupted 10/0 nylon to ensure that the sclerostomy is water-tight around the tube (Fig. 9.6). The Pars Plana ClipTM is then anchored to the episclera with interrupted 8/0 silk through the two eyelets (Fig. 9.7). 3.4.

Closure The Ahmed Glaucoma Valve tube and Clip is then covered by a graft of eye bank cornea, sclera, or other material. If cornea is used, it should be prepared in

Figure 9.6 (See color insert) The tube of the Ahmed valve is inserted through the superotemporal sclerostomy. [email protected]

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Figure 9.7 (See color insert) The Pars Plana ClipTM is anchored to the episclera with 8/0 silk sutures through the eyelets.

advance by dissecting off the epithelial half of the cornea through the midstroma with a 57 blade using only the endothelial half. The half-thickness cornea graft is sutured to the episclera with interrupted 10/0 nylon sutures, to prevent postoperative erosion of the implant tube and Clip through the conjunctiva (Fig. 9.8). Water-tight closure of Tenon’s capsule and conjunctival flap, in separate layers with a continuous 7/0 vicryl sutures is then performed (Fig. 9.9). The superonasal sclerostomy and peritomy is closed in turn with 7/0 vicryl suture. In cases where an anterior chamber maintainer is used, this is now removed followed by hydration of the limbal wound with BSS. In cases where a pars plana infusion is used, the infusion cannula is removed with immediate closure of the sclerostomy by the preplaced 7/0 vicryl suture.

Figure 9.8 (See color insert) Half-thickness cornea graft is sutured to the episclera with interrupted 10/0 nylon sutures to cover the tube and the Pars Plana ClipTM . [email protected]

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Figure 9.9 (See color insert) Water-tight closure of Tenon’s capsule and conjuctival flap.

Top-up with filtered air can be injected on a short 30-gage needle through the inferotemporal limbal wound into the anterior chamber, or through the closed inferotemporal sclerostomy into the vitreous cavity, if the eye is soft. Subconjunctival injection of steroid and antibiotic should be placed inferonasally.

4.

RESULTS AND COMPLICATIONS OF PARS PLANA GDI

Various studies (8,10 – 15) in the last decade have reported the experience of combined GDI surgery with pars plana vitrectomy and pars plana tube insertion. These are summarized in Table 9.1. A wide variety of different glaucoma diagnosis were reported in these studies. In addition, variability in the definition of surgical success, difference in the surgical techniques, and the different types of GDI used make interpretation of the results difficult. There are significant postoperative complications, some secondary to hypotony, shared with conventional GDI surgery with anterior chamber tube placement. Serous choroidal effusions were reported in 36% in one series (13). Suprachoroidal hemorrhage occurred in up to 6% of cases (15). In addition, complications specific to pars plana vitrectomy are also encountered, specifically, rhegmatogenous retinal detachment in 6– 12% of cases (12,15). Patient should be fully informed about potential complications prior to surgery. Nevertheless, satisfactory intraocular pressure control without further glaucoma surgery (with or without glaucoma medication) is achieved in 72.5– 94% of the cases (8,10 –15). Considering the severity of the glaucoma treated, these results show promise for the management of these selected cases of refractory glaucoma. Before proceeding with combined GDI surgery and pars plana tube insertion, considerations should be given to ensure that the advantages associated with the reduced risk of anterior segment problems outweighs the additional risk of posterior segment complications of the pars plana vitrectomy. [email protected]

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10

13

17

50

9

34

Smiddy et al. (11)

Varma et al. (8)

Kaynak et al. (12)

Luttrull et al. (13)

Joos et al. (14)

Sidoti et al. (15)

NVG Aphakic G Pseudophakic G ACG Congenital G Angle recession G Aphakic G Pseudophakic G Aphakic G Pseudophakic G Angle recession G 28 ACG NVG POAG CACG Uveitic G Aphakic G AC tube with AC complications CACG, POAG, Uveitic G, NVG with PKP or PBK

Glaucoma diagnosis

PPV þ tube reposition PPV þ PPT + PKP

85

76

Baerveldt Molteno Ahmed

72

78

94

Baerveldt

88

100

94

Molteno Schocket

69

70

65

% Stable or improved VA

Baerveldt

100

Baerveldt

PPV þ PPT þ tube ligation PPV þ PPT

PPV þ PPT þ pneumatic stenting

90

75

% IOP control

Molteno Baerveldt

Molteno Schocket

GDI type

PPV þ PPT þ tube ligation

PPV þ PPT 8 PPV þ ACT 12

Type of surgery

6 – 32

2 – 42

3 – 41

4 – 71

12– 28

3 – 24

4.2 – 28

F/U interval (months)

SCE 12% SCH 6% VH 6% RRD 6%

No retinal complications Hypotony 12% SCE 6% VH 6% RRD 12% SCE 36% SCH 4% VH 2% RRD 8% NLP 10% RRD 11%

SCE 20%

Complications

Note: G, glaucoma; NVG, neovascular glaucoma; ACG, angle closure glaucoma; POAG, primary open angle glaucoma; CACG, chronic angle closure glaucoma; PKP, penetrating keratoplasty; PBK, pseudophakic bullous keratopathy; PPV, pars plana vitrectomy; PPT, pars plana tube; ACT, anterior chamber tube; SCE, serous choroidal effusion; SCH, suprachoroidal hemorrhage; VH, vitreous hemorrhage; RRD, rhegmatogenous retinal detachment; NLP, no light perception.

20

No. of eyes

Granham et al. (10)

Reference

Table 9.1 Results and Complications of Pars Plana Glaucoma Damage Implant Surgery

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REFERENCES 1. 2. 3. 4. 5.

6. 7. 8. 9. 10. 11. 12. 13.

14. 15.

Katz GJ, Higginbotham EJ, Lichter PR et al. Motomycin C versus 5-fluorouracil in high-risk glaucoma filtering surgery. Ophthalmology 1995; 102:1263 – 1269. The Fluorouracil Filtering Surgery Study Group. Five-year follow-up of the fluorouracil filtering surgery study. Am J Ophthalmol 1996; 121:349– 366. Patel A, Thompson JT, Michels RG, Quigley HA. Endolaser treatment of the ciliary body for uncontrolled glaucoma. Ophthalmology 1986; 93:825 –830. Trope GE, Ma S. Mid-term effects of neodymium:YAG transcleral cyclophotocoagulation in glaucoma. Ophthalmology 1990; 97:73 – 75. Schocket SS, Nirankari VS, Lakhanpal V et al. Anterior chamber tube shunt to an encircling band in the treatment of neovascular glaucoma and other refractory glaucomas; a long-term study. Ophthalmology 1985; 92:553 – 562. Lloyd MA, Sedlak T, Heuer DK et al. Clinical experience with the single-plate Molteno implant in complicated glaucomas: update of a pilot study. Ophthalmology 1992; 99:679 – 687. Lloyd MA, Baervrldt G, Heuer DK et al. Initial experience with the Baerveldt implant in complicated galucomas. Ophthalmology 1994; 101:651 – 658. Varma R, Heuer DK, Lundy DC et al. Pars plana Baerveldt tube insertion with vitrectomy in glaucomas associated with pseudophakia and aphakia. Am J Ophthalmol 1995; 119:401 – 407. Siegner SW, Netland PA, Urban RC Jr et al. Clinical experience with the Baerveldt glaucoma drainage implant. Ophthalmology 1995; 102:1298 –1307. Grandham SB, Costa VP, Katz LJ et al. Aqueous tube-shunt implantation and pars plana vitrectomy in eyes with refractory glaucoma. Am J Ophthalmol 1993; 116:189– 195. Smiddy WE, Rubsamen PE, Grajewski A. Vitrectomy for pars plana placement of a glaucoma seton. Ophthalmic Surg 1994; 25:532 – 535. Kaynak S, Tekin NF, Durak I et al. Pars plana vitrectomy with pars plana tube implantation in eyes with intractable glaucoma. Br J Ophthalmol 1998; 82:1377– 1382. Luttrull JK, Avery RL, Baerveldt G, Easley KA. Initial experience with pneumatically stented Baerveldt implant modified for pars plana insertion for complicated glaucoma. Ophthalmology 2000; 107:143 – 150. Joos KM, Lavina AM, Tawansy KA, Agarwal A. Posterior repositioning of glaucoma implants for anterior segment complications. Ophthalmology 2001; 108:279 – 284. Sidoti PA, Mosny AY, Ritterband DC, Seedor JA. Pars plaa tube insertion of glaucoma drainage implants and penetrating Keratoplasty in patients with coexisting glaucoma and corneal disease. Ophthalmology 2001; 108:1050 –1058.

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10 Full-Thickness Filtering Glaucoma Surgery Maurice H. Luntz Manhattan Eye, Ear and Throat Hospital, New York; New York Eye, Ear Infirmary, New York; Beth Israel Medical Center, New York; Mount Sinai School of Medicine, New York; New York University School of Medicine, New York, New York, USA

Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada

1. Introduction 2. Subscleral Scheie Procedure 3. Surgical Technique 3.1. Conjunctival Flap (5 Magnification) 3.2. Scleral Flap and Paracentesis (7 to 10 Magnification) 3.3. Fistula and Iridectomy (10 Magnification) 3.4. Closure (5 Magnification) 4. Subscleral Trephine 5. Surgical Technique 5.1. Conjunctival Flap (5 Magnification) 5.2. The Scleral Flap (7 to 10 Magnification) 5.3. Corneal-Scleral Trephining (7 to 10 Magnification) 6. Sclerectomy 6.1. Anterior Lip Sclerectomy 6.2. Posterior Lip Sclerectomy References

1.

93 94 94 95 95 96 97 98 98 98 98 99 99 99 99 100

INTRODUCTION

Prior to 1968, glaucoma filtering operations were full-thickness procedures, that is, a fistula was made at the limbus through the full thickness of the sclera and aqueous drained freely into the subconjunctival space. In 1968, John Cairns (1) described trabeculectomy. In the trabeculectomy procedure, an one-third thickness lamellar scleral flap is 93

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fashioned to cover the scleral fistula. The scleral flap retards the aqueous outflow through the fistula and significantly reduces the risk of postoperative complications, in particular, over-filtration, flat anterior chamber (AC), hypotony, and suprachoroidal hemorrhage. Owing to its greater safety compared with full-thickness procedures, trabeculectomy has become the standard filtration procedure for glaucoma surgery. Although trabeculectomy adds to the safety of filtering surgery, reducing the risk of postoperative complications, it also slows and restricts aqueous drainage. The result is that trabeculectomy only infrequently achieves intraocular pressure (IOP) reduction into the low teens (10 –12 mmHg) when compared with full-thickness procedures. Recent longitudinal studies have demonstrated the importance of achieving IOP levels into the low teens in patients with optic nerve head cupping and visual field loss (2). The ability to achieve these IOP levels with trabeculectomy became feasible when antimetabolites were used in conjunction with trabeculectomy. At present, the most effective antimetabolite in use is mitomycin C. The higher success rate has come with a price. The effect of these antifibrotic agents is not confined to fibroblasts entering the area of bleb formation, but destroys cells in the surrounding conjunctiva and the surrounding blood vessels. Postoperatively, a thin-walled bloodless bleb forms, which is prone to hypotony, suprachoroidal hemorrhage (2), and leakage of aqueous through poor healing of the conjunctival incision and/or breaks in the bleb (positive Seidel) and risk of endophthalmitis (3,4). These are serious and sightthreatening complications and have led to a resurgence of interest in full-thickness procedures without the use of antimetabolites as a means of achieving low IOP levels. The full-thickness procedures most popular at this time are trabeculectomy but without suturing the lamellar scleral flap, the subscleral Scheie, the subscleral trephine procedure, and setons, because of their relative safety when compared with other full-thickness procedures. These full-thickness procedures have been modified and are performed under a small scleral flap which acts as a “ball valve,” restricts aqueous flow and protects the limbal conjunctiva.

2.

SUBSCLERAL SCHEIE PROCEDURE

The subscleral Scheie procedure, first described by Soll in 1973 (5) is a modification of the procedure which was first described by Harold Scheie in 1958 (6). The procedure was subsequently modified and used with excellent results by Luntz et al. (7). The operation interposes a lamellar flap of sclera between the classical Scheie fistula and the limbal conjunctiva. The scleral flap is designed to reinforce the conjunctiva at the limbus, to reduce the rate of aqueous flow through the fistula, in this way to reduce the incidence of over-filtration and minimize postoperative flat or shallow AC. By deflecting aqueous humor posteriorly, the flap also results in a more posterior and diffuse bleb (Fig. 10.1). The scleral flap is not sutured as in trabeculectomy and this operation is a partially guarded full-thickness procedure as opposed to a trabeculectomy, which is a fully guarded procedure.

3.

SURGICAL TECHNIQUE

A suitable area of conjunctiva is selected. The best site is virgin, untraumatized conjunctiva, preferably the upper nasal quadrant. Where conjunctival scarring is present, an area [email protected]

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Figure 10.1

95

Aqueous flow in subscleral Scheie.

of normal or near-normal conjunctiva is selected, but only in the superior conjunctiva. If the superior conjunctiva is severely scarred, this procedure is contraindicated and a seton should be used.

3.1.

Conjunctival Flap (53 Magnification)

A limbus-based conjunctival flap is preferred to a fornix-based flap for this operation. Using Westcott scissor, a conjunctival incision 7 mm in width is made in the fornix, 7 mm behind and parallel to the surgical limbus. The incision is carried through the conjunctival tissue and Tenon’s to sclera, and scleral surface is laid bare. Hemostasis is obtained using a pencil bipolar cautery. Dissection is then carried forward using either a Westcott or Troutman scissors toward the surgical limbus, separating conjunctiva and Tenon’s fascia from sclera. As the limbus is approached, Tenon’s capsule and episcleral tissue fuse, and a disposable Beaver knife (#75 or #69) is used to dissect into the limbal area, dissecting just forward of the surgical limbus. The limbus-based conjunctival flap is rotated forward onto the cornea and held there by an assistant using a #28 Hoskins forceps (Katena). 3.2.

Scleral Flap and Paracentesis (73 to 103 Magnification)

A scleral flap hinged at the limbus, extending posteriorly from the limbus for 1.5 mm and 5 mm in length, is marked out on the sclera beneath the conjunctival flap using the bipolar cautery. A 5 mm incision is made 1.5 mm posterior and parallel to the limbus along this marked-out area, extending through one-third of the scleral thickness, and each end of the incision is joined to the limbus by two radial incisions, also extending through one-third of the scleral thickness. Using a diamond blade, the scleral flap is dissected from the posterior incision to the limbus, raising a 1/3 thickness scleral flap, 5 mm in length and 1.5 mm in width, hinged at the limbus. A temporal paracentesis is made with a 158 superblade (Alcon). [email protected]

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Fistula and Iridectomy (103 Magnification)

The scleral flap is rotated forward and held there by the assistant, exposing the underlying scleral bed. Using the diamond knife, a 5 mm long incision is made in the deep scleral bed, parallel to the limbus and immediately posterior to the hinged area of the scleral flap (Fig. 10.2). This incision is carried through 1/3 the thickness of the deep scleral bed and a row of cautery burns using a bipolar cautery is applied to the posterior wall of this incision (Fig. 10.3). The cautery causes retraction of the posterior lip of the incision, widening the incision area. The incision is then deepened to Descemet’s membrane using the diamond knife and a second row of cautery applications is made along the posterior lip, deep to the first row of cauteries, further retracting the posterior lip of the incision. The next step is to enter the AC using the diamond knife across the full 5 mm length of the incision (Fig. 10.4). To perform this safely, the surgeon lifts the anterior lip of the incision with a #19 Hoskins forceps and the assistant lifts the posterior lip of the scleral incision with a second pair of forceps. Using the diamond blade, the AC is entered at one end of the 5 mm long scleral incision, and with the sharp edge of the blade pointing upward, the incision can be carried across to the other end, completing the opening into the AC. Using pressure on the posterior lip of the incision in the deep scleral bed, iris is prolapsed into this incision. If iris does not prolapse, it should be carefully grasped and pulled through the fistula with a #28 Hoskins forceps. Holding the iris with the Hoskins forceps, a peripheral iridectomy is made. The iris is then allowed to slip back into the AC, ensuring that it is not incarcerated in the incision. If this occurs, iris can be freed

Figure 10.2

Dissection scleral flap—subscleral Scheie. [email protected]

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Figure 10.3

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Cautery to incision—subscleral Scheie.

by using a jet of balanced salt solution (BSS) through the incision. Healon or a comparable viscoelastic is injected through the paracentesis incision to maintain the AC.

3.4.

Closure (53 Magnification)

The conjunctival flap is rotated back into the fornix, covering the 1/3 thickness scleral flap which is not sutured. The incision in Tenon’s capsule is sutured with interrupted #10/0 nylon sutures using 10 interrupted sutures. Approximately 10 interrupted or continuous #10/0 nylon sutures unite the cut conjunctival edges. A drop of an antibiotic–steroid combination is instilled into the conjunctival sac at the completion of surgery. BSS is injected through the temporal paracentesis incision to deepen the AC. The BSS egresses through the scleral fistula and fills the bleb. Ensure a negative Seidel using a Fluorescein strip. The steroid–antibiotic combination is used for 1–10 days postoperatively, depending on the extent of postoperative iritis. As soon as the AC reaction is improved to a level of 1þ flare and no cells, and postoperative infection is no longer anticipated, this medication is replaced with a topical steroid for another month. By this time, the eye should be quiet and the patient can be weaned off the steroid drops. If the AC shallows postoperatively, homatropine 5% twice daily is added. The treatment of postoperative complications is reviewed elsewhere. Transient ocular hypertension may follow some fistulizing procedures, lasting from 2 days to 6 weeks. The reason for this is obscure, but may be related to postsurgical edema of the trabecular meshwork, to obstruction of the fistula by blood, to early failure of the bleb, or to the use of steroids or cycloplegics. If blood is a factor, the pressure will gradually drop to a normal postoperative level once the blood is resorbed. Massage used three to four times a day may be helpful during the ocular hypertensive period and the technique of massage is described elsewhere in this book. [email protected]

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Figure 10.4

4.

Subscleral Scheie—completed incision.

SUBSCLERAL TREPHINE

For the first half of the 20th century, corneal-scleral trephine, which is a full-thickness filtration, was the most popular procedure for the treatment of chronic open angle glaucoma. It fell into disuse when trabeculectomy became popular because of the smaller risk of complications with trabeculectomy. The corneal-scleral trephine operation was first described by Robert Elliot in 1909 (8). The procedure has become popular once again as fullthickness procedures have increased in popularity over the past few years. The modern corneal-scleral trephine procedure should be a partially guarded procedure performed under 1/3 thickness lamellar-scleral flap, similar to that described for subscleral Scheie.

5. 5.1.

SURGICAL TECHNIQUE Conjunctival Flap (53 Magnification)

Using Westcott scissors, a conjunctival incision 7 mm in width is made in the fornix 7 mm behind and parallel to the surgical limbus. The conjunctival dissection is then carried out in the same way as described in the previous section for subscleral Scheie. When the surgical limbus is reached, the dissection is carried forward into the surgical limbus and just anterior to the vascular arcade in the corneal periphery.

5.2.

The Scleral Flap (73 to 103 Magnification)

A 1.5 mm wide by 5 mm long 1/3 thickness scleral flap is raised in the same way as described in the previous section for the subscleral Scheie procedure, except that the [email protected]

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dissection toward the limbus is carried across the surgical limbus for 0.5 mm exposing deep corneal lamellae. 5.3.

Corneal-Scleral Trephining (73 to 103 Magnification)

A 1.5 mm trephine is used. The scleral flap is rotated forward using a #19 Hoskins forceps, exposing the surgical limbus and anterior corneal lamellae, and the trephine is placed so that one-third of the diameter of the trephine lies anterior to the surgical limbus in the corneal lamellae and two-thirds behind the surgical limbus in the sclera. The trephine is rotated alternately clockwise and anti-clockwise slowly. As the trephine proceeds, it is slightly tilted to the temporal side and careful watch is maintained for penetration of the AC on the temporal side. As the trephine enters the AC, there is a flow of aqueous humor from this area and the AC will shallow. Great care must be taken not to continue the trephining once the AC is perforated because of the danger of a collapsed AC, in which case the trephine may damage the anterior lens capsule, causing a traumatic cataract. The trephine is removed and trephine incision is completed using Vannas scissors. The trephine disk is then removed and a peripheral iridectomy is performed using a Hoskins forceps to pull iris through the opening in order to do the iridectomy. The conjunctivaTenon’s flap is then replaced and the conjunctival incision in the fornix is sutured, separately suturing Tenon’s capsule with #8/0 vicryl or #10/0 nylon continuous suture, and suturing the conjunctiva separately with a continuous #10/0 nylon suture.

6.

SCLERECTOMY

The partially guarded subscleral Schei procedure and trephine are the most widely used full-thickness procedures at present. However, there are other types of sclerectomy that have been described, particularly in the first half of the 20th century. These have for the most part fallen into disuse. 6.1.

Anterior Lip Sclerectomy

Anterior lip sclerectomy is performed using a conjunctival and 1/3 thickness scleral flap, exactly as described in the trephine and subscleral Scheie procedures. In this procedure, the 1/3 thickness scleral flap is rotated forward, exposing the surgical limbus area. An incision is made as described for subscleral Scheie procedure, 5 mm long and 1.5 mm behind the limbus, but no cautery is used. The incision is carried through into the AC using a diamond knife. Using a punch specially designed for the purpose, the sclera is punched out in the anterior lip of this incision, creating a fistula in the anterior lip of the scleral incision. Closure of the conjunctiva is performed in the same method as described for subsceral Scheie. 6.2.

Posterior Lip Sclerectomy

This procedure is performed in exactly the same way as that described for anterior lip sclerectomy, except that the punch in this instance is used in the posterior lip of the sclerectomy, producing a fistula in the posterior lip of the scleral incision. Care must be taken not to punch into the ciliary body. As previously noted, the anterior lip sclerectomy and posterior lip sclerectomy are not widely used at this time. [email protected]

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REFERENCES 1. 2.

3. 4. 5. 6. 7. 8.

Cairns JE. Trabeculectomy—preliminary report of a new method. Am J Ophthamol 1968; 66:673 – 679. The AGIS Investigators. The advanced glaucoma intervention study (AGIS) VII: The relationship between control of intraocular pressure and visual field deterioration. Am J Ophthalmol 2000; 130:429 – 440. Greenfield DS, Suner IJ, Miller MP. Endophthalmitis after trabeculectomy with mitomycin C. Ophthalmology 1996; 103:650 – 656. Higginbotham EJ, Stevens RK, Musch DC. Bleb-related endophthalmitis after trabeculectomy with mitomycin C. Ophthalmology 1996; 103:650 – 656. Soll DB. Intrascleral filtering procedure for glaucoma. Am J Ophthalmol 1973; 75:392– 394. Scheie HS. Retraction of scleral wound edges as a fistulizing procedure in glaucoma. Am J Ophthalmol 1958; 45:220 – 229. Luntz MH, Harrison R, Schenker H. Glaucoma Surgery. Baltimore: Williams and Wilkins, 1984:84 – 90. Elliot RH. Ophthalmoscope 1909; 7:804 – 807.

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11 How to Do a Surgical Iridectomy Maurice H. Luntz Manhattan Eye, Ear and Throat Hospital, New York; New York Eye, Ear Infirmary, New York; Beth Israel Medical Center, New York; Mount Sinai School of Medicine, New York; New York University School of Medicine, New York, New York, USA

Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada

1. Surgical Treatment for Angle Closure Glaucoma 2. Surgical Techniques for Peripheral Iridectomy for Angle Closure Glaucoma 2.1. Mechanism of Action 2.2. Surgical Techniques 2.2.1. Surgical Incision (10 Magnification) 2.2.2. Iridectomy (10 Magnification) 2.3. Return of the Iris to Anterior Chamber 2.4. Suturing the Incision 3. Results 4. Peripheral Iridectomy (Alternative Technique) 5. Complications 6. Recurrence—Acute Angle Closure References

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101 102 102 102 102 103 104 104 105 105 105 105 105

SURGICAL TREATMENT FOR ANGLE CLOSURE GLAUCOMA

In 1857, the German ophthalmologist Albrecht von Graefe announced at the first International Congress of Ophthalmology held in Brussels, that he had discovered a surgical cure for acute glaucoma (1). This involved a sector iridectomy, which he observed to effect a long lasting cure. He published this observation in 1869. This discovery represented a major milestone in the history of ophthalmic surgery. Before von Greafe’s discovery, acute glaucoma had been a blinding disease treated by leeches and venesection. von Graefe had observed the hypotensive effect of a sector iridectomy performed for corneal staphyloma, and this led him to try it for acute glaucoma. It was not until 1920 that E.J. Curran, an American, noted that angle closure glaucoma was associated with pupil block and suggested that peripheral iridectomy was as effective in curing acute glaucoma as was sector iridectomy (2). This has remained until recently 101

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the specific surgical treatment, but today the increased use of the argon or YAG laser to create a hole in the iris (laser iridectomy) has largely replaced surgical iridectomy. In geographic areas where a laser is not available, surgical peripheral iridectomy is the only option. Some patients (e.g., Laplanders) have very thick irides, in which a laser has difficulty in penetrating, and in these patients surgical peripheral iridectomy is an option. Surgical peripheral iridectomy is performed under local anesthesia as an ambulatory operation.

2. 2.1.

SURGICAL TECHNIQUES FOR PERIPHERAL IRIDECTOMY FOR ANGLE CLOSURE GLAUCOMA Mechanism of Action

Peripheral iridectomy is a safe surgical procedure and is highly successful. The objective is to create an opening for unhampered aqueous flow from the posterior to the anterior chamber, reducing the pressure build-up in the posterior chamber from relative pupil block, thereby allowing the iris to fall backward and open the angle. It is unnecessary to make the opening in the iris either basal or sector as long as the aqueous can flow freely through it. The equalization of pressure between the posterior and the anterior chambers, following iridectomy, will separate the iris from the posterior corneal surface if the apposition has not become permanent. The effect of iridectomy on these irido-corneal attachments is to open localized areas of the angle where the closure is not permanent. The angle might only open adjacent to the iridectomy. This is due to loculation of the aqueous behind the iris as a result of widespread scar formation in the angle, limiting the free flow of aqueous. In these longstanding cases, it is useful to do two peripheral iridectomies, one in each superior quadrant, because this may reach more than one locule of aqueous and open more of the angle than would be achieved by only one iridectomy. Nevertheless, even in the earlier situation, one iridectomy, by equalizing anterior and posterior chamber pressures, will in most cases prevent further acute angle closure attacks. Any residual ocular hypertension after peripheral iridectomy is due to either chronic angle closure or an open angle mechanism (primary or secondary).

2.2.

Surgical Techniques

Anesthesia: Topical anesthesia (alcaine-proparacaine hydrochloride 0.5% from Alcon) with intracameral preservative-free lidocaine 1% from Astra. Alternatively, the procedure can be performed using only topical 2% xylocaine jelly. 2.2.1. Surgical Incision (10 Magnification) The operation is preferably performed through a corneal incision leaving the conjunctiva unmolested. A 3 mm long incision is made in the cornea just anterior to the limbus and at the anterior edge of the limbal corneal vessels. The incision is best sited in the upper nasal quadrant using a #75 Beaver microblade. The corneal stroma is dissected down to Descemet’s membrane. At this point, the incision is grasped with Hoskin #28 forceps (Keeler) and, keeping the cornea pulled slightly upward and away from the iris, the anterior chamber is entered with the knife over the full 3 mm length of the incision (Fig. 11.1). [email protected]

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Figure 11.1

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Corneal incision.

2.2.2. Iridectomy (10 Magnification) Once the anterior chamber is entered, pressure is applied on the scleral side of the incision (Fig. 11.2) with a flat iris spatula in an attempt to prolapse the iris into the incision, in which case it is pulled through the incision using a #28 Hoskin forceps. When the iris does not prolapse into the incision, the forceps is carefully introduced into the anterior chamber, using 10 magnifications for good visualization of the iris surface. The iris is grasped with the forceps held in the left hand and pulled into the incision. The iris is then grasped at a point closer to the pupil with a second #28 Hoskin forceps held in the right hand and pulled out of the incision. Failure to hold the iris nearer the pupil before pulling it through the incision may result in tearing the iris base, in irido-dialysis, and in intraocular bleeding. With the iris exteriorized, the surgeon ensures that both the stromal and the pigment layers are held in the forceps (pigment layer is usually easily visible through the iris stroma). Using DeWecker scissors and cutting parallel to the limbus, the portion of the iris held in the forceps is removed (Fig. 11.3).

Figure 11.2

Prolapse iris into incision. [email protected]

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Figure 11.3

Surgical iridectomy.

A peripheral iredectomy results at the junction of the outer and middle third of the iris surface. This is the ideal position for the peripheral iridectomy because the major iris vessels are avoided.

2.3.

Return of the Iris to Anterior Chamber

In most cases, the iris, once released, will slip back through the incision into the anterior chamber, and the peripheral iridectomy can be visualized through the cornea. In the event the iris becomes incarcerated in the incision, pressure on the scleral side of the incision with a flat iris spatula will generally dislodge it. Failing that, the cornea is stroked with an iris spatula from the center of the cornea upward to the limbus. When the iris still remains incarcerated in the incision, the two edges of the incision are held apart and a jet of balanced salt solution directed into the incision will dislodge the iris. Once the iris is back in the anterior chamber, the surgeon should ascertain that the iridectomy included the pigment layer by demonstrating a red reflex through the iridectomy with retroillumination using the co-axial microscope light and also ensure that the pupil is round.

2.4.

Suturing the Incision

One or two 10-0 nylon sutures are placed across the center of the corneal incision at full corneal depth and tied to provide good apposition but not too tightly. The sutures are cut on the knot which is buried on the corneal side of the incision. There is no necessity to reform the anterior chamber as it is not lost during the procedure. The surgeon also must ensure that the pupil is round. Subconjunctival injection of antibiotics and steroids is unnecessary. An antibiotic – steroid combination is used for a few days, postoperatively. The suture can be left indefinitely or removed after 3 months. Suture-induced astigmatism is minimal because of the small size of the incision. There is minimal postoperative uveitis or discomfort. An eye patch is not necessary.

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RESULTS

Peripheral iridectomy is the most satisfying surgical procedure. When meticulous surgical technique is used, a patent iridectomy is always obtained, and this will cure .80% of primary angle closure glaucoma (3). Late cataract formation is the commonest complication. This may develop years later. Other complications are exceptionally rare but include wound leak, iritis, hyphema, malignant glaucoma, and endophthalmitis. Failure to excise the pigment layer of the iris will result in a nonfunctioning iridectomy. This is readily corrected using bursts of an argon laser set at 50 mm, 0.5 W power, and 0.2 s exposure, which will remove the pigment layer. 4.

PERIPHERAL IRIDECTOMY (ALTERNATIVE TECHNIQUE)

A conjunctival flap including Tenon’s fascia is made 4 mm from cornea and 5 mm in length. Incision into the anterior chamber is made for 3 mm with a diamond knife or #75 Beaver microblade. The incision line is in the mid-limbal position. A “knuckle” of iris is prolapsed by gentle pressure on the posterior lip. Full thickness iridectomy is performed with DeWecker scissors applied tangentially, the iris being grasped with #28 Hoskin forceps. Loose iris pigment is irrigated away. A single suture of 10-0 nylon is usually adequate to close the incision, which should be tested for watertight closure by pressing with the tip of a fine forceps. The conjunctival flap is closed with a short continuous 10-0 nylon suture. The anterior chamber is usually not lost but must be seen to be formed before allowing the patient to leave the operating room table. An antibiotic – steroid combination is used for a few days, postoperatively. 5.

COMPLICATIONS

Complications are few. There is a danger of injury to the ciliary body and hemorrhage if the limbal incision is made too far posteriorly. Failure to obtain a watertight closure of the incision can lead to a flat anterior chamber, and immediate surgical repair is mandatory. The other complications listed under peripheral iridectomy with a corneal incision can also occur. 6.

RECURRENCE—ACUTE ANGLE CLOSURE

Acute angle closure may recur in the presence of a patent peripheral iridectomy in patients with plateau iris or a plateau iris component to a primary pupil block mechanism. Patients with this anomaly should be warned that there may be a recurrence. Plateau iris can be treated by combining peripheral iridectomy with laser gonioplasty. REFERENCES 1. 2. 3.

von Graefe A. Arch Ophthalmol 1869; 15:108, 228. Curran EJ. Arch Ophthalmol 1920; 49:131. Luntz MH. In: Turtz AL, ed. Ophthalmology. Vol. 1. Saint Louis, USA: The C.V. Mosby Company, Chapter 9, 1969:100.

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12 Combined Cataract and Glaucoma Surgery Ruth Lapid-Gortzak University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada and Ben Gurion University of the Negev, Israel

David S. Rootman, Yvonne M. Buys, and Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada

1. Indications 2. Outcomes of Phacotrabeculectomy 3. Contra-Indications 4. Patient Information and Informed Consent 5. Techniques 6. Operative Technique: One-Site Phacotrabeculectomy 7. Two-Site Phacotrabeculectomy Technique 8. Postoperative Care 9. Comments 10. Tips 11. Complications References

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INDICATIONS

Combined cataract and glaucoma filtration surgery is indicated in: 1.

2.

Patients with vision impairing cataract and uncontrolled or marginally controlled glaucoma with maximum tolerated medical therapy or patients with medically uncontrolled glaucoma and a cataract which is likely to become visually significant in the near future. Patients with vision impairing cataract and glaucoma controlled with multiple medications.

There are several advantages of combined surgery over staged procedures including decreased risk with one operation and anesthetic compared to two, decreased cost both in terms of health care costs and costs to the patient, faster visual rehabilitation, and decreased incidence of early postoperative pressure spikes, which is of major importance in patients 107

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with advanced optic nerve cupping or visual field loss (1,2). Phacotrabeculectomy is also beneficial in that it may reduce the long-term need for glaucoma medications (1,3).

2.

OUTCOMES OF PHACOTRABECULECTOMY

Combined phacotrabeculectomy has been shown in several studies to result in long-term intra-ocular pressure reduction and improved vision (4,5). The visual success rates range between 62.5% and 98% (visual acuity better than 20/40). Pressure control without medication ranges between 66% and 96% (5 – 12). Evidence, however, suggests that trabeculectomy alone achieves better long-term pressure control than combined phacotrabeculectomy (13 –18). This has led some surgeons to advocate a two-step approach, surgically controlling pressure first, followed later by phacoemulsification. The effect on bleb function and IOP of subsequent cataract surgery in the presence of a filtering bleb is debatable. Several published studies have reported failure rates (usually defined as the need for additional glaucoma medication or further filtration surgery) of 0 – 33%, 15 – 24 months following phacoemulsification in a previously filtered eye (19 – 25). These studies were mostly retrospective. Two of these (19,23) compared the success rate with matched control groups of trabeculectomy only, and did not find a statistically significant difference suggesting that the failure rate of filtration following subsequent phacoemulsification may be the same as the natural course of a trabeculectomy.

3.

CONTRA-INDICATIONS

In certain circumstances, combined procedures should not be performed: 1. 2. 3.

4.

If the lens opacity is not significantly affecting vision, or likely to do so soon. When the optic nerve is healthy and the pressure well controlled on one or two medications. When glaucoma surgery is likely to fail because of bleb fibrosis, for example, neovascular glaucoma.

PATIENT INFORMATION AND INFORMED CONSENT

The patient should be informed that the goal of surgery is to improve vision by cataract surgery and to gain better short and possibly long-term control of IOP. The patient should be told that surgery may not free them indefinitely from use of medication or possible future glaucoma surgery to control pressure. The patient should be made aware that the filtration procedure will not cure the glaucoma or reverse existing visual field loss. Together with the usual consent information pertaining to possible complications from cataract surgery, the patient should also be informed about the issues relating to filtration surgery such as the need for digital massage or suture removal or lysis, anterior chamber reformation, bleb problems including infection, and the increased risk of choroidal hemorrhage, along with the expected fluctuation in visual acuity that accompanies such interventions. It is important that patients are made aware that visual recovery is usually slower than that experienced after phacoemulsification alone and good vision is not expected for 2– 6 weeks after surgery. Post-operative visual acuity can be influenced by astigmatism induced by the operative wound and sutures. [email protected]

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TECHNIQUES

Combined cataract with filtration surgery can be performed with varying techniques. The more commonly utilized techniques are 1. 2. 3. 4. 5.

phacotrabeculectomy, one site, phacotrabeculectomy, two sites, scleral tunnel phacotrabeculectomy, scleral tunnel ECCE (Blumenthal technique) with trabeculectomy, combined nonpenetrating surgery, for example, phacoviscocanulostomy.

Other variations in technique include limbal vs. fornix based flaps; variations in suturing techniques such as suture-less and releasable suture technique; incision variations with scleral tunnels, smile incisions, large vs. small incisions; and the use of antimetabolites. In terms of IOP lowering, there is modest evidence to suggest that two-site phacotrabeculectomy achieves lower IOP than one-site surgery and combined surgery augmented with mitomycin-C (MMC) and not with 5-fluorouracil results in lower IOP (26). There is no evidence to suggest that fornix- or limbal-based flaps influence the final IOP in phacotrabeculectomies (27 – 29). Presently, there is insufficient scientific evidence to recommend newer alternatives such as phacoemulsification combined with trabecular aspiration, viscocanalostomy, deep sclerectomy, endoscopic laser cycloablation, or trabeculectomy in the surgical management of coexisting cataract and glaucoma. We will describe a standard one-site combined phacotrabeculectomy technique with releasable sutures, which we have used with good success for more than a decade, and a two-site procedure, which evidence-based analysis has shown to have some advantages in terms of long-term management of glaucoma over the one-site procedure (17).

6.

OPERATIVE TECHNIQUE: ONE-SITE PHACOTRABECULECTOMY 1. 2.

3. 4. 5. 6. 7. 8.

9.

Neurolept anesthesia is administered by an accompanying anesthesiologist. Topical 0.5% tetracaine is instilled. A 0.5 cc of xylocaine 1% with epinephrine is injected in the sub-Tenon space of in upper right quadrant, as far superiorly as possible (for a right-handed surgeon). Skin prep with 10% povidone iodine. Lashes are draped. The speculum is inserted. A 8/0 silk corneal bridle suture is placed at the 11:30 o’clock position partial thickness through peripheral cornea. A 158 blade is used to create a paracentesis at the 2 o’clock position. At 11:30 o’clock, a fornix-based peritomy is performed, using a crescent blade and a nontoothed forceps, at the posterior limbus with the knife edge following the contor of the globe. Dissection under the conjunctiva and Tenon’s capsule is done with a Wescott scissors. The dissection is carried posteriorly into the upper right-handed quadrant in the space between the superior and medial (or lateral in the right eye) rectus muscle (Fig. 12.1). If the Tenon capsule is very dense or fibrotic, a tenonectomy is performed, by excision with Wescott scissors. If MMC use is planned, the tenonectomy is usually omitted. Hemostasis of the vessels in the area of the planned scleral flap is done, using wet-field cautery. Vessels should be coagulated without [email protected]

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Figure 12.1

10.

11.

12.

Peritomy with the crescent blade at the limbus, following the contor of the globe.

charring of the underlying tissues. By applying cautery through a wet methylcellulose sponge, hemostasis without charring can usually be achieved. This technique decreases the amount of cautery energy applied directly to the tissues. A Weck-cell soaked in 0.4 mg/mL of MMC is then applied. MMC is applied for 1–3 min, on the sclera where the scleral flap is planned and posteriorly under the conjunctiva and Tenon’s capsule. A narrow long pledget 2 4 mm is useful to direct the application posteriorly. The scleral surface exposed to MMC is irrigated with 40 cc of BSS. This can be done by inserting the phacoemulsification probe under the conjunctiva and applying irrigation only. Dissection of the scleral flap: A half-thickness rectangular flap of 3.5 4 mm is dissected, using a 0.12 forceps and a crescent-shaped knife held with the blade at 908 to the sclera to outline the flap. Take care to keep the same plane for the whole flap (Fig. 12.2).

Figure 12.2

Formation of the scleral flap. [email protected]

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13. 14. 15. 16. 17.

18.

19.

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A standard scleral type dissection is done with the blade parallel to the surface directed anteriorly into clear cornea. Enter the anterior chamber at the limbal base of the scleral flap with a 3.0 mm keratome. Intra-ocular nonpreserved xylocaine 1% is injected, this being particularly important if iris manipulation is required. Fill the anterior chamber with viscoelastic through the paracentesis. In cases of small nondilating pupils, a pupil-widening procedure is performed, either with the use of iris hooks, or with flexible Grieshaber hooks. A bimanual maneuver with a cyclodialysis spatula in the left hand through the paracentesis incision and a Kuglin hook through the incision at 12 o’clock works well by dilating the pupil horizontally and vertically and is sufficient to increase lens exposure in most cases. In cases where the iris is floppy, thin, or iridoschisis is present, it is preferred to use flexible iris hooks to keep the iris dilated and away from the aspiration of the phacoemulsification handpiece. Perform a circular curvilinear capsulorrhexis with a cystotome, and an Uttrata forceps. Vision blue enhancement of the anterior capsule can be used if needed. In patients with pseudoexfoliation, this maneuver should be done with extreme caution because of the weakened nature of the zonules in these patients. Hydrodissection of the lens, with the 27 gage canula on a 2 cc syringe filled with BSS. Elevate the anterior capsule with the canula. Take care to mobilize the nucleus, while avoiding intra-operative capsular block or tears in the posterior capsule, by depressing the posterior lip of the operative wound while injecting steadily. This will allow the excess viscoelastics to be released from the eye, and eliminate pressure build-up which can potentially rupture the posterior capsule. Phacoemulsification of the nucleus and its removal from the bag is performed with the surgeon’s bimanual phaco-chop technique of choice (Fig. 12.3).

Figure 12.3 Nuclear cracking during phacoemulsification. The phacoemulsification probe is inserted through the ostium for the trabeculectomy. [email protected]

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21. 22.

23. 24.

25. 26.

27.

28. 29. 30.

Irrigation and aspiration (I/A) of the cortical remnants is then performed. Polishing of the posterior capsule is performed if needed, with the automated I/A or manually with the hydrodissection needle. Digital pressure on the syringe will regulate the amount of vacuum applied, and allows for the gentle removal of cortical remnants. Inject viscoelastic into the bag via the paracentesis wound, and reform the anterior chamber. Insert a foldable intra-ocular lens with the technique varying with the type of lens and injector-tube used. We prefer an acrylic lens (Acrysof, SA60, Alcon, Fort Worth, TX) as it is nonreactive and has an excellent injector system. Miochol is then injected via the paracentesis to constrict the pupil prior to the iridectomy. With a 158 blade, the trabeculectomy is performed under the scleral flap by excising a rectangular 3 2 mm piece of tissue including trabecular meshwork. Radial incisions are made from posterior to anterior into the anterior chamber, with the trabeculectomy excision between these two radial incisions (Fig. 12.4). A wide peripheral iridectomy is performed by grasping the peripheral iris tissue and exteriorizing it towards the trabeculostomy site, followed by cutting it with a De Wecker scissors parallel to the limbus. The base of the peripheral iridectomy should be slightly wider than the width of the scleral flap incision at the limbus to avoid iris incarceration in the ostium. Avoid excess traction on the iris and the ciliary body as this may cause hemorrhage or an excessively large iridectomy that can be visually disturbing. Evacuate the intra-ocular viscoelastics using I/A through the main incision (Fig. 12.5). Reform the anterior chamber with BSS via the paracentesis, as needed. Suture the scleral flap with 3 –4 interrupted buried 10/0 nylon sutures. The length of the bites should be relatively long, to make post-operative laser suture lysis easier to perform. Our preferred technique, however, is to utilize a “U”-shaped releasable suture (30). This technique is described elsewhere in this book. Pressure applied with a dry methyl-cellulose sponge over the scleral flap should not cause a leak. The function of the trabeculectomy

Figure 12.4

Trabeculectomy performed with a 158 blade. [email protected]

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Figure 12.5 Conjunctival sutures with buried knots. Notice the loop of the releasable suture on the cornea (inverted U).

31.

7.

fistula is assessed by injecting BSS into the anterior chamber via the paracentesis checking for depth of the anterior chamber, the tension of the globe, and leakage of fluid across the scleral flap sutures. The conjunctiva is then repositioned and closed with 10/0 nylon sutures in a water-tight manner. Two-wing sutures with bites through the peripheral cornea and one central horizontal mattress suture work best in our hands. Take extra care to burry all knots for patient comfort. Although closure with a continuous 8/0 vicryl is an option, we believe nylon causes less irritation than a braided absorbable suture with less tendency to suture erosion.

TWO-SITE PHACOTRABECULECTOMY TECHNIQUE

The phacoemulsification is performed through a clear corneal incision at the temporal limbus. We describe the technique for surgery on the right eye by a right-handed surgery. 1.

2.

3.

The sites of the trabeculectomy and phacoemulsification are determined according to whether the eye operated upon is the right or the left, and on which hand the surgeon is used to holding the phaco-probe. For example, a right-handed surgeon operating on a right eye could make the trabeculectomy in the upper nasal or upper temporal quadrant and the phaco would be done through temporal clear cornea. The trabeculectomy site is prepared to the point prior to entering the anterior chamber as described in the previous chapter or as described in the chapter on trabeculectomy. The phacoemulsification site is prepared as follows: At the 9 o’clock position (for the right-handed surgeon), a clear corneal incision is made with a 3.0 mm keratome. The tunnel is made in a self-sealing beveled fashion: the first part 908 to the corneal surface, than a section parallel to the corneal surface, till the whole anterior triangular part of the keratome is intra-corneal, then the posterior stroma and Descemet’s membrane are penetrated and the [email protected]

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4. 5.

8.

anterior chamber is entered. Phacoemulsification and intra-ocular lens implantation are completed. Viscoelastic is left in the anterior chamber. The trabeculectomy is then completed. The viscoelastic is removed from the anterior chamber and the corneal wound closed with one 10/0 nylon suture. At the end of surgery, there should be: a. No leak from the trabeculectomy site. b. The anterior chamber should be deep. c. The eye should not be firm to palpation. d. The bleb should easily be inflated by injection of BSS via the paracentesis site.

POSTOPERATIVE CARE

At the end of surgery, apply an antibiotic and steroid drops, and a protective shield. A patch is not needed as the lid function is normal owing to the absence of lid akinetic block (31). Combined antibiotic and steroid eye-drops are commenced, instilled every 2 h, with a shield for protection on the day of surgery. The antibiotic is stopped on day 4, the steroid is tapered after 6 weeks. The patient is seen the following day when the visual acuity, the IOP, and the bleb are assessed. See other chapters in this book for postoperative management of filtration surgery. 9.

COMMENTS 1.

2.

3.

4.

5.

6.

We do not recommend a tenonectomy when releasable sutures are employed, especially if MMC is used. If Tenon’s capsule is very hypertrophic or if laser suturelysis is planned, it can be excised. Small pupils: Many techniques are available to mechanically dilate small pupils, such as iris stretching with hooks, Grieshaber flexible iris hooks, or sphincterotomies. Stretching results in small tears to the iris sphincter and enlargement of the pupil. Iris hooks are sometimes useful in patients with thin irides such as seen in nanophthalmic eyes or those with pale irides and in patients who have been on miotics for many years. IOL types: Different IOLs exhibit different biocompatibility. Braga-Mele et al. reported that some types of silicone foldable lenses may prolong the inflammatory response after combined procedures compared with PMMA lenses (32). One study suggested that some acrylic lenses may be associated with IOP elevation, compared with silicone lenses (33). Acrylic lenses have a good record of biocompatibility, with a similar profile to PMMA lenses. The newer generation silicone lenses may be more biocompatible and thus one may consider their use if the surgeon prefers, however the literature does not support this. MMC—The use of MMC enhances the success rate of the phacotrabeculectomy, especially in patients who have risk factors for failure (34,35). We routinely use MMC in phacotrabeculectomies, as the cataract surgery itself is a risk factor for failure. MMC use is also associated with a higher incidence of blebitis, wound leaks, and hypotony (36,37). In our experience, flat chambers occur less commonly with phacotrabeculectomy, than with trabeculectomy, likely because of the support of the IOL and decrease in volume compared with the crystalline lens. Avascular cystic blebs seem to occur less often after phacotrabeculectomy compared with trabeculectomy alone. [email protected]

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TIPS 1.

2.

3.

4.

5.

6.

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Hydrodissection should always be done carefully. Excess fluid must be allowed to egress by pressing the nucleus down a little, allowing fluid to escape from the bag into the anterior chamber and from there out of the eye through the incision. This avoids rupture of the posterior capsule. (The pseudoexfoliative capsule is especially prone to this.) Phacoemulsification of the nucleus should be done using low vacuum, and 50% ultrasound, making short-deep grooves before cracking. This prevents interfering with the edge of capsulorrhexis and breaching the posterior capsule. It is important to make the groove deep rather than long to enable cracking of the nucleus. Leave sufficient lens material at the 6 o’clock position to enable grasping of the lens with aspiration and fragmentation with a chopper. Should you suspect a rent in the posterior capsule, then visco-dissection may help stem the defect and prevent the downward movement of the nucleus. If the vitreous does prolapse into the anterior chamber, an anterior vitrectomy should be done protecting as much capsule as possible. If capsular support is adequate, a posterior chamber IOL can be placed in the bag or in the sulcus. The lens should be placed with the haptics at right angles to the rent so that the IOL will be stable and not enlarge the hole in the capsule. When placement in the capsular bag is impossible, the IOL should be placed in the sulcus. Make sure to switch to an appropriately sized lens for sulcus fixation. In those rare cases that the capsular support is entirely lacking, the IOL may need to be sutured trans-sclerally, as an AC lens may not be the best choice in POAG. In the case of a nucleus dropped into the vitreous, do not chase it posteriorly. Resist the temptation to do a large vitrectomy through the anterior segment incision. Consult a vitreo-retinal surgeon, and have the nucleus retrieved from the vitreous. This should be done as soon as possible, but does not necessarily have to take place the same day. Extensive removal of the vitreous through the anterior segment can be dangerous and may result in retinal problems. Pseudoexfoliation: The zonules in pseudoexfoliation are often unstable. They can be stabilized by use of an intra-capsular tension ring. Another technique of stabilizing the lens is using Grieshaber hooks that grasp the bag at the capsulorrhexis edge, together with the iris edge. The downside of this technique is that the hooks can cause shallowing of the anterior chamber, making manipulation more difficult. Post-operative problems: Early post-operative pressure elevation is often related to retention of viscoelastics. Avoid release of scleral flap sutures at this time, as this may result in a flat anterior chamber with hypotony. Treat this IOP spike with ocular massage or a paracentesis.

COMPLICATIONS

See the relevant chapters on intra-operative, early, and late complications of filtration surgery. Complications of cataract surgery: Intra-operative complications and methods to avoid them are mentioned in the technique section. Early postoperative complications include wound leak, increased IOP, IOL dislocation, and endophthalmitis. The major late complications of cataract surgery include endophthalmitis, cystoid macular edema, [email protected]

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and retinal detachment. 1.

2.

3.

4.

5.

6.

Conjuntival wound leak: Can be treated by administering an aqueous suppressant and/or a bandage contact lens or by suturing the wound, if the wound edges dehisce. Most leaks around the sutures resolve within 48 h. We do not recommend a patch to manage this condition. Early pressure spikes should be treated by digital massage and/or topical antiglaucoma medication. Sutures should not be removed early, as this may lead to shallowing of the anterior chamber. Dislocation or malposition of the IOL. If there is capture of the IOL by the iris in the AC, then dilation of the pupil, with supine positioning of the patient, followed by pupil constriction with pilocarpine after the IOL has returned to its position is a good remedy to try. More severe dislocations of the lens usually need surgical intervention with repositioning with or without securing the lens with a suture through the iris or sclera. Acute post-operative endophthalmitis is rare. This should be suspected if there is markedly decreased vision, pain, extraordinary anterior chamber reaction, and cellular reaction in the vitreous. See relevant chapter in this book for management of blebitis or endophthalmitis. Cystic macular edema (CME) occurs in 1– 2% of patients and is clinically relevant in 10% of these cases. CME should be treated with a course oral acetazolamide 125 –250 mg TID – QID, and topical NSAID, for a few weeks. Beware of using topical NSAID in a patient with dry eyes, or a connective tissue disease as this can lead to corneal melting. Retinal detachment complicates 1 in 1000 cataract surgeries.

In summary, combined phacotrabeculectomy achieves short- and long-term pressure control in glaucoma patients undergoing cataract surgery. In our experience, there is a lower incidence of flat chambers after combined phacotrabeculectomy than after trabeculectomy alone. Ischemic and leaking blebs seem to be less common. Early post-operative pressure spikes are more easily controlled with combined phacotrabeculectomy compared with cataract surgery alone (1,38). Long-term pressure control is often better with combined phacotrabeculectomy than after cataract surgery alone (18,39,40). However, evidence suggests trabeculectomy alone probably achieves better long-term pressure control than combined phacotrabeculectomy (13 –15).

REFERENCES 1. 2. 3. 4. 5. 6.

Hopkins JJ, Apel A, Trope GE, Rootman DS. Early intraocular pressure after phacoemulsification combined with trabeculectomy. Ophthalmic Surg Lasers 1998; 29:273– 279. Porges Y, Ophir A. Surgical outcome after early intraocular pressure elevation following combined cataract extraction and trabeculectomy. Ophthalmic Surg Lasers 1999; 30:727– 733. Storr-Paulsen A, Bernth-Petersen P. Combined cataract and glaucoma surgery. Curr Opin Ophthalmol 2001; 12:41 – 46. Mamalis N, Lohner S, Rand AN, Crandall AS. Combined phacoemulsification, intraocular lens implantation, and trabeculectomy. J Cataract Refract Surg 1996; 22:467– 473. Perasalo R, Flink T, Lehtosalo J, Ralli R, Sulonen J. Surgical outcome of phaco-emulsification combined with trabeculectomy in 243 eyes. Acta Ophthalmol Scand 1997; 75:581 – 583. Beckers HJ, De Kroon KE, Nuijts RM, Webers CA. Phacotrabeculectomy. Doc Ophthalmol 2000; 100:43 – 47.

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9. 10. 11.

12. 13. 14.

15.

16. 17. 18.

19. 20. 21.

22.

23. 24. 25.

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Lederer CM Jr. Combined cataract extraction with intraocular lens implant and mitomycinaugmented trabeculectomy. Ophthalmology 1996; 103:1025 – 1034. Berestka JS, Brown SV. Limbus- versus fornix-based conjunctival flaps in combined phacoemulsification and mitomycin C trabeculectomy surgery. Ophthalmology 1997; 104:187 – 196. Honjo M, Tanihara H, Negi A et al. Trabeculotomy ab externo, cataract extraction, and intraocular lens implantation: preliminary report. J Cataract Refract Surg 1996; 22:601 – 606. Manners TD, Mireskandari K. Phacotrabeculectomy without peripheral iridectomy. Ophthalmic Surg Lasers 1999; 30:631– 635. Anand N, Menage MJ, Bailey C. Phacoemulsification trabeculectomy compared to other methods of combined cataract and glaucoma surgery. Acta Ophthalmol Scand 1997; 75:705 – 710. Arnold PN. No-stitch phacotrabeculectomy. J Cataract Refract Surg 1996; 22:253– 260. Bellucci R, Perfetti S, Babighian S, Morselli S, Bonomi L. Filtration and complications after trabeculectomy and after phaco-trabeculectomy. Acta Ophthalmol Scand Suppl 1997; 44 – 45. Caprioli J, Park HJ, Weitzman M. Temporal corneal phacoemulsification combined with superior trabeculectomy: a controlled study. Trans Am Ophthalmol Soc 1996; 94:451 – 463; discussion 463– 468. Derick RJ, Evans J, Baker ND. Combined phacoemulsification and trabeculectomy versus trabeculectomy alone: a comparison study using mitomycin-C. Ophthalmic Surg Lasers 1998; 29:707 – 713. Wyse T, Meyer M, Ruderman JM et al. Combined trabeculectomy and phacoemulsification: a one-site vs a two-site approach. Am J Ophthalmol 1998; 125:334– 339. Friedman DS, Jampel HD, Lubomski LH et al. Surgical strategies for coexisting glaucoma and cataract: an evidence-based update. Ophthalmology 2002; 109:1902 –1913. Gimbel HV, Meyer D, DeBroff BM, Roux CW, Ferensowicz M. Intraocular pressure response to combined phacoemulsification and trabeculotomy ab externo versus phacoemulsification alone in primary open-angle glaucoma. J Cataract Refract Surg 1995; 21:653 –660. Park HJ, Kwon YH, Weitzman M, Caprioli J. Temporal corneal phacoemulsification in patients with filtered glaucoma. Arch Ophthalmol 1997; 115:1375– 1380. Chen PP, Weaver YK, Budenz DL, Feuer WJ, Parrish RK II. Trabeculectomy function after cataract extraction. Ophthalmology 1998; 105:1928– 1935. Manoj B, Chako D, Khan MY. Effect of extracapsular cataract extraction and phacoemulsification performed after trabeculectomy on intraocular pressure. J Cataract Refract Surg 2000; 26:75 – 78. Crichton AC, Kirker AW. Intraocular pressure and medication control after clear corneal phacoemulsification and AcrySof posterior chamber intraocular lens implantation in patients with filtering blebs. J Glaucoma 2001; 10:38– 46. Casson R, Rahman R, Salmon JF. Phacoemulsification with intraocular lens implantation after trabeculectomy. J Glaucoma 2002; 11:429 – 433. Rebolleda G, Munoz-Negrete FJ. Phacoemulsification in eyes with functioning filtering blebs: a prospective study. Ophthalmology 2002; 109:2248 – 2255. Derbolav A, Vass C, Menapace R, Schmetterer K, Wedrich A. Long-term effect of phacoemulsification on intraocular pressure after trabeculectomy. J Cataract Refract Surg 2002; 28:425 – 430. Jampel HD, Friedman DS, Lubomski LH et al. Effect of technique on intraocular pressure after combined cataract and glaucoma surgery: an evidence-based review. Ophthalmology 2002; 109:2215 – 2224, quiz 2225, 2231. Lemon LC, Shin DH, Kim C, Bendel RE, Hughes BA, Juzych MS. Limbus-based vs fornixbased conjunctival flap in combined glaucoma and cataract surgery with adjunctive mitomycin C. Am J Ophthalmol 1998; 125:340 – 345. Shingleton BJ, Chaudhry IM, O’Donoghue MW, Baylus SL, King RJ, Chaudhry MB. Phacotrabeculectomy: limbus-based versus fornix-based conjunctival flaps in fellow eyes. Ophthalmology 1999; 106:1152– 1155.

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118 29.

30. 31. 32.

33. 34.

35.

36.

37. 38.

39. 40.

Lapid-Gortzak et al. Kozobolis VP, Siganos CS, Christodoulakis EV, Lazarov NP, Koutentaki MG, Pallikaris IG. Two-site phacotrabeculectomy with intraoperative mitomycin-C: fornix- versus limbusbased conjunctival opening in fellow eyes. J Cataract Refract Surg 2002; 28:1758 – 1762. Maberley D, Apel A, Rootman DS. Releasable “U” suture for trabeculectomy surgery. Ophthalmic Surg 1994; 25:251– 255. Trope GE, Buys YM, Flanagan J, Wang L. Is a tight patch necessary after trabeculectomy? Br J Ophthalmol 1999; 83:1006 – 1007. Braga-Mele R, Cohen S, Rootman DS. Foldable silicone versus poly(methyl methacrylate) intraocular lenses in combined phacoemulsification and trabeculectomy. J Cataract Refract Surg 2000; 26:1517 –1522. Lemon LC, Shin DH, Song MS et al. Comparative study of silicone versus acrylic foldable lens implantation in primary glaucoma triple procedure. Ophthalmology 1997; 104:1708 – 1713. Shin DH, Ren J, Juzych MS et al. Primary glaucoma triple procedure in patients with primary open-angle glaucoma: the effect of mitomycin C in patients with and without prognostic factors for filtration failure. Am J Ophthalmol 1998; 125:346– 352. Shin DH, Kim YY, Sheth N et al. The role of adjunctive mitomycin C in secondary glaucoma triple procedure as compared to primary glaucoma triple procedure. Ophthalmology 1998; 105:740 – 745. Yang KJ, Moster MR, Azuara-Blanco A, Wilson RP, Araujo SV, Schmidt CM. Mitomycin-C supplemented trabeculectomy, phacoemulsification, and foldable lens implantation. J Cataract Refract Surg 1997; 23:565 – 569. Zacharia PT, Schuman JS. Combined phacoemulsification and trabeculectomy with mitomycin-C. Ophthalmic Surg Lasers 1997; 28:739 – 744. Tezel G, Kolker AE, Kass MA, Wax MB. Comparative results of combined procedures for glaucoma and cataract: II. Limbus-based versus fornix-based conjunctival flaps. Ophthalmic Surg Lasers 1997; 28:551– 557. Anders N, Pham T, Holschbach A, Wollensak J. Combined phacoemulsification and filtering surgery with the ‘no-stitch’ technique. Arch Ophthalmol 1997; 115:1245– 1249. Storr-Paulsen A, Pedersen JH, Laugesen C. A prospective study of combined phacoemulsification-trabeculectomy versus conventional phacoemulsification in cataract patients with coexisting open angle glaucoma. Acta Ophthalmol Scand 1998; 76:696– 699.

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13 Ultrasound Biomicroscopy in Glaucoma Surgery Charles J. Pavlin and Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada

1. Introduction 2. Theoretical Considerations 3. Clinical Use of Ultrasound Biomicroscopy 3.1. Technique 3.2. Measuring Ocular Structures 4. Ultrasound Biomicroscopy in Glaucoma Surgery 4.1. Filtering Surgery 4.2. Assessing Filtration 4.3. Other Forms of Filtering Surgery 4.4. Blood in the Filter 4.5. Valves 4.6. Overfiltration 4.7. Malignant Glaucoma 5. Conclusion References

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INTRODUCTION

The use of ultrasound frequencies in the 40 –100 MHz range is a relatively new development in ultrasound imaging of the eye. This technique has been developed and refined at the University of Toronto over the past decade (1– 3). We have applied the term ultrasound biomicroscopy to this technique because of similarities to optical biomicroscopy, that is, the observation of living tissue at microscopic resolution. Such systems have provided resolution approaching that of optical microscopy, which is not available using any other imaging means. The ability to image subsurface phenomenon at microscopic resolution has brought new understanding to a variety of glaucoma entities. The ability to 119

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image the relationship of subsurface structures in real time can clarify mechanisms and aid in understanding complications in glaucoma surgery.

2.

THEORETICAL CONSIDERATIONS

Mechanical waves and vibrations occur over a wide range of frequencies called the acoustic spectrum. This spectrum extends from the audible range (10–20,000 Hz), with which we are all familiar, to the range of phonons (.1012 Hz) that comprise the vibrational states of matter. Higher frequency ultrasound provides higher resolution on the order of 20 – 40 mm, but the penalty to be paid is loss of penetration. All human tissues exhibit ultrasound attenuation coefficients that increase with frequency. The maximum penetration that could be achieved for a 10 MHz system is 50 mm. For a 60 MHz system, penetration is only 5 mm. The penetration limits prevent imaging of the posterior pole, but are sufficient to gain valuable information on events in the anterior segment of glaucoma entities (4 – 8).

3.

CLINICAL USE OF ULTRASOUND BIOMICROSCOPY

High resolution ultrasound scans used in this chapter have been performed with the original instrument constructed in our laboratories and the commercial instrument based on this design. In the laboratory, we use instruments with frequencies between 40 and 100 MHz. The commercial instrument uses a 50 MHz transducer, which is a good compromise between resolution and penetration. Several other instruments are currently available with frequencies varying from 20 to 50 MHz. 3.1.

Technique

The technique of eye examination using ultrasound biomicroscopy is similar to conventional B-scan examination of the anterior segment. A fluid immersion technique is required to provide an adequate standoff from the structures being examined. This is necessary to avoid distortion of the image close to the transducer and to prevent contact of the transducer with the eye. An eyecup is used to hold the eyelids open and allow more rapid patient preparation. These eyecups resemble those used in conventional ultrasound biometry, with a lip that slides under the eyelids and holds the cup in place. They differ from biometry eyecups in being shallower and having a distinct flair that allows a view of scanning head position. Figure 13.1 shows an examination being performed with one of these eyecups. A solution of 1% methyl cellulose is an excellent coupling medium with sufficient viscosity to prevent fluid loss during examination. Air bubbles have to be carefully avoided, both in the fluid and on the concave surface of the transducer. Unlike conventional 10 MHz B-scan, high frequency transducers are generally not covered by a membrane. A membrane would provide excessive sound attenuation and defeat the purpose of doing examinations at this frequency. Since the transducer is moving, contact with the eye and resulting corneal abrasion must be carefully avoided. The presence of an articulated arm is valuable in improving control of the scanning head. Careful attention must be paid to the screen image to prevent the scanning head from getting too close to the eye. In practice, we have found that contact with the eye has been an extremely rare occurrence. Any part of the eye that can be approached directly over the surface can be examined. The cornea and anterior segment structures are easily examined in any meridian. The most easily interpreted images are radial and orientated, so that the sclera is on the [email protected]

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Figure 13.1 Ultrasound biomicroscopic examination being performed in an eye cup filled with 1% methylcellulose.

left side of the screen. The conjunctiva, underlying sclera, and peripheral retina can be examined by rotating the eye as far as possible away from the region being examined. 3.2.

Measuring Ocular Structures

Ultrasound biomicroscopy expands our ability to accurately measure ocular structures (4,9). Measurement accuracy is improved by ultrasound biomicroscopy, which has an axial resolution 5– 10 times that of conventional 10 MHz ultrasound. We perform measurements on the screen during examination using electronic calipers. Stored images can be transferred to a computer and measured using imaging software. Measuring a structure accurately with ultrasound requires a knowledge of the speed of sound in the structure being examined. We have used a speed of sound of 1540 m/s to make the majority of measurements. This speed is used in conventional ultrasound scanning to measure distances in most tissue. Conventional ultrasound is capable of measuring relatively large distances such as anterior chamber depth. However, ultrasound biomicroscopy increases measurement accuracy of such structures because the shorter wavelength allows a finer positioning of end points and the exact measurement position can be defined more precisely. A number of ocular structures such as the ciliary body, sclera, and iris cannot be measured by other techniques because of inadequate resolution and the inability to differentiate these structures from adjacent tissue. 4. 4.1.

ULTRASOUND BIOMICROSCOPY IN GLAUCOMA SURGERY Filtering Surgery

Ultrasound biomicroscopy can be used to image at depth the surgical site of filtering surgery. Features that can be defined include the internal scleral ostium, the intrascleral [email protected]

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Figure 13.2 A medium reflective filtering bleb (B). The scleral opening (arrow) is imaged communicating with a intrascleral pathway.

pathway, and the filtering bleb itself (Fig. 13.2). The internal ostium usually appears as a wedge-shaped opening with clear fluid in the gap. The intrascleral pathway varies in size. At times, there is a distinct fluid filled pathway through the sclera that can be measured. At other times, this pathway can be discerned as a more subtle lower reflective line

Figure 13.3 (See color insert) A filtering bleb (B) contains clear spaces and low reflective episcleral tissue. [email protected]

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Figure 13.4 In pupillary block, the iris shows anterior bowing narrowing the angle (arrow) and a small iris lens contact. S, sclera, C, cornea, I, iris, CP, ciliary processes, z, zonule, L, lens.

intrasclerally without obvious separation of the superior and inferior scleral walls. The intrascleral pathway can generally be traced back to the superficial entry point below the bleb. The bleb itself is quite variable in appearance. The height of the bleb can be measured from the conjunctival surface, to the highly reflective underlying sclera. The internal reflectivity can vary. The usual appearance is medium reflective tissue interspersed with some clear fluid spaces (Fig. 13.3). The medium reflective areas indicate the fluid filled, spongy episcleral tissue. Rarely is the entire bleb filled with clear fluid

Figure 13.5 In plateau iris the ciliary processes (CP) are forward supporting the peripheral iris producing peripheral angle narrowing (arrow). [email protected]

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Figure 13.6 Anterior synechiae show an angled appearance of the iris with attachment to the trabecular meshwork (arrow).

except in the case of an encapsulated bleb. This type of bleb is usually thin walled and can be imaged by transillumination clinically. Other features that can be imaged include the state of the surrounding angle, the presence of anterior synechiae, and the relationship of residual iris and ciliary processes to the internal ostium. The angle appearance is distinctive in pupillary block (Fig. 13.4), plateau iris (Fig. 13.5), and anterior synechia (Fig. 13.6). In the case of the pseudophakic eye, the position of the optics and haptics and their relationship to the surgical site can be imaged (Fig. 13.7).

Figure 13.7

A case of an anterior chamber IOL with haptics buried in the angle (arrow). [email protected]

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Assessing Filtration

Ideally, ultrasound biomicroscopy could be used to predict the functional status of filtering blebs and to help ascertain the site of failure of filtration. This is often possible, but not always. Yamamoto et al. (10) classified blebs into four categories: low reflective, high reflective, encapsulated, and flattened. They found that good control was generally associated with low reflective blebs and poor control with encapsulated and flattened blebs. McWhae and Crichton (11) used a blinded study to predict filtering function in postsurgical eyes. They used the presence of a patent filtration pathway from the anterior chamber to the bleb and the presence of a bleb space to indicate good bleb function. Evidence of obstruction of the internal orifice, obstruction of the trapdoor flap, and absence of bleb cavity were evidence of poor function. Several cases did not fit clearly into these categories. They found a correlation of 86% between ultrasound biomicroscopy grade and clinical findings. Correlation was weakest in those in which medication was still required to control intraocular pressure. Other authors have found varied correlation of ultrasound biomicroscopy appearance and function (12 – 15). 4.3.

Other Forms of Filtering Surgery

Various types of nonpenetrating filtering surgery have evolved over the past several years. These include deep sclerectomy with collagen implant and viscocanalostomy. Ultrasound biomicroscopy has been used to image these entities (16 – 18). In deep sclerectomy with implants, the presence of a filtering bleb, a supraciliary hypoechoic area, and hyporeflectivity of the scleral tissue around the decompression space have been associated with good control. In viscocanalostomy, the presence of a nonreflective scleral chamber has been associated with good glaucoma control. 4.4.

Blood in the Filter

Autologous injection of blood has been used to prevent overfiltration. In eyes that have had this procedure, ultrasound biomicroscopic imaging shows the presence of red cells in the passageways of the filtering procedure (Fig. 13.8). Red cells can be imaged in the bleb, the intrascleral pathway, and the anterior chamber. 4.5.

Valves

Various valves have been used to improve the results of filtering surgery in difficult cases. Ultrasound biomicroscopy can be a valuable means of detecting the position of these valves, and to determine the cause of nonfunctioning valves. The valve itself is easily imaged in its path into the anterior chamber because of the high reflectivity of the plastic used, and its distinctive tubular appearance. The position of the tip of the valve and its relationship to intraocular structures is easily determined (Fig. 13.9). Causes of nonfiltration that can be detected by imaging include failure of the valve to enter the anterior chamber, occlusion of the tip of the valve by iris, or obstruction of the tip of the valve by other materials. 4.6.

Overfiltration

In patients with shallow chambers and hypotony following filtering surgery, several distinct features can be imaged with ultrasound biomicroscopy. The shallowing of the chamber can be imaged and quantitatively measured. A very common finding is the [email protected]

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Figure 13.8 Ultrasound biomicroscopy image of filtering bleb with injected blood (B) above the sclera (S).

presence of a supraciliary effusion. The appearance of an effusion consists of a separation of the ciliary body from the overlying sclera (Fig. 13.10). The effusion extends forward close to the scleral spur. Such an effusion can be part of a larger choroidal effusion or be confined to the ciliary body region. The space between the ciliary body and sclera is low reflective, and crossed by thin lines representing cross-sections of the thin connective tissue septae that join the ciliary body and sclera, which are now expanded by

Figure 13.9 (See color insert) Ultrasound biomicroscopy image of Ahmed valve. The iris is partially obstructing the opening of the tube (arrow). [email protected]

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Figure 13.10 A supraciliary effusion (E). The effusion appears as a low reflective space between the pars plana and sclera with cross sections of tissue septa.

fluid. The ciliary processes and iris are imaged as being rotated forward around the scleral spur. Grigera et al. (19) presented 15 patients with flattening of the anterior chamber following filtering surgery. All patients were low or normotensive when examined, and

Figure 13.11 Ultrasound biomicroscopy image cyclodialysis cleft. The ciliary body is disinserted from the scleral spur (arrow). [email protected]

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Figure 13.12 (See color insert) Ultrasound biomicroscopy image of anterior chamber in malignant glaucoma. The anterior chamber (AC) is extremely shallow. C, cornea, L, lens.

all patients displayed a supraciliary effusion on ultrasound biomicroscopy. These effusions were not detected clinically and were not apparent on B-scan in a large number. These findings show that supraciliary effusions are an integral part of the sequelae of overfiltration, and that detection of these effusions is dependant on the sophistication of the method one uses to look for them (20). Other causes of possible hypotony can be imaged and ruled out. This includes wound leaks, particularly at cataract sites with combined or sequential procedures (21).

Figure 13.13 (See color insert) Ultrasound biomicroscopic image in malignant glaucoma. The iris (I) and ciliary processes (CP) are rotated forward closing the angle. The lens is forward. There is a supraciliary effusion (E) present. C, cornea, S, sclera. [email protected]

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Such sites are indicated by a gap in the surgical incision site internally, possibly combined with a shallow bleb at the surgical site. Cyclodialysis caused by surgical procedures can be imaged as a separation of the ciliary body from the scleral spur (22) and the extent of the dialysis measured (Fig. 13.11). In patients with inflammatory conditions, ciliary body membranes can be detected if present, and their relationship to the ciliary processes and presence of traction ascertained. 4.7.

Malignant Glaucoma

The ultrasound biomicroscopic appearance in the acute stage of malignant glaucoma shows several distinct features. The ciliary processes and iris are rotated forward closing the angle. The chamber is extremely shallow with the anterior position of the lens (Fig. 13.12). A supraciliary effusion is present (Fig. 13.13). We have previously shown that supraciliary effusions are found by ultrasound biomicroscopy (23), and postulated that effusions may have a major role in the clinical presentation of malignant glaucoma. We have subsequently examined a number of patients with malignant glaucoma and found supraciliary effusions, in the majority, in the acute phase. Other authors have reported similar findings (24). Supraciliary effusions can occur in other settings such as venous obstruction (e.g., vein occlusions and retinal detachment surgery) and following inflammatory episodes (25 –28). Some of these patients develop angle closure glaucoma characterized by shallow anterior chambers. Ultrasound biomicroscopy in these cases shows effusions with anterior rotation of the ciliary processes and iris. This is identical to the ultrasound biomicroscopic appearance in cases of malignant glaucoma. The clinical presentation is essentially identical to that of malignant glaucoma with shallow or flat anterior chambers. Medical treatment that includes hypotensive agents and cycloplegics is the same. The similarity of the clinical presentation of malignant glaucoma and effusion-based glaucoma has been noted in the past. These two entities, however, have been divided essentially by the presence or absence of an effusion as detected by the methods available at the time. If the effusion was not detected by clinical or B-scan examination, then the clinical case was assumed to be caused by aqueous misdirection. The increased precision of ultrasound biomicroscopy in detecting these effusions forces us to reassess our classification of these entities (29). Further clinical research will be required in future to fully verify these mechanisms. Ultrasound biomicroscopy will be an important tool as it is the only method available at this time that consistently detects small effusions. A greater understanding of the sequence of events in malignant glaucoma should lead to an improved treatment approaches. 5.

CONCLUSION

Ultrasound biomicroscopy allows subsurface imaging of various sequelae in glaucoma surgery. This imaging method can be helpful in determining the cause of underfiltration and overfiltration, and in the diagnoses and follow up of complications. REFERENCES 1.

Pavlin CJ, Sherar MD, Foster FS. Subsurface ultrasound microscopic imaging of the intact eye. Ophthalmology 1990; 97:244– 250. [email protected]

130 2. 3. 4. 5. 6. 7. 8.

9.

10. 11. 12.

13.

14.

15.

16.

17.

18.

19.

20. 21. 22. 23.

Pavlin and Trope Pavlin CJ, Harasiewicz K, Sherar MD, Foster FS. Clinical use of ultrasound biomicroscopy. Ophthalmology 1991; 98:287– 295. Pavlin CJ, Foster FS. Ultrasound Biomicroscopy of the Eye. New York: Springer Verlag Inc, 1994. Pavlin CJ, Harasiewicz K, Foster FS. Ultrasound biomicroscopy of anterior segment structures in normal and glaucomatous eyes. Am J Ophthalmol 1992; 113:381 – 389. Pavlin CJ, Ritch R, Foster FS. Ultrasound biomicroscopy in plateau iris syndrome. Am J Ophthalmol 1992; 113:390 – 395. Potash SD, Tello C, Liebmann J, Ritch R. Ultrasound biomicroscopy in pigment dispersion syndrome. Ophthalmology 1994; 101:332 –339. Pavlin CJ, Foster FS. Plateau iris syndrome: changes in angle opening associated with dark, light, and pilocarpine administration. Am J Ophthalmol 1999; 128:288 – 291. Woo EK, Pavlin CJ, Slomovic A, Taback N, Buys YM. Ultrasound biomicroscopic quantitative analysis of light– dark changes associated with pupillary block. Am J Ophthalmol 1999; 127:43 – 47. Tello C, Liebmann J, Potash SD, Cohen H, Ritch R. Measurement of ultrasound biomicroscopy images: intraobserver and interobserver reliability. Invest Ophthalmol Vis Sci 1994; 35:3549 – 3552. Yamamoto T, Sakuma T, Kitazawa Y. An ultrasound biomicroscopic study of filtering blebs after mitomycin C trabeculectomy. Ophthalmology 1995; 102(12):1770 – 1776. McWhae JA, Crichton AC. The use of ultrasound biomicroscopy following trabeculectomy. Can J Ophthalmol 1996; 31(4):187– 191. Avitabile T, Russo V, Uva MG, Marino A, Castiglione F, Reibaldi A. Ultrasoundbiomicroscopic evaluation of filtering blebs after laser suture lysis trabeculectomy. Ophthalmologica 1998; 212(suppl 1):17– 21. Martinez-Bello C, Rodriguez-Ares T, Pazos B, Capeans C, Sanchez-Salorio M. Changes in anterior chamber depth and angle width after filtration surgery: a quantitative study using ultrasound biomicroscopy. J Glaucoma 2000; 9(1):51 – 55. Jinza K, Saika S, Kin K, Ohnishi Y. Relationship between formation of a filtering bleb and an intrascleral aqueous drainage route after trabeculectomy: evaluation using ultrasound biomicroscopy. Ophthalmic Res 2000; 32(5):240 – 243. Ito K, Matsunaga K, Esaki K, Goto R, Uji Y, Supraciliochoroidal fluid in the eyes indicates good intraocular pressure control despite absence of obvious filtering bleb after trabeculectomy. J Glaucoma 2002; 11(6):540 – 542. Chiou AG, Mermoud A, Underdahl JP, Schnyder CC. An ultrasound biomicroscopic study of eyes after deep sclerectomy with collagen implant. Ophthalmology 1998; 105(4): 746– 750. Marchini G, Marraffa M, Brunelli C, Morbio R, Bonomi L. Ultrasound biomicroscopy and intraocular-pressure-lowering mechanisms of deep sclerectomy with retculated hyaluronic acid implant. J Cataract Refract Surg 2001; 27(4):507 – 517. Negri-Aranguren I, Croxatto O, Grigera DE. Midterm ultrasound biomicroscopy findings in eyes with successful viscocanalostomy. J Cataract Refract Surg 2002; 28(5): 752– 757. Grigera D, Moreno C, Fava O, Girado SG. Ultrasound biomicroscopy in eyes with anterior chamber flattening after trabeculectomy. Can J Ophthalmol 2002; 37(1):27 – 32 (discussion 32– 33). Sugimoto K, Ito K, Esaki K, Miyamura M, Sasoh M, Uji Y. Supraciliochoroidal fluid at an early stage after trabeculectomy. Jpn J Ophthalmol 2002; 46(5):548 – 552. Sicco thoe Schwartzenburg GW, Pavlin CJ. Occult wound leak diagnosed by ultrasound biomicroscopy in patients with post-operative hypotony. J Cataract Refract Surg 2001. Gentile RC, Pavlin CJ, Liebmann JM et al. Diagnosis of traumatic cyclodialysis by ultrasound biomicroscopy. Ophthalmic Surg Lasers 1996; 27:97– 105. Trope GE, Pavlin CJ, Bau A, Baumal CR, Foster FS. Malignant glaucoma: clinical and ultrasound biomicroscopic characteristics. Ophthalmology 1994; 101:1030 – 1035.

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Ultrasound Biomicroscopy 24. 25. 26.

27. 28.

29.

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Liebmann JM, Weinreb RN, Ritch R. Angle closure glaucoma associated with occult annular ciliary body detachment. Arch Ophthalmol 1998; 116:731 – 735. Fourman S. Angle closure glaucoma complicating cilio-choroidal detachment. Ophthalmology 1989; 96:646 – 653. Pavlin CJ, Easterbrook M, Harasiewicz K, Foster FS. An ultrasound biomicroscopic analysis of angle-closure glaucoma secondary to ciliochoroidal effusion in IgA nephropathy. Am J Ophthalmol 1993; 116:341 – 345. Pavlin CJ, Rutnin SS, Devenyi R, Wand M, Foster FS. Supraciliary effusions and ciliary body thickening after scleral buckling procedures. Ophthalmology 1997; 104:433– 438. Yuki T, Kimura Y, Nanbu S, Kishi S, Shimizu K. Ciliary body and choroidal detachment after laser photocoagulation for diabetic retinopathy: a high-frequency ultrasound study. Ophthalmology 1997; 104:1259– 1264. Pavlin CJ. The importance of supraciliary effusions in the pathophysiology of malignant glaucoma. Can J Ophthalmol 2002; 37(1) (discussion 32 – 33).

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Section II: Management of Complications

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14 Overview: An Approach to the Diagnosis of Early Postoperative Complications Yvonne M. Buys University Health Network and University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada

Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada

1. Introduction 1.1. Formed Anterior Chamber and High Intraocular Pressure 1.2. Formed Anterior Chamber and Low Intraocular Pressure 1.3. Shallow/Flat Anterior Chamber and High Intraocular Pressure 1.4. Shallow/Flat Anterior Chamber and Low Intraocular Pressure

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INTRODUCTION

The success of filtration surgery depends greatly on the early recognition and appropriate management of postoperative complications. Although the list of potential complications following filtration surgery is extensive, in most scenarios a short differential can be obtained by knowing only three key elements; anterior chamber depth, intraocular pressure, and bleb status. Figure 14.1 details a useful algorithm to assist in correctly diagnosing complications in the early postoperative period. The first differentiation occurs with the anterior chamber, which is either formed or shallow/flat. The second is the intraocular pressure which is either elevated or low and final assessment is the filtration bleb. Using this systematic approach, complications during the early postoperative period are easy to diagnose.

1.1.

Formed Anterior Chamber and High Intraocular Pressure

Following Fig. 14.1 to the left, in the presence of a formed anterior chamber, the next differentiation occurs with the intraocular pressure, which will be high, normal or low. In the case of a formed anterior chamber and elevated intraocular pressure, the bleb status will narrow the differential. If the bleb is elevated, the intraocular pressure high, 135

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Blocked Osteium

nonpatent

iridectomy

Aqueous Shutdown

No Seidel

Wound Leak

Seidel positive

check for leak

Pupil Block

flat/shallow

high

bleb

low

Aqueous Misdirection

check for leak

shallow/flat

Aqueous Shutdown

Suprachoroidal Hemorrhage

No Seidel

Wound Leak

Seidel positive

Overfiltration

elevated

IOP

shallow/flat

patent

mass

bleb formed or shallow funduscopy no mass

Anterior Chamber

Figure 14.1 Early postoperative trabeculectomy complications—diagnostic considerations.

Tight Flap

formed

bleb

low

Expected Outcome or Overfiltration (IOP<4mmHg)

Osteium occluded

gonioscopy

Encysted bleb

Osteium patent

flat

formed

bleb

high

IOP

formed

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and the anterior chamber formed, the most likely diagnosis is an encysted bleb. Another possibility is that the bleb is formed with something other than aqueous, for example, viscoelastic. If the anterior chamber is formed, intraocular pressure high, and the bleb flat, then aqueous is not flowing through the trabeculectomy either because the scleral-flap sutures are too tight or there is a physical blockage to filtration, such as blood, iris, or vitreous in the osteium. Gonioscopy will exclude vitreous in the osteium. If the osteium is clear, then digital ocular massage will usually establish the flow of aqueous around the flap edges and lower the intraocular pressure. If ocular massage is unsuccessful, then suture lysis or release is the next step. 1.2.

Formed Anterior Chamber and Low Intraocular Pressure

Continuing on the left side of Fig. 14.1, the next group of scenarios involves a formed anterior chamber and low intraocular pressure. Again, the knowledge of the bleb status will lead to the correct diagnosis. In the case of a formed anterior chamber, low intraocular pressure, and a formed bleb, the diagnosis is overfiltration (,4 mmHg) or the expected outcome (if the intraocular pressure is within the target range). In the case of a formed anterior chamber, low intraocular pressure, and a flat bleb, one must carefully look for a conjunctival wound leak. In the absence of a leak, the diagnosis is aqueous shutdown. 1.3.

Shallow/Flat Anterior Chamber and High Intraocular Pressure

Proceeding with the right side of Fig. 14.1, with a shallow/flat anterior chamber, the next point of differentiation is the intraocular pressure. In the case of a shallow/flat anterior chamber and an elevated intraocular pressure, funduscopy will diagnose a suprachoroidal hemorrhage. The clinical presentation of a suprachoroidal hemorrhage is usually dramatic and will also include severe pain. In the absence of a suprachoroidal hemorrhage one must determine whether the iridectomy is patent. In the case of a shallow/flat anterior chamber, elevated intraocular pressure, normal funduscopy, and absence of a patent iridectomy, the most likely diagnosis is pupil block. In the presence of a shallow/flat anterior chamber, elevated intraocular pressure, no suprachoroidal hemorrhage, and patent iridectomy, the diagnosis is aqueous misdirection. It is important to understand that an elevated intraocular pressure in the scenario of a shallow/flat anterior chamber could be 8 mmHg. The causes of a flat anterior chamber are either hypotony or posterior pressure. For hypotony to be the cause of a shallow/flat anterior chamber, the intraocular pressure should be ,4 mmHg. If the anterior chamber is shallow/flat and the intraocular pressure is .4 mmHg one should consider posterior pressure, such as aqueous misdirection, pushing the iris –lens diaphragm forward creating a shallow/flat anterior chamber. The diagnosis of early aqueous misdirection can be easily missed when the intraocular pressure is in the single digits. 1.4.

Shallow/Flat Anterior Chamber and Low Intraocular Pressure

The definition of a low intraocular pressure which is unable to maintain an anterior chamber is usually ,4 mmHg. A possible exception occurs when the anterior chamber is flat, with lens corneal touch, where tonometry can be inaccurate. When the anterior chamber is shallow/flat and the intraocular pressure is low, the next assessment is the filtration bleb. The combination of a shallow/flat anterior chamber, low intraocular pressure, and formed bleb is consistent with overfiltration. In the case of a shallow/flat [email protected]

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anterior chamber, low intraocular pressure, and shallow/flat bleb one must carefully look for a wound leak. In the absence of a leak, funduscopy or a B scan will likely reveal a choroidal. Using this algorithm, the diagnosis of an early postoperative complication following trabeculectomy surgery is simplified. The following chapters will deal with the diagnosis and management of these and other complications in detail.

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A. Management of High Intraocular Pressure with a Deep Chamber

15 Massage: Techniques and Complications Yvonne M. Buys University Health Network and University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada

Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada

1. Introduction 2. Indications 3. Mechanism and Technique 3.1. Surgeon Technique 3.2. Patient Technique 4. Complications 4.1. Surgeon Induced 4.2. Patient Induced 5. Outcome 6. Conclusion References

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INTRODUCTION

Ocular massage is likely the most commonly used maneuver to improve the surgical success in the postoperative management of trabeculectomies. The intended purpose of ocular massage is to encourage the flow of aqueous humor through the ostium and into the subconjunctival space thus elevating and enlarging the filtration bleb, lowering intraocular pressure and preventing any obstructions to filtration from becoming permanent. 2.

INDICATIONS

The main role of ocular massage is in the early postoperative period when the patient presents with underfiltration leading to elevated intraocular pressure in the presence of a flat bleb and deep anterior chamber (Fig. 14.1 from Chapter 14). The goal of massage is to either establish a bleb or identify a failing bleb. When the conjunctival wound 139

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becomes stable loosening of the scleral flap with either suture lysis or release, in possible combination with digital ocular massage, should be considered as a more definitive approach to establish filtration.

3.

MECHANISM AND TECHNIQUE

Despite the popularity of ocular massage, there is no consensus among physicians regarding the technique, duration, and frequency (1). A survey of glaucoma specialists in the US found that all respondents performed ocular massage; however, there was tremendous variation in technique and only 25% could cite any literature supporting ocular massage to actually improve bleb function (1). The most popular technique is to apply focal, steady pressure to the globe or lid while the patient is looking up (1). The proposed mechanism is to temporarily increase intraocular pressure by pressing on the globe thus forcing aqueous through the filtration site (Fig. 15.1) (2). Variations on this technique include applying focal pressure to the conjunctiva at the radial edge of the scleral flap using an anesthetic moistened cotton tip applicator (3) or the round end of a Schocket doubleended scleral depressor (4). This variation attempts to misalign the flap edges to create a space for aqueous to flow and at the same time disrupt any fibrous membranes or flush out any debris which may be occluding the trabeculectomy (Fig. 15.2) (4). Using the Goldmann applanation tonometer to intermittently apply pressure of 50– 60 mmHg to the globe has also been reported to decrease intraocular pressure and elevate the bleb

Figure 15.1 Digital pressure applied 1808 away from the bleb with the patient looking. By temporarily increasing intraocular pressure aqueous is forced through the filtration site (insert). [email protected]

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Figure 15.2 Digital pressure applied to the edge of bleb with the patient looking down creating a misalignment of the scleral flap edge forming a space for aqueous to flow (insert). This can disrupt fibrous membranes in the scleral flap or flush out any debris which may be preventing filtration.

(5). Quaranta has described a hand held device which consists of two small pistons that alternately exert pressure on each side of the bleb area through the upper lid (6). In a study of 50 trabeculectomies, this device was found to be effective in 46 cases with no response in 4 cases. No complications were reported in this series (6). As previously mentioned, ocular massage is usually performed in the early or intermediate postoperative period. Immediately following surgery, it is best done by the physician, however, in the later stages patients may be instructed to perform this maneuver. Despite careful instructions, some patients may be unable to massage correctly and there have been reports of complications following patients massaging their own eye (7 –11). Generally, most physicians will vary the frequency of ocular massage according to the bleb status (1). The length of time that compression is applied is usually determined by the bleb response. In a survey of glaucoma, specialists performing ocular massage 42% applied compression for 2 –5 s and 33% for 10– 20 s. Ocular massage was reported to be continued according to the bleb status with 50% of respondents continuing massage for 1 month (1).

3.1.

Surgeon Technique

Generally, Dr. Buys performs digital ocular massage in the first few postoperative days when the intraocular pressure is above the target pressure due to either hemorrhage or inflammatory debris blocking the ostium or a tight scleral flap. It is important to ensure by gonioscopy that neither iris nor vitreous is blocking the ostium because ocular massage in this scenario could lead to prolapse. At the slit-lamp, Dr. Buys instructs the patient to look down and through the upper lid applies gentle steady pressure adjacent to the bleb keeping an eye on both the bleb, for signs of elevation, and the anterior chamber, for signs of shallowing (Fig. 15.2). The intraocular pressure is measured [email protected]

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following this procedure and if not sufficiently lowered massage is repeated. Dr. Trope applies intermittent pressure, every 2 –3 s, at the tip of the scleral flap (if triangular) or next to a radial incision depending on the patient’s ocular sensitivity.

3.2.

Patient Technique

In the later postoperative period (day 3 on) with a failing bleb despite suture lysis or release, use of antimetabolites, or needling, digital ocular massage may be taught to the patient. Generally, Dr. Buys reserves this to patients who exhibit a response to massage in the office. When instructing patients on self massage, Dr. Buys prefers they do not press near the bleb and instead instructs the patient to look up and using the pad of their index finger to apply gentle steady pressure through the lower lid into the globe (Fig. 15.1). Dr. Buys recommends applying steady pressure for 10 s, followed by a rest period of 10 s, then by pressure for a further 10 s. Dr. Buys has the patient perform massage in the office and measures the intraocular pressure before and after to establish proper technique. It is important to remain vigilant for complications and stress that the patient report any change in ocular status immediately. The number of applications of massage per day will vary depending on the bleb status and response to massage, but typically it is recommended four times a day. Dr. Trope follows a similar practice pattern but instructs patients to massage intermittently (every 1 –2 s for 10 s) through the upper lid.

4.

COMPLICATIONS

There are several reports in the literature of complications secondary to ocular massage including wound dehiscence, hypotony and related complications, shallowing of the anterior chamber (12), hyphema, iris incarceration (8), suture rupture, bleb rupture (7), endophthalmitis secondary to bleb rupture (8), subretinal hemorrhage (10), choroidal hemorrhage, late wound dehiscence in a corneal graft (9), and corneal ectasia (11).

4.1.

Surgeon Induced

The most commonly encountered surgeon induced complications include shallowing or flattening of the anterior chamber and hemorrhage from the ostium. In the case of shallowing of the anterior chamber usually waiting a few minutes is sufficient to allow the anterior chamber to spontaneously reform. If the anterior chamber remains shallow cycloplegics should be considered. Hemorrhage from the ostium is also relatively common and generally resolves with conservative management. It is important to inform the patient prior to massage that their visual acuity may be temporarily reduced owing to hypotony or hemorrhage. Iris incarceration can be induced by either the surgeon or the patient. Prior to performing digital ocular massage gonioscopy is important to confirm that iris is not blocking the ostium because massage in this scenario will likely result in iris prolapse. Poor surgical technique can contribute to this complication. A large basal, full thickness, peripheral iridectomy, and a slightly anterior trabeculectomy decrease the risk of this complication (8). There is also the theoretical risk of worsening of glaucoma secondary to the temporarily marked increase in intraocular pressure, well over 100 mmHg at the time of massage (13), and decreased blood flow during massage (14). It is for this reason, Dr. Trope applies intermittent as opposed to continuous pressure during massage. [email protected]

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Patient Induced

Most of the cited complications secondary to digital ocular massage occur while the patient performs this maneuver (7 –11). For example, in the case of corneal ectasia this patient reported performing aggressive massage (.1 min, 50 times a day). However, this patient also received 5-fluorouracil (10 mg for 14 days). Both of these factors likely contributed to this complication (11). Prospective studies on ocular massage reported no complications in 144 trabeculectomies (6,12,15,16) suggesting that the incidence of complications is relatively low.

5.

OUTCOME

There are no reports regarding ocular massage enhancing or predicting success in the early postoperative period. In the late postoperative period, at least 3 months following trabeculectomy, there are two studies evaluating the effectiveness of digital ocular massage (12,16). One study evaluated the acute effect on intraocular pressure in 15 trabeculectomies 3 –6 months following surgery and recorded a mean decrease in intraocular pressure of 51% from baseline or 6.5 mmHg. The intraocular pressure remained .2 mmHg lower than baseline for 90 min in 50% of cases and .180 min in 30% (12). A 6 month randomized trial on the long-term effectiveness of digital ocular massage on elevated intraocular pressure in the late postoperative period found no effect following ocular compression performed for 10 s followed by a 5 s rest then a further 10 s of pressure three times daily on 15 patients and 14 controls (16). This suggests that massage is effective up to but not more than 6 months. We recommend patients to discontinue massage at 6 months postsurgery.

6.

CONCLUSION

Despite the scarcity of controlled randomized trials, digital ocular massage remains an important adjunct to trabeculectomy surgery. The main role of ocular massage is to establish flow of aqueous through the ostium in the early postoperative period. In the intermediate postoperative period, digital ocular massage should be used in conjunction with other techniques including laser suture lysis, releasable sutures, antimetabolites, antiinflammatory agents, and bleb needling to improve bleb function. The role of digital ocular massage in the late postoperative period is less well established (12,16). Finally, although ocular massage is usually considered an innocuous procedure it is not devoid of complications. For this reason, in the early postoperative period this maneuver is best left to the physician. However, when the conjunctival and scleral wounds become stable, patients can be instructed on the technique and at the same time be informed to immediately report any change in their ocular status. REFERENCES 1. 2. 3.

Wieland M, Spaeth GL. Use of digital compression following glaucoma surgery. Ophthalmic Surg 1988; 19:350 –352. Kane H. What we know about digital ocular massage. Rev Ophthalmol 1998; 5:65 – 73. Traverso CE, Greenidge KC, Speath GL, Wilson RP. Focal pressure: a new method to encourage filtration after trabeculectomy. Ophthalmic Surg 1984; 15:62 –65. [email protected]

144 4. 5. 6. 7. 8. 9. 10.

11.

12. 13. 14. 15.

16.

Buys and Trope Parrow KA, Shin DH. Enhancing filtration in the early postoperative trabeculectomy refractory to digital massage. Ophthalmic Surg 1990; 21:401 – 403. Kalvin NH. The use of applanation tonometer massage in formation of filtering blebs. Eye Ear Nose Throat Monograph 1970; 49:275 – 276. Quaranta L. A new device for ocular massage after trabeculectomy. Acta Ophthalmol Scand 1999; 77:355 – 356. Miller GR, Kurstin J. Ruptured filtering bleb after ocular massage. Arch Ophthalmol 1966; 76:363. Segrest DR, Ellis PP. Iris incarceration associated with digital ocular massage. Ophthalmic Surg 1981; 12:349 –351. MacRae SM, VanBuskirk EM. Late wound dehiscence after penetrating keratoplasty in association with digital massage. Am J Ophthalmol 1986; 102:391. Ruderman JM, Jampol LM, Krueger DM. Visual loss caused by subretinal hemorrhage and rupture of Bruch’s membrane after digital ocular massage. Am J Ophthalmol 1988; 106:493 – 494. Baldassare RD, Brunette I, Desjardins DC, Amyot M. Corneal ectasia secondary to excessive ocular massage following trabeculectomy with 5-fluorouracil. Can J Ophthalmol 1996; 31:252 – 254. Kane H, Gaasterland DE, Monsour M. Response of filtered eyes to digital ocular pressure. Ophthalmology 1997; 104:202– 206. Honda Y, Kawano S, Negri A, Koizumi K. Pressure profile of ophthalmic surgical procedures: an experimental study on the rabbit eye. Ophthalmic Surg Lasers 1982; 13:387– 391. Jay WM, Aziz MZ, Green K. Effect of digital massage on intraocular pressure and ocular and optic nerve blood flow. Acta Ophthalmol 1986; 64:58 – 62. Johnstone MA, Ziel CJ, Wellington DP. Effect of digital pressure (DP) on intraocular pressure (IOP) and anterior chamber depth (ACD) in the early postoperative period after filtering surgery. Invest Ophthalmol Vis Sci 1994; 35S:1420. Henderer JD, Heeg MC, Spaeth GL, Moster MR, Myers JS, Schmidt CM, Katz LJ, Steinmann WC. A randomized trial of the long-term effects of digital ocular compression in the late postoperative period. J Glaucoma 2001; 10:266– 270.

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16 Glaucoma Suture Lysis Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada

1. 2. 3. 4.

Introduction Indications Timing Methods 4.1. Laser Settings 4.2. Outcome 5. Complications 5.1. Immediate Complications 5.2. Early Lysis Complications 5.3. Late Lysis Complications 6. Conclusion References

1.

145 145 145 146 147 147 147 147 147 148 148 148

INTRODUCTION

Glaucoma suture lysis is widely used postoperatively to achieve target pressures (1 – 3). The procedure is easy to perform but is associated with significant complications in a minority of patients. These complications should be borne in mind before suture lysis is performed (3,4). 2.

INDICATIONS 1. 2. 3.

3.

Uncontrolled postoperative intraocular pressure (IOP) despite ocular massage; IOP over target; low bleb, failing bleb, or inadequately filtering bleb.

TIMING

Suture lysis should be delayed 48 –72 h if possible. Very early suture lysis predisposes to excessive filtration and hypotony. Suture lysis is most effective when performed from 145

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day 4 to week 3 after trabeculectomy; however, recent studies suggest that suture lysis can be effective for up to 21 weeks after trabeculectomy when MMC has been added to the procedure (5,6). We find that suture lysis is often ineffective after week 4 even when MMC has been utilized.

4.

METHODS

A Hoskins lens is our preferred lens for suture lysis (2). This lens increases magnification by 1.3 times, reduces the spot size by 0.83 times, and increases energy to the suture by 1.7 times. It allows for excellent blanching of the conjunctiva, and the lip helps keep the lid out of the way. Lysis has been successfully performed utilizing a disposable glass micropipette (7), a Zeiss and other indentation gonioscopy lenses (8), a 20 gage fiber optic endo laser probe (9), and the other lysis lenses (10,11). After application of a drop of topical anesthetic, the trabeculectomy site should be carefully assessed. If the overlying conjunctiva is injected, a drop of 2.5% phenylephrine should be placed on the eye to cause vasoconstriction and optimum visualization of the underlying scleral sutures. The lysis lens should be placed directly over the scleral sutures and compress conjunctiva onto the scleral surface. This compression causes deturgescence and blanching of the conjunctiva allowing visualization of the suture (Fig. 16.1) One suture should be cut at a time followed by ocular massage. The suture closest to the limbus should be lysed first. The distal sutures must be performed lastly, as cutting them tends to produce larger blebs and hypotony. The lysis lens can be used to initiate the massage.

Figure 16.1

(See color insert) Visualization of scleral suture through Hoskins lens.

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Laser Settings

Initially, a 50 mm argon spot size at 0.1 s with an energy level of 0.2 W should be used. Energy settings should be increased as required, up to 0.8 W. Lysis can also be performed using other lasers such as the krypton laser. Krypton may be safer than argon in the presence of blood (12). 4.2.

Outcome

Successful lysis is recognized by not only a defect in the suture but also separation of the suture edges. Laser-induced conjunctival edema can produce a white spot over the suture. It should not be mistakenly presumed that this edema is successful lysis. Suture separation must be visualized.

5.

COMPLICATIONS

Complications occur in 30% of patients after lysis (4). It is therefore very important to monitor all postlaser patients 1 h after the procedure and again at 24 and 48 h. 5.1.

Immediate Complications 1.

2.

5.2.

Wound dehiscence: Excessive searching for sutures with the lens can traumatize the underlying conjunctiva. It is therefore of utmost importance to consider the strength of the underlying conjunctival wound before performing suture lysis. Conjunctival wound dehiscence is an indication for immediate surgical repair. Conjunctival perforation: It is possible to perforate conjunctiva with the laser especially if the suture is covered by hemorrhage. A small perforation will usually heal within 24 h with conservative management. The eye must not be massaged until the overlying conjunctiva has healed. If the bleb leaks, aqueous suppressants and an eye patch will usually allow the laser-induced conjunctival button hole to heal. Surgical repair may be needed if conservative measures fail to stop the leak.

Early Lysis Complications 1.

2.

3.

Hypotony occurs in 21% of patients after lysis (4). It is therefore important not to massage the eye too vigorously immediately after laser. Massage should initially be performed by the surgeon under direct vision as outlined in the chapter by Dr. Buys. Massage by the patient should only be undertaken if the patient has been appropriately educated and the bleb carefully assessed. Shallow or flat anterior chamber: Shallow or flat anterior chambers occur in 18% of cases after suture lysis (4,13). Massage can initiate or worsen this situation. Shallow or flat chambers usually respond well to cycloplegia and standard aqueous suppressant and patching therapy. External aqueous leaks: With successful lysis, external aqueous leaks through the wound site occur in 9% of cases (4). Conservative management with or without aqueous suppressants resolves this situation.

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4.

5.

6. 5.3.

Late Lysis Complications 1. 2. 3.

6.

Iris incarceration: Sudden decompression in the presence of a small peripheral iridectomy can lead to iris incarceration into the osteum. Should this occur, surgical replacement of the iris is indicated. Malignant glaucoma: Malignant glaucoma occurs in 2% of patients after lysis (4). The onset of malignant glaucoma after lysis usually develops within 48 h of the procedure and is likely due to sudden ocular decompression associated with successful lysis. Individuals predisposed to malignant glaucoma include those with pre-existing narrow angles and high IOP prior to lysis. Hyphema: Hyphema occurs in 2% of cases (4) and usually resolves within 72 h.

Hypotonous maculopathy has been reported after lysis (14); progressive lens opacity (15); large filtering blebs with or without dellen formation.

CONCLUSION

Numerous studies have shown that suture lysis effectively improves outcome after trabeculectomy. The procedure is easy to perform but is associated with important complications, most of which developed within the first 48 h after lysis. Recognition of these complications and appropriate management will usually lead to excellent visual and pressure related outcomes.

REFERENCES 1. 2. 3. 4. 5. 6. 7. 8.

9. 10. 11. 12.

Lieberman MF. Suture lysis by laser and goniolens. Am J Ophthalmol 1983; 95:257 – 258. Hoskins HD, Migliazzo C. Management of failing filtering blebs with the argon laser. Ophthalmic Surg 1984; 15:731– 733. Morinelli EN, Sidoti PA, Heuer DK, Minkler DS, Baerveldt G, LaBree L, Lee PP. Laser suture lysis after mitomycin C trabeculectomy. Ophthalmology 1996; 103(2):306– 314. Macken P, Buys Y, Trope GE. Glaucoma laser suture lysis. Br J Ophthalmol 1996; 80:398 – 401. Pappa KS, Derick RJ, Weber PA et al. Late argon laser suture lysis after mitomycin C trabeculectomy. Ophthalmology 1993; 100:1268 –1271. Kapetansky FM. Laser suture lysis after trabeculectomy. J Glaucoma 2003; 12:316– 320. Tomey KF. A simple device for laser suture lysis after trabeculectomy. Arch Ophthalmol 1991; 109:14 – 15. Savage JA, Simmons RJ. Staged glaucoma filtering surgery with planned early conversion from scleral flap to full thickness operation using argon laser. Ophthalmic Laser Ther 1986; 1:201 – 210. Salamon SM. Trabeculectomy flap suture lysis with endolaser probe. Ophthalmic Surg 1987; 18:506 – 507. Mandelcorn RM, Crossman JL. A new argon laser suture lysis lens. Ophthalmic Surg 1994; 25:480 – 481. Ritch R, Potash S, Liebmann JM. A new lens for argon laser suture lysis. Ophthalmic Surg 1994; 25:126 – 127. Hill R, Brown R, Heuer DK. Laser suture lysis for non valved aqueous drainage implants. J Glaucoma 2003; 12:390 – 391. [email protected]

Glaucoma Suture Lysis 13. 14. 15.

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Melamed S, Ashkenazi I, Glovinski J, Blumenthal M. Tight scleral flap trabeculectomy with post operative laser suture lysis. Am J Ophthalmol 1990; 109:303 –309. Jampel HD, Pasquale LR, Dibernado C. Hypotony maculopathy following trabeculectomy with mitomycin C. Arch Ophthalmol 1992; 110:1049– 1050. Savage JA, Condon GP, Lytle RA, Simmons RJ. Laser suture lysis after trabeculectomy. Ophthalmology 1998; 95:1631– 1638.

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17 Releasable Sutures Ruth Lapid-Gortzak University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada and Ben Gurion University of the Negev, Israel

David S. Rootman and Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada

1. 2. 3. 4.

Introduction Indications for Releasable Sutures Methods Techniques 4.1. Releasable U-Suture—Rootman Technique 4.2. Releasable Suture with Buried Ends According to Migdal 4.3. Releasable Suture According to Cohen and Osher’s Method 4.4. Kolker’s Modification 4.5. Johnstone’s Technique (X-Shaped Pattern) 5. Complications References

1.

151 151 152 152 152 153 154 155 155 156 157

INTRODUCTION

Following trabeculectomy, one seeks a balance between over- and underfiltration. Methods to increase filtration include ocular massage suture lysis or releasable sutures. Preference depends on the surgeon’s experience and the patient’s acceptance, and the availability of an argon laser and suture lysis lens.

2.

INDICATIONS FOR RELEASABLE SUTURES

Releasable sutures are used to control elevated intraocular pressure (IOP) in the early period after trabeculectomy, to increase the volume of a flat bleb, or achieve a desired target pressure. 151

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METHODS

Two techniques are used to perform suture after operative adjustment of the trabeculectomy flaps (1 –5). 1. 2.

4. 4.1.

The scleral flap is tightly sutured and the sutures lysed with an argon laser (see elsewhere in this book). The scleral flap is sutured utilizing a slipknot on the 10/0 nylon suture, leaving the long end accessible on the corneal surface, so that it can be grasped and removed, thereby releasing the flap.

TECHNIQUES Releasable U-Suture—Rootman Technique (3) 1. 2.

3. 4.

5.

6.

Trabeculectomy with a rectangular 4 3.5 mm flap is performed, as described elsewhere in this book. A 10/0 double-armed suture is passed radially from anterior to posterior, partial thickness through the cornea at the limbus near the temporal edge of the scleral flap. The suture exits the cornea at the limbal base of scleral flap just in front to the former attachment of the conjunctiva (Fig. 17.1). The next bite is taken through the scleral flap at the posterior temporal corner, and then passed through the temporal sclera on the posterior edge of the flap bed (Fig. 17.1). The other needle of the double-armed suture is placed in a similar fashion through the cornea and the limbus to the base of the scleral flap at the opposite nasal edge of the scleral flap. The suture is passed through the scleral flap on its posterior-nasal corner, and then passed through the base of the sclera bed.

Figure 17.1 Releasable U-suture. A double slipknot is placed, which is released by pulling the corneal loop (see arrow). [Reprinted with permission, from Ref. (3), Slack Inc.] [email protected]

Releasable Sutures

7. 8. 9.

10.

11.

12.

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The suture is tightened with a loop forming on the cornea, 2 mm anterior to the limbal-based hinge of the scleral flap. The suture end with the needle is grasped with a tying forceps and a small loop is created on top of the scleral flap. A slipknot is formed with three throws at the distal end of the suture. This triple knot is now secured without subsequent throws to allow for release of the suture with traction on the corneal side of the suture. The loop is pulled and tightened (Fig. 17.1). The other end of the suture is adjusted in a similar way, and an inverted U-shape suture ensues. Inflate the eye with balanced salt solution prior to tightening the second arm of the suture to ensure that there is not undue tension as this will result in premature release of the releasable suture. The “U,” horizontal portion of the suture should be just lightly snug on the cornea. This will result in the epithelium healing over the suture with no exposed ends. The conjunctival flap is sutured in place using 10/0 monofilament nylon as described in Chapter 12 with three 10/0 nylon interrupted sutures with knots buried.

The suture is released by uncovering the epithelium over the top of the horizontal, corneal portion of the suture that is anterior on the flap. Sometimes, undermining of the conjunctiva with a 25-gage needle is necessary. Then the suture loop is lifted with steady tension on one of the loops to release one slipknot. The second releasable suture can be removed depending on the result of the first suture arm removal. 4.2.

Releasable Suture with Buried Ends According to Migdal 1.

2.

A shallow bite is performed through episcleral tissue (in order to anchor the suture) temporal or nasal to the scleral flap at the limbus. This is passed in a radial direction from posterior to anterior. Then a bite is taken partial thickness through sclera at the limbus, exiting in the limbal area [Fig. 17.2(a)].

Figure 17.2 (a) Releasable sutures, according to Migdal. The first suture enters from the limbus through the cornea (1), then through the scleral flap (2), and the sclera (3). (b) The first suture is completed as a slipknot that can be released from the corneal end of the suture. The corneal end of the suture is left free under the conjunctiva. The second corner of the scleral flap is sutured with a simple mattress suture. [email protected]

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3.

4.

4.3.

A full thickness bite is then taken through the posterior lip of the scleral flap, followed by a bite through the sclera, at 458 to the radial edge of the flap [Fig. 17.2(a)]. The suture is tied using three loops, grasping the loop of the suture that is protruding at the corner of the scleral flap [Fig. 17.2(a) and (b)]. The suture is released by uncovering the anterior intra-corneal loop (between 1 and 2) and pulling the suture out. The slipknot will untie and release the scleral flap.

Releasable Suture According to Cohen and Osher’s Method (1) 1.

2. 3.

4. 5. 6. 7.

Flap suture: A nylon 10/0 suture is passed toward the limbus from posterior to anterior and through the sclera posterior to the border of the base of the scleral flap, and exits just before the edge of the scleral dissection. The needle is then passed through the scleral flap from the undersurface through to the anterior surface. The suture is then passed partial thickness through the limbus and exits through peripheral clear cornea. The suture is passed in a radial direction. The corneal end of the suture is left long (Fig. 17.3). The end of the suture that secures the scleral bed to the dissected flap is then tied with three throws. The second throw is then tied as a bow rather than as a square knot, so the entire knot becomes a bowtie like slipknot. The position of the slipknot is checked, tension on the corneal side of the knot should cause the slipknot to undo. A second such suture is inserted at the other side of the flap. The flap edge parallel to the limbus is secured with a regular nonreleasable 10/0 nylon interrupted suture.

To release the suture, the free corneal end of the suture is pulled to release the knot as indicated in the postoperative period. Should the IOP be acceptable, then the releasable suture is released after 2 –3 weeks, when the fistula is considered more healed. Longer time may be advisable if antimetabolites have been used.

Figure 17.3 Releasable sutures according to Cohen’s method. The end of the suture is left free on the corneal surface. [email protected]

Releasable Sutures

4.4.

Kolker’s Modification (2) 1. 2.

4.5.

155

The corneal end of the suture is passed superficially through the peripheral cornea, parallel to the limbus similar to the method of Cohen. The suture is cut flush with the cornea following the placement of the posterior end of the suture and releasable knot, at the exit site on the cornea. This leaves an intra-corneal loop without an irritating suture end that can later be grasped to release posteriorly the bowtie knot that is anchoring the flap (Fig. 17.4).

Johnstone’s Technique (5) (X-Shaped Pattern) 1. 2.

3.

4.

5.

This technique utilizes a limbus based conjunctival flap. A 10/0 nylon suture is passed in a double-armed fashion through the posterior edge of the scleral flap in a horizontal mattress fashion, from the scleral side through the corner of the scleral flap, through the posterior cut scleral edge, to complete a loose mattress suture. The knot is buried in the posterior scleral edge. The suture is tied with minimal tension (Fig. 17.5). A double-armed 10/0 nylon suture is passed from the corneal side through the conjunctiva and superficial cornea at the limbus, at the temporal edge of the sclera, but not through the scleral flap. The other arm of the double-armed 10/0 nylon suture is passed through the cornea and the limbus through the conjunctival flap, just as with the other end, and exits at the nasal edge of the sclera, without penetration of the scleral flap. One arm of the suture is passed underneath the limb of the mattress suture that lies on top of the posterior part of the scleral flap forming a triangle. The double-armed suture is now tied, and the tension on the first mattress suture is adjusted by pulling anteriorly on the suture loop. The shape of these

Figure 17.4 Releasable sutures according to Kolker et al. (2). The corneal end of the suture is stretched and cut. It is then allowed to slip into its intra-corneal suture tunnel. [email protected]

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Figure 17.5 Johnstone’s envelope technique of releasable sutures. [Printed with permission, from Ref. (5).]

6.

sutures combined is like that of the back of an envelope, two triangles with the apices touching. The knot of the anterior triangular loop suture is buried in the tissue of the limbal area.

When need arises, the corneal limb of the anterior tension suture is cut, and thus the tension on the mattress suture is relieved, leading to loosening of the scleral trabeculectomy flap (Fig. 17.5). Releasable sutures allow the surgeon independence from an argon laser and a suture lysis lens. Less pressure is applied to the wound, which may lead to fewer shallow anterior chambers and conjunctival wound leaks. Releasable sutures can also be used on those patients who cannot cooperate with a laser procedure due to sensitivity following surgery, or in those patients where subconjunctival hemorrhage, edema, or scarring of the Tenon’s capsule makes visualization of the suture for argon laser lysis impossible. The releasable suture technique makes the post-trabeculectomy pressure adjustment a slit-lamp and forceps procedure only, which is economically advantageous, as well as technically simple and comfortable for the patient (2,3). We prefer the inverted U-suture technique as it enables the release of either arm or both arms of the suture. Although the whole suture is in place and covered with epithelium, it causes no discomfort to the patient; whereas releasable sutures with loose ends often irritate the patient and allow for a continuous suture tract from outside to inside.

5.

COMPLICATIONS

Releasable sutures can be complicated by epithelial defects and infection. With the releasable U-suture, the suture is covered by epithelium until the suture removed, thus reducing the risk of infection. Releasable sutures with untied or unburied ends can irritate and cause a corneal epithelial defect. Postoperative complications caused by releasable sutures are similar to those reported for laser suture lysis (Chapter 16). A number of studies have reported excellent [email protected]

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outcomes with releasable sutures (4), especially when compared to nonreleasable procedures (2,3). In summary, releasable sutures are a simple, inexpensive, and easily performed means of regulating early postoperative IOP.

REFERENCES 1. 2. 3. 4. 5.

Cohen JS, Osher RH. Releasable suture in filtering and combined surgery. Ophthalmol Clin N Am 1988; 1:187– 197. Kolker AE, Kass MA, Rait JL. Trabeculectomy with releasable sutures. Arch Ophthalmol 1994; 112:62 – 66. Maberley D, Apel A, Rootman DS. Releasable “U” suture for trabeculectomy surgery. Ophthalmic Surg 1994; 25:251 – 255. Raina UK, Tuli D. Trabeculectomy with releasable sutures: a prospective, randomized pilot study. Arch Ophthalmol 1998; 116:1288– 1293. Johnstone MA, Wellington DP, Ziel CJ. A releasable scleral-flap tamponade suture for guarded filtration surgery. Arch Ophthalmol 1993; 111:398– 403.

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18 The Failing Bleb: Risk Factors and Diagnosis Paul R. Healey Western Sydney Eye Hospital; University of Sydney, Centre for Vision Research (Westmead Millennium Institute); and Save Sight Institute, Sydney, Australia

Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada

1. 2. 3. 4. 5.

6.

7. 8.

9.

Introduction Wound Healing Following Penetrating Ocular Injuries Impact of Surgical Technique on Wound Healing Natural History of the Bleb Preoperative Risk Factors for Bleb Failure 5.1. Larger Studies 5.2. Smaller Studies 5.2.1. Cataract Surgery 5.2.2. Aphakia 5.2.3. Younger Age 5.2.4. Long-Term Use of Glaucoma Medications 5.2.5. Skin Color and Race 5.2.6. Other Risk Factors Perioperative Risk Factors for Failure 6.1. Conjunctival Wound Position 6.2. Combined Surgery Postoperative Risk Factors for Bleb Failure Postoperative Signs of Reducing Bleb Function 8.1. Intrascleral Obstruction 8.2. Bleb Fibrosis 8.2.1. Bleb Vascularity, Corkscrew Vessels, and Hemorrhage 8.2.2. Bleb Area and Height 8.2.3. Bleb Wall Thickness and Conjunctival Transparency 8.2.4. Presence of Tenon’s Cysts or Bleb Encapsulation 8.2.5. Bleb Leak 8.2.6. Presence of Microcysts 8.3. Late Failure Intervening in the Failing Bleb 9.1. Preoperative/Perioperative

160 160 161 161 162 162 163 163 163 163 163 164 164 164 164 165 165 166 166 166 167 169 169 170 170 171 171 171 171 159

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9.2. Early Postoperative Period 9.2.1. Local Corticosteroids 9.2.2. Flap Manipulation 9.2.3. Fluorouracil 9.2.4. Systemic Antifibrosis Therapy 9.3. Late Postoperative Period 10. Conclusion References

1.

172 172 172 172 172 173 173 173

INTRODUCTION

Obstruction of aqueous outflow causing raised intraocular pressure (IOP) following trabeculectomy is usually regarded as a surgical complication. Although undesired, it is in fact the normal and appropriate response to a penetrating eye injury. Wound healing is a fundamental biological process that is critical for survival. In most living organisms, wound-healing systems are very well developed. Establishment of prolonged trans-scleral aqueous flow sufficient to maintain a steady-state pressure gradient of just the right size represents a highly abnormal state and can only be achieved by inducing a partial failure of normal wound-healing responses.

2.

WOUND HEALING FOLLOWING PENETRATING OCULAR INJURIES

Trabeculectomy creates a penetrating wound between the anterior chamber and the subconjunctival space. From the moment the conjunctiva is incised, a complex cascade of protective and reparative processes is set in motion. These are detailed in Chapter 4 and the subject of numerous reviews and studies (1 – 4). It is essential to understand the dynamic nature of wound healing in order to adequately diagnose and manage both the risk factors for failure and the scarring process itself. The basic process is probably similar to that seen after a penetrating skin wound, with the exceptions of the presence of aqueous humor and the trans-scleral pressure gradient. The initial phase is principally hematological with coagulation and formation of platelet/fibrin clot within minutes. White blood cells recruited to the wound secrete a number of growth factors that transform quiescent fibrocytes in the surrounding tissue into fibroblasts, the primary cells responsible for the production and contraction of the ubiquitous collagen scar. Activated fibroblasts migrate to the wound and begin to proliferate after 5 days, their numbers peaking after 2 weeks (5,6). In skin and probably also in subconjunctival tissue, migrating fibroblasts exert traction forces on the collagen matrix of the tissue surrounding the wound and remodel it along the lines of stress (7). The tissue stress induces the fibroblasts to secrete growth factors for which they also express receptors and produce collagen, which further increases traction. This autocrine (self-stimulating) process is fundamental to wound contraction and usually results in closure of the wound (8). The third phase is characterized by a relatively rapid reduction in the number of T-cells, small blood vessels, and fibroblasts from the wound site by apoptosis (9,10). [email protected]

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It is coincident with a maturation of the collagen scar (replacement of type III collagen with type I) (11). Little is known about the factors that initiate or regulate this phase. However, there is some evidence that reduction in tissue tension (12) and T-Cells (13) play key roles.

3.

IMPACT OF SURGICAL TECHNIQUE ON WOUND HEALING

Given the strength of the healing forces, it is a little surprising that external fistularizing surgery for glaucoma could have long-term success. Although good surgical technique plays a role, it is most likely the flow of aqueous through the sclerostomy that retards wound closure (14). Unguarded full thickness sclerostomies allow the greatest initial outflow rates. It was the associated complications of early over-filtration that lead to the adoption of the trabeculectomy with a scleral flap even though pressure control was not as good (14). Until relatively recently, hypotony with significant shallowing of the anterior chamber was considered a reasonable trade-off for adequate flow in the early postoperative period. In an attempt to reduce the complications of early over-filtration and with the understanding of the inflammatory response to hypotony, controlling initial flow with increased scleral flap suture tension has been advocated (15). The microperforating trabeculectomy procedures such as deep sclerectomy producing lower initial flow rates than trabeculectomy are notable for their low rates of hypotony and stable early IOPs (16 – 19). As the anterior chamber is not entered and no iridectomy is performed, the damage to the blood –eye barrier is presumably less. However, published trials show higher IOPs than standard trabeculectomy with longer follow-up (16 – 18). The trade-off for more stable eyes with better vision in the early postoperative period may be an increased ability for scar tissue to bridge the scleral flap. However, the increasing use of antimetabolites in trabeculectomy has shifted the balance once again towards wound-healing failure.

4.

NATURAL HISTORY OF THE BLEB

Although bleb morphology is recognized as important to the outcome of trabeculectomy (3,14), there is no clear agreement as to what constitutes the best appearance of a bleb. This may be due to the effect of preoperative risk factors on bleb morphology, variations in surgical technique (including the use of antimetabolites), and changes in bleb appearance over time (3,14,20,21). It is also due to the design of many published studies that define success as an absolute IOP level (sometimes higher than the preoperative IOP) and after relatively short follow-up periods. The ideal trabeculectomy bleb allows aqueous to pass from the bleb (into the vascular system or transconjunctivally) at a rate which lowers IOP to the target range. Its structure and function should maximize its life while minimizing symptoms. In an eye with a functioning bleb, aqueous outflow from the bleb is a major determinant of IOP. Normally, the flow rate is determined by inflow to the bleb (scleral flap resistance), local tissue resistance (bleb wall thickness), and total area of drainage. Several studies have suggested an additional direct toxic effect of Mitomycin C (MMC) on the ciliary body (22 –25). This raises the possibility that part of the pressure-lowering effect of MMC trabeculectomy is also due to an MMC-induced decrease in aqueous production. The degree to which bleb outflow is pressure dependant or involves significant active cellular transport is uncertain. [email protected]

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Histopathological studies have shown late failed blebs to have dense, thick, organized, but acellular collagen walls (26,27). In blebs that failed early, large numbers of inflammatory cells and fibroblasts were present (27). In contrast, functioning blebsexcised postmortem showed loose connective tissue with histologically clear spaces thought to contain aqueous and to correspond to clinically visible microcysts (26,28). In addition, mitomycin-treated blebs excised for hypotony showed abnormally arranged and developed collagen fibrils (29). These studies are consistent with our ideas of the wound-healing process and the clinical observation that drainage over a large surface area or through a very thin bleb wall is associated with lower IOPs. Very thin-walled bleb are, however, at risk of manifest leak and the potentially blinding complications of hypotony and infection. Although the precise mechanism leading to this morphology is unknown, it does not appear to be solely antimetabolites, as increasing antimetabolite treatment area has been reported in an animal model to increase bleb survival without leading to the bleb morphology associated with infection or late leak (30).

5.

PREOPERATIVE RISK FACTORS FOR BLEB FAILURE

The first step in the management of the failing bleb is the preoperative identification of risk factors for failure and the preparation of a detailed management plan focused on inducing an appropriate degree of wound-healing failure. Trabeculectomy success rates vary greatly and most studies examining risk factors for failure suffer from small numbers, limited follow-up, and an overly optimistic definition of success. However, reports from large studies with long follow-up periods and a concurrence of risk factors from small studies can help to define eyes which are more likely to fail and which require more aggressive suppression of wound-healing. 5.1.

Larger Studies

The Advanced Glaucoma Intervention Study (AGIS) followed 789 eyes of 591 patients aged 35– 80 years with advanced glaucoma between recruitment (1988 – 1992) and 2001. Eyes were randomized to the treatment sequences of either argon laser trabeculoplasty (ALT)–trabeculectomy–trabeculectomy or trabeculectomy–ALT–trabeculectomy. Preintervention factors associated with failure of trabeculectomy were higher IOP and diabetes. Any postoperative complication but especially marked inflammation or elevated IOP was also associated with increased risk of failure. Younger age was found to be a risk factor. However, this effect was predominantly due to increased risk amongst young subjects with poor preoperative visual acuity. Associations of borderline significance included “black” race (31). Another report from the same group (32) found male gender to be associated with bleb encapsulation which itself was associated with higher IOP. It did not find a statistically significant association with previous laser trabeculoplasty, suggesting that this previously reported risk factor (33) may be relatively unimportant. The fluorouracil filtering surgery study (FFSS) (34) followed 213 patients with previous cataract surgery or failed filtering surgery, for 5 years. Subjects were randomized to either trabeculectomy alone or trabeculectomy with postoperative subconjunctival 5-fluorouracil injections. All procedures used a limbus-based conjunctival flap. Fiftyfour (51%) of the 105 eyes in the 5-fluorouracil group and 80 (74%) of the 108 eyes in the standard filtering surgery group were classified as failures on the basis of IOP .21 mmHg (P , 0.001, Mantel –Cox survival analysis). Risk factors for failure [email protected]

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included high IOP, a short time interval after the last procedure involving a conjunctival incision, the number of procedures with conjunctival incisions, and Hispanic ethnicity. Patients in the 5-fluorouracil group had a higher risk of late-onset bleb leaks (9%) than those in the standard filtering surgery group (2%). 5.2.

Smaller Studies

There are many reports from small studies of risk factors for trabeculectomy failure. As expected, the strength of individual risk factors varies widely. However, several factors have been consistently reported to increase risk of failure. Almost all smaller studies define failure as IOP .21 mmHg. This very conservative definition tends to underestimate failure rates, as do the generally short follow-up times. 5.2.1.

Cataract Surgery

Cataract surgery prior to trabeculectomy has been identified as a risk factor for bleb failure when associated with a conjunctival incision (34). Pseudophakia without conjunctival incisions or posterior capsule loss has also been suggested to be a risk factor for failure (33,35,36) although the strength of the published evidence is relatively poor (37). 5.2.2.

Aphakia

The largest study of aphakia followed 82 patients for 6 months to 10 years (38). Fiftyone percent of patients either required further glaucoma surgery or lost light perception. A further 10% could not maintain IOP of ,21 mmHg with medication or 25 mmHg without. In a subgroup of 20 eyes of patients younger than 50 years, 95% failed. In other reports, failure rates as low as 20% have been reported at 1 year (39,40). 5.2.3. Younger Age In addition to the AGIS (31), several smaller studies have suggested reduced success with younger patient age (41), particularly when comparing adults with children (20,42 – 45). Other small series showed quite good results at up to 2 years (46) particularly when children with other associated ocular conditions were excluded (47). Because open-angle glaucoma prevalence is strongly associated with age (48), studies of trabeculectomy in younger patients have almost always included complex and secondary glaucomas. This has led to the suggestion that the primary reason for poorer results in younger adults and children is not age itself (35), but associated risk factors. 5.2.4.

Long-Term Use of Glaucoma Medications

One of the most important risk factors for bleb failure identified to date is the conjunctival cellular profile, originally reported in association with the long-term use of some topical glaucoma medications. In a cohort study of trabeculectomy on 106 patients, preoperative treatment with miotic or sympathomimetic topical glaucoma medications for 3 years or more substantially reduced success (93% for beta-blockers vs. 72% for miotics and 45% for miotics and sympathomimetics) (49). Failure was associated with increased numbers of inflammatory cells (macrophages and lymphocytes) and fibroblasts in the conjunctiva. In another study, treatment with fluoromethalone 1% for 1 month preoperatively reduced cell numbers in these tissues and improved success rate of trabeculectomy compared with matched controls (82% vs. 50%) (50). The same author also reported that a number of other conditions thought to be independent risk factors for bleb [email protected]

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failure, such as age, race, and uveitis, are characterized by conjunctival histology that is likely to increase the chance of failure (35). 5.2.5. Skin Color and Race Several studies, including the AGIS, have reported lower trabeculectomy success rates amongst residents of the United States of America described as “black.” Although the meaning of the term is not clear, it is generally considered to describe subjects with a significant proportion of their ancestry from Africa. Similarly, the FFSS reported increased failure in a subgroup identified as “Hispanic ethnicity.” Race or ethnicity is usually used as a socio-economic measure, which by acting as a surrogate for a number of environmental risk factors is associated with different health problems and outcomes. It has also been held to have some biological value on the basis of an increased prevalence of dermal keloid formation, thicker tenon’s capsule, or conjunctival cell population (51). However, the biological relationship to race is tenuous (52). The few reports of bleb failure rates from Africa do not appear to support the assertion of a large difference from studies in other populations (53 –55). 5.2.6.

Other Risk Factors

Neovascular Glaucoma and Diabetes. Neovascular glaucomas are generally considered to reduce the success of trabeculectomy although the state of active neovascularization at the time of surgery is important (56). Diabetes (non-neovascular) has been reported to be an independent risk factor for bleb failure (57,58). Uveitis. The results of trabeculectomy in uveitis are generally thought to be poor and antimetabolites are frequently used. However, published reports on trabeculectomy outcome in uveitis with 5FU and MMC or with no antimetabolites are surprisingly good (59 –63). Application of results is made difficult by the wide variety and intensity of uveitic disease and IOP rise secondary to chronic corticosteroid use. Angle Closure. There are few reports of trabeculectomy outcome in primary angle-closure glaucoma (PACG). Aung (64) reported only 56% of blebs maintained IOP ,21 mmHg over a mean of 22 months in 57 Singaporeans unresponsive with PACG to medical therapy. However, a retrospective case review of combined phacotrabeculectomy for PACG in Singaporeans found a much higher 81% bleb survival over a similar time (65).

6. 6.1.

PERIOPERATIVE RISK FACTORS FOR FAILURE Conjunctival Wound Position

Conjunctival wound position may influence bleb failure. Most published studies failed to find a difference although their power was low (66 –71). The largest reported study (of 100 trabeculectomies) found a higher failure with limbus-based conjunctival flaps compared with fornix-based flaps (72). Similar results have recently been reported in MMC trabeculectomy in children and young adults (73). 6.2.

Combined Surgery

A relatively large number of studies have examined the effect of combined cataract and glaucoma surgery. Some have reported this as risk factor for bleb failure. However, as with many studies in this area, methodological rigor is somewhat lacking (74). Two [email protected]

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systematic reviews of published studies examined evidence for an effect of technique in combined surgery (37) and different methods of dealing with cataract in the presence of glaucoma (75). In both studies, IOP was the main outcome measure. Studies of combined surgery vs. trabeculectomy alone consistently suggested relatively reduced bleb function in eyes undergoing the combined procedure. In this group, cataract extraction by nucleus expression was associated with higher IOPs than phacoemulsification. Studies examining wound site suggested slightly reduced bleb function when the cataract extraction and trabeculectomy components of the procedure were performed through the same site compared to separate sites.

7.

POSTOPERATIVE RISK FACTORS FOR BLEB FAILURE

Any disease that increases intraocular or conjunctival inflammation can lead to an increase in wound healing and bleb failure. Uveitis and intraocular hemorrhage in particular may lead to a rapid increase in wound-healing response. Ocular procedures can have the same effect. Reports of the impact of cataract surgery on functioning trabeculectomies are contradictory with some studies failing to find a difference in IOP and one reporting needle revision or additional IOP-lowering medications were needed in 30% of cases (76). A recent prospective study examined 47 eyes with pre-existing functioning blebs which underwent clear corneal approach phacoemulsification and posterior chamber implantation of a copolymer acrylic intraocular lens (77). After 1 month, 76% of eyes had increased IOP. A failure rate of 44% after 2 years was also reported despite the use of topical steroids for twice the duration of isolated cataract surgery. Table 18.1 summarizes the principal risk factors for bleb failure along with an estimation of their strength based on published studies. Table 18.1

Risk Factors for Bleb Failure Strength of risk (based on published studies)

Risk factor Previous conjunctival surgery Conjunctival inflammation/miotics/adrenaline Uveitis/neovascularization High preoperative IOP High postoperative IOP Diabetes Cataract surgery (preoperative) Race Combined cataract extraction and trabeculectomy Limbus-based conjunctival flap Postoperative cataract surgery Time from surgery

8. 8.1.

Strong Strong Strong Weak – moderate Strong Moderate Weak – strong Weak – strong Moderate Weak – moderate Weak – strong Strong

POSTOPERATIVE SIGNS OF REDUCING BLEB FUNCTION Intrascleral Obstruction

Any intraocular material drawn into the sclerostomy can occlude aqueous flow and cause bleb failure. This includes blood or fibrin clot, iris, vitreous, ciliary processes, and even [email protected]

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lens capsule. With surgical techniques now placing the entry point in the cornea rather than sclera (the opening should be called a keratotomy; however, the term sclerostomy is more widely understood and is used here for historical reasons), the most common causes of obstruction are posterior corneal tissue from an incomplete sclerostomy and iris tissue which may remain intrascleral after iridectomy. Forward rotation of the ciliary body and iris root in aqueous misdirection syndrome or suprachoroidal hemorrhage can also occlude a sclerostomy. Although such obstruction can be the primary cause of trabeculectomy failure, fibrosis of the bleb will cause a secondary failure unless the obstruction is promptly removed. Intraocular viscoelastic material can also transiently obstruct the sclerostomy. Although sodium hyaluronate may have anti-inflammatory properties, injection of viscoelastic material into the anterior chamber may be associated with early postoperative pressure rises (78 – 80).

8.2.

Bleb Fibrosis

Bleb fibrosis is the most common cause of bleb failure. Preoperative glaucoma medications, surgical trauma and inflammation can frequently cause aqueous hypo-secretion in the early postoperative period. Thus, low IOP in the early postoperative period is not always an indicator of good bleb development. In the absence of techniques to directly measure cellular activity in human trabeculectomy, bleb appearance is used as an indicator of wound healing. A number of clinical signs have been suggested as risk factors for bleb failure (see Table 18.2). They include increased bleb vascularity, presence of hemorrhage, corkscrew-shaped vessels, bleb height and extent, bleb wall thickness and conjunctival transparency, presence of tenon’s cysts or bleb encapsulation, suture-line contraction in limbus-based conjunctival flaps, bleb leak with and without pressure, and presence of microcysts. Most of these are signs of wound healing or aqueous flow. As wound healing is a dynamic process, these signs change over time. Unfortunately, there are relatively few published studies on the relationship between such clinical signs and bleb outcome and grading is mostly subjective (81 – 87). Recently, two groups have independently published standardized bleb-grading protocols. The Indiana Bleb Appearance Grading Scale (88) (Fig. 18.1) has been devised for slit-lamp assessment and the Moorfields Bleb Grading System (81) (Fig. 18.2) for grading from bleb photographs. Neither group has published the relationship between grading and outcomes as yet but both systems represent a significant advance in standardization of bleb assessment.

Table 18.2

Signs of Bleb Failure

Sign High IOP Increased bleb vascularity Reduced bleb area High bleb Tenon’s cyst Wound leak Microcysts

Strength of sign (based on published studies) Strong Strong Strong Moderate Moderate Moderate Strong sign of good bleb function

[email protected]

Failing Bleb

Figure 18.1

8.2.1.

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The Indiana bleb appearance grading scale.

Bleb Vascularity, Corkscrew Vessels, and Hemorrhage

Bleb vascularity is the most commonly described sign reported to influence bleb failure and is graded in both the Indiana (Fig. 18.1) and Moorfields (Fig. 18.2) bleb grading systems. It reflects dilatation, migration, and possibly neovascularization within the conjunctiva and subconjunctival tissues. Increased vascularity both reflects increased woundhealing activity (vessel dilatation, angiogenesis, and contraction) and increases delivery of many cellular and chemical constituents of the wound-healing process. Picht and Grehn (87,89) reported a retrospective review of 55 trabeculectomies (76% primary trabeculectomy without antimetabolites) and classified them according to favorable or unfavorable outcome. Increased vascularity within the first month was associated with an increased failure rate at 3 months. Other authors have made similar clinical observations (85). In a prospective observational study of MMC trabeculectomy (0.1 mg/mL MMC for 5 min under a limbus-based conjunctival flap), Sacu et al. (90) reported that all 49 eyes studied had exactly the same grade of vascularity throughout the study period (postoperative weeks 1 and 2) despite differences in IOP at 1, 3, 6, and 12 months. The use of MMC may have confounded this assessment. Compared with 5FU or nonantimetabolite trabeculectomies, MMC blebs tend to appear more inflamed or have greater vascularity in the early postoperative period. The same study reported the presence of corkscrew vessels in weeks 1 or 2 to be associated with higher IOP at 1, 3, 6, and 12 months. Of the eight eyes that developed encapsulated blebs, four had corkscrew vessels (90). Picht and Grehn (87,89) also found corkscrew vessels more prevalent in blebs with a poorer outcome. The corkscrew appearance of vessels is probably due to [email protected]

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Figure 18.2

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(See color insert) The Moorfields bleb grading system.

contraction of surrounding tissue. As such it is an important sign of fibroblast function. Suture-line contraction in limbus-based blebs and conjunctival retraction in fornixbased blebs are signs of the same process. Avascular areas may also develop in filtering blebs. In a mature bleb, marked conjunctival thinning may be present and diffuse transconjunctival aqueous flow (“bleb sweating”) apparent with fluoroscein staining. This “polycystic” bleb morphology was categorized many years prior to antimetabolite trabeculectomy (91). In antimetabolite trabeculectomy, [email protected]

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avascularity can also develop. Although it is associated with low IOPs, thin avascular blebs are associated with bleb leak and late endophthalmitis. There is some evidence that late endophthalmitis is more likely after antimetabolite use although the literature is not entirely consistent (92–103). Conjunctival wound position influences the incidence of thin-wall cystic blebs as well as endophthalmitis in MMC trabeculectomies. Inferior MMC blebs have been reported to have an eightfold increased risk of endophthalmitis compared with superior blebs (104). In younger patients, limbus-based trabeculectomies flaps more commonly developed cystic blebs, late hypotony, and endophthalmitis (73). The presence of blood is one of the fundamental drivers of the inflammatory and wound-healing responses. Although it is logical that hemorrhage would increase inflammation and wound-healing intensity, there is very little published data to support this. Sacu (90) did not find a relationship between the presence of subconjunctival hemorrhage and IOP in his series of MMC trabeculectomies. However, human serum has been reported to have an anti-apoptotic effect that can overcome the cytotoxicity of MMC on human tenon’s fibroblasts (105). 8.2.2.

Bleb Area and Height

The area of bleb drainage is a critical determinant of bleb outflow and thus IOP. In a retrospective case review of nonantimetabolite trabeculectomies, eyes with more diffuse blebs had lower IOPs than those with blebs the same size as the scleral flap when examined between 1 and 5 years postoperatively (84). Although localized or focal blebs are relatively easy to discern, the full extent of a very diffuse bleb can be very difficult to estimate. Measurement of bleb area by high frequency ultrasound biomicroscopy also shows an inverse relationship between bleb area and IOP (106). Bleb height is a measure of bleb pressure rather than flow. It reflects equilibrium between outward forces and resistance in the bleb wall. Shingleton (85) described bleb height in relation to IOP in an effort to aid diagnosis of the causes of bleb failure. Although high flow and a lax conjunctiva may cause a high bleb and hypotony from over-filtration, a high bleb is also seen with low flow across the bleb wall and high IOP in bleb encapsulation (85). Picht and Grehn (87,89) reported both encapsulation and higher blebs were associated with poor bleb outcome. Both bleb area and height are assessed in the grading systems in Figs. 18.1 and 18.2. 8.2.3. Bleb Wall Thickness and Conjunctival Transparency Assessment of bleb wall thickness and conjunctival transparency is an attempt to gage the resistance to flow out of the bleb. Maumenee (86) hypothesized in 1960 that condensation and compression of collagen in the bleb wall reduced its permeability to aqueous. Molteno et al. (107) have reported decreased permeability of the capsule surrounding his glaucoma drainage device in response to high intrableb pressure. A histological study reported thick dense collagenous tissue in the wall of an encapsulated bleb (26). Sacu et al. (90) examined conjunctival transparency in MMC trabeculectomies but did not find an association with IOP. 8.2.4.

Presence of Tenon’s Cysts or Bleb Encapsulation

Encapsulation of the bleb, also known as a cyst of Tenon’s capsule (108) occurs during the fibroblastic phase of wound-healing. It is usually localized to the scleral flap, is high and has a thick wall. IOP is usually close to preoperative levels. The cysts are in direct communication with the anterior chamber. Its wall markedly thickened and composed [email protected]

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of collagen, fibroblasts, and vascular tissue and the inner surface of the wall is acellular (26,108). The management of bleb encapsulation is dealt with in Chapter 19. Although IOP often falls with time, bleb encapsulation does represent failure of bleb function and is associated with more interventions and higher IOPs in the longer term (32,89). 8.2.5. Bleb Leak Bleb leaks are discussed in detail in Chapter 23. Early bleb leak is a result of incomplete wound closure at the time of surgery, wound contraction, or buttonholing of the conjunctiva and should be differentiated from late-onset bleb leaks which develop with progressive bleb thinning and microtrauma. Profuse leak can cause hypotony with anterior chamber shallowing and choroidal effusions. This not only may increase inflammation but also restrain the surgeon from giving otherwise necessary anti-inflammatory and antimetabolite treatments. The FFSS identified early wound leak as a risk factor for long-term bleb failure in limbus-based trabeculectomies (109). The effect of wound leak in fornix-based trabeculectomies and with MMC is not clear. 8.2.6.

Presence of Microcysts

Of all the signs associated with blebs, the presence of microcysts in the conjunctiva is the most commonly associated with a good outcome (Fig. 18.3). Rather than reflecting wound healing, microcysts appear to be areas of local conjunctival aqueous flow (26). As such their presence indicates not only bleb structure but also function. The relationship to bleb function and IOP appears consistent across the very small literature and does not appear to be influenced by MMC (85,87,89,90).

Figure 18.3

Conjunctival microcysts overlying a functioning bleb. [email protected]

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Microcysts are particularly useful to demarcate the functional area of a very low bleb such as that found after phacotrabeculectomy with high-dose MMC. They may persist for many years, although they are not always present in all quadrants of blebs with good function. With time, the appearance of microcysts changes from an early more visible form to a mature form, which is not as easily seen. 8.3.

Late Failure

Increasing time from surgery has been widely reported as a risk factor for bleb failure. However, little is known about the precise mechanisms of late failure. Histology of late failing blebs shows dense collagen scars and relatively few inflammatory cells (26,27). The process appears to be a slow continuation of the fibroblast activity seen in the earlier postoperative period. 9.

INTERVENING IN THE FAILING BLEB

The use of antimetabolites in trabeculectomy and interventions for specific postoperative complications are considered in other chapters in this book. The following is an overview of measures thought to be beneficial for bleb survival. Key interventions are summarized in Table 18.3. Table 18.3

Interventions for the Failing Bleb

Intervention

Optimal time of intervention

Local corticosteroids 5-Fluorouracil Increasing trans-scleral flow

Early Early Early (suture adjustment, needling) Late (needling) Early

Oral Predisone/NSAID/Colchicine

9.1.

Preoperative/Perioperative

The most important intervention to prevent bleb failure is appropriate patient selection for trabeculectomy and preoperative selection of antimetabolite for higher-risk cases. The use of high-dose MMC in low-risk patients can lead to prolonged hypotony and vision loss. In contrast, in sufficiently high-risk patients, a high-dose MMC bleb can still fail rapidly. Cessation of sympathomimetic drops combined with topical fluoromethalone for 30 days preoperativly (50) and preoperative subconjunctival triamcinolone in the area of the future bleb (110,111) have been reported to improve postoperative outcomes in higher-risk patients. During surgery, fornix-based conjunctival flaps, two-site surgery for phacotrabeculectomy and larger treatment areas when using antimetabolites may all reduce the risk of bleb failure. 9.2.

Early Postoperative Period

9.2.1. Local Corticosteroids The first 6 –8 weeks after trabeculectomy are a critical time in the wound-healing process. Application of topical steroids is a standard clinical practice after trabeculectomy. [email protected]

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Strength and frequency can be tailored to the degree of bleb inflammation or preoperative risk factors. A prospective trial of topical prednisolone acetate 1% in nonantimetabolite trabeculectomies reported better IOP and glaucoma control and fewer additional glaucoma interventions in the corticosteroids group at 5 and 10 years. No added benefit of systemic prednisolone was found (112 – 114). We use topical steroids for 6 months in higher-risk cases and longer where necessary in pseudophakic patients. Subconjunctival steroids are also regularly given intraoperatively at the completion of the trabeculectomy. Although Dexamethasone 4 mg/mL is common, longer-acting depots of betamethasone or triamcinolone can help to reduce the frequency of postoperative steroid drops. 9.2.2. Flap Manipulation Trans-scleral aqueous flow maintains tissue space and retards bridging by scar tissue. Ocular massage, suturelysis and tension adjustment of adjustable trapdoor sutures are all advocated to improve function in response to impending bleb failure. The effect of these measures decreases as the wound heals. Unless wound-healing has been severely retarded (e.g., high-dose MMC), they have little effect after 6 weeks. 9.2.3.

Fluorouracil

The FFSS and many other studies have shown the benefit of postoperative subconjunctival injections of 5FU in reducing the wound-healing response. Although the FFSS protocol demanded two injections per day, 1808 from the bleb, practice has now switched to weekly or bi-weekly injections of 5 –10 mg behind the bleb. One trial reported very good results with five weekly injections following combined cataract and glaucoma surgery (115). Fluorouracil can also be used on an ad hoc basis with both the frequency and the dose of 5FU titrated to the bleb appearance (116). Concern about the potential severe complications of inadvertent intraocular administration of MMC (117) has prevented its widespread use as a subconjunctival injection although a number of studies have reported it to be of benefit (118 – 124). 9.2.4. Systemic Antifibrosis Therapy Oral systemic therapy to prevent bleb failure has been advocated for many years by Molteno (82,125). The therapy consists of Prednisolone 2.5– 10 mg tid, Diclofenac SR 100 mg daily, and Colchicine 0.2– 0.3 mg tid. This can be combined with topical Atropine 1% tid and Adrenaline 1% tid to the affected eye. In a prospective noncomparative case series, 77 eyes were treated in this manner for threatened bleb failure. The therapy was commenced 1 –4 weeks post surgery (mean 11 days) and continued for 1 –11 weeks (mean 6). The authors reported that after 3 –4 days there was a consistent and marked reduction in bleb vascularity often accompanied by bleb extension and reduction in IOP. Six blebs failed between weeks 4 –11 but were restored with IOP control after needling while on the therapy. After 12 years, 11% of eyes had IOP .21 mmHg or required further glaucoma surgery. Systemic side effects were encountered in nine patients and described as minor. Seven required oral histamine type 2 receptor antagonists (82).

9.3.

Late Postoperative Period

Traditionally, late bleb failure has not been treated itself. Rather, IOP-lowering medications were reintroduced or further glaucoma surgery performed. There are no reports [email protected]

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suggesting a postoperative time period beyond which bleb failure does not occur. The little histopathological evidence available suggests late failure is associated with excessively dense and thick bleb walls (26) suggesting that some aspect of the wound-healing response continues indefinitely. The most widely reported intervention for bleb failure in the late postoperative period is needle revision. This is discussed in Chapter 20. If signs of bleb inflammation develop, reintroduction of topical corticosteroids may be beneficial. We use 5FU and intensive topical steroids for an extended period to prevent bleb failure after subsequent cataract surgery.

10.

CONCLUSION

Bleb failure due to wound healing is the single most important challenge in modern glaucoma-filtering surgery. An understanding of the timing and phases of the woundhealing process, combined with thorough risk-factor assessment and careful postoperative examination of the bleb will greatly aid the glaucoma surgeon in timely and appropriate interventions to maximize function and longevity of the trabeculectomy bleb.

REFERENCES 1. Skuta GL, Parrish RK. Wound healing in glaucoma filtering surgery. Surv Ophthalmol 1987; 32:149 – 170. 2. Costa VP, Spaeth GL, Eiferman RA, Orengo-Nania S. Wound healing modulation in glaucoma filtration surgery. Ophthalmic Surg 1993; 24:152– 170. 3. Azuara-Blanco A, Katz LJ. Dysfunctional filtering blebs. Surv Ophthalmol 1998; 43:93– 126. 4. Ritch R, Shields MB, Krupin T. The Glaucomas. 2nd ed. Mosby, 1996. 5. Desjardins DC, Parrish RK, Folberg R et al. Wound healing after filtering surgery in owl monkeys. Arch Ophthalmol 1986; 104:1835 –1839. 6. Miller MH, Grierson I, Unger WI, Hitchings RA. Wound healing in an animal model of glaucoma fistulizing surgery in the rabbit. Ophthalmic Surg 1989; 20:350– 357. 7. Harris AK, Stopak D, Wild P. Fibroblast traction as a mechanism for collagen morphogenesis. Nature 1981; 290:249 – 251. 8. Tomasek JJ, Gabbiani G, Hinz B et al. Myofibroblasts and mechano-regulation of connective tissue remodelling. Nat Rev Mol Cell Biol 2002; 3:349– 363. 9. Clark RA. Regulation of fibroplasia in cutaneous wound repair. Am J Med Sci 1993; 306:42 – 48. 10. Crowston JG, Akbar AN, Constable PH et al. Antimetabolite-induced apoptosis in Tenon’s capsule fibroblasts. Invest Ophthalmol Vis Sci 1998; 39:449 –454. 11. Ehrlich HP. The role of connective tissue matrix in wound healing. Prog Clin Biol Res 1988; 266:243 – 258. 12. Fluck J, Querfeld C, Cremer A et al. Normal human primary fibroblasts undergo apoptosis in three-dimensional contractile collagen gels. J Invest Dermatol 1998; 110:153 – 157. 13. Crowston JG, Salmon M, Khaw PT, Akbar AN. T-lymphocyte – fibroblast interactions. Biochem Soc Trans 1997; 25:529– 531. 14. Spaeth GL, Joseph NH, Fernandes E. Trabeculectomy: a re-evaluation after three years and a comparison with Scheie’s procedure. Ophthalmic Surg 1975; 6:27– 38. 15. Khaw PT, Wells AP, Lim KS. Surgery for glaucoma. Br J Ophthalmol 2003; 87:517. 16. O’Brart DP, Rowlands E, Islam N, Noury AM. A randomised, prospective study comparing trabeculectomy augmented with antimetabolites with a viscocanalostomy technique for the management of open angle glaucoma uncontrolled by medical therapy. Br J Ophthalmol 2002; 86:748 – 754. [email protected]

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112. Roth SM, Spaeth GL, Starita RJ et al. The effects of postoperative corticosteroids on trabeculectomy and the clinical course of glaucoma: five-year follow-up study. Ophthalmic Surg 1991; 22:724 –729. 113. Starita RJ, Fellman RL, Spaeth GL et al. Short- and long-term effects of postoperative corticosteroids on trabeculectomy. Ophthalmology 1985; 92:938– 946. 114. Araujo SV, Spaeth GL, Roth SM, Starita RJ. A ten-year follow-up on a prospective, randomized trial of postoperative corticosteroids after trabeculectomy. Ophthalmology 1995; 102:1753 – 1759. 115. Gandolfi SA, Vecchi M. 5-Fluorouracil in combined trabeculectomy and clear-cornea phacoemulsification with posterior chamber intraocular lens implantation. A one-year randomized, controlled clinical trial. Ophthalmology 1997; 104:181 –186. 116. Krug JH Jr, Melamed S. Adjunctive use of delayed and adjustable low-dose 5-fluorouracil in refractory glaucoma. Am J Ophthalmol 1990; 109:412– 418. 117. Morrow GL, Stein RM, Heathcote JG et al. Ocular toxicity of mitomycin C and 5-fluorouracil in the rabbit. Can J Ophthalmol 1994; 29:268 – 273. 118. Ben SGJ, Glovinsky Y. Needle revision of failed filtering blebs augmented with subconjunctival injection of mitomycin C. Ophthalmic Surg Lasers Imaging 2003; 34:94 – 99. 119. Iester M, Ravinet E, Mermoud A. Postoperative subconjunctival mitomycin-C injection after non-penetrating glaucoma surgery. J Ocul Pharmacol Ther 2002; 18:307 – 312. 120. You YA, Gu YS, Fang CT, Ma XQ. Long-term effects of simultaneous subconjunctival and subscleral mitomycin C application in repeat trabeculectomy. J Glaucoma 2002; 11:110 – 118. 121. Kapetansky FM, Kapetansky SD. Antimetabolite use in revising failing filtering blebs. Semin Ophthalmol 1999; 14:144– 151. 122. Mardelli PG, Lederer CM Jr, Murray PL et al. Slit-lamp needle revision of failed filtering blebs using mitomycin C. Ophthalmology 1996; 103:1946 – 1955. 123. Tressler CS, Cyrlin MN, Rosenshein JS, Fazio R. Subconjunctival versus intrascleral mitomycin-C in trabeculectomy. Ophthalmic Surg Lasers 1996; 27:661– 666. 124. Apostolov VI, Siarov NP. Subconjunctival injection of low-dose Mitomycin-C for treatment of failing human trabeculectomies. Int Ophthalmol 1996; 20:101 – 105. 125. Vote B, Fuller JR, Bevin TH, Molteno AC. Systemic anti-inflammatory fibrosis suppression in threatened trabeculectomy failure. Clin Experiment Ophthalmol 2004; 32:81 – 86.

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19 Encapsulated Bleb Adael S. Soares, Marcelo T. Nicolela, and Paul E. Rafuse Dalhousie University, Halifax, Nova Scotia, Canada

Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada

1. 2. 3. 4. 5. 6.

Introduction Clinical Signs and Symptoms Histology Pathophysiology Incidence and Risk Factors Treatment 6.1. Medical Treatment 6.2. Surgical Treatment 6.2.1. Needling 6.2.2. Surgical Excision of the Tenon’s Cyst 7. Long-Term Complications After Bleb Encapsulation 8. Summary References

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179 180 180 180 181 182 182 183 183 183 183 184 184

INTRODUCTION

Several factors influence the outcome of a glaucoma filtering surgery, including surgical technique (1), use of antimetabolites (2 –6), race (7 –10), and history of previous conjunctival surgery (8). Despite meticulous measures during the pre-, intra-, and postoperative period to increase success rates, complications such as encapsulated blebs occur. In the early postoperative period, intraocular pressure (IOP) is frequently low for several days. This occurs because of decreased aqueous humor formation due to inflammation (11) and/or improved outflow through the new fistula. Between the second and the fourth week after surgery, IOP rises slightly as conjunctival scarring around the newly formed fistula begins to increase outflow resistance (12). It is during this period that bleb encapsulation might develop. 179

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CLINICAL SIGNS AND SYMPTOMS

Encapsulated blebs (also termed cysts of Tenon’s capsule, “cystic” blebs and exteriorization of the anterior chamber) have a characteristic clinical appearance: highly elevated and localized (dome-shaped) filtering bleb, firm to palpation, with vascular engorgement of the overlying conjunctiva, and absence of microcysts (Fig. 19.1). The sclerotomy is patent on gonioscopy and the IOP is usually elevated, but can also be normal (11 – 14). The patients may experience pain or discomfort, usually because of tear film disturbance caused by the large filtering bleb, which can even lead to dellen formation (11,15). Interference of the superior lid function caused by a large elevated bleb can result in ptosis (11,15).

3.

HISTOLOGY

Successful trabeculectomy bleb walls have a subconjunctival extracellular connective tissue layer of low density containing microcystic spaces for the passage of aqueous humor (16). The histology of an encapsulated bleb has a thick-subconjunctival connective tissue membrane with areas of active fibroblast proliferation. These blebs are not considered true cysts because they do not have an epithelial wall lining (15,17,18).

4.

PATHOPHYSIOLOGY

The pathophysiology of encapsulated blebs is still unknown. Scott and Quigley (12) theorized that during the first 2 weeks after surgery, there is cellular proliferation and

Figure 19.1 (See color insert) Slit-lamp photograph of an encapsulated bleb, with its characteristic dome-shaped appearance and enlarged conjunctival vessels. [email protected]

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synthesis of extracellular material in the bleb wall and episcleral surface in contact with the bleb wall (19). The IOP remains at low normal levels due to decreased aqueous humor production. Between the second and the fourth postoperative week, aqueous flow returns to normal expanding the bleb cavity. In a bleb wall which is porous with microcysts, aqueous passes into conjunctival vessels or the tear film, maintaining IOP under control. Conversely, in a thick-walled nonporous bleb wall, increased aqueous flow causes bleb wall compression with increased wall tension, preventing further aqueous drainage. A vicious cycle of inadequate fluid movement occurs and high IOP develops. In addition, high IOP may slow and even stop blood vessel flow around the bleb cavity (conjunctival and episcleral), further impairing aqueous drainage (12). Other important processes occur during wound healing. Fibroblast proliferation with collagen synthesis in the extracellular space is followed by wound contraction. During this process, two different groups of fibroblast have been observed. The first group, called myofibroblast, synthesizes contractile proteins. These proteins are identified as a major source of wound contraction and scarring seen during the healing process (20,21). The other group of fibroblast synthesizes collagen (20). It is theorized that the myofibroblasts are mainly involved in the formation of flat, scarred bleb, whereas in thick-walled, encapsulated blebs, the noncontractile collagen-producing fibroblasts play a major role (22). Inflammatory mediators present after filtering surgery are implicated as important triggers of the healing process and consequently bleb encapsulation (22,23). Interestingly, 5-fluorouracil, which inhibits fibroblasts proliferation (24) and increases the long-term trabeculectomy success (2,3,5), does not reduce the rate of encapsulated blebs (3,5,25 –27). It is speculated that collagen-producing fibroblasts are less sensitive to 5-fluorouracil than the myofibroblasts (22,26,28).

5.

INCIDENCE AND RISK FACTORS

The reported incidence of encapsulated filtering blebs following glaucoma filtering surgeries ranges from 2.5% to 29.0% (3,12,14,17,25,26,28 – 34). Differences in surgical technique likely contribute to the enormous variation of these reported incidence rates, such as full thickness vs. guarded procedures, tenonectomy vs. nontenonectomy, and limbus- vs. fornix-based conjunctival flaps. Other factors that may influence the reported incidences are biased selection of patients and the diagnostic criteria used to define encapsulated blebs. As an example, Richter et al. (14) and Schwartz et al. (29) did not require elevated IOP for the diagnosis of encapsulation, whereas in the study performed by Ophir and Ticho (26) elevated IOP was a prerequisite for this diagnosis. The commonly reported risk factors related to the occurrence of encapsulated blebs include presurgical argon laser trabeculoplasty, topical steroid use, postoperative inflammation, glove powder in the bleb, among others (see Table 19.1 for a full list). The diversity of risk factors indicates that there is no known single etiologic factor. It is speculated that most of these risk factors are associated with intraocular inflammation (17), conjunctival inflammation (22,23), or increased predisposition to wound healing (37). The role of anti-fibroproliferative agents such as 5-fluorouracil and mitomycin-C on the bleb encapsulation process has not been fully elucidated. Despite inhibiting fibroblast proliferation (24,38,39), these agents, particularly 5-fluorouracil, appear not to decrease bleb encapsulation rates following trabeculectomy (3,5,30). The rate of encapsulation following trabeculectomies with mitomycin-C is more controversial, with some studies reporting low rates (6,28) and others reporting rates similar to surgeries without antifibroproliferative agents (25,27,33). Possible explanations from the discrepancy in the [email protected]

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Table 19.1 Risk Factors Implicated in the Development of Encapsulated Blebs Argon laser trabeculoplasty (14,34) Prior conjunctival surgery (31) History of Tenon’s cysts on the other eye (31,34) Long-term use of sympathomimetics (31) Long-term use of beta-blockers (14) Male gender (30,33,34) Corticoisteroid therapy (35,36) Unusual postoperative inflammation (18) and uveitis (23) Congenital glaucoma (14) Juvenile glaucoma (14) Trabeculectomy on the fellow eye (37) Glove powder (30)

findings could include different surgical technique, dose of mitomycin-C, definition of bleb encapsulation, and studied population. In conclusion, it is still unclear whether anti-fibroproliferative agents inhibit the development of encapsulated blebs. Most studies support the idea that 5-fluorouracil does not decrease the incidence of encapsulated blebs. Mitomycin-C, however, may prevent or delay the development of encapsulated blebs.

6.

TREATMENT

The management of encapsulated blebs is either medical or surgical. Medical treatment alone is successful in over 70% of cases, but IOP may stabilize in the high teens (Table 19.2). 6.1.

Medical Treatment

Medical treatment involves the use of antiglaucoma drops, particularly aqueous humor suppressants, and digital massage (12,14,17,26,31 –33,40). The most common medications used are beta-blockers, alpha-2 agonists and carbonic anhydrase inhibitors. Scott and Table 19.2

Success Rate of Medical Treatment for Encapsulated Blebs Success rate

First author Van Buskirk (18) Sherwood (31) Richter (14) Scott (12) Shingleton (40) Campagna (33) Costa (32) Mandal (17)

Year of publication

Number of successes/total number of encapsulated blebs

Success (%)

1982 1987 1988 1988 1990 1995 1997 1999

3/7 74/77 41/56 18/18 35/49 26/29 10/11 15/18

42.9 92.0 73.2 100 71.0 89.6 90.9 83.3

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Quigley (12) proposed that by lowering the IOP with medication, the bleb wall becomes less compressed with reopening of its fluid and vascular channels, thus increasing aqueous humor absorption and IOP lowering. Steroids should be used with caution in this condition. Although they reduce inflammation, their IOP elevating properties may prevent IOP reduction and aqueous outflow through the bleb wall. Encapsulated blebs are often self-limited, allowing the physician to decrease the number or, sometimes, discontinue the antiglaucoma medications initiated with the diagnosis of encapsulation (17). If medical treatment fails to lower the IOP to adequate target levels, surgical management including bleb needling or excision of the Tenon’s cyst, with or without anti-fibroproliferative agents, is indicated. 6.2.

Surgical Treatment

6.2.1.

Needling

This procedure entails creating openings in the cyst’s wall transconjunctivally using a 25or 30-gage needle (Fig. 19.2). Our personal preference is to use a 30-gage needle. It is important to perforate the cyst’s wall in several areas, temporally, nasally, and superiorly if possible. Needling can be performed at the slit-lamp or in a surgical room with an operative microscopy (usually in a minor-surgery setting), under topical anesthesia. Antifibroproliferative agents (5-fluorouracil and mitomycin-C) can also be injected before or after the procedure, adjacent to the cyst, 908 or 1808 away from it (13,41). Ocular massage should be performed after needling to keep the needle tracks open. Multiple needle revisions are sometimes required. Despite being a relatively safe procedure, complications such as bleb leaks, hyphema, corneal edema, ocular hypotony, serous or hemorrhagic choroidal detachment, blebitis, and endophthalimitis have been reported (13,41,42). 6.2.2. Surgical Excision of the Tenon’s Cyst This procedure is performed under peribulbar, retrobulbar, or topical anesthesia. After placement of a superior bridle corneal suture, the conjunctiva posterior to the dome of the encapsulated bleb is incised and carefully dissected over the cyst toward the limbus. Once the cyst is exposed, scissors are then used to excise the cyst completely. The flow through the scleral fistula is tested after filling the anterior chamber with BSS through a paracentesis. Additional flap sutures can be placed if necessary. The conjunctiva is then carefully closed with running sutures (11,17). Anti-fibroproliferative agents can also be used in this procedure (17). After needling or excisional bleb revision, corticosteroid, antibiotic, and cycloplegic eye drops are prescribed. There are several reports on the effectiveness of the different surgical modalities for treatment of encapsulated blebs. Most studies report good success following needling (70%) (11,13) and surgical excision of the cyst (90%) (11). In cases of failure after surgical excision of the Tenon’s cyst, additional surgical procedures such as a new trabeculectomy with mitomycin-C, glaucoma drainage device implantation, or cyclodestructive procedures can be employed for IOP control (14,28,32,40).

7.

LONG-TERM COMPLICATIONS AFTER BLEB ENCAPSULATION

Little information is available regarding the effects of an encapsulated bleb on the prognosis of glaucoma. Sherwood et al. (31) reported that glaucoma patients with encapsulated blebs do not have a higher proportion of visual field progression, loss of visual acuity, or [email protected]

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Figure 19.2 (See color insert) Needling procedure. Under sterile conditions, a lid retractor is placed and a 30 gage bent needle is advanced into the cyst through a remote conjunctival entry; side-to-side movements of the needle are used to tear the wall of the cyst (A). At the end of the procedure, topical fluorescein 2% is applied to test for leakage (B).

cataract extraction when compared with patients without bleb encapsulation. Our experience suggests that patients with bleb encapsulation usually have higher long-term IOP and require more glaucoma medications. 8.

SUMMARY

Bleb encapsulation can occur after trabeculectomy with or without anti-proliferative agents, usually between the second and the fourth postoperative week. The characteristic dome-shaped appearance is associated with a varied number of risk factors. Proper recognition and treatment are fundamental to long-term pressure control. Most cases respond to medical management, but bleb needling or surgical excision of the cyst might be required in some cases. REFERENCES 1.

2. 3. 4. 5. 6. 7.

8.

Jampel HD, Friedman DS, Lubomski LH et al. Effect of technique on intraocular pressure after combined cataract and glaucoma surgery: an evidence-based review. Ophthalmology 2002; 109:2215 – 2224; quiz 2225, 2231. The Fluorouracil Filtering Surgery Study Group. Five-year follow-up of the fluorouracil filtering surgery study. Am J Ophthalmol 1996; 121:349– 366. Ophir A, Ticho U. A randomized study of trabeculectomy and subconjunctival administration of fluorouracil in primary glaucomas. Arch Ophthalmol 1992; 110:1072 –1075. Palmer SS. Mitomycin as adjunct chemotherapy with trabeculectomy. Ophthalmology 1991; 98:317 – 321. Ruderman JM, Welch DB, Smith MF, Shoch DE. A randomized study of 5-fluorouracil and filtration surgery. Am J Ophthalmol 1987; 104:218 – 224. Skuta GL, Beeson CC, Higginbotham EJ et al. Intraoperative mitomycin versus postoperative 5-fluorouracil in high-risk glaucoma filtering surgery. Ophthalmology 1992; 99:438– 444. Broadway D, Grierson I, Hitchings R. Racial differences in the results of glaucoma filtration surgery: are racial differences in the conjunctival cell profile important? Br J Ophthalmol 1994; 78:466 – 475. Broadway DC, Chang LP. Trabeculectomy, risk factors for failure and the preoperative state of the conjunctiva. J Glaucoma 2001; 10:237 – 249. [email protected]

Encapsulated Bleb 9. 10. 11. 12. 13. 14. 15. 16. 17. 18. 19. 20. 21. 22. 23. 24. 25.

26. 27. 28. 29.

30. 31. 32. 33. 34. 35.

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Miller RD, Barber JC. Trabeculectomy in black patients. Ophthalmic Surg 1981; 12:46– 50. Scott IU, Greenfield DS, Schiffman J et al. Outcomes of primary trabeculectomy with the use of adjunctive mitomycin. Arch Ophthalmol 1998; 116:286 – 291. Pederson JE, Smith SG. Surgical management of encapsulated filtering blebs. Ophthalmology 1985; 92:955 – 958. Scott DR, Quigley HA. Medical management of a high bleb phase after trabeculectomies. Ophthalmology 1988; 95:1169– 1173. Hodge W, Saheb N, Balazsi G, Kasner O. Treatment of encapsulated blebs with 30-gauge needling and injection of low-dose 5-fluorouracil. Can J Ophthalmol 1992; 27:233 – 236. Richter CU, Shingleton BJ, Bellows AR, Hutchinson BT, O’Connor T, Brill I. The development of encapsulated filtering blebs. Ophthalmology 1988; 95:1163 – 1168. Feldman RM, Gross RL, Wilson RP, Spaeth GL, Varma R, Eagle RC. Encapsulated filtering blebs. Arch Ophthalmol 1987; 105:1589. Addicks EM, Quigley HA, Green WR, Robin AL. Histologic characteristics of filtering blebs in glaucomatous eyes. Arch Ophthalmol 1983; 101:795 – 798. Mandal AK. Results of medical management and mitomycin C-augmented excisional bleb revision for encapsulated filtering blebs. Ophthalmic Surg Lasers 1999; 30:276– 284. Van Buskirk EM. Cysts of Tenon’s capsule following filtration surgery. Am J Ophthalmol 1982; 94:522 – 527. Jampel HD, McGuigan LJ, Dunkelberger GR, L’Hernault NL, Quigley HA. Cellular proliferation after experimental glaucoma filtration surgery. Arch Ophthalmol 1988; 106:89 – 94. Gabbiani G, Chaponnier C, Huttner I. Cytoplasmic filaments and gap junctions in epithelial cells and myofibroblasts during wound healing. J Cell Biol 1978; 76:561– 568. Ariyan S, Enriquez R, Krizek TJ. Wound contraction and fibrocontractive disorders. Arch Surg 1978; 113:1034 – 1046. Ophir A. Encapsulated filtering bleb. A selective review—new deductions. Eye 1992; 6:348–352. Ophir A, Ticho U. Delayed filtering bleb encapsulation. Ophthalmic Surg 1992; 23:38 – 39. Yamamoto T, Varani J, Soong HK, Lichter PR. Effects of 5-fluorouracil and mitomycin C on cultured rabbit subconjunctival fibroblasts. Ophthalmology 1990; 97:1204– 1210. Prata JA, Minckler DS, Baerveldt G, Lee PP, LaBree L, Heuer DK. Trabeculectomy in pseudophakic patients: postoperative 5-fluorouracil versus intraoperative mitomycin C. Ophthalmic Surg 1995; 26:73– 77. Ophir A, Ticho U. Encapsulated filtering bleb and subconjunctival 5-fluorouracil. Ophthalmic Surg 1992; 23:339 –341. Katz GJ, Higginbotham EJ, Lichter PR et al. Mitomycin C versus 5-fluorouracil in high-risk glaucoma filtering surgery. Extended follow-up. Ophthalmology 1995; 102:1263 – 1269. Azuara-Blanco A, Bond JB, Wilson RP, Moster MR, Schmidt CM. Encapsulated filtering blebs after trabeculectomy with mitomycin-C. Ophthalmic Surg Lasers 1997; 28:805 –809. Schwartz AL, Van Veldhuisen PC, Gaasterland DE, Ederer F, Sullivan EK, Cyrlin MN. The advanced glaucoma intervention study (AGIS): 5. Encapsulated bleb after initial trabeculectomy. Am J Ophthalmol 1999; 127:8 – 19. Oh Y, Katz LJ, Spaeth GL, Wilson RP. Risk factors for the development of encapsulated filtering blebs. The role of surgical glove powder and 5-fluorouracil. Ophthalmology 1994; 101:629–634. Sherwood MB, Spaeth GL, Simmons ST et al. Cysts of Tenon’s capsule following filtration surgery. Medical management. Arch Ophthalmol 1987; 105:1517 – 1521. Costa VP, Correa MM, Kara-Jose N. Needling versus medical treatment in encapsulated blebs. A randomized, prospective study. Ophthalmology 1997; 104:1215– 1220. Campagna JA, Munden PM, Alward WL. Tenon’s cyst formation after trabeculectomy with mitomycin C. Ophthalmic Surg 1995; 26:57 – 60. Feldman RM, Gross RL, Spaeth GL et al. Risk factors for the development of Tenon’s capsule cysts after trabeculectomy. Ophthalmology 1989; 96:336 – 341. Starita RJ, Fellman RL, Spaeth GL, Poryzees EM, Greenidge KC, Traverso CE. Short- and long-term effects of postoperative corticosteroids on trabeculectomy. Ophthalmology 1985; 92:938 – 946.

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186 36. 37. 38.

39. 40. 41.

42.

Soares et al. Loftfield K, Ball SF. Filtering bleb encapsulation increased by steroid injection. Ophthalmic Surg 1990; 21:282 –287. Mietz H, Jacobi PC, Welsandt G, Krieglstein GK. Trabeculectomies in fellow eyes have an increased risk of tenon’s capsule cysts. Ophthalmology 2002; 109:992– 997. Khaw PT, Sherwood MB, Doyle JW et al. Intraoperative and post operative treatment with 5-fluorouracil and mitomycin-c: long term effects in vivo on subconjunctival and scleral fibroblasts. Int Ophthalmol 1992; 16:381– 385. Smith S, D’Amore PA, Dreyer EB. Comparative toxicity of mitomycin C and 5-fluorouracil in vitro. Am J Ophthalmol 1994; 118:332 – 337. Shingleton BJ, Richter CU, Bellows AR, Hutchinson BT. Management of encapsulated filtration blebs. Ophthalmology 1990; 97:63 – 68. Allen LE, Manuchehri K, Corridan PG. The treatment of encapsulated trabeculectomy blebs in an out-patient setting using a needling technique and subconjunctival 5-fluorouracil injection. Eye 1998; 12:119– 123. Shin DH, Juzych MS, Khatana AK, Swendris RP, Parrow KA. Needling revision of failed filtering blebs with adjunctive 5-fluorouracil. Ophthalmic Surg 1993; 24:242 – 248.

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20 Needling Procedures in Postoperative Management of Glaucoma Surgery Tarek Shaarawy University of Geneva, Geneva, Switzerland

Pieter Gouws and Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada

Andre´ Mermoud University of Lausanne, Lausanne, Switzerland

1. Technique 1.1. Interval Between the Surgery and Needling 1.2. Repeated Needling 1.3. Adjunctive Antimetabolite Use with Needling 1.4. How much to Inject? 1.5. Where to Inject? 2. Complications 3. Potential Risk Factors for Failure of Needling Procedure 4. Take-Home Message References

188 189 189 189 189 190 190 190 191 191

Ferrer (1) first described a small transconjunctival incision to salvage a failing glaucoma surgery in 1941. He termed the procedure “conjunctival dialysis.” Pederson and Smith (2) described the needling procedure as it is currently known and performed in 1985. Over the last 20 years, multiple publications (1 –15) have reported needling as part of the armamentarium of postfiltering surgery interventions. Currently, its use is advocated not only to incise encysted blebs, but also to raise flat ones. With its reported success rates, it is reasonable to recommend that prior to re-operation in the cases of flattened or encysted blebs, a needling procedure should be considered. A major problem in achieving successful control of IOP after filtering surgery is the development of fibrosis and/or fibrous capsule around the surgical site, which may severely restrict the reabsorption of aqueous humor. Needle revision (with or without 5-fluorouracil [5-FU] or mitomycin C [MMC]) has been reported in several recent studies to be successful in restoring adequate function to fibrosed or encapsulated filtering blebs in 45 –93% (5 – 12,15) of cases. The procedure allows a surgeon to create an opening(s) in the wall of an encapsulated bleb or raise a flattened bleb, with a small-gage needle via subconjunctival insertion at the slit-lamp or in the operating room. 187

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TECHNIQUE

The technique of needling an encapsulated bleb is described in Chapter 19. Needling involves instillation of topical anesthetic drops (e.g., Amethocaine 0.1%) and Apraclonidine 0.5% or 1% for vasoconstriction (optionally Phenylephrine 2.5% can be used), a preoperative antibiotic (e.g., Ofloxacine 2.5%), and lid scrub with povidone –iodine solution to the eyelids and periorbital area. A lid speculum is placed in the eye. Needling can be performed with the naked eye at the slit-lamp, or preferably in a treatment room under an operating microscope. The patient is instructed to look to the direction that would ensure maximum exposure to the surgery site [downwards in the case of a 12 o’clock surgical site (Fig. 20.1)]. A corneal stay suture is advisable if the patient is anxious or moving. A 30 or 29 gage needle is mounted on a 1 mL (insulin) syringe. The syringe is left straight or bent with a blade breaker to a “bent bayonet” shape if required. The needle is introduced beneath the conjunctiva near the surgical site, usually using an entry site 5– 6 mm temporal to the site of the scleral flap. A small amount of local anesthetic or BSS can be injected subconjunctivally (e.g., 0.1 mL xylocaine) to elevate the conjunctiva off the sclera so as to prevent conjunctival or vessel perforation. However, we do not find this necessary in most cases. If visualization of the needle tip is difficult due to congestion or too much conjunctival elevation, a suture-lysis lens is placed on the conjunctiva to deturgess or flatten it allowing for excellent visualization of the needle tip and the edges of the scleral flap. The tip of the needle should be carefully moved in order to penetrate under the edge of the flap edge through the fibrous capsule. The needle is then carefully advanced under the flap and the flap elevated with a sweeping motion (Fig. 20.1). Some authors enter the anterior chamber with the needle tip, but if this is done care should be taken not to perforate the ciliary body as this can cause a hyphema (13). Entering the anterior chamber is not recommended in phakic patients. If the initial needling seems not to elevate the flap, slightly deeper penetration should be attempted to disrupt the scleral periflap fibrosis. The needle is then withdrawn in the same track. As this is done, a bleb will immediately form. Suturing of the conjunctiva

Figure 20.1

Needle is advanced carefully under the flap and the flap elevated. [email protected]

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is not usually required. Slit-lamp examination and tonometry as well as Seidel testing should usually be performed 15 min after the procedure. After the procedure, a topical steroid (e.g., Prednisolone 1%) and an antibiotic (e.g., Chloramphenicol 0.5%) are usually prescribed for 1 week or 10 days. A course of 4 days of subconjunctival 5-FU can be applied to the eye (10). 1.1.

Interval Between the Surgery and Needling

In some reports, blebs have been needled as early as 3 days postoperatively (14). On the other end of the spectrum, some surgeons have attempted needling years after the initial surgery (6,8,9,15). A short interval between the initial surgery and needling has been associated with success (3), whereas other studies showed that time interval is of no importance with respect to a successful outcome (14,15). We suggest that massage and suture removal/lysis be performed prior to needling during the first 6 weeks post surgery. 1.2.

Repeated Needling

Needling can be repeated if it is deemed necessary. Some eyes can undergo multiple needling procedures when an initial improvement is followed by recurrence of fibrosis. Up to 10 separate needlings have been reported in the literature (5). 1.3.

Adjunctive Antimetabolite Use with Needling

Antimetabolites can be injected during needling. This has been repeatedly advocated, (3,4,10,12) but no randomized controlled trials have been performed to determine whether there are any benefits of adjunctive 5-FU or MMC. Authors using either 5-FU or MMC have justified their methodology on hypothetical basis (10). In light of our knowledge of the pathophysiological process involved in wound healing, and as the needling manipulation by itself constitutes further trauma and thus further stimulus for wound healing, the use of adjunctive antimetabolites is reasonable. We recommend the use of 5-FU for 4 days post needling. 1.4.

How much to Inject?

5-FU has been administered in concentrations ranging from 25 mg/mL to 50 mg/mL and in volumes ranging from 0.1 mL to 0.2 mL. Total doses ranged from 1 mg to 5 mg. MMC concentrations of 0.28 mg/mL to 0.50 mg/mL have been used (12). The nontoxic dose of 5-FU injected intravitreal has been reported as 1 mg (16 – 18), which probably explains why needling procedures where 5-FU is injected into or very close to the bleb have not been reported to be associated with increased incidence of complications (5,8,15). Mitomycin is a toxic drug and we do not use it with our needling procedures. 1.5.

Where to Inject?

Some surgeons prefer to inject antimetabolites in the quadrant opposite to the site of surgery, whereas other authors inject at the same site of the needling (5,8,15). We prefer the former site. [email protected]

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COMPLICATIONS

Needling is a relatively safe procedure that is generally not associated with grave complications. Common and transient complications include subconjunctival hemorrhage, transient conjunctival wound leak, and hyphema. Ocular hypotony may occur, and although rare, choroidal effusion has been reported (19,20). Aqueous may occasionally leak from the needle entry site for several days but does not usually require repair. One group reported that rapid closure of the entry wound is facilitated by immediate postneedling tamponade of the entry site with a cotton bud soaked in local anesthetic (15). The incidence of minor complications has been reported between 20% and 38%. Fortunately, more serious complications are unusual. Malignant glaucoma or aqueous misdirection has been reported following needling (21,22). Libre (23) reported a case of transient lens clouding 5 min after needling and 5-FU injection, the patient’s vision decreased to counting fingers due to anterior lens capsule opacification. This resolved ,24 h, with the patients vision returning to preneedling levels. It was concluded that entry of 5-FU into the anterior chamber after needling precipitated the lens-clouding. Chen and Palmberg (24) reported a case of endophthalmitis after needling.

3.

POTENTIAL RISK FACTORS FOR FAILURE OF NEEDLING PROCEDURE

Generally speaking, needling procedures tend to fail in younger rather than in older patients. Success is usually higher in White patients compared to Afro-Caribbean or Asian patients. Etiologically, success seems to be higher in patients suffering from primary open angle glaucoma compared eyes with other glaucoma forms. It seems that patients with previous exposure to 5-FU, MMC, or b-irradiation have a lower success rates. This perhaps reflects the fact that antifibrotic agents are usually used in eyes considered to be at a greater risk of failure. None of these parameters were found to be statistically significant in the largest prospective interventional study by Broadway et al. (15). They did, however, find a statistically significant difference in success following bleb needling in patients in whom the IOP immediately postneedling was ,11 mmHg. Shin et al. (8) reported that immediate postneedling IOP was .10 mmHg as a statistically significant predictor for failure of needling. Shin et al. also found that preneedling IOP was .30 mmHg and lack of MMC use during the trabeculectomy or combined procedures to be clinically significant predictors of needling failure. Kaplan –Meier survival analysis of bleb survival following needling suggests a 3 year survival of 40% (with IOP reduced by 30% from baseline with no or reduced medication) in Broadway et al. (Fig. 20.2) and a 28% survival in Shin et al. (success as target IOP achieved with no more than two medications).

4.

TAKE-HOME MESSAGE

Bleb needling should be considered when a bleb fails post surgery. It has multiple advantages over re-operations. It can be done at the slit-lamp in an office setting, is simple and repeatable, and has the potential to be effective. Also, it is relatively safe. Needling does not prevent the surgeon from later resorting to other methods of IOP reduction if it fails. [email protected]

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Figure 20.2 Kaplan – Meier survival analysis of bleb survival following needling. Three-year survival of 40% (with IOP reduced by 30% from baseline with no or reduced medication) (15).

The needling procedure is more likely to succeed if an immediate lowering of IOP below 11 mmHg is achieved.

REFERENCES 1. 2. 3. 4. 5. 6. 7. 8.

9. 10. 11. 12.

Ferrer H. Conjunctival dialysis in the treatment of glaucoma recurrent after sclerectomy. Am J Ophthalmol 1941; 24:788 – 790. Pederson JE, Smith SG. Surgical management of encapsulated filtering blebs. Ophthalmology 1985; 92:955 – 958. Gillies WE, Brooks AMV. Restoring the function of the failed bleb. Aust NZJ Ophthalmol 1991; 19:49 – 51. Hodge W, Saheb N, Balazsi G, Kasner O. Treatment of encapsulated blebs with 30-gauge needling and injection of low-dose 5-fluorouracil. Can J Ophthalmol 1992; 27:233 – 236. Fagerli M, Løfors KT, Elsa˚s T. Needling revision of failed filtering blebs after trabeculectomy: a retrospective study. Acta Ophthalmol Scand 2003; 81:577– 582. Iwach AG, Delgado MF, Novack GD, Nguyen N, Wong PC. Transconjunctival mitomycin-C in needle revisions of failing filtering blebs. Ophthalmology 2003; 110:734 – 742. Ophir A, Wasserman D. 5-Fluorouracil-needling and paracentesis through the failing filtering bleb. Ophthalmic Surg Lasers 2002; 33:109 – 116. Shin DH, Kim YY, Ginde SY, Kim PH, Eliassi-Rad B, Khatana AK, Keole NS. Risk factors for failure of 5-fluorouracil needling revision for failed conjunctival filtration blebs. Am J Ophthalmol 2001; 132:875 –880. Ung CT, Von Lany H, Claridge KG. Late bleb needling. Br J Ophthalmol 2003; 87:1430 – 1431. Shin DH, Juzych MS, Khatana AK et al. Needling revision of failed filtering blebs with adjunctive 5-fluorouracil. Ophthalmic Surg 1993; 24:242 – 248. Meyer J, Guhlmann M, Funk J. How successful is the filtering bleb “needling”? [in German]. Klin Monatsbl Augenheilkd 1997; 210:192 –196. Mardelli CM, Lederer CM Jr, Murray PL et al. Slit-lamp needle revision of failed filtering blebs using mitomycin C. Ophthalmology 1996; 103:1946 – 1955. [email protected]

192 13. 14. 15.

16. 17. 18.

19. 20.

21. 22. 23. 24.

Shaarawy et al. Azuara-Blanco A, Katz LJ. Dysfunctional Filtering Blebs. Surv Ophthalmol 1998; 43:93 – 126. Cohen JS, Shaffer RN, Hetherington J, Hoskins D. Revision of filtration surgery. Arch Ophthalmol 1977; 95:1612 – 1615. Broadway D, Bloom PA, Bunce C, Thiagarajan M, Khaw PT. Needle revision of failing and failed trabeculectomy blebs with adjunctive 5-fluorouracil: Survival anal Ophthalmol 2004; 111:665 – 673. Blumenkranz MS, Ophir A, Claflin AJ, Hajek A. Fluorouracil for the treatment of massive periretinal proliferation. Am J Ophthalmol 1982; 94:458– 467. Blankenship GW. Evaluation of a single intravitreal injection of 5-fluorouracil in vitrectomy cases. Graefes Arch Clin Exp Ophthalmol 1989; 227:565 – 568. Blumenkranz M, Hernandez E, Ophir A, Norton EW. 5-fluorouracil: new applications in complicated retinal detachment for an established antimetabolite. Ophthalmology 1984; 91:122 – 130. Howe LJ, Bloom P. Delayed suprachoroidal haemorrhage following trabeculectomy bleb needling. Br J Ophthalmol 1999; 83:757. Syam PP, Hussain B, Anand N. Delayed suprachoroidal hemorrhage after needle revision of trabeculectomy bleb in a patient with hairy cell leukemia. Am J Ophthalmol 2003; 136:1155 – 1157. Mathur R, Gazzard G, Oen F. Malignant glaucoma following needling of a trabeculectomy bleb [letter]. Eye 2002; 16:667– 668. Ramanathan US, Kumar V, O’Neill E, Shah P. Aqueous misdirection following needling of trabeculectomy bleb. Eye 2003; 17:441– 442. Libre PE. Transient, profound cataract associated with intracameral 5-fluorouracil. Am J Ophthalmol 2003; 135:101 – 102. Chen PP, Palmberg PF. Needling revision of glaucoma drainage device filtering blebs. Ophthalmology 1997; 104:1004– 1010.

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B. Management of Flat Anterior Chamber with High Intraocular Pressure

21 Suprachoroidal Hemorrhage in Filtering Surgery and Practical Management Ravikrishna Nrusimhadevara, R. G. Devenyi, and Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada

1. Introduction 2. Mechanism and Predisposing Factors 3. Clinical Picture and Diagnosis 4. Prevention 5. Treatment 6. Prognosis References

1.

193 193 194 194 195 196 196

INTRODUCTION

Suprachoroidal hemorrhage is a devastating complication which is associated with all types of intraocular surgery (1 – 12) or penetrating trauma (13 – 15). Suprachoroidal hemorrhage is most commonly seen following glaucoma filtering surgery (16 – 18). It can occur with or without expulsion of ocular contents. Suprachoroidal hemorrhage associated with expulsion of intraocular contents is generally termed an expulsive hemorrhage and if it occurs in an intact eye it is termed a non-expulsive choroidal hemorrhage. Suprachoroidal hemorrhage can occur both intraoperatively and postoperatively (19,20).

2.

MECHANISM AND PREDISPOSING FACTORS

The most widely accepted theory for the cause of suprachoroidal hemorrhage is the rupture of short and long posterior ciliary blood vessels owing to sudden hypotony during surgery or trauma leading to accumulation of arterial blood in the suprachoroidal space (21). The amount of blood determines the extent of the choroidal detachment. Preoperative risk factors include advanced age, uncontrolled preoperative intraocular pressure with sudden 193

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decompression, severe intraocular inflammation, aphakia, and high myopia in young patients. Suggested vascular factors contributing to suprachoroidal hemorrhage include arterial hypertension, generalized arteriosclerosis, local vascular sclerosis, necrosis of intraocular arterioles, hypotension, and diabetes (22). Intraoperative sudden uncontrolled decompression of the anterior chamber, vitreous loss, and use of antimetabolites increase the risk of suprachoroidal hemorrhage (23). Conditions with increased venous pressure or vascular anomalies such as Sturge–Weber syndrome, orbital AV fistulas, prominent episcleral vessels, and nanophthalmos are known to precipitate intraoperative suprachoroidal hemorrhage. Postoperatively, prolonged hypotony, use of antimetabolites (24,25), excessive inflammation, and Valsalva’s maneuver can precipitate the occurrence of a suprachoroidal hemorrhage. Events leading to delayed non-expulsive choroidal hemorrhage (DNECH) include coughing and vomiting associated with recovery from general anesthesia (15,23,26,27). General anesthesia has been implicated in suprachoroidal hemorrhage (23,26–28); therefore, local anesthesia is preferable for glaucoma procedures. Should the use of general anesthesia be mandatory, preoperative use of antiemetics has been suggested (23). Thiopental sodium is known to cause elevation of intraocular pressure, so it should be avoided for induction (29). A history of suprachoroidal hemorrhage in one eye should always alert the surgeon, as it places the patient at a higher risk for suprachoroidal hemorrhage in the second eye. 3.

CLINICAL PICTURE AND DIAGNOSIS

Sudden excruciating pain with a flat anterior chamber and raised intraocular pressure either intraoperatively or postoperatively and a choroidal mass should lead to the prompt suspicion of suprachoroidal hemorrhage. The diagnosis is made by careful clinical examination and ultrasonography. Ophthalmoscopy will show an immobile, smooth dome-shaped elevation. Ultrasonography is of hallmark importance, as it helps distinguish serous choroidal detachments from hemorrhagic choroidal detachments and determines the right time for surgical drainage. Ultrasonographically, the choroidal detachments appear as immobile, smooth, thick dome-shaped echoes on B scan [Fig. 21.1(A), (B), (C)]. A scan shows high reflective echoes with fresh blood and low reflective echoes in areas if mixed with serous fluid (30) [Fig. 21.1(A)]. Suprachoroidal hemorrhage occurring during surgery is composed of arterial blood. Those occurring postoperatively can have a serous component. This is due to hemorrhage occurring in hypotonous eye with serous choroidal effusions. About 10 – 14 days after the hemorrhage, lysis of the clot occurs and the reflectivity decreases. Once the suprachoroidal reflectivity is reduced, drainage of the suprachoroidal blood will be facilitated owing to this liquefaction process. 4.

PREVENTION

It is essential to control intraocular pressure preoperatively to reduce the effects of sudden decompression during filtration surgery. This can be done by using topical medications, osmotic diuretics, acetazolamide, and slow-controlled decompression via a surgical paracentesis. In high-risk cases such as nanophthalmos, Sturge –Weber syndrome, superior vena cava syndrome, and orbital AV fistulas, prophylactic posterior sclerotomy (23) should be performed. A prophylactic posterior sclerotomy (31,32) is created by performing a full thickness sclerotomy, 1.5 –2 mm long, 3 – 4 mm posterior to the surgical limbus. This sclerotomy serves to drain suprachoroidal blood, preventing elevation of intraocular pressure and [email protected]

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Figure 21.1 (A) B scan of a patient with suprachoroidal hemorrhage, (B) B scan showing 3608 choroidal detachment with suprachoroidal blood, and (C) B scan picture showing choroidal detachment with blood in suprachoroidal space and vitreous cavity.

related complications. We also recommend closure of the eye as quickly as possible in an at-risk situation. Tip: In cases undergoing filtration surgery predisposed to suprachoroidal hemorrhage, we recommend the use of a preplaced scleral suture utilizing a 10/0 nylon suture through the scleral flap into the scleral bed margin prior to entering the anterior chamber. Leave the suture long enough, so a loop can be made to allow the flap to be adequately retracted. Once the sclerectomy has been created and peripheral iridectomy performed, the wound should be quickly closed with the help of this preplaced suture. Rapid restoration of intraocular pressure via rapid wound closure and anterior chamber reformation with air or viscoelastic may prevent choroidal hemorrhage. 5.

TREATMENT

Intraoperatively, the prompt identification of a suprachoroidal hemorrhage is of hallmark importance. Failure to identify this in time can lead to expulsion of the intraocular contents. Sudden pain with unexplained shallowing of the anterior chamber and iris prolapse must alert the surgeon. The eye will feel hard. At the earliest suspicion, the first step should [email protected]

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be to close the surgical wound as quickly as possible (see preceeding Tip) and to examine the eye for a suprachoroidal hemorrhage. A full thickness sclerotomy should be made in the involved quadrant, 3– 4 mm posterior to the limbus to help drain the suprachoroidal blood. If the hemorrhage is massive, sclerotomies should be placed in all four quadrants. A sclerostomy is made by creating a 5 mm conjunctival opening parallel to the limbus followed by a cut down through the sclera to the suprachoroidal space. Once the sclera is exposed, a No. 57 blade is used to gently scratch the sclera radially, 1.5 mm in length, 3 – 4 mm from the limbus taking care to avoid cutting through the choroidal tissue, thus preventing intraocular hemorrhage and vitreous loss. The scleral wound is not sutured but the conjunctiva is sutured in two layers. In cases of DNECH, diagnosis is confirmed by ophthalmoscopy and ultrasonography. Transillumination with a muscle light will show loss of red reflex. The increased intraocular pressure should be monitored closely and attempts made to lower the intraocular pressure by all available medical methods. Visualization of the posterior segment can be difficult in cases where hemorrhage has broken through the retina causing a vitreous hemorrhage. Serial ultrasonography should be used to monitor the status of the detachment and the reflectivity of the suprachoroidal collection. The suprachoroidal contents are highly reflective on A scan in a fresh case of suprachoroidal hemorrhage. Serial monitoring of the clot and its liquefaction is done by assessing declining reflectivity on A scan. The ideal time to drain is 10 –14 days (33); by this time blood is typically fluid enough to drain easily through a sclerotomy. The suprachoroidal blood is best drained by a vitreoretinal surgeon performing posterior sclerotomies as described earlier with simultaneous injection of saline or balanced salt solution into the vitreous cavity using a continuous infusion line via pars plana (34). Various additional maneuvers have been described such as rolling a cotton-tipped applicator towards the drainage site and introducing blunt cyclodialysis spatula into the suprachoroidal space to displace the clots (35). However, we feel that the suprachoroidal blood should be allowed to drain passively with reformation of the anterior chamber and intravitreal injection of balanced salt solution. No attempt should be made to grasp or pull the clots physically. Use of continuous air infusion with an air pump connected to the eye (30), heavy perfluorocarbon liquids to express the suprachoroidal blood (36), and injections of viscoelastics (37) can also been utilized. In the presence of extensive vitreous incarceration or partial extrusion of ocular contents, vitrectomy is indicated (38). The use of more aggressive vitreous surgery with newer adjuncts such as perfluorocarbon in cases of suprachoroidal hemorrhage associated with rhegmatogenous retinal detachment has improved the prognosis for more complex cases which were previously considered inoperable (30,36,38). 6.

PROGNOSIS

Visual recovery can be highly variable. The reported results range from loss of light perception to 20/40 (15,27,28,30,36,38,39). Visual prognosis and poorer outcomes are reported in eyes with complex hemorrhages, that is, those associated with vitreous incarceration in the wound and retinal detachment (40). REFERENCES 1.

Ariano ML, Ball SF. Delayed nonexpulsive suprachoroidal hemorrhage after trabeculectomy. Ophthalmic Surg 1987; 18(9):661– 666. [email protected]

Suprachoroidal Hemorrhage 2. 3. 4. 5. 6. 7. 8. 9. 10.

11. 12. 13. 14. 15.

16.

17. 18. 19.

20. 21. 22. 23. 24. 25. 26. 27.

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Canning CR, Lavin M, McCartney AC, Hitchings RA, Gregor ZJ. Delayed suprachoroidal haemorrhage after glaucoma operations. Eye 1989; 3(Pt 3):327 – 331. Howe LJ, Bloom P. Delayed suprachoroidal haemorrhage following trabeculectomy bleb needling. Br J Ophthalmol 1999; 83(6):757. Kennedy CJ, Roden DM, McAllister IL. Suprachoroidal effusion following argon laser trabeculoplasty. Aust NZ J Ophthalmol 1996; 24(3):279 – 282. Fastenberg DM, Perry HD, Donnenfeld ED, Schwartz PL, Shakin JL. Expulsive suprachoroidal hemorrhage with scleral buckling surgery. Arch Ophthalmol 1991; 109(3):323. Lakhanpal V, Schocket SS, Elman MJ, Dogra MR. Intraoperative massive suprachoroidal hemorrhage during pars plana vitrectomy. Ophthalmology 1990; 97(9):1114– 1119. Tabandeh H, Flynn HW Jr. Suprachoroidal hemorrhage during pars plana vitrectomy. Curr Opin Ophthalmol 2001; 12(3):179– 185. Duncker GI, Rochels R. Delayed suprachoroidal hemorrhage after penetrating keratoplasty. Int Ophthalmol 1995; 19(3):173– 176. Ingraham HJ, Donnenfeld ED, Perry HD. Massive suprachoroidal hemorrhage in penetrating keratoplasty. Am J Ophthalmol 1989; 108(6):670– 675. Kay MD, Epstein RJ, Torczynski E. Histopathology of acute intraoperative suprachoroidal hemorrhage associated with transscleral intraocular lens fixation. J Cataract Refract Surg 1993; 19(1):83– 87. Price FW Jr, Whitson WE, Ahad KA, Tavakkoli H. Suprachoroidal hemorrhage in penetrating keratoplasty. Ophthalmic Surg 1994; 25(8):521– 525. Purcell JJ Jr, Krachmer JH, Doughman DJ, Bourne WM. Expulsive hemorrhage in penetrating keratoplasty. Ophthalmology 1982; 89(1):41 –43. Martorina M. Spontaneous corneal perforation with expulsive hemorrhage. Ann Ophthalmol 1993; 25(9):324– 325. van Meurs JC, van den Bosch WA. Suprachoroidal hemorrhage following a Valsalva maneuver. Arch Ophthalmol 1993; 111(8):1025– 1026. Reynolds MG, Haimovici R, Flynn HW Jr, DiBernardo C, Byrne SF, Feuer W. Suprachoroidal hemorrhage. Clinical features and results of secondary surgical management. Ophthalmology 1993; 100(4):460 –465. Speaker MG, Guerriero PN, Met JA, Coad CT, Berger A, Marmor M. A case – control study of risk factors for intraoperative suprachoroidal expulsive hemorrhage. Ophthalmology 1991; 98(2):202– 209. Tuli SS, WuDunn D, Ciulla TA, Cantor LB. Delayed suprachoroidal hemorrhage after glaucoma filtration procedures. Ophthalmology 2001; 108(10):1808– 1811. Taylor DM. Expulsive hemorrhage. Am J Ophthalmol 1974; 78(6):961 – 966. Cantor LB, Katz LJ, Spaeth GL. Complications of surgery in glaucoma. Suprachoroidal expulsive hemorrhage in glaucoma patients undergoing intraocular surgery. Ophthalmology 1985; 92(9):1266– 1270. Nichamin LD. Acute intraoperative suprachoroidal hemorrhage. J Cataract Refract Surg 1994; 20(1):106– 108. Wolter JR, Garfinkel RA. Ciliochoroidal effusion as precursor of suprachoroidal hemorrhage: a pathologic study. Ophthalmic Surg 1988; 19(5):344 – 349. Norman SJ. Cataract surgery and its complications. 2003; 489 – 495. Frenkel RE, Shin DH. Prevention and management of delayed suprachoroidal hemorrhage after filtration surgery. Arch Ophthalmol 1986; 104(10):1459– 1463. The Fluorouracil Filtering Surgery Study Group. Risk factors for suprachoroidal hemorrhage after filtering surgery. Am J Ophthalmol 1992; 113(5):501– 507. Gressel MG, Parrish RK. Fluorouracil and suprachoroidal hemorrhage. Arch Ophthalmol 1987; 105(2):169. Tarakji MS, Matta CS. Expulsive hemorrhage: report of five cases. Ann Ophthalmol 1978; 10(9):1269– 1271. Ruderman JM, Harbin TS Jr, Campbell DG. Postoperative suprachoroidal hemorrhage following filtration procedures. Arch Ophthalmol 1986; 104(2):201– 205.

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198 28. 29. 30.

31. 32. 33. 34. 35. 36.

37. 38.

39. 40.

Nrusimhadevara, Devenyi, and Trope Frenkel RE, Shin DH. Suprachoroidal hemorrhage after glaucoma filtering surgery. Am J Ophthalmol 1987; 104(4):444 –445. Vail D. Subchoroidal expulsive hemorrhage occuring during thiopental sodium anesthesia: its treatment by sclerotomy. Arch Ophthalmol 1949; 42:562 – 566. Abrams GW, Thomas MA, Williams GA, Burton TC. Management of postoperative suprachoroidal hemorrhage with continuous-infusion air pump. Arch Ophthalmol 1986; 104(10):1455– 1458. Bellows AR, Chylack LT Jr, Epstein DL, Hutchinson BT. Choroidal effusion during glaucoma surgery in patients with prominent episcleral vessels. Arch Ophthalmol 1979; 97(3):493 – 497. Christensen GR, Records RE. Glaucoma and expulsive hemorrhage mechanisms in the Sturge– Weber syndrome. Ophthalmology 1979; 86(7):1360– 1366. Lakhanpal V. Experimental and clinical observations on massive suprachoroidal hemorrhage. Trans Am Ophthalmol Soc 1993; 91:545 –652. Shaffer RN. Posterior sclerotomy with scleral cautery in the treatment of expulsive hemorrhage. Am J Ophthalmol 1966; 61(5):1307– 1311. Bellows AR, Chylack LT Jr, Hutchinson BT. Choroidal detachment. Clinical manifestation, therapy and mechanism of formation. Ophthalmology 1981; 88(11):1107– 1115. Desai UR, Peyman GA, Chen CJ, Nelson NC Jr, Alturki WA, Blinder KJ et al. Use of perfluoroperhydrophenanthrene in the management of suprachoroidal hemorrhages. Ophthalmology 1992; 99(10):1542 –1547. Shin DH, Frenkel RE. The use of viscoelastic substances in the drainage of postoperative suprachoroidal hemorrhage. Ophthalmic Surg 1989; 20(12):895. Lakhanpal V, Schocket SS, Elman MJ, Nirankari VS. A new modified vitreoretinal surgical approach in the management of massive suprachoroidal hemorrhage. Ophthalmology 1989; 96(6):793– 800. Gressel MG, Parrish RK, Heuer DK. Delayed nonexpulsive suprachoroidal hemorrhage. Arch Ophthalmol 1984; 102(12):1757 – 1760. Wirostko WJ, Han DP, Mieler WF, Pulido JS, Connor TB Jr, Kuhn E. Suprachoroidal hemorrhage: outcome of surgical management according to hemorrhage severity. Ophthalmology 1998; 105(12):2271 –2275.

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22 Malignant Glaucoma Dimitrios Kourkoutas 401 Hellenic Army General Hospital, Athens, Greece

Charles J. Pavlin and Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada

1. Introduction: Terminology 2. Definition: Clinical Diagnosis 3. Pathophysiology 3.1. Aqueous Humor Misdirection 3.2. Slackness or Laxity of the Lens Zonules 3.3. Positive Pressure Phenomenon 4. Differential Diagnosis 4.1. Suprachoroidal Hemorrhage 4.2. Pupillary Block 5. Management 5.1. Risk Factors: Prevention 5.2. Medical Treatment 5.3. Laser Treatment 5.4. Surgical Treatment 5.4.1. Pars Plana Vitrectomy (PPV) 5.4.2. Combined PPV and Pars Plana Tube Insertion 5.4.3. Chandler’s Technique 5.4.4. Alternative Surgical Procedures in Pseudophakic and Aphakic Eyes 5.5. Fellow Eye 6. Conclusion References

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Malignant glaucoma, or aqueous misdirection, is a rare but serious form of secondary angle closure glaucoma that usually follows intraocular surgery. Despite, recent improvements in the diagnosis and management of this condition it continues to generate controversy regarding its pathogenesis and treatment. 199

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INTRODUCTION: TERMINOLOGY

In 1869, von Graefe (1) described a rare complication that followed peripheral iridectomy (PI) for acute angle closure glaucoma. The condition was characterized by shallowing of the anterior chamber (AC) together with high intraocular pressure (IOP), and usually resulted in blindness. von Graefe used the term “malignant” glaucoma because it did not respond to conventional therapy and its propensity to progress to blindness. Consequently, the term malignant glaucoma expresses its seriousness and not a neoplastic disease. Other terms have also been used to describe this condition. Weiss and Shaffer (2) suggested the term ciliary block glaucoma based on the theory that obstruction to normal aqueous flow was due to apposition of the ciliary processes against the lens equator or anterior hyaloid. The term aqueous misdirection (3) implies that aqueous humor is diverted posteriorly due to ciliary block. The term direct lens block angle closure (4) was suggested to describe the fact that a forward shift of the lens results in this syndrome. All these terms reflect the pathogenesis of the condition unlike the prognostic term malignant glaucoma which is still widely used by ophthalmologists. Because of the fact that there is no agreement regarding the pathogenesis, we use the term malignant glaucoma in this chapter although we feel it should be dropped as soon as the pathogenesis has been clearly elucidated. We also strongly advise ophthalmologists to use this term with caution in front of patients. They may misinterpretate this name and think they have a form of eye cancer.

2.

DEFINITION: CLINICAL DIAGNOSIS

Classically, malignant glaucoma presents clinically with the following characteristics: 1. 2.

3. 4. 5.

Axial shallowing or flattening of the AC (both centrally and peripherally). Increased IOP, which initially may start low or normal. Generally, the IOP is higher than expected in an eye with a flat AC from overfiltration or bleb leakage, that is, .4 –6 mmHg; however, the IOP usually progressively rises. Patent PI excluding pupillary block. Absence of clinically visible posterior segment abnormalities on ophthalmoscopy or B-scan ultrasound. Ultrasound biomicroscopic (UBM) evidence of a low supraciliary effusion (5,6).

The typical presentation occurs in a phakic patient following filtration surgery for uncontrolled angle closure glaucoma developing in 2– 4% of the operated eyes (7). The onset of this condition may occur from the first postoperative day to many months or years later. Malignant glaucoma has been reported in association with intracapsular (8) and extracapsular cataract surgery with anterior or posterior chamber intraocular lens (IOL) implantation (8,9), aphakia (10,11), and with or without an associated filtering procedure (12). More recently, it has been reported in a patient with a phakic posterior chamber IOL for myopia correction (13), following deep sclerectomy (14), glaucoma drainage device (Baerveldt valve) implantation (15), retinal detachment surgery with buckling (16), and pars plana vitrectomy (PPV) (17). Malignant glaucoma may also develop after needling of a trabeculectomy bleb (18). [email protected]

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It has also been reported to occur following laser procedures such as Nd:YAG transscleral photocoagulation (19), laser iridotomy (20,21), Nd:YAG posterior capsulotomy (22), and laser release of scleral flap sutures (5,23). Malignant glaucoma has also been associated with other ocular disorders such as central retinal vein occlusion (24), retinopathy of prematurity (25), corneal hydrops in keratoconus (26), inflammation (4) and trauma (4,27), and endophthalmitis secondary to fungal keratomycosis (28) and nocardia asteroides (29). The topical use of miotics has been reported to induce the onset of malignant glaucoma, when used in unoperated eyes (30) as well as in eyes after filtering surgery (31). Spontaneous malignant glaucoma has been reported in two eyes with no previous history of surgery, no miotic use, or any other causative factor (32,33). There are reports in the literature of bilateral angle closure glaucoma secondary to cilio-choroidal effusion associated with the administration of topiramate (34,35), sulfacontaining medications (36,37), and the systemic use of an angiotensin II antagonist (38). Whether these clinical conditions should be included within the malignant glaucoma category has not been established. Nevertheless, the presence of flat AC, ciliary body detachment detectable only by UBM, normal fundoscopic findings in most of the eyes and raised IOP make the presentation of these cases of secondary angle closure glaucoma clinically indistinguishable from that of malignant glaucoma.

3.

PATHOPHYSIOLOGY

Many aspects of the pathogenetic mechanism of malignant glaucoma remain unresolved leading to the development of a variety of theories with the following being the most popular ones. 1. 2. 3. 3.1.

Aqueous humor misdirection (3); slackness or laxity of the lens zonules (39); positive pressure phenomenon (40).

Aqueous Humor Misdirection

Shaffer (3) originally proposed that an accumulation of aqueous either into (within vitreous pockets) or behind the vitreous causes the forward displacement of the iris –lens or iris –vitreous diaphragm and the anterior rotation of the ciliary body. This hypothesis is supported by evidence provided by Buschmann’s echographic study, demonstrating echo free parts found in the vitreous body of aphakic eyes with malignant glaucoma that may represent fluid-filled vacuoles (41). At this point, we should also note that the presence of echo free areas of the vitreous is a common finding in older normal individuals, thus not always suggesting the presence of misdirected aqueous. The mechanisms leading to the posterior diversion of the aqueous are still uncertain. It seems very likely that the following theories may be involved to variable degrees in the posterior pooling of aqueous. The ciliolenticular block theory was introduced by Weiss and Shaffer (2). According to this theory, the ciliary processes are rotated forward and pressed against the lens equator or the anterior hyaloid. The anteriorly rotated ciliary body by producing ciliolenticular or ciliovitreal contact inhibits normal anterior aqueous flow and causes aqueous to be diverted posteriorly. UBM studies by us and others confirmed the anterior rotation of the ciliary processes which, however, were found to press against the peripheral iris (5,6,14,42 – 44) rather than against the lens. The presence of a low supraciliary fluid [email protected]

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level (5,6), also imaged by UBM, is likely responsible for the forward movement of the ciliary body and the ciliolenticular block. In addition, the anterior hyaloid may contribute to the ciliolenticular block and to the posterior pooling of the aqueous, by two possible mechanisms: 1.

2.

3.2.

In 1978, Shaffer (45) postulated that breaks in the anterior hyaloid near the vitreous base allow for the posterior diversion of aqueous into the vitreous. He suggested that the vitreous breaks prevent forward aqueous flow, acting as oneway valves. However, the existence of such a mechanism has not been proven. Epstein et al. (46) provided evidence that there may be resistance to aqueous permeability through the vitreous body. It has been postulated that this resistance is increased by the elevation of ocular pressure (39,46,47). Additional experimental confirmation of the earlier data was provided by Fatt (47) who measured the hydraulic flow conductivity of animal vitreous in vitro and noted that as pressure increases in the vitreous it becomes dehydrated and fluid conductivity decreases. In addition, the forward displacement of the vitreous against the anterior structures (ciliary body, lens, and iris) (due to the posterior-to-anterior pressure difference) leads to a decrease of the available anterior diffusional area through which fluid flows (41,46,48). This increases the vitreous resistance to forward fluid flow and malignant glaucoma is more likely to happen (40,46).

Slackness or Laxity of the Lens Zonules

Chandler and Grant (39) suggested that weak or slack zonular fibers, as well as pressure from the vitreous allow partial subluxation of the lens –iris diaphragm. The laxity of the zonules may be the result of pseudoexfoliation (5), prolonged angle closure (49) or ciliary muscle spasm induced by miotics, surgery, trauma, inflammation, or unknown factors (4). Supraciliary effusion with anterior rotation of the ciliary processes aids this process (5,6,14,42 –44). 3.3.

Positive Pressure Phenomenon

Quigley et al. (40) recently proposed a mechanism for malignant glaucoma development, attributable to the following factors: (1) positive pressure phenomenon (due to choroidal expansion) and (2) poor vitreous fluid conductivity. Patients at higher risk to develop this condition are older persons with a high prevalence of posterior vitreous detachment. Choroidal expansion increases the pressure behind the vitreous gel. This partially compressed vitreous (in the predisposed eye) is likely to have higher than normal resistance to fluid flow. When the usual anterior-to-posterior transvitreal flow is insufficient to equalize the pressure differential between the vitreous cavity and the posterior chamber and AC, the compressed vitreous further decreases its water conductivity. The compressed vitreous then moves forward, carrying the iris – lens diaphragm with it. Increases in choroidal volume can move the lens forward. In the average human eye, the choroidal volume is 480 mL and the AC volume is 150 mL. Consequently, if the choroid expands by 20%, it would occupy 100 mL of space, equal to 2/3 of the AC volume. This forward movement is more dramatic if there is reduced pressure from an incision in the AC, leading to malignant glaucoma. It is important to note that choroidal volume expansion has not been validated to date as an etiological factor in malignant glaucoma. [email protected]

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We and others have reported that supraciliary effusions are found in malignant glaucoma by UBM (5,6). Our findings in conjunction with Quigley’s recent theory of positive pressure phenomenon (40) suggested that ciliary body rotation and choroid expansion play pivotal roles in the pathophysiology of malignant glaucoma. The development of a supraciliary effusion can be attributed to several mechanisms (50). The accumulation of fluid in the supraciliary space is likely the result of ocular hypotony, following filtration surgery. In addition, ciliary body inflammation, abnormal response to surgery or a toxic effect from mitomycin-C on the ciliary body can explain the presence of supraciliary fluid in malignant glaucoma. Following filtration surgery, a relatively small effusion would be required in a narrow angled eye, to rotate the ciliary body and move the iris and lens forward enough to flatten the AC and close the angle. Liebmann et al. (6) suggested that the presence of a supraciliary effusion in a subgroup of patients with malignant glaucoma indicates that in these patients “aqueous misdirection” plays a less prominent role in the development of the condition. Liebmann et al. (6), in addition, hypothesize that patients require surgical intervention are more likely to have pure aqueous misdirection as the primary cause of malignant glaucoma whereas eyes that respond to medical treatment have a supraciliary effusion. This last theory has not been proven. We propose the following sequence of events (Fig. 22.1) in malignant glaucoma. Following filtration surgery, overfiltration results in ocular hypotony. Ocular hypotony and ciliary body inflammation contribute to the development of a small supraciliary fluid accumulation. The effusion rotates the ciliary body anteriorly and moves the iris and lens diaphragm forward. Laxity of the lens zonules and, possibly, choroidal thickening are additional factors that contribute to forward movement of lens against the ciliary body (ciliolenticular block) pressing the iris against the cornea. The peripheral iris closes the angle and the lens margin, iris remnants or ciliary processes block the filtering

Figure 22.1

Malignant glaucoma: sequence of events. [email protected]

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ostium (5), despite the presence of a patent iridectomy, resulting in a rise in IOP. The aqueous is directed posteriorly rather than anteriorly and the amount of the misdirected aqueous is increased as a vicious cycle develops. The vitreous is pressurized by fluid transfer across the anterior hyaloid face; its fluid conductivity is decreased reducing uveoscleral outflow through the choroid leading to increased pressure from aqueous accumulation in the vitreous cavity providing additional forward momentum to the lens position. In conclusion, although some basic information about malignant glaucoma awaits confirmation, it seems likely that most aspects of the described mechanisms contribute in variable degrees to the development of this form of glaucoma. Future research is required to fully verify the role of choroidal expansion, water flow from the vitreous and the relevance of supraciliary effusions. UBM will be an important tool as it is the only method available at this time that consistently detects small effusions.

4.

DIFFERENTIAL DIAGNOSIS

Early detection and appropriate intervention are critical to the successful management of malignant glaucoma. It is also important to remember that the accurate diagnosis of this form of glaucoma is a clinical one and requires the exclusion of the following important entities.

Table 22.1

Differential Diagnosis of Malignant Glaucoma Malignant glaucoma

Pupillary block

Suprachoroidal hemorrhage Axial AC shallowing

AC

Axial AC shallowing

IOP Pain Relief by iridectomy Fundus

Normal or elevated IOP Ocular discomfort No

Peripheral AC shallowing (iris bombe´) High IOP Severe acute pain Yes

Normal

Normal

Onset

1st postoperative day to many months or years later

Early or late postoperatively

4.1.

High IOP Severe acute pain No Choroidal elevation (dark reddish-brown) During surgery or first 5 days postoperatively

Suprachoroidal Hemorrhage

The eye with a suprachoroidal hemorrhage typically has an acute onset of severe ocular pain, associated with a flat AC and markedly elevated IOP. Suprachoroidal hemorrhage can occur during surgery or in the postoperative period, following ocular surgical procedures. The eye is usually quite inflammed. Ophthalmoscopy reveals the presence of single or multiple dark reddish-brown choroidal elevations that are frequently similar in size to those in serous choroidal detachment but can be seen in the posterior pole to the vortex veins. [email protected]

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The use of ultrasound examination (A- and B-scan) is helpful in the following clinical circumstances: 1. 2. 3.

If the posterior pole cannot be visualized on ophthalmoscopy, due to corneal or medial opacities; to provide echographic clues in order to differentiate suprachoroidal hemorrhage from serous choroidal detachment; to follow the course of the suprachoroidal hemorrhage and determine whether intervention should take place and when.

The B-scan echographic findings in suprachoroidal hemorrhage reveal the presence of large dome-shaped elevations that extend to the posterior pole, inserting next to rather than into the optic disc. On B-scan, detection of spontaneous motion from the blood vessels on the surface of the hemorrhagic choroidal detachments is occasionally helpful to establish the diagnosis of suprachoroidal hemorrhage, especially in the presence of appositional (kissing) configuration (51). Typically, reflective echoes are noted in the suprachoroidal space on both B- and A-scan due to the presence of hemorrhage (52). Early echographic finding indicates a large, solid clot in the suprachoroidal space surrounded by fluid blood. As the clot becomes older it also becomes less reflective on A-scan and less dense on B-scan (53). Echography may be useful to follow the course of the clot appearance and size and to determine the optimal time for drainage. Small suprachoroidal hemorrhages usually spontaneously absorb. Larger hemorrhages are drained after the clot lysis at about 2 weeks (see Chapter 21 in this book for further management of this condition). 4.2.

Pupillary Block

Pupillary block glaucoma should be ruled out because it can mimic malignant glaucoma as a shallow AC with elevated IOP. Nevertheless, there are two very important clinical features that help to make an accurate diagnosis. Following filtration surgery, malignant glaucoma presents with axial shallowing of the AC as the entire iris – lens diaphragm is shifted forward with high normal or raised IOP. On the other hand, in pupillary block glaucoma the IOP is usually high, the pupil is middilated, the central AC is formed and the peripheral iris is typically bowed forward (iris bombe´). Attention should also be directed to the presence of a patent iridectomy. The presence of a patent iridectomy is of significant diagnostic value because it will relieve pupillary block, although it has no effect in malignant glaucoma. Consequently, if an iridectomy is present and clearly patent then the diagnosis of pupillary block is ruled out. If there is no iridectomy present or if there is any doubt about the patency of the existing iridectomy, then another one should be created (Table 22.1). It is important to remember that malignant glaucoma is characterized by a normal posterior segment anatomy on ophthalmoscopy and B-scan ultrasound examination and that the UBM finding consistent with the diagnosis of malignant glaucoma is the presence of a small amount of annular supraciliary fluid (5,6) that is not clinically observable. 5.

MANAGEMENT

Malignant glaucoma is a serious complication of intraocular surgery. Prevention, early detection, and timely intervention are critical for optimal results and successful management. [email protected]

Figure 22.2

Management of malignant glaucoma. Source: modified from Ref. (54).

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Malignant Glaucoma

5.1.

207

Risk Factors: Prevention

The major risk factors for the development of malignant glaucoma include uncontrolled angle closure glaucoma (5), preoperative shallow AC, hyperopia, nanophthalmos and short axial length, pseudoexfoliation (5), partial or total closure of the AC during the time of surgery (10), and the presence of malignant glaucoma in the fellow eye (4). Sudden decompression of the eye as a result of suture lysis or corneal perforation is an important cause of malignant glaucoma (5,7). Furthermore, discontinuation of cycloplegics and aqueous suppressants, in an eye with controlled malignant glaucoma, is associated with recurrence of this form of glaucoma (5). Finally, there is evidence that plateau iris configuration is a risk factor for the development of malignant glaucoma (42). Preoperative measures include discontinuation of miotics and use of aqueous suppressants and hyperosmotics to lower the IOP before the eye is surgically opened. Intraoperative maneuvers include paracentesis of the AC, so as to slowly decompress the eye with uncontrolled IOP, as well as the use of preplaced sutures to facilitate the rapid closure of the incision and minimize surgically induced hypotony. A PI should always be performed. Tight flap sutures prevent overfiltration. At the end of the operation, the AC should be reformed with air or viscoelastic to ensure that the chamber maintains its depth. Postoperatively, cycloplegic therapy should start in the operating room and continue for weeks or months. Corticosteroids should always be used to minimize uveal tract inflammation. In addition, close monitoring of the AC depth and cautious laser suture lysis are also critical to successful management of malignant glaucoma. It is important to be aware of the eyes at particular risk of developing malignant glaucoma. Follow them closely in the early postoperative period, because the early stages of the disease can be easily overlooked. IOP, that is, inappropriate for the clinical presentation of the eye could be an early sign of malignant glaucoma. For example, progressive shallowing of the AC associated with an IOP of 4 – 6 mmHg and slowly rising is consistent with the early diagnosis of malignant glaucoma (often the bleb is formed at this time). The development of high resolution imaging techniques has proved helpful in the diagnosis and management of malignant glaucoma. The configuration of anterior segment structures can be assessed by using UBM (5,14,42– 44,54) in order to preoperatively evaluate the risk of malignant glaucoma and establish a diagnosis of aqueous misdirection especially during the early postoperative period. In addition, slit-lamp adapted optical coherence tomography (OCT) (55), a new noninvasive high resolution imaging technique, may be helpful in recognizing the early stages of malignant glaucoma by objectively monitoring AC depth. Once malignant glaucoma is suspected vigorous medical treatment should be initiated for 5– 7 days.

5.2.

Medical Treatment

Medical treatment may require 5 –7 days for a response to develop, and is effective in 50% of the cases (5,11) (Fig. 22.2). In 1962, Chandler and Grant (39) were the first to report successful relief of malignant glaucoma, by using mydriatic – cycloplegic eyedrops. Cycloplegics tighten the zonules (39), pull the lens – iris diaphragm backwards against the force of the vitreous and break the ciliary block (45) by relaxing the ciliary body muscle. Additionally, in order to reduce the amount of aqueous humor that may be pooling posteriorly, its production should be decreased by using aqueous suppressants such as [email protected]

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carbonic anhydrase inhibitors (CAI), beta-blockers, and alpha two-agonists. The use of hyperosmotics, which was introduced in 1963 by Weiss et al. (56), should also be initiated for several days to reduce the amount of misdirected aqueous. Glycerol is given orally as a 50% aqueous solution at 1.0 –1.5 g/kg body weight (note: a 100 cc bottle of 50% glycerol contains 50 g of glycerol; do not give to diabetics). Mannitol is given intravenously at 1 – 2 g/kg body weight over 45 min (note: a 500 cc bag of 20% mannitol contains 100 g of mannitol). Topical corticosteroids are used to reduce the uveal tract inflammation and minimize the risk of developing suprachoroidal effusion. If the condition is relieved, aqueous suppressants can be cautiously withdrawn but only after many months of treatment. Hyperosmotics and CAIs are the first to be discontinued, followed by the alpha two-agonists (54). Be very cautious when stopping beta-blockers. We have seen recurrences occur on discontinuing beta-blockers. It is of great importance that the treatment with cycloplegic drops be continued indefinitely to prevent recurrences. A problem with long-term cycloplegia is sensitization to atropine drops (57,58). Hyoscine (scopolamine) drops can be used in place of atropine. The nonstructurally related cycloplegic agents such as tropicamide and cyclopentolate hydrochloride can also be used. If medical treatment fails to reverse the aqueous misdirection and deepen the AC in 5 – 7 days, laser or surgery treatment is indicated. When there is lens –cornea touch, surgery should be performed immediately, in order to prevent the formation of PAS, cataract, and damage to the corneal endothelium. 5.3.

Laser Treatment

If the condition persists despite the earlier treatment attempts, then it is reasonable to try one of the noninvasive laser approaches. The choice of the appropriate laser procedure depends on whether the eye to be treated is phakic, pseudophakic, or aphakic. The Nd:YAG laser has proven useful to disrupt the vitreous face and zonules when treating aphakic and pseudophakic malignant glaucoma (59 – 62). Do not attempt this procedure in phakic eyes. Nd:YAG laser disruption of the anterior hyaloid, which was suggested by Epstein et al. (59), creates communication channels through the previously impermeable vitreous face and re-establishes the anterior flow of aqueous. The Nd:YAG laser (3 – 11 mJ) can be applied through either the PI or the pupil, combined with capsulotomy. Try to disrupt the capsule and anterior hyaloid off centre, if possible. We have found the procedure works better the further away one disrupts the hyaloid from the centre of the IOL. If successful, anterior hyaloid photodisruption results in immediate deepening of the AC. More recently, Carassa et al. (63) reported successful treatment of malignant glaucoma in five pseudophakic eyes with contact transscleral diode laser cyclophotocoagulation after failure of Nd:YAG laser hyaloidotomy. The treatment involved the application of 20 laser spots over 3608, 1.5 mm posterior to the limbus. The power employed was 4.0 J. The mechanism of action was attributed to coagulative shrinkage and posterior rotation of the ciliary processes. In addition, reduction of aqueous production due to ciliary body photocoagulation presumably contributes to curing the condition. Herschler (64) reported successful relief of malignant glaucoma, in five of six cases, by Argon laser shrinkage of the ciliary processes. There is no indication if Herschler attempted the laser in phakic or pseudophakic eyes. Theoretically, this technique could be cautiously used in phakic patients. However, it is advisable to use this procedure only in pseudophakic and aphakic patients. Permanent argon laser shrinkage of two to four ciliary processes exposed through the PI effectively cured the condition, presumably [email protected]

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either by shrinking the ciliary processes disrupting the ciliolenticular block or by causing thermal rupture of the adjacent anterior hyaloid membrane (59,65). The power employed varied from 100 to 300 mW. The duration of treatment was 0.1 s and the spot size was 100 – 200 mm. All patients were maintained on atropine after the laser application. Slight deepening of the AC may happen immediately after treatment but the full effect is delayed for 3– 5 days. This laser procedure was also found effective by Weber et al. (66) in aphakic eyes, even without the use of cycloplegics.

5.4.

Surgical Treatment

In cases of malignant glaucoma refractory to medical and laser treatments, one of the surgical approaches should be tried next. Historically, posterior sclerotomy [Weber (67)] and lens extraction (68 –71) were used to treat malignant glaucoma. The success of the technique was attributed either to loss of vitreous (70) or to the incision made in the anterior hyaloid face (3,11). Chandler reported successful management with reformation of the AC by using air in one case of malignant glaucoma (72). Reformation of the AC should be attempted following poor response to medical therapy and prior to PPV. If the IOP is in single digits the AC can be reformed either by injecting a viscoelastic substance or, more effectively by injecting air, in addition to cycloplegics and aqueous suppressants administration. Air or viscoelastic injection forces the lens back and can break the vicious cycle. If the IOP is high, this technique will likely fail as air or viscoelastic is rapidly forced out of the AC through the surgical ostium. A large air bubble should be placed in the AC when performing this procedure to ensure the lens is pushed well back and the AC deepened. 5.4.1. Pars Plana Vitrectomy (PPV) PPV is the preferred surgical technique for phakic, pseudophakic, and aphakic eyes, reflecting recognition of the central role of the vitreous in malignant glaucoma. The primary indication for PPV is failure of medical and other interventions (73). PPV is performed using a standard three-port technique and the major goal of this surgery is to disrupt the anterior hyaloid and reestablish the anterior aqueous flow. It is very important to instruct the retina surgeon to reform the AC at the end of the procedure preferably with a large air bubble. The existing outcome data in the literature indicates that the success rate of PPV is generally better in pseudophakic eyes than in phakic eyes (Table 22.2). Failure of PPV in Table 22.2

PPV Success Rate in Malignant Glaucoma

Pseudophakic eyes Phakic eyes without lensectomy Phakic eyes with lensectomy Aphakic eyes

Weiss et al. (75)

Momoeda et al. (76)

Lynch et al. (77)

Byrnes et al. (74)

Harbour et al. (73)

Tsai et al. (78)

100% (1/1) 100% (2/2) —

—

100% (4/4) — —

90% (9/11) 50% (5/10) —

—

—

90% (9/10) 71% (5/7) 100% (7/7) —

67% (4/6) 25% (1/4) 50% (5/10) —

100% (6/6)

— 100% (5/5) —

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phakic eyes is mostly related to the difficulty in disrupting the anterior vitreous adjacent to the lens, without at the same time damaging the lens. In one series of patients [Byrnes et al. (74)], 30% of the operated patients developed cataract as a post-PPV complication. The success rate of PPV increases significantly in phakic eyes if lensectomy is performed. Lensectomy should only be performed in combination with PPV, in the presence of substantial corneal oedema or dense cataract or when the AC remains shallow despite PPV (73). PPV, in general, appears to have several advantages over other surgical procedures (73): 1. 2.

PPV is a controlled technique, unlike Chandler’s technique (79) where a needle is directed blindly into the vitreous. The risk of recurrent malignant glaucoma is minimized because the vitreous is removed and the anterior hyaloid face is disrupted.

The following are important steps during PPV that optimize the success rate of the procedure: 1. 2. 3.

4.

5. 6.

The presence of a patent PI should be always confirmed. When placing the sclerostomies try to avoid prior filtration areas. In phakic eyes, failure of the PPV in malignant glaucoma is related to incomplete vitreous excision from around the lens. Consequently, in every case of malignant glaucoma in phakic eyes, pupil dilation should be maximized to improve visualization for the vitreoretinal surgeon during the PPV. In small pupils with shallow AC, consideration should be given to mechanically stretching the iris after deepening the AC with a viscoelastic agent (74). It is also advisable that one sclerotomy site be made proximal to the PI, in order to improve visualization and avoid damaging the lens with the vitrectomy instrument [Byrnes et al. (74)]. The anterior hyaloid must be disrupted and any vitreous adhesions or capsular and zonular material behind the iridectomy sites removed (77), in order to establish unobstructed communication between the AC and the vitreous cavity. Intraoperative deepening of the AC must always be visualized. This is usually consistent with long-term success without further surgery (73). Medical treatment should be continued postoperatively for weeks or months. After the eye has been stable for several weeks following PPV, aqueous suppressants can be gradually withdrawn (see Section 5.2 of this chapter) but only under careful ophthalmic observation. Phakic patients should remain on cycloplegics postsurgery.

Complications of PPV for malignant glaucoma consist of cataract formation in 30% (phakic eyes) (74), retinal detachment in 9.5% (74), transient exudative retinal detachment in one eye (73), serous choroidal detachment in the range of 4.7– 8.3% (73,74), corneal decompensation in 25% (73), and bleb failure in the range of 12.5 – 21% (73,74). The intraoperative development of suprachoroidal hemorrhage in one eye has also been reported (73). Of significance is the fact that in cases of malignant glaucoma a successful PPV can be followed by failure of a previously filtering bleb. 5.4.2. Combined PPV and Pars Plana Tube Insertion Azuara-Blanco et al. (80) reported the insertion of a pars plana tube (Baerveldt valve) with PPV in two cases of malignant glaucoma with a flat (from PASs) AC. This technique [email protected]

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successfully relieved the malignant glaucoma, controlled the IOP and prevented recurrence of this condition. This procedure may be an alternative surgical approach in cases with diffuse PASs and severe glaucomatous neuropathy (80) (see Chapter 21 in this book on methods to perform such surgery). 5.4.3.

Chandler’s Technique

Chandler described a three-step surgical technique for malignant glaucoma, which was refined by him in 1968 because of the high rate of cataract formation in phakic eyes (71,79). This and similar techniques have been described (81). Chandler’s technique is still an alternative procedure if PPV is not available. Following are the steps that should be performed to ensure maximal success of the procedure. Step 1: Confirmation of the Communication Between Posterior Chamber and AC. The presence of a patent PI must be confirmed before the patient enters the operating room. If there is no iridectomy present or if there is any doubt about the patency of the existing iridectomy, then another one should be created. If the AC deepens in the presence of a patent PI then the procedure is terminated. Step 2: Corneal Paracentesis. Use a Wheeler knife or a similar instrument, to create a self-sealing beveled incision in the peripheral cornea. Step 3: Sclerotomies to Explore for Suprachoroidal Fluid. Two sites in the two inferior quadrants of the eye are chosen as sclerotomy sites. The conjunctiva and Tenon’s capsule are opened. The sclera is then incised radially with a #15 blade. The scleral incision should be 3 mm in length and the center of the incision should be placed 3.5 mm posterior to the limbus (81). Precise placement of the sclerotomies is essential to provide access to the anterior vitreous face. In the presence of suprachoroidal fluid, the AC is filled with BSS and the procedure is terminated if the AC deepens. In the absence of suprachoroidal fluid vitreous surgery should be performed. Step 4: Vitreous Surgery. Prior to entering the vitreous cavity, diathermy is applied at the inner edges of the scleral wound, not directly to the choroid. An 18-gage needle is carefully passed through the sclerotomy, into the vitreous cavity to a depth of 12 mm, in the direction of the optic nerve head. Then the needle is gently moved from side to side in a 4 mm arc and 1 – 1.5 mL of fluid is aspirated followed by needle removal. Step 5: Reformation of the AC. In addition, a large air bubble is injected in the AC to deepen the chamber to a depth greater than usually encountered. Finally, scleral and conjunctival wounds are closed with interrupted sutures. The use of atropine eyedrops should be continued postoperatively for several weeks or months. Complications are almost always due to lack of attention to the details of the procedure. Hemorrhage can occur if diathermy is not applied around the sclerotomy wound. Retinal damage can occur if the needle is misdirected and not aimed at the optic nerve. Cataract formation can follow anterior placement of the scleral incision. A too posterior sclerotomy site results in failure of the procedure because the anterior hyaloid is not incised. Transient postoperative choroidal detachment and punctate retinal hemorrhages have also been reported that resolve spontaneously (81). 5.4.4.

Alternative Surgical Procedures in Pseudophakic and Aphakic Eyes

Francis et al. (82) reported a slit-lamp needle procedure for the management of malignant glaucoma after trabeculectomy, in pseudophakic eyes. The procedure can be performed under topical anesthesia ( proparacaine hydrochloride eyedrops) through a single selfsealing corneal paracentesis. A paracentesis is made in the peripheral cornea adjacent to [email protected]

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the iridectomy with a 27-gage needle. The needle is advanced through the iridectomy into the posterior chamber. The anterior hyaloid is then disrupted and a small amount of fluid is aspirated through the needle tip. Prior to withdraw the needle, the AC is reformed by air, BSS, or viscoelastic. This procedure was reported to be successful in two pseudophakic patients either by establishing fluid communication through the broken hyaloid face or by creating enough room for the AC structures to move posteriorly. The procedure is not meant to replace other therapies and was performed only after medical and laser treatment failed. Recently, Lois et al. (83) described an alternative surgical approach to the management of pseudophakic malignant glaucoma via the anterior segment. Firstly, an AC infusion cannula is placed through a self-sealing peripheral corneal paracentesis, in the inferotemporal quadrant. Next, a similar beveled corneal incision is made 1 –2 h from the preexisting PI or iridotomy and a vitreous cutter is introduced into the AC. The cutter is directed through the iridectomy and zonulectomy, hyaloidectomy, and anterior vitrectomy are performed. Thus, a communication between the AC and the posterior segment is established. The AC deepened intraoperatively. Using this technique, they effectively treated five cases of pseudophakic malignant glaucoma. The only complication reported was failure of a previously filtering bleb in one case. The advantages of this surgical procedure include the following: (1) Increased safety and lack of risks associated with PPV. (2) It is a simple procedure performed through the anterior segment making it an attractive therapeutic procedure for glaucoma/anterior segment surgeons. Tsai and Tseng (84) suggested the use of combined anterior vitrectomy and trabeculectomy with mitomycin-C in pseudophakic eyes with malignant glaucoma and extensive PASs. Firstly, a conventional trabeculectomy with mitomycin-C is performed. Next, the vitreous cutter is introduced into the vitreous cavity through the internal ostium and the PI. An AC infusion Simcoe cannula is placed through a self-sealing peripheral corneal paracentesis, in the temporal quadrant. A partial anterior vitrectomy is performed via the PI similar to the process previously described by Lois et al. (83). This deepens the AC and establishes a communication channel between the AC and the vitreous cavity. Finally, the scleral and conjunctival flaps are closed as in conventional trabeculectomy. This procedure successfully relieved malignant glaucoma in one pseudophakic eye with extensive PASs and may be an alternative surgical approach to combined PPV and pars plana tube insertion—introduced by Azuara-Blanco et al. (80). Moreover, it could possibly be used in cases of pseudophakic malignant glaucoma following conventional trabeculectomy, as vitrectomy via the anterior segment lacks of the risks associated with PPV and is technically simpler for the anterior segment surgeon to perform. 5.5.

Fellow Eye

The presence of malignant glaucoma in one eye is a major risk factor for aqueous misdirection development in the contralateral eye (39). In order to provide a greater margin of safety for that fellow eye, precautions should always be taken in the pre-, intra- and postoperative period as previously described. Chaudhry et al. (85) suggested the use of prophylactic PPV during cataract surgery to prevent aqueous misdirection in high-risk fellow eyes. They reported one case that underwent combined prophylactic PPV, ECCE, and trabeculectomy with mitomycin-C and a second case that underwent combined prophylactic PPV and phacoemulsification. PPV preceded the cataract extraction and established an unobstructed communication between the vitreous cavity and the AC. Complications associated with PPV are well known and have been described elsewhere in this chapter (73,74). In addition, medical [email protected]

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treatment alone is effective in resolving 50% of the malignant glaucoma cases (5,11). Without further evidence, we feel prophylactic PPV should not be performed on eyes without malignant glaucoma.

6.

CONCLUSION

Despite the fact that the pathogenesis of malignant glaucoma is not fully understood, there is good agreement that this condition is probably related to an abnormal anatomical relation among the ciliary processes, the lens, the zonules, and the anterior hyaloid. The vitreous plays an important role in the pathogenesis of aqueous misdirection. Choroidal expansion may be an additional causative factor in the pathophysiology of this condition but this needs confirmation. Recognition of eyes at risk and early diagnosis are critical for optimal management of this condition. The development of high resolution imaging techniques (UBM, slit-lamp OCT) is providing useful information. Management of malignant glaucoma is in evolution. Medical therapy resolves the condition in 50% of the cases. PPV is the preferred surgical technique for cases of malignant glaucoma that are unresponsive to medical therapy. Establishment of a direct and unobstructed communication between the vitreous cavity and the AC is important for optimal surgical success.

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Kourkoutas, Pavlin, and Trope Rheindorf O. Ueber glaukom. Klin Monatsbl Augenheilkd 1887; 25:148 –172. Chandler PA. Malignant glaucoma. Trans Am Ophthalmol Soc 1950; 48:128 – 143. Chandler PA, Simmons RJ, Grant WM. Malignant glaucoma. Medical and surgical treatment. Am J Ophthalmol 1968; 66(3):495 –502. Chandler PA. Malignant glaucoma. Am J Ophthalmol 1951; 34(7):993 – 1000. Harbour JW, Rubsamen PE, Palmberg P. Pars plana vitrectomy in the management of phakic and pseudophakic malignant glaucoma. Arch Ophthalmol 1996; 114(9):1073– 1078. Byrnes GA, Leen MM, Wong TP, Benson WE. Vitrectomy for ciliary block (malignant) glaucoma. Ophthalmology 1995; 102(9):1308– 1311. Weiss H, Shin DH, Kollarits CR. Vitrectomy for malignant (ciliary block) glaucomas. Int Ophthalmol Clin 1981; 21(1):113– 119. Momoeda S, Hayashi H, Oshima K. Anterior pars plana vitrectomy for phakic malignant glaucoma. Jpn J Ophthalmol 1983; 27(1):73– 79. Lynch MG, Brown RH, Michels RG, Pollack IP, Stark WJ. Surgical vitrectomy for pseudophakic malignant glaucoma. Am J Ophthalmol 1986; 102(2):149– 153. Tsai JC, Barton KA, Miller MH, Khaw PT, Hitchings RA. Surgical results in malignant glaucoma refractory to medical or laser therapy. Eye 1997; 11(Pt 5):677– 681. Chandler PA. A new operation for malignant glaucoma: a preliminary report. Trans Am Ophthalmol Soc 1964; 62:408 – 424. Azuara-Blanco A, Katz LJ, Gandham SB, Spaeth GL. Pars plana tube insertion of aqueous shunt with vitrectomy in malignant glaucoma. Arch Ophthalmol 1998; 116(6):808– 810. Epstein DL. The malignant glaucoma syndromes. In: Chandler and Grant’s Glaucoma. 4th ed. Williams and Wilkins, 1997:285 – 302. Francis BA, Wong RM, Minckler DS. Slit-lamp needle revision for aqueous misdirection after trabeculectomy. J Glaucoma 2002; 11(3):183 –188. Lois N, Wong D, Groenewald C. New surgical approach in the management of pseudophakic malignant glaucoma. Ophthalmology 2001; 108(4):780– 783. Tsai YY, Tseng SH. Combined trabeculectomy and vitrectomy for pseudophakic malignant glaucoma and extensive peripheral anterior synechia-induced secondary glaucoma. J Cataract Refract Surg 2004; 30(3):715– 717. Chaudhry NA, Flynn HW Jr, Murray TG, Nicholson D, Palmberg PF. Pars plana vitrectomy during cataract surgery for prevention of aqueous misdirection in high-risk fellow eyes. Am J Ophthalmol 2000; 129(3):387 – 388.

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C. Management of a Flat Chamber with Low Intraocular Pressure

23 Management of the Leaking Bleb Andrew C. Crichton University of Calgary, Calgary, Alberta, Canada

Garry P. Condon Drexel University College of Medicine, Allegheny General Hospital, Pittsburgh, Pennsylvania, USA

Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada

1. Introduction and Incidence of Bleb Leaks 2. Clinical Questions 3. Clinical Definitions 3.1. Early Bleb Leaks 3.2. Late Bleb Leaks 3.3. Observation 3.4. Nonincisional Correction of the Bleb Leak 3.4.1. Technique 3.5. Incisional Repair of Bleb Leaks 3.5.1. Options for Incisional Repair of Bleb Leak 4. Conclusion References

1.

217 218 218 218 218 219 219 219 219 220 223 224

INTRODUCTION AND INCIDENCE OF BLEB LEAKS

Modern glaucoma surgical techniques including the use of anti-metabolites such as mitomycin and 5-fluorouracil have allowed surgeons to obtain a much higher success rate with long-term results. Unfortunately, by pushing the envelope of success, a significant number of patients suffer from the situation where the attempts to suppress healing have been too successful. This manifests itself with an increased incidence of hypotony and bleb leaks. Recent reviews of a large series of trabeculectomy have found the incidence of bleb leak to be 2.6% [14 out of 525 patients] (1) and 8.3% [20 out of 239 eyes] (2). A separate study by 217

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Soltau (3) identified bleb leak as a significant factor for bleb-related infections. The focus of this chapter is on the management of bleb leaks.

2.

CLINICAL QUESTIONS

Several questions must be asked when assessing a bleb leak: 1. 2. 3. 4. 5.

Was there a precipitating event (recent trabeculectomy, eye rubbing, a blow to the eye)? How ischemic is the appearance of the bleb? Is the bleb infected? What would the impact be if the bleb failed (severity of glaucoma, previous procedures)? How damaged/inflammed is the surrounding conjunctiva?

These questions are essential in allowing us to determine whether conservative management is possible or aggressive surgical reconstruction is required.

3.

CLINICAL DEFINITIONS

Bleb leaks may occur either early postoperatively or late postoperatively, even following a procedure by many years. 3.1.

Early Bleb Leaks

Early leaks are usually due to imperfect closure or defective conjunctiva. Imperfect closure especially of a fornix-based flap often leads to a leak, but this usually spontaneously closes in 2 – 6 weeks as long as the scleral wound is well covered by the conjunctiva. If the leak persists beyond 6 weeks, we recommend closure of the leaking area with 8/0 vicryl or 10/0 nylon. If the conjunctiva retracts and exposes the scleral flap, the conjunctiva should be immediately undermined and resutured to peripheral cornea with a continuous 8/0 vicryl or 10/0 nylon suture. If during surgery a leak is predicted due to defective/buttonholed/friable conjunctiva, consideration should be given to aborting the use of anti-metabolite and establishing a tight scleral flap closure. Any buttonhole must be repaired at the time of surgery. Usually, the conjunctiva will heal spontaneously especially if the steroid dose is reduced and postoperative 5-fluorouracil can be given with subsequent suture lysis when appropriate. 3.2.

Late Bleb Leaks

The management of late bleb leaks constitutes a more difficult and complex situation. The problem usually occurs when an anti-metabolite has previously been used and typically occurs with thin cystic blebs. The patient may complain of a teary eye especially on waking and fluctuating or decreased vision (due to hypotony). On occasion, however, the patient may present for routine follow-up with no symptoms and normal pressures, and only an index of suspicion on the part of the ophthalmologist will lead to detection of the leak. A simple Seidel test is all that is required. Once a bleb leak has been identified, the three options of management are (1) observation, (2) nonincisional maneuvers, and (3) incisional surgical repair. [email protected]

Management of the Leaking Bleb

3.3.

219

Observation

Observation is justifiable if the patient has previously been doing very well and there was a precipitating event. On occasion, a patient will have suffered a blow to the eye followed by a leak. In addition, some patients will recognize that eye rubbing during sleep is a problem. In both cases, a shield at bedtime may allow the leak to heal over a matter of weeks. Antibiotic coverage, although controversial, should be considered either for the duration of the leak or for the immediate administration at the first signs or symptoms of blebitis (pain, discharge, reduced vision, redness). Aqueous suppressants may decrease flow and help the leak to seal. We do not recommend patching at this time as the patch compresses the eye, increasing flow through the leak. If the leak is not resolved within 2 –3 weeks, we recommend expedited incisional correction of the leak. 3.4.

Nonincisional Correction of the Bleb Leak

Surgical correction of bleb leaks can be broken down into two categories: nonincisional and incisional. Suggestions for nonincisional maneuvers include patching, bandage lenses, laser, cryoacrylate glue, autologous fibrin tissue glue, and autologous blood injections. Initial reports using blood injections for bleb leaks showed promise with resolution of leakage in four of seven eyes and four of six eyes, respectively (4,5). In a larger series of patients reviewed by Burnstein (6) and Choudhri (7), the results were less positive. Burnstein reported that 72% of 32 eyes failed outright and for the remaining nine eyes, bleb leaks recurred in 33%. Asrani (8) described the use of autologous fibrin tissue glue. In their study, different medical maneuvers were tried including fibrin tissue glue. Success was achieved in nine of 12 patients in the fibrin tissue glue group and, interestingly, overall only 31.4% of 35 leaks did not respond to nonincisional treatment. Geyer (9) used the continuous wave Nd:YAG laser with some promising results. 3.4.1.

Technique

The technique for autologous blood injection is very simple. It involves drawing 1 mm of blood from an arm vein, changing to a 30 gage needle, and then immediately inserting the needle under direct vision into anesthetized subconjunctiva 1 – 2 mm from the bleb. The needle is then advanced into the bleb area. The blood is then released into the bleb, filling the bleb itself. It is important to warn the patient that this procedure can result in blood reflux through the ostium into the anterior chamber causing temporary (up to 10 days) vision loss. Burnstein (10) retrospectively compared surgical conjunctival advancement to nonincisional techniques in a review of 51 patients between 1986 and 1999. The bleb leaks occurred at least 2 months after trabeculectomy. Success was defined as resolution of bleb leak and intraocular pressures ,21 mmHg. Nonincisional treatment was successful in only 32% of cases (12 of 37 eyes). Of the 34 eyes in the surgical conjunctival advancement group, 100% had closure of the leak but leak recurrence eventually developed in two patients and 11 required glaucoma medication. 3.5.

Incisional Repair of Bleb Leaks

As bleb leaks and hypotony occurred more frequently throughout the early 1990s, the need for better correction of the problem became more apparent. Initially, there was some reluctance to excise a filtering bleb, as there was concern that the glaucoma control would be [email protected]

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lost. With experience, we have realized that despite bleb revision, glaucoma control is maintained in the majority of cases (11 –20). We, therefore, feel the best and most appropriate approach to late bleb leaks is expedited surgical repair of the leak depending to some degree on the clinical questions as outlined in Introduction.

3.5.1.

Options for Incisional Repair of Bleb Leak

Conjunctival mobilization

Existing bleb management

Conjunctival advancement Conjunctival pedicle graft Autologous free graft

De-epithelialization Excision Scleral re-enforcement (if necessary)

For the most part, the techniques involve the same principles. The choice of conjunctival repair initially depends on conjunctival availability/mobility at the time of surgery. For pedicle/conjunctival advancement, enough conjunctiva must be available behind the bleb to allow for advancement over the existing bleb site. If the bleb is large and/or surrounding conjunctiva is adherent to underlying sclera, an autologous flap should be used. Management of the Existing Bleb. The existing bleb can be managed by either de-epithelialization, using mechanical scraping or alcohol, or by total excision of the bleb. Good results have been reported in literature using either technique, but we prefer not to remove the total bleb. We de-epithelialize the existing bleb with an alcohol prep and for the most part do not attempt to repair the scleral flap. Some clinicians, however, evaluate the trabeculectomy flap at the time of excision to determine whether patch grafting is necessary. It would also be reasonable to consider scleral re-enforcement if the eye is hypotonous without a leaking bleb. Re-suturing the sclera has not proven to be satisfactory, thus necessitating grafting of donor sclera, donor pericardium, or autologous tenons to increase resistance. LaBorwit (19) found autologous tenons the most satisfactory material, but Kosmin (20) achieved good results with donor sclera. Conjunctival Repair. Conjunctival repair can be broken into two stages: preparing recipient tissue and mobilizing the conjunctiva for patching. Initially, dissection is done around the bleb undermining the conjunctiva to ensure adequate mobility. The peripheral cornea must also be prepared. Although some authors proposed lamellar keratectomy, we, as well as many others, feel that a simple debriding of the epithelium at the peripheral cornea will allow the conjunctiva to stick. Conjunctival mobilization can be done by advancement, pedicle grafts, or autologous autografts. After the conjunctiva has been mobilized, it can then be sutured into place using either wing sutures or continuous sutures. We prefer continuous suture of 9/0 nylon, 9/0 vicryl, or 10/0 nylon. Conjunctival Advancement. If the conjunctiva is very mobile and the bleb is small, a simple mobilization of the conjunctiva can be performed. If the conjunctival flap is noted to be quite tight, a relaxing incision should be made in the conjunctiva posteriorly, the size depending on the requirements for relaxation. The posterior edge of the conjunctiva can be sutured to the sclera and the wound posterior to the incision left to re-epithelialize. A relaxing incision may decrease the possibility of ptosis or diplopia, two of the complications that can occur with conjunctival advancement. Conjunctival Pedicle Flap. For moderate to large blebs, the use of a rotated conjunctival pedicle flap maintains a blood supply, allows a naturally curved limbal junction and minimizes ptosis. Measure the bleb to determine the required flap width, and outline the flap with light cautery [Fig. 23.1(A) and (B)]. [email protected]

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Dissect the flap of underlying Tenon’s capsule and incise along the posterior edge of the bleb, creating a completely vascularized pedicle flap based to the nasal or temporal side [Fig. 23.2(A) and (B)]. Raise the flap of Tenon’s capsule and remove only the existing bleb epithelium with alcohol or the entire bleb depending on whether scleral reinforcement is planned. A pericardial or scleral patch graft, if needed, is attached, and then the pedicle flap is rotated anteriorly and draped across it [Fig. 23.3(A) and (B)]. The edges are trimmed as

Figure 23.1

(See color insert) Measuring the bleb.

Figure 23.2

(See color insert) Dissecting and raising the flap.

Figure 23.3

(See color insert) A pericardial or scleral patch graft. [email protected]

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Figure 23.4

(See color insert) Edges trimmed as necessary and anchored to the limbus region.

necessary and anchored to the limbus region, using a continuous nylon suture, which prevents the conjunctiva from retracting. The posterior edge of the graft is tacked with Vicryl suture to the anterior edge of Tenon’s capsule, which epithelializes rapidly [Fig. 23.4(A) and (B)]. Autologous Conjunctival Graft. We prefer this technique especially when the bleb is of larger size or the surrounding conjunctiva is immobile and/or inflammed. 1.

2. 3.

4.

5.

6. 7.

8.

Measure the bleb size both anterior/posterior and side-to-side. Remember if the bleb is high domed, add an additional 2– 3 mm to the measurements all round in both diameters. Using a pen, mark out the size of donor conjunctiva ideally in the inferonasal quadrant (keep the inferotemporal quadrant for possible later seton insertion). Inject local anesthetic subconjunctivally into the delineated area and carefully dissect out the donor conjunctiva and tenons. Utilize enough conjunctiva to cover the leaking bleb without tension (or the conjunctiva will retract and expose the leak) including limbal conjunctiva if required. At all costs, avoid cutting underlying muscles. Place the donor conjunctiva epithelial side up (the pen mark side up) on a wet piece of cotton gauze. Keep the donor conjunctiva wet, while preparing its bed. De-epithelialize the bleb with alcohol. Dissect around the bleb as close to the bleb as possible. Undermine the recipient conjunctiva, thus mobilizing it to receive the donor conjunctiva without tension. Place the donor conjunctiva over the de-epithelialized bleb. Use four 10/0 nylon sutures to fixate the edge of the donor to the edge of the recipient conjunctiva. We then fixate the donor to limbus and recipient conjunctiva with a running 10/0 nylon suture. Do not attempt to repair the inferior defect. It will heal over in a few days without problem. Postoperatively, we recommend an eye patch and shield for 3 days with antibiotic steroid combination (e.g., Tobradex QID) for 4 days followed by steroid use for a further 3 –6 weeks depending on reaction to the donor. The sutures can be removed after 4– 6 weeks if required. If the bleb continues to leak despite donor conjunctival grafting or conjunctival advancement, we then recommend closing the scleral trabeculectomy site with a donor scleral patch graft followed by repeat trabeculectomy at a distant site if necessary. [email protected]

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Resurfacing options pluses and minuses Simple conjunctival advancement Free conjunctival graft Conjunctival pedicle flap (2) Irregular redundant limbal edge (þ) Ptosis least likely (þ) Handles large blebs (2) Potential retraction from limbus (2) Longer procedure (þ) Naturally curved limbal (2) Invites ptosis (2) Potential to slough edge (2) Limited to small blebs (þ) Maintains blood supply (þ) Minimal ptosis concern

The table below summarizes the different techniques, the year of the study, the number of patients, and the success rate. Most authors define success as pressure .6 and ,21 mmHg with resolution of the leak and no need for subsequent glaucoma surgery. It should be noted that amniotic membrane transplantation is not included in the table. A large review by Budenz (21) reported that amniotic membrane transplant in 15 patients was not as helpful as conjunctival advancement.

Techniques Advancement and excision Advancement and excision Advancement and excision Advancement and De-epithelialization

Author

2000

16

12

van de Geijn (12) 2002

36

Budenz (13)

1999

Catoira (14)

Success

Meds

Repeat Glaucoma Surgeries

Scleral Grafts

62.50%

0

1

26

15/16 (93.8%) 1 hypotony 31/36 (86.1%)

45.20%

5

2

26

26

22/26 (84.6%)

50%

2

0

2000

30

17

20%

1

0

Advancement and Burnstein (10) De-epithelialization De-epithelialization Harris (15) Free Autograft

2002

34

34

24/30 (80%) 3 leaks 12/17 in leak group 27/34 (79.4%)

32.40%

3

not noted

2000

47

47

46/47 (97.9%) hypotony not specified

0

—

Excise and Autograft Excise and Autograft

Wilson (16) Schynder (17)

1994 2002

4 16

4 14

0.41 (number of patients not reported) 25% 37.50%

0 1

— 0

Pedicle Advancement LaBorwit (19) or Free Graft

2000

31

13

4/4 (100%) (83.3%) 1 hypotony, 1 leak, 1 increased IOP (leaks only) 6% of total 12/13 (93.3%) patient 1 hypotony group

0

Advancement with Scleral Graft

1997

8

8

8/8 (100%)

0

Preferred autologous tenons over donor tissue number not specified 8

Myers (11)

Patients Leaks Year in Series in Series

Kosmin (20)

37.50%

% represents percentage of patients requiring glaucoma medication.

4.

CONCLUSION

The management of bleb leaks continues to be a challenging problem. Fortunately, attempts at surgical repair can provide very good results that allow preservation of the bleb in most cases. It must be remembered, however, that many of these patients will go on to require glaucoma medications and some will need additional glaucoma surgery. It is always important to evaluate each individual patient to try to weigh the risk of visual [email protected]

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loss from hypotony or endophthalmitis vs. the risk of visual loss due to surgical complications or loss of glaucoma control. Depending on the urgency of the situation, conservative measures can be tried for a short while but fortunately should surgical repair be required, evidence shows that repair allows for safer outcomes much of the time. REFERENCES 1. 2.

3. 4. 5. 6. 7.

8. 9. 10.

11. 12. 13. 14. 15. 16. 17.

18. 19. 20. 21.

Greenfield DS, Liebmann JM, Jee J, Ritch R. Late-onset bleb leaks after glaucoma filtering surgery. Arch Ophthalmol 1998; 116(4):443– 447. DeBry PW, Perkins TW, Heatley G, Kaufman P, Brumback LC. Incidence of late-onset bleb-related complications following trabeculectomy with mitomycin. Arch Ophthalmol 2002; 120(3):297– 300. Soltau JB, Rothman RF, Budenz DL, Greenfield DS, Feuer W, Liebmann JM, Ritch R. Risk factors for glaucoma filtering bleb infections. Arch Ophthalmol 2000; 118(3):338– 342. Leen MM, Moster MR, Katz LJ, Terebuh AK, Schmidt CM, Spaeth GL. Management of overfiltering and leaking blebs with autologous blood injection. Arch Ophthalmol 1996; 114(5):633–634. Smith MF, Magauran RG, Betchkal J, Doyle JW. Treatment of postfilteration bleb leaks with autologous blood. Ophthalmology 1995; 102(6):868– 871. Burnstein A, WuDunn D, Ishii Y, Jonescu-Cuypers C, Cantor LB. Autologous blood injection for late-onset filtering bleb leak. Am J Ophthalmol 2001; 132(1):36 –40. Choudhri SA, Herndon LW, Damji KF, Allingham RR, Shields MB. Efficacy of autologous blood injection for treating overfiltering or leaking blebs after glaucoma surgery. Am J Ophthalmol 1997; 123(4):554 –555. Asrani SG, Wilensky JT. Management of bleb leaks after glaucoma filtering surgery. Use of autologous fibrin tissue glue as an alternative. Ophthalmology 1996; 103(2):294– 298. Geyer O. Management of large, leaking, and inadvertent filtering blebs with the neodymium:YAG laser. Ophthalmology 1998; 105(6):983– 987. Burnstein Al, WuDunn D, Knotts SL, Catoira Y, Cantor LB. Conjunctival advancement versus nonincisional treatment for late-onset glaucoma filtering bleb leaks. Ophthalmology 2002; 109(1):71– 75. Myers JS, Yang CB, Herndon LW, Allingham RR, Shields MB. Excisional bleb revision to correct overfiltration or leakage. J Glaucoma 2000; 9(2):169 – 173. van de Geijn, Lemij HG, de Vries J, de Waard PW. Surgical revision of filtration blebs: a follow-up study. J Glaucoma 2002; 11(4):300 – 305. Budenz DL, Chen PP, Weaver YK. Conjunctival advancement for late-onset filtering bleb leaks: indications and outcomes. Arch Ophthalmol 1999; 117(8):1014– 1019. Catoira Y, Wudunn D, Cantor LB. Revision of dysfunctional filtering blebs by conjunctival advancement with bleb preservation. Am J Ophthalmol 2000; 130(5):574– 579. Harris LD, Yang G, Feldman RM, Fellman RL, Starita RJ, Lynn J, Chuang AZ. Autologous conjunctival resurfacing of leaking filtering blebs. Ophthalmology 2000; 107(9):1675– 1680. Wilson MR, Kotas-Neumann R. Free conjunctival patch for repair of persistent late bleb leak. Am J Ophthalmol 1994; 117(5):569 – 574. Schnyder CC, Shaarawy T, Ravinet E, Achache F, Uffer S, Mermoud A. Free conjunctival autologous graft for bleb repair and bleb reduction after trabeculectomy and nonpenetrating filtering surgery. J Glaucoma 2002; 11(1):10 – 16. Wadhwani RA, Bellows AR, Hutchinson BT. Surgical repair of leaking filtering blebs. Ophthalmology 2000; 107(9):1681– 1687. LaBorwit SE, Quigley HA, Jampel HD. Bleb reduction and bleb repair after trabeculectomy. Ophthalmology 2000; 107(4):712– 718. Kosmin AS, Wishart PK. A full-thickness scleral graft for the surgical management of a late filtration bleb leak. Ophthalmic Surg Lasers 1997; 28(6):461 – 468. Budenz DL, Barton K, Tseng SC. Amniotic membrane transplantation for repair of leaking glaucoma filtering blebs. Am J Ophthalmol 2000; 130(5):580– 588. [email protected]

24 Remodeling the Filtration Bleb J. E. Morgan Cardiff University, Cardiff, UK

Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada

1. Introduction 2. Bleb Types 2.1. The Ideal Filtration Bleb 2.2. The Dysmorphic Bleb 2.3. The Elevated Bleb 2.4. The Diffuse Bleb 2.5. The Avascular Bleb 2.6. Prophylaxis: Avoiding Dysmorphic Blebs 3. Management 3.1. The Elevated Bleb 3.2. Remodeling the Bleb with Compression Sutures 3.3. The Diffuse Bleb 4. Conclusion References

1.

225 226 226 226 227 228 229 229 230 230 231 233 233 234

INTRODUCTION

Although major advances have been made in the medical management of glaucoma, filtration surgery (trabeculectomy) remains a common operation for patients with poorly controlled intraocular pressure (IOP) and progressive vision loss. Evidence from a recent clinical trial (1) that this vision loss can occur at IOPs within the statistical normal range has increased the clinical challenge for glaucoma physicians in achieving therapeutic target IOPs. Although these advances may, in the long-term, be successful in halting visual field loss, it is important that the eye remains comfortable and that the quality of vision (not just the visual acuity) is maintained. The clinician may be happy with the IOP and provide a 225

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reassuring prognosis for the preservation of vision. At the same time, the patient may be disappointed with an operation that has resulted in an uncomfortable eye (2 – 4) and a reduced visual perception. In many cases, symptoms relate to the presence of a filtration bleb that uses too much conjunctival area, is too elevated or a combination of both. Advances in the management of postoperative ocular scarring have been a great help in achieving low target pressures. Unfortunately, commonly used anti-scarring agents such as 5 fluorouracil (5FU) and mitomycin C, do not guarantee an ideal bleb configuration. Alternatively, some patients may have a comfortable eye but still be distressed by the cosmetic appearance of the bleb. As the signs and symptoms of the dysmorphic and dysesthetic bleb are recognized, the glaucoma surgeons should be familiar with techniques for the postoperative manipulation of the bleb that do not adversely affect the long-term control of IOP. Achieving these goals can be a daunting task but fortunately, a number of treatments have been developed that can make their attainment relatively straightforward.

2. 2.1.

BLEB TYPES The Ideal Filtration Bleb

The ideal bleb is one that is both asymptomatic and cosmetically acceptable. In general, blebs that satisfy these criteria are diffuse with margins that blend into normal conjunctiva and are minimally elevated (Fig. 24.1). The most unobtrusive and cosmetically acceptable blebs are those in which the conjunctival vascularity in the center of the bleb matches the surrounding conjunctiva that is not involved in the filtration site.

2.2.

The Dysmorphic Bleb

Dysmorphic blebs are characterized by excessive elevation, excessive distribution, or abnormal vascularization. These features can occur in combination to generate a wide range of bleb appearances.

Figure 24.1 Diffuse and low bleb following routine glaucoma filtration surgery (fornix based flap). Some conjunctival pallor can be seen but this is mostly covered by the upper lid and is cosmetically acceptable. Mitomycin C (0.4 mg/mL) was applied to the sclera and underside of the conjunctiva prior to the creation of the sclerostomy. [email protected]

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Figure 24.2 Elevated bleb close to the disc margin. The tear film at the limbal margin of the bleb is unstable and will predispose to the formation of dellen.

2.3.

The Elevated Bleb

In general, elevated blebs are thin walled and cystic in appearance and usually arise several months after filtration surgery. They tend to have a well-demarcated boundary and are relatively avascular. In contrast, Tenon’s cysts which occur in the early postoperative phase usually have diffuse with boundaries and are well vascularized. The management of blebs with Tenon’s cysts is dealt with in more detail in Chapter 6. Elevated cystic blebs (Fig. 24.2) cause discomfort, either as a direct result of the configuration of the bleb or because of surrounding effects on the ocular surface. The commonest symptom is a foreign body sensation which is localized to the site of the bleb. In many cases, this may be associated with moderate epiphora and slight reduction in vision. Large elevated blebs can cause difficulties with lid closure (Fig. 24.3). Patients may have to resort to placing the upper lid manually over the bleb so that full lid closure can be achieved. In some cases, a large bleb can also prevent lid elevation, resulting in a mechanical ptosis (Fig. 24.4). If untreated, this can cause long-term damage to the levator aponeurosis complex in which the ptosis persists following management of the bleb dysmorphology. The ptosis can usually be treated by resection of the levator aponeurosis. Large blebs also affect the margin of the upper lid and predispose to the development of

Figure 24.3 Elevated bleb which prevents lid closure. Manual placement of the upper lid was required to ensure that it would pass over the bleb for lid closure to occur. [email protected]

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Figure 24.4 Elevated bleb causing mechanical ptosis. The lid could be manually elevated by the patient to sit over the bleb to adopt a configuration shown in Fig. 24.3.

upper lid entropion. The combination of lash misdirection in the vicinity of a large and thin walled bleb can be particularly problematic and increases the risk for the development of endophthalmitis. Elevated blebs can be associated with local instability of the tear film resulting in drying of the cornea and the formation of dellen (5). This can be seen during the anterior segment examination as pooling of fluorescein at the junction of the bleb and the corneal limbus. Dellen can be a particular problem in cases where the elevated bleb has expanded to cover the limbus and encroach on the cornea (Fig. 24.5). Local drying of the exposed part of the bleb can also occur and, unless the bleb is covered by the lid, even mild rubbing of the eye can traumatize the bleb. The identification of elevated blebs is usually straightforward and the close association of related ocular pathology assists in the diagnosis. These blebs can also arise in locations away from the filtration site and either be cosmetically unacceptable or uncomfortable (Fig. 24.5).

2.4.

The Diffuse Bleb

With diffusely draining blebs, discomfort relates to the involvement of large areas of the limbal conjunctiva in aqueous outflow. The symptoms are less specific compared with

Figure 24.5 Elevated bleb arising in the nasal conjunctiva. The filtration site for this eye was located superotemporally. Eversion of the lower lid punctum occurred and the patient suffered from chronic epiphora. [email protected]

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cystic blebs; a typical complaint is of a mild foreign body sensation and that the eye feels “soft.” Both these symptoms are exacerbated by blinking. Chronic epiphora can also be a problem, either because the punctum is occluded or everted by oversized blebs or because the flow of tears to the conjunctival fornix is restricted (Fig. 24.5). The relationship between the location of a diffusely draining bleb and degree of ocular irritation can be quite variable. Some eyes have 3608 of elevated conjunctiva and cause the patient little distress, whereas others with not more than 1808 of conjunctival elevation are quite symptomatic. In general, these blebs do not disrupt the tear film and are not associated with the formation of dellen. However, they can be associated with ocular hypotony if the bleb is over draining and in these cases, the management plan should, in the first instance, be directed at increasing the IOP rather than the modulation of the bleb configuration. Identification of the distribution of aqueous drainage can be difficult and careful examination is required to demarcate the extent of the bleb. 2.5.

The Avascular Bleb

Finally, for some patients, the cosmetic appearance of the bleb may be an issue. In the management of elevated or diffuse blebs, this is an obvious factor for consideration. However, in eyes with low and restricted blebs, the appearance of the bleb may not be satisfactory because of the degree and distribution of conjunctival vascularity. In blebs with excessive scarring, the margin of the bleb may be demarcated by a line of increased vascularity representing a zone of excessive postoperative scarring. Within this zone, the bleb may be pale and elevated. With the increasing use of anti-scarring agents such as mitomycin C, the devascularization of the bleb can cause conjunctival pallor which may be of cosmetic concern to some patients. 2.6.

Prophylaxis: Avoiding Dysmorphic Blebs

Ideally, consideration should be given to the avoidance of bleb dysmorphology when surgery is planned. The most comfortable bleb is one that is low and diffuse with a drainage area that is subtarsal. A major advance in achieving this aim has been the development of improved techniques for the delivery of agents such as mitomycin C and 5FU to minimize postoperative scarring. More recently agents such as anti-TGF beta antibodies have been introduced that show great promise in providing an optimal postoperative bleb configuration (6). The site of the conjunctival incisions at the time of surgery may also be an important factor in determining the long-term bleb configuration. In general, diffuse low lying blebs are more frequently associated with the use of fornix based conjunctival incisions compared with limbal incisions. With fornix based incisions, anti-metabolites can be positioned subconjunctivally over a wide sector behind the filtrations site. Recent evidence suggests a lower rate of bleb related complications with fornix compared with limbal flaps in filtration surgery augmented with MMC (7). Early approaches to the application of agents such as MMC used limbal based incisions because of anxieties that compromised wound healing at the limbus would result in persistent aqueous leaks. Although the rate of wound leak was low with this approach, it often resulted in the development of thin walled cystic blebs at the corneal limbus that drained over a relatively small area of conjunctiva. These problems were particularly acute with the early use of mitomcyin C and may have accounted for the relatively high rate of postoperative endophthalmitis associated with its use. The preferred method for the application of these agents is now to use a fornix based conjunctival flap so that the agent can be applied to a wide area of conjunctiva at away [email protected]

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from the corneal limbus. At the time of application, meticulous care is taken with the anterior (cut) edge of the conjunctiva to ensure that it does not come into contact with the anti-scarring agent. When the conjunctiva is sutured in place it is important to apply sutures that tension the conjunctiva at its anterior (leading) edge. In some cases, a continuous running suture can be required to ensure that the leading edge of the conjunctiva remains applied to the corneal margin. With the controlled application of mitomycin C, these simple developments have resulted in a marked improvement in the configuration of the blebs which lie low and drain diffusely (Fig. 24.1). These blebs also have an improved cosmetic appearance as the demarcation between those parts of the bleb treated with anti-scarring agents and the untreated part can be quite diffuse. Great care has to be taken in deciding the dose of anti-scarring agent, particularly when using agents such as mitomcyin C. With prolonged application at high concentration these can result in devascularized blebs which not only place the eye at increased risks for the development of endophthalmitis but also are cosmetically unattractive. The dose of agents should be determined on clinical grounds and varied according to the risk of postoperative bleb failure. Unfortunately, dysmorphic blebs will occur in spite of the surgeon’s best efforts. In considering the management of these blebs, we will deal separately with elevated and diffuse blebs. These are not mutually exclusive entities and management techniques can be combined where appropriate to achieve the desired outcome.

3. 3.1.

MANAGEMENT The Elevated Bleb

In assessing the elevated bleb, the distinction should be drawn between Tenon’s cysts (see Chapter 6) that arise in the early postoperative (within 2 –3 months following surgery) and the cystic blebs that arise after this period. When examining the lid margin, misdirected lashes or upper lid entropion may require immediate correction if the risk of bleb trauma from misdirected lashes is high. The simplest procedure is to epilate the lashes but it is important that the lashes are removed completely. Broken lashes can represent a greater risk for bleb damage as they are stiffer and can perforate thin conjunctiva. Cryotherapy to individual lash roots may be required to ensure complete removal of the lash. Attention should also be given to the stability of the tear film. If dellen are present they indicate areas of tear film instability and local corneal dehydration. If untreated, they can result in epithelial breakdown and predispose to the development of bacterial keratitis. In most cases, dellen respond well to topical lubricants applied regularly at first but then as required. Gentle massage through the lids over the dellen can be a useful way of improving corneal hydration following the instillation of topical lubricants. The other feature of elevated blebs is that because they are often thin walled, they are prone to develop small leaks which can be hard to detect. It is important that these leaks are excluded in any assessment of the bleb as they increase the risk of bleb infection and hinder the reliable control of IOP. If a leak is identified, antibiotic drops should be started to minimize the risk of endophthalmitis as the patient is prepared for surgical revision of the bleb (see Chapter 23). The simplest approach to the elevated bleb is to re-contour the anterior edge of the bleb. This can be done quite simply under topical anesthetic by applying light diathermy to the bleb surface. It is critical that the bleb does not become adherent to the diathermy as the surface of the bleb will be removed and major bleb revision will then be required. [email protected]

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The appeal of this approach is that it can be applied as required to remodel the bleb surface. In our experience, it is well tolerated by patients and can be repeated as required. Other methods that have been advocated to alter the bleb surface contour include laser treatment and cryotherapy. If a leak has been identified, the simplest approach to sealing the bleb is subconjunctival injection of autologous blood (8). This is simple and safe for the patient and does not carry the risks associated with the use of commercially available fibrinogen. Fibrinogen can be prepared from the patient’s own serum but this is not a viable option in many clinics. The appeal of subconjunctival blood is that it can be given under topical anesthesia as an office procedure. In some cases, this can be combined with cautery, diathermy, cryotherapy, or laser (9) to the site of leakage. The principle disadvantage with this technique is that when used in isolation it can comprise bleb function and result is excessive scarring around the filtration site. In some cases, blood can enter the anterior chamber and result in marked increases in IOP (10). When using autologous blood, it is important to establish whether the patient is using anti-coagulation medications such as warfarin or aspirin. If these are used, clotting will be delayed and there is an increased risk that blood will enter the anterior chamber. In these cases, diathermy can be applied at the time of subconjunctival injection so that the delivered thermal energy restricts the blood to the injection site. It is advisable to warn the patient that they will have a large subconjunctival hematoma and to reassure them that this is an anticipated side effect of the treatment. 3.2.

Remodeling the Bleb with Compression Sutures

The development of conjunctival compression sutures for the treatment of dysmorphic blebs (11 –13) has been a very useful advance in the management of these blebs. Nylon (10-0) or Vicryl (9-0) can be positioned as mattress sutures to run over selected portions of the bleb to provide physical compression bleb. Mattress sutures are inserted, under topical anesthesia, using a cutting edge needle, first at the limbus to run posteriorly to be anchored in conjunctiva—Tenon’s two-thirds of the way back from the corneal limbus to the globe equator. Insertion of the anterior (limbal) suture is usually straightforward. The key to successful placement of the posterior suture is that they are inserted into Tenon’s tissue and not just the conjunctiva. If suturing at this depth does not provide a firm anchor point, the suture can be secured by taking a bite that includes the superficial layers of the sclera. As the eye retains full mobility, the patient is asked to look in the required direction to obtain adequate exposure of the posterior conjunctival areas. The anchor points for the sutures can be adjusted to suite variations in bleb morphology and sutures can be removed and reinserted as the configuration of the bleb responds to treatment. The width of the mattress suture will influence the degree of tension that can be applied to compress the bleb; the broader the bite used to secure the mattress suture in the corneal limbus and conjunctiva, the greater the tension that can be applied. Sutures can be used singly to demarcate one side of the bleb (Fig. 24.6) or two sutures (Fig. 24.7) can be used to demarcate both sides of the bleb. Sutures can also be used to demarcate areas of the bleb that require excision to reform the ocular contour at the limbus (Fig. 24.8). In these cases both ends of the suture are anchored at the limbus. Compression sutures can be used effectively in combination with the subconjunctival injection of autologous blood (3,14). They are inserted prior to the injection and will limit the distribution of injected blood and can be used to prevent the passage of blood into the anterior chamber (Figs. 24.6 and 24.7). Blood is used because it increases the efficacy of compression and ensures continued apposition of layer induced by compression. [email protected]

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Figure 24.6 Single compression suture with subconjunctival injection of autologous blood. Note that the blood has been excluded from the filtration site to ensure that the IOP was kept a satisfactory level. Sutures were inserted to limit excessive flow of aqueous into the nasal conjunctival sector. The tension in the suture and its insertion site in the conjunctiva can be seen.

The sutures usually stay in place for up to 6 weeks. To facilitate scarring at the site of injection, anti-inflammatory medications are not usually given postinsertion. Topical antibiotic drops are given routinely for the first 2 weeks. Successful compression sutures usually become subconjunctival after 2 weeks while still exerting a compressive effect on the deeper layers of the conjunctiva. Loose sutures should be removed as early as possible to limit the risk of infection. Importantly, autologous blood injection and bleb compression can be repeated and customized to suite the configuration of the bleb. If required, sutures can be used to compress the limbal aspect of the bleb which can be excised once the scar line has sealed this from the functioning parts of the bleb (Fig. 24.8). The use of multiple procedures is usually quite acceptable to patients because they can be performed under topical anesthesia and carry little risk to the eye. If the bleb fails to respond to these measures, total bleb revision may be required. In its simplest form, the bleb is excised and unaffected adjacent conjunctiva mobilized to cover the filtration site. For the excision of small blebs, the conjunctiva posterior to the

Figure 24.7 Compression sutures have been inserted either side of an over draining bleb and subconjunctival injections of autologous blood given. This resulted in satisfactory resolution of the bleb dysmorphology and preservation of IOP control. [email protected]

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Figure 24.8 A suture has been inserted to compress the leading edge of a cystic bleb. The suture is anchored in the limbus either side of the bleb and runs parallel to the limbus. After several weeks, a scar line formed under the compression suture to seal off the part of the bleb overlying the limbus. This part of the bleb was then reduced by gentle cautery applied to the bleb surface to achieve a satisfactory bleb contour.

filtration site can be mobilized and the anterior edge anchored to the limbus using 10-0 nylon mattress sutures. They have the advantage that they can apply sufficient traction to the conjunctiva without the development of small button holes at the site of insertion. If insufficient conjunctiva is available adjacent to the bleb, donor conjunctiva (15) can be obtained from the ipsilateral or contralateral eye to cover the filtration site. 3.3.

The Diffuse Bleb

The treatment of these blebs can be difficult. Conventional management has included cryotherapy to demarcate the region of drainage or the insertion of conjunctival sutures to anchor the conjunctiva to the underlying sclera. Compression sutures have been a significant advance in the management of these blebs. We almost always use the compression sutures in combination with autologous blood and usually plan to fill the entire drainage distribution of the bleb. In this case, the compression sutures provide a very effect barrier to prevent the passage of blood into the anterior chamber (Fig. 24.7). Blood injections can be repeated, as required, to facilitate adherence of the bleb to the underlying Tenons. The configuration of the compression sutures can also be adjusted during the course of clinical management to demarcate further subconjunctival blood injections as required or to adjust the degree of aqueous drainage. In cases of ocular hypotony compression sutures can be applied in a cruciate pattern so that they rest on the scleral flap and increase the resistance to the outflow of aqueous. In cases where these measures are not successful, revision of the sclerostomy may be required. If the scleral flap is deficient, a scleral patch graft can be used; these can most easily be obtained as a partial thickness graft from the ipsilateral eye at a site diametrically opposite the filtration site.

4.

CONCLUSION

There are many procedures for the management of dysmorphic and over filtering blebs. Ideally, surgery should be planned to minimize the risk for the development of the [email protected]

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dysmorphic bleb. Careful assessment is required to plan the strategy for bleb revision. Treatments should be given in a step-like fashion rather than as a single major bleb revision. In the majority of cases compression sutures, when used in combination with subconjunctival blood injection, can be used to remodel the majority of blebs and reduce the need for major bleb revision surgery.

REFERENCES 1.

2. 3. 4. 5. 6.

7.

8. 9. 10. 11. 12.

13. 14. 15.

The advanced glaucoma intervention study (AGIS): 7. The relationship between control of intraocular pressure and visual field deterioration. The AGIS investigators. Am J Ophthalmol 2000; 130(4):429– 440. Budenz DL, Hoffman K, Zacchei A. Glaucoma filtering bleb dysesthesia. Am J Ophthalmol 2001; 131(5):626– 630. Morgan JE, Diamond JP, Cook SD. Remodelling the filtration bleb. Br J Ophthalmol 2002; 86(8):872– 875. Barton K. Bleb dysesthesia. J Glaucoma 2003; 12(3):281 – 284. Soong H, Quigley H. Dellen associated with filtering blebs. Arch Ophthalmol 1983; 101(3):385– 387. Mead AL, Wong TT, Cordeiro MF, Anderson IK, Khaw PT. Evaluation of anti-TGF-beta2 antibody as a new postoperative anti-scarring agent in glaucoma surgery. Invest Ophthalmol Vis Sci 2003; 44(8):3394– 3401. Wells AP, Cordeiro MF, Bunce C, Khaw PT. Cystic bleb formation and related complications in limbus- versus fornix-based conjunctival flaps in pediatric and young adult trabeculectomy with mitomycin C. Ophthalmology 2003; 110(11):2192– 2197. Leen M, Moster M, Katz L, Terebuh A, Schmidt C, Spaeth G. Management of overfiltering and leaking blebs with autologous blood injection. Arch Ophthalmol 1995; 113:1050 –1055. Wright M, Brown E, Maxwell K, Cameron J, Walsh A. Laser-cured fibrinogen glue to repair bleb leaks in rabbits. Arch Ophthalmol 1998; 116:199 – 202. Alward W. Marked intraocular pressure rise following blood injection into a filtering bleb. Arch Ophthalmol 1995; 113:1232 – 1233. Palmberg P, Zacchei A. Compression sutures—a new treatment for leaking or painful filtering blebs. Invest Ophthalmol Vis Sci 1996; 37(3):S444. Palmberg P. Late complications after glaucoma filtering surgery. In: Leader B, Calckwood J, eds. Proceedings of the 45th Annual Symposium of the New Orleans Academy of Ophthalmology. The Hague: Kugler Publications, 1996. Ducharme J, Lara S, Palmberg P. Long-term follow-up of compression sutures for filtering bleb leaks or dysesthesia. Invest Ophthalmol Vis Sci 1998; 39(4):S941. Haynes WL, Alward WL. Combination of autologous blood injection and bleb compression sutures to treat hypotony maculopathy. J Glaucoma 1999; 8(6):384 – 387. Buxton J, Lavery K, Liebmann J, Buxton D, Ritch R. Reconstruction of filtering blebs with free conjunctival autografts. Ophthalmology 1994; 101(4):635– 639.

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25 Management of Flat Anterior Chambers and Choroidal Effusions Ridia Lim Eye Associates and Prince of Wales and Westmead Hospitals, Sydney, Australia

Ivan Goldberg Eye Associates and Sydney Eye Hospital, Sydney, Australia

Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada

1. Introduction 2. Differential Diagnosis of Low Intraocular Pressure and Shallow AC Following Glaucoma Surgery 3. Clinical Assessment of a Shallow AC with Choroidal Effusions 4. Management 4.1. Intraoperative Techniques to Prevent Occurrence 4.2. Address the Specific Cause 4.2.1. Wound Leaks and Over Filtration 4.2.2. Conservative Management of Shallow AC with Choroidal Effusion Without Leak or Over Filtration 4.2.3. Surgical Management 5. Surgical Treatment Options 5.1. AC Reformation 5.2. Drainage of Choroidal Effusions 5.3. Scleral Flap Repair 6. Conclusions References

1.

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INTRODUCTION

Flat anterior chambers (ACs) and choroidal effusions are well described complications of glaucoma filtration surgery, including trabeculectomy and drainage implant surgery. More common during the era of full-thickness glaucoma filtration surgery, both complications became less frequent with guarded trabeculectomy. However, with anti-metabolite use, 235

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particularly mitomycin C (MMC), they have become more common once more. Preoperative planning can reduce their occurrence and timely treatment prevents adverse outcomes. In a recent national survey of ophthalmologists performing trabeculectomy in the United Kingdom, the prevalence of shallow AC was 23.9% and choroidal effusions, 14.1% (1). Flat AC with lenticulo-corneal touch occurred in 0.2% of cases. AC reformation was performed in 1.2% of cases and choroidal drainage in 0.3% of cases. As indicated by this and other studies, most shallow ACs tend to resolve spontaneously within 3 weeks (2). Once lenticulo-corneal touch occurs, it rarely reverses with conservative measures. Progression of cataract is universal following a flat AC with lenticulo-corneal touch and most eyes with chronic or recurrent choroidal effusions develop cataract (3). 2.

DIFFERENTIAL DIAGNOSIS OF LOW INTRAOCULAR PRESSURE AND SHALLOW AC FOLLOWING GLAUCOMA SURGERY 1. 2. 3.

4.

3.

Leaking bleb (see chapter on leaking blebs). Over filtering bleb (see chapter on over filtration). Pupil block may be associated with any level of intraocular pressure (IOP) (usually high) and needs to be excluded. It may coexist with aqueous hyposecretion and so may appear as low IOP and shallow AC. Choroidal effusions—pathogenesis: Certain conditions predispose to the formation of choroidal effusions. Supra-choroidal fluid derived from the choroidal vessels accumulates when hypotony is coupled with abnormal vascular permeability, thickened sclera (causing reduced transscleral outflow), or where hydrostatic pressure is abnormally high (as with raised episcleral pressure in Sturge –Weber syndrome) (4). Postoperative and/or intraoperative hypotony, particularly in the setting of high preoperative pressures, is a risk for formation of choroidal effusions. Ocular hypotony alters pressure relationships that normally prevent fluid accumulating in the supra-choroidal space. Aqueous hyposecretion occurs as a consequence of iridocyclitis. Inflammation alters the vascular permeability of choroidal vessels, resulting in fluid leakage. With raised episcleral pressure, effusions are a particular risk, especially acute intraoperative effusions: prophylactic sclerotomies should be considered in these cases. In nanophthalmic eyes, thick sclera reduces transscleral outflow, compresses the vortex veins, and restricts venous outflow promoting the formation of intraoperative or postoperative choroidal effusions. Once formed, a choroidal effusion exacerbates hypotony establishing a vicious cycle: uveoscleral outflow increases and the associated ciliochoroidal detachment leads to aqueous hyposecretion, thereby worsening the hypotony. If MMC has been used during the trabeculectomy, it may penetrate the sclera, cause toxicity to ciliary epithelium, and also contribute to hypotony. Interestingly, choroidal effusions have been noted to be less common with hypotony maculopathy (5).

CLINICAL ASSESSMENT OF A SHALLOW AC WITH CHOROIDAL EFFUSIONS

A patient with a shallow AC and choroidal effusions requires careful clinical assessment. Of particular importance is status of the cornea, grading of AC depth, IOP level, bleb [email protected]

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extent, choroidal effusion size, and clinical course. Assessment is dynamic: it is the clinical course over time, which guides the therapy. Each case needs to be assessed on its own merits. 1.

2. 3.

4.

5.

6.

Assessment of the AC: Is the AC shallow or flat? Observers mean different things when they describe the AC as “flat.” We use this term to describe cases of lenticulo-corneal touch with “shallow” applied to all other situations. Documentation is important as shallow chambers, that is, those whose depth is shallower than normal or shallower than the other eye, usually spontaneously resolve with conservative measures whereas flat chambers with lenticulocorneal touch need urgent surgical intervention (2,6). It is important to document carefully the amount of irido-corneal touch in millimeters from the limbus. Spaeth (6) classifies flat AC from 1 to 3: grade 1 is peripheral iridocorneal touch, grade 2 is central irido-corneal touch, and grade 3 is lenticulocorneal touch. A classification of AC depth from 1 to 4 also exists (2). An attempt may be made to perform gonioscopy to exclude a cyclodialysis cleft. Gonioscopy is difficult to perform with a shallow AC (especially if the eye is hypotonous) and is not productive if the AC is flat. Always assess and document the state of the cornea (with or without corneal edema/folds in Descemet’s membrane). Assessment of the bleb: Examine the bleb for extent. What is its size? Is there evidence of bleb function? Is there a wound leak? Use 2% fluorescein to look for a wound leak. Careful assessment of the bleb is usually the key to successful management of the case. If a wound leak is discovered, repair will resolve the situation. Most flat chambers, however, are due to over filtration associated with a large bleb. This scenario usually resolves in 1 –3 weeks with conservative treatment consisting of mydriatics and limited steroid use (Dr. Morgan’s chapter on management of over filtering blebs). IOP assessment: In cases with shallow or flat chambers due to leakage or over filtration, IOP should always be low. Choroidal effusions can be associated with IOP levels from 0 to 5 mm Hg as fluid fills the posterior segment and partially reinflates the eye. If IOP is measured in the high single digits, always reconsider your diagnosis and think of aqueous misdirection glaucoma or a supra-choroidal arterial hemorrhage. Aqueous misdirection glaucoma is not associated with clinically visible effusions whereas choroidal hemorrhage is usually associated with pain, large choroidal masses, and very high IOP. Pupil block may be associated with any level of IOP and also needs to be excluded. Choroidal effusion assessment: Assess choroidal effusions for size and extent; are they “kissing” or not “kissing”? Kissing choroidals are an indication for surgical drainage. Assess the retina: exclude a serous retinal detachment. Choroidals are dark raised swellings unlike retinal detachments which are much paler. Ultrasound can determine the nature and extent of the supra-choroidal fluid. Effusions are typically dome shaped on B-scan, with a highly reflective anterior border and little internal reflectivity on A-scan. Ultrasound biomicroscopy (UBM) can yield further information, particularly about the presence of cyclodialysis clefts. Assess degree of intraocular inflammation: Assess the level of anterior uveitis and the extent to which it is contributing to the hypotony and choroidal effusions. [email protected]

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MANAGEMENT

4.1.

Intraoperative Techniques to Prevent Occurrence

Prevention is better than cure; anticipation and recognition of predisposing conditions is important. Meticulous technique with each step of the trabeculectomy is crucial. Controlled ocular decompression attempting to avoid intraoperative hypotony is important. With extremely high preoperative IOP, consider lowering the IOP before surgery using a systemic agent: slowly injected intravenous acetazolamide (250 –500 mg) or intravenous mannitol (0.5 –2 g/kg over 45 min). On the operating table, reduce IOP gradually by entering the eye first via a paracentesis and allow aqueous to exit slowly. Consider an AC maintainer to avoid intraoperative hypotony in extremely high-risk cases. Intraoperative use of a viscoelastic does not prevent flat AC. A small, randomized trial comparing leaving or not leaving sodium hyaluronate in the AC showed an equal prevalence of hypotony in the two groups (7): the two cases of flat AC reported were in the viscoelastic group at postoperative days 4 and 7. If the AC tends to shallow at the end of surgery, we prefer to add additional scleral trapdoor sutures, and to consider cycloplegics “on the table”. To reduce the chance of postoperative hypotony, some surgeons favor tight scleral flap closure to ensure AC stability with later laser suture lysis or releasable suture removal. We advise surgeons to check the tension on scleral flap sutures intraoperatively so as to attain the desired IOP postoperatively. This is the difficult art of trabeculectomy surgery. Inflate the AC with balanced salt solution (BSS) and observe the rate of aqueous egress under the scleral flap: rapid free flow of aqueous means the sutures are too loose; a tiny flow or flow occurring with minimal pressure on the globe is probably optimal; and if flow only occurs with pressure to the posterior lip of the flap, the flap is probably sutured too tightly. Think carefully before using anti-metabolites, especially MMC. Even if its use is planned, reassess this need intraoperatively. Avoid MMC if the conjunctiva is torn or very thin, especially with minimal Tenon’s capsule. Concentrations used vary from 0.2 to 0.5 mg/mL for 1 – 5 min; consider using a lower concentration for a shorter duration. Carefully protect the edges of the conjunctiva during the application and wash away excess MMC at the end of the application. If using a fornix-based flap, close with wing sutures and consider a continuous limbal suture (8/0 vicryl). Close limbal based flaps in two separate layers especially if MMC is used. Pay meticulous attention to wound closure and check the wound at the end of the procedure with 2% fluorescein for water tightness. Treat inflammation vigorously after the surgery. All filtering surgery should include an adequate paracentesis. Draw a diagram of your surgery, clearly indicating the site and direction of the paracentesis, to facilitate any postoperative accessibility. 4.2.

Address the Specific Cause

To treat a flat AC effectively, it is crucial to ascertain its cause (see Fig. 25.1). 4.2.1.

Wound Leaks and Over Filtration

Determine if there is a wound leak or an over filtering bleb and treat them (see chapter on leaking blebs and over filtration). Leaking wounds increase the risk of infection and bleb failure and reparative surgery is required when conservative measures fail. Conservative measures may include short-term aqueous suppressants, reducing steroids, and a bandage [email protected]

Management of Flat ACs and Choroidal Effusions

Step 1

Q1. Is there a leak? Yes No Q2. Is there over-filtration?

Step 2

Yes

No

Step 3

Q3. Is there lenticulocorneal touch?

Yes

No Step 4

Q4. Are the choroidals “kissing”?

Yes

Q5. Combination (shallowing AC, large choroidals) + failing bleb?

Treat leak-aqueous suppressants, reduce steroids, contact lens ± resuture wound ± resuture flap

See this volume, chapter on leaking blebs

Treat over-filtration- reduce steroids, contact lens ± Simmons shell ± bleb compression sutures ± autologous blood ± resuture flap

See this volume, chapter on over-filtration

Reform AC ± choroidal drainage ± resuture scleral flap

Drain choroidals and reform AC

If it fails

No

Step 5

239

Yes

Reform AC ± drain choroidal effusions ± resuture scleral flap

No

Step 6

Treat conservativelysteroids, cycloplegics ± Simmons shell

Figure 25.1

A management flowchart of flat anterior chamber with choroidal effusions.

contact lens. Surgical treatment may be required for over filtration not responding to conservative management, in particular, if there is hypotony maculopathy. Conservative measures: mydriatics, reducing steroids, contact lens, and Simmons shell should be tried for over filtration. A Simmons shell requires high maintenance with daily dressings and review. The platform must be positioned and stabilized carefully (8). It is inconvenient and frequently leads to corneal abrasion (9). A way to minimize this is to use a large diameter (17 –19 mm) contact lens under the Simmons shell. To stop rotation of the shell, sutures are tied through a side hole and fixed by tape to the skin of the lateral canthus. If this fails and the bleb is large, autologous blood injections with compressions sutures can be tried (see chapter on over filtration).

4.2.2.

Conservative Management of Shallow AC with Choroidal Effusion Without Leak or Over Filtration Postoperative inflammation must be treated vigorously. This prevents formation of posterior synechiae, peripheral anterior synechiae, reduces iridocyclitis, and possibly reduces uveoscleral outflow. The ciliary muscle must be completely paralyzed; using a cycloplegic-mydriatic relaxes the lens – iris diaphragm, prevents its forward movement, discourages AC shallowing, and minimizes pupil block. During this assessment, ensure the peripheral iridectomy is patent—if it is not, complete it with laser. Pressure dressing is contraindicated in shallow AC as eyelid closure, compression on the cornea, and Bell’s phenomenon may further shallow the AC. Furthermore, we do not routinely pad our trabeculectomy patients after surgery as nonpadded eyes are at no greater risk than padded eyes for shallow and flat ACs (10) prolonged padding for shallow ACs may lead to [email protected]

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bleb fibrosis and failure (2). Furthermore, it makes the patient feel uncomfortable and may predispose to infection. 4.2.3. Surgical Management Signs of poor visual or bleb outcome require surgery, sooner rather than later. There are some absolute indications for surgery. 1.

2.

3.

4.

5.

A flat AC with lenticulo-corneal touch is an emergency and should be operated on immediately. It can threaten vision from endothelial cells loss (direct trauma) and cause corneal decompensation. There can be .50% endothelial cell loss following lenticulo-corneal touch (11). Endothelial cell loss following iridocorneal touch is not usually clinically significant. A shallow AC does not influence the outcome of filtering surgery but a flat AC is associated strongly with bleb failure (2,12). Peripheral anterior synechiae can form and compromise the filtration procedure. “Kissing” choroidal effusions threaten vision as they may result in retinal adhesion. Smaller choroidal effusions tend to resolve slowly when the factors that initiated their formation have been reversed; however, “kissing” choroidals may not and surgical attention is required. The only time “kissing” choroidals can be left is if the chamber is reformed and IOP has increased (either spontaneously or with surgery) and the “kissing” has been present for only 1 –2 days and is noted to be resolving. A shallow chamber present for .7 –10 days with or without choroidals requires surgical reformation utilizing air, viscoelastic, or gas. We prefer not to drain choroidals unless they are “kissing.” If repeated AC reformation fails, we recommend draining choroidals with AC reformation. If that fails to resolve the over filtration, the wound will need to be resutured by opening the conjunctiva and placing additional sutures into the wound at the leaking areas (often found close to the limbus). Relative indications for surgical intervention; these include a progressively shallowing AC, choroidal effusions close to touching, a hemorrhagic choroidal detachment that is suspected with low IOP because of inflammation, or a flattening bleb with signs of bleb failure. A filtration bleb requires some aqueous flow through the bleb for survival and prolonged hypotony with a flattening bleb is not a good prognostic sign, especially in combination, these may warrant surgical intervention.

SURGICAL TREATMENT OPTIONS

In cases of hypotony due to over filtration reforming the AC, draining the choroidal effusions and resuturing the scleral flap or a combination of these will resolve the situation. 5.1.

AC Reformation

The best place to correct a flat AC is in an operating or treatment room, using an operating microscope for maximal control; reformation at the slit lamp is an option. The AC can be inflated with air, BSS, viscoelastics (of varying viscosities), or gas. Reforming the AC is a fast, less invasive, and often an effective way of treating flat or shallow AC and choroidal effusions. It is less traumatic than draining choroidal effusions; is associated with a lower [email protected]

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long-term IOP when compared with observation alone; is associated with fewer complications and with a better visual acuity outcome long-term when compared with choroidal drainage (6). This is the first option if the AC is flat (lenticulo-corneal touch), if the AC is shallow with corneal edema for .7 –10 days, or if there is a progressive shallowing of the AC with signs of bleb failure. For the procedure, topical anesthesia is usually sufficient. A sterile technique is mandatory and an antiseptic, such as povidone-iodine, should be used to disinfect the eye, even when this is performed at the slit lamp. A speculum is used to keep the eye open and then air, viscoelastic, or gas is injected via the temporal paracentesis. If access via the paracentesis is not possible then a 30 gage needle can be used to enter the AC. This may be technically challenging with a flat or very shallow AC. It is more hazardous in a phakic eye and must be performed using an operating microscope. Always ensure ocular stability by holding the eye with fine-toothed forceps preferably at the 3 or 9 o’clock position. Insert the needle starting 0.5 mm from the limbus under peripheral conjunctiva with the bevel facing towards the surgeon. On entering the AC the needle tip will touch the iris. As it does so, rotate the syringe 458 so that the bevel enters the AC. Inject and reform the AC at this time. Be very careful not to penetrate the iris and damage the lens. Remember touching the iris can be painful for the patient hence the need for firm ocular stability. Be very careful not to damage the bleb area while performing this maneuver. Descemet’s membrane tear and detachment are possible complications of this procedure. This complication occurs if the needle is not fully in the AC before the viscoelastic is injected. A method to reduce this risk is by leaving some air in the needle (6). There is greater resistance to air injection if the needle is intracorneal and not intracameral. Take care; with a sufficient push, air can be injected into the cornea causing disruption to the lamellae producing a transient “shattered glass” appearance. This appearance, however, has minimal long-term consequences. In only reforming the AC, air, gas, or viscoelastic can be used; fast redistribution means that BSS will not alone maintain the AC. Any of these three may alter the hypotony-choroidal effusion vicious cycle; with a formed AC and increased IOP the choroidal effusions absorb. Longer lasting gases, such as sulfur hexafluoride (SF6) and perfluoropropane (C3F8), have been advocated (13,14). Air and gas do cause some endothelial cell loss and cataract in rabbits and humans (15,16); viscoelastics have a wider safety margin for corneal endothelium and the lens. Sodium hyaluronate (Healonw) does not maintain the AC for very long, usually only a day or so (Table 25.1) (17). The most appealing viscoelastic is Healonw5; this is cohesive in low shear situations and fractures into smaller fragments with higher flow rates (18,19). One of us (Trope G) finds air most useful in these cases. On injecting gas or air, if the patient is phakic, dilating the pupil may increase the lens – gas contact area and thus the potential for cataract formation (14). Cycloplegia, however, is an important part of the management. In some cases, gases may be successful where air and viscoelastics have failed (13). Usually an isovolumetric, nonexpansile mixture of air and gas is used (mixed with air so that the bubble does not increase in size), for example, 40 – 50% SF6 and 12– 15% C3F8. When these concentrations are used, the detrimental effect to corneal endothelium is equivalent to air alone. Success has been reported with 20– 40% SF6 with minimal effect on the lens and cornea (20). A recent report of two cases used a combination of 100% SF6 and Healon with success (21). If using air or viscoelastic, the AC should be fully inflated or hyper-inflated taking care not to raise the IOP excessively. If using gas in nonexpansile concentrations, the AC can be filled and the size of the bubble is limited by the size of the AC (0.2 mL) (14). However, caution must be exercised if higher concentrations are to be used; 100% [email protected]

[email protected]

Kind to lens and cornea Inexpensive Accessible Does not last long Will not work if used alone

Advantages

5 days

Kind to lens and corneal endothelium

Kind to lens and corneal endothelium Can cause transient IOP rise Does not last long

Lasts longer than air or SF6

Cataract 15% C3F8: same toxic effect as air on corneal endothelium

Cataract 50% SF6: same toxic effect as air on corneal endothelium

b

Can cause transient IOP rise Relatively new and few reports

OVDb

Viscoelastic A range of OVD are available ,3 days

Insoluble gas 12 – 15% is nonexpansile 12% lasts for up to 3 weeks

Healon 5

Insoluble gas 40 –50% is nonexpansile ,4 days for 20% 2 – 7 days for 40 – 50% An intermediate gas

Healon

C3F8a

SF6a

Percentages indicate the mixture of intraocular gas with air. OVD, ophthalmic viscosurgical device, includes classic viscoelastics such as Healon as well as newer substances such as Healon 5.

a

Disadvantages

,5 days

,1 day

Expected time in AC

Inexpensive Accessible Lasts longer than BSS Cataract Mildly toxic effect on corneal endothelium

Soluble gas —

Isotonic saline —

Air

Properties Variations

BSS

Table 25.1 Substances Used to Reinflate the Anterior Chamber

242 Lim, Goldberg, and Trope

Management of Flat ACs and Choroidal Effusions

243

C3F8 will quadruple in size over several days and could potentially cause very high IOP. The advantages and disadvantages of each substance are outlined in the Table 25.1.

5.2.

Drainage of Choroidal Effusions

The second operative option is draining the choroidal effusions via a sclerotomy. Draining the choroidal effusions and reforming the AC reverses both the pathologies present. It is mandatory if the choroidal detachments are “kissing,” if the effusions are touching the posterior surface of the lens, or when AC reformation alone fails to restore the AC and bleb function and there is a significant effusion present. Drainage of choroidal effusions should only be performed in an operating room. Often a corneal stay suture is not necessary. Reform the AC with BSS or viscoelastic through the operative paracentesis (or a newly created one). Make a circumferential infero-temporal and/or infero-nasal conjunctival incision 3 – 5 mm from the limbus. Create a 2 – 4 mm long horizontal sclerotomy with #11 Bard-Parker blade (or similar) centered 3.5 mm from the limbus over the pars plana [Fig. 25.2(a)]. Using diathermy if needed, gently cut down till the supra-choroidal space is entered. The sclerotomy can be extended to create two full thickness cuts meeting at an angle (in the shape of an “L” or “T”). A spatula can be introduced between the pars plana and sclera [Fig. 25.2(a)]. Drain supra-choroidal fluid and reform the AC with BSS or viscoelastic. Repeat this process until no further fluid can be drained. You can encourage more fluid drainage with gentle pressure on the globe with a cotton bud alongside the sclerotomy or by reforming the AC while lifting the lips of the sclerotomy [Fig. 25.2(b)]. Drainage can take time. To document a cyclodialysis cleft, dilute 2% fluorescein with BSS and inject it into the AC to see if it passes through the sclerotomy (22). As supra-choroidal fluid is light yellow in color, recognizing the fluorescein may be challenging. Suspect a cleft if the AC fails to remain formed. Examine the posterior segment with an indirect ophthalmoscope to document shrinkage of the effusions. Leave the sclerotomy open and close the conjunctiva with a Vicryl suture. Preferably use a viscoelastic to reform the AC at the end of the procedure. Choroidal effusion drainage is associated with a worse outcome for

Figure 25.2 Posterior sclerotomy: (From Maurice H Luntz and Raymond Harrison. Glaucoma Surgery, 2nd ed). (a) Scleral incision and introducing a flat spatula and (b) draining fluid. [email protected]

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visual acuity (6). Possible complications include infection, inflammation, and suprachoroidal hemorrhage (22). 5.3.

Scleral Flap Repair

This involves re-opening the drainage bleb. This is done in the operating room under topical or sub-Tenon’s anesthesia. The sutures are then removed from the conjunctival wound and the wound edges gently opened. Be prepared to deal with some bleeding but use cautery sparingly so as not to damage the conjunctiva. To repair the scleral flap, place 10/0 nylon sutures across the leaking areas. These are often found close to the limbus. If this is not possible (e.g., scleral thinning or dehiscence), a scleral patch graft may be necessary. Be prepared for this possibility. To close the conjunctiva effectively, resection of thin, ischemic leaking tissue may be necessary to close the defect. A conjunctival (advancement pedicle or sliding) flap or an autograft from the inferior conjunctiva or the other eye may be necessary. Suturing down the flap with AC reformation and choroidal drainage definitively raises the IOP and reverses the cycle of hypotony and choroidal effusion. However, because the conjunctiva is disturbed at the fistula site, there is a significant risk of bleb fibrosis and failure.

6.

CONCLUSIONS

The timing of surgical treatment for shallow or flat AC, with or without choroidal detachment, depends on early recognition and diagnosis of vision threatening or bleb threatening complications. Corneal decompensation, retinal adhesion, and fixed chorioretinal folds are likely causes of permanent vision loss. In addition, bleb function may be compromised by periods of hypotony. Milder degrees of choroidal effusion and shallow AC usually resolve with time and without surgical intervention. Among interventions, AC reformation yields the best visual and IOP outcomes for shallow or flat chambers and should be used as the first invasive step; air, viscoelastics, and gases can be used and choice of substance depends on surgeon preference and availability. If this fails, choroidal effusion drainage with or without scleral flap repair should be considered. REFERENCES 1. 2. 3. 4. 5. 6. 7. 8.

Edmunds B, Thompson JR, Salmon JF, Wormald RP. The National Survey of Trabeculectomy. III. Early and late complications. Eye 2002; 16:297–303. Stewart WC, Shields MB. Management of anterior chamber depth after trabeculectomy. Am J Ophthalmol 1988; 106:41 – 44. Berke SJ, Bellows AR, Shingleton BJ, Richter CU, Hutchinson BT. Chronic and recurrent choroidal detachment after glaucoma filtering surgery. Ophthalmology 1987; 94:154 – 162. Brubaker RF, Pederson JE. Ciliochoroidal detachment. Surv Ophthalmol 1983; 27:281 – 289. Fannin LA, Schiffman JC, Budenz DL. Risk factors for hypotony maculopathy. Ophthalmology 2003; 110:1185 – 1191. Spaeth GL, Katz LJ, Terebuh AK. Glaucoma surgery. In: Tasman W, Jaegar EA, eds. Duane’s Clinical Ophthalmology. Philadelphia: Lippincott Williams and Wilkins, 2000:1 – 62. Hung SO. Role of sodium hyaluronate (Healonid) in triangular flap trabeculectomy. Br J Ophthalmol 1985; 69:46 – 50. Simmons RJ, Kimbrough RL. Shell tamponade in filtering surgery for glaucoma. Ophthalmic Surg 1979; 10:17– 34. [email protected]

Management of Flat ACs and Choroidal Effusions 9. 10. 11.

12. 13. 14. 15. 16. 17. 18. 19. 20. 21.

22.

245

Rajeev B, Thomas R. Corneal hazards in use of Simmons shell. Aust NZ J Ophthalmol 1991; 19:145 – 148. Trope GE, Buys YM, Flanagan J, Wang L. Is a tight patch necessary after trabeculectomy? Br J Ophthalmol 1999; 83:1006 – 1007. Fiore PM, Richter CU, Arzeno G, Arrigg CA, Shingleton BJ, Bellows AR, Hutchinson BT. The effect of anterior chamber depth on endothelial cell count after filtration surgery. Arch Ophthalmol 1989; 107:1609 – 1611. Kim YY, Jung HR. The effect of flat anterior chamber on the success of trabeculectomy. Acta Ophthalmol Scand 1995; 73:268 – 272. Wilson MR, Yoshizumi MO, Lee DA, Martin W, Higginbotham EJ. Use of intraocular gas in flat anterior chamber after filtration surgery. Arch Ophthalmol 1988; 106:1345. Franks WA, Hitchings RA. Intraocular gas injection in the treatment of cornea – lens touch and choroidal effusion following fistulizing surgery. Ophthalmic Surg 1990; 21:831– 834. Lee DA, Wilson MR, Yoshizumi MO, Hall M. The ocular effects of gases when injected into the anterior chamber of rabbit eyes. Arch Ophthalmol 1991; 109:571– 575. Asamoto A, Yablonski ME. Post-trabeculectomy anterior subcapsular cataract formation induced by anterior chamber air. Ophthalmic Surg 1993; 24:314 – 319. Schipper I. Re-forming the flat anterior chamber with Healon. J Cataract Refract Surg 1996; 22:1002 – 1003. Hoffman RS, Fine IH, Packer M. Stabilization of flat anterior chamber after trabeculectomy with Healon5. J Cataract Refract Surg 2002; 28:712 – 714. Gutierrez-Ortiz C, Moreno-Lopez M. Healon5 as a treatment option for recurrent flat anterior chamber after trabeculectomy. J Cataract Refract Surg 2003; 29:635. Beigi B, O’Keefe M, Algawi K, Acheson R, Burke J. Sulphur hexafluoride in the treatment of flat anterior chamber following trabeculectomy. Eye 1997; 11(Pt 5):672 – 676. Geyer O, Segev E, Steinberg JM, Buckman G. Stabilization of post-trabeculectomy flat anterior chamber with Healon and sulfur hexafluoride. J Cataract Refract Surg 2003; 29:2026 – 2028. Bellows AR, Chylack LT Jr, Hutchinson BT. Choroidal detachment. Clinical manifestation, therapy and mechanism of formation. Ophthalmology 1981; 88:1107 – 1115.

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26 Hypotony Maculopathy Catherine M. Birt and Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada

1. Definition 2. Cause(s) 3. Diagnosis 4. Incidence 5. Risk Factors 6. Management 7. Prognosis Acknowledgment References

1.

247 248 248 249 249 249 251 251 251

DEFINITION

Hypotony maculopathy is a change in the structure of the retina and choroid as a result of lower than normal intraocular pressure (IOP). It is most often seen after filtration surgery. Hypotony is usually defined as an IOP of 6 mmHg for over 24 hours (1). Lower than normal IOP (“statistical” hypotony) is rarely significant if short term (2). However, prolonged hypotony can lead to structural changes in the retina, which may have an effect on the vision of the patient. This circumstance is called hypotony maculopathy, where the macula shows changes ranging from fine striae radiating out from the fovea to more definite choroidal folds, tortuous and engorged retinal blood vessels, and occasionally a swollen disc (3) (Fig. 26.1). However, there is no leakage from the vessels. Vision is usually impaired by these changes, although not all patients with hypotony will develop subsequent maculopathy and vision loss (4). The cause of vision loss is probably due to mechanical distortion of the photoreceptors due to the wrinkling and folding of the choroid and retina. With prolonged hypotony there may be permanent changes in the retinal pigment epithelium and neurosensory retina, leading to permanent visual loss (5). A further possibility, which may explain the fluctuating vision sometimes reported, is that hypotony may induce variable amounts of astigmatism as the lid closes over a soft globe (6,7). 247

[email protected]

248

Birt and Trope

Figure 26.1

2.

(See color insert) Fundus photograph detailing choroidal folds.

CAUSE(S)

The usual causes of hypotony are overfiltration, or a leaking filtration bleb in the postoperative period. Hypotony from aqueous shutdown is rare (2), although ciliary body toxicity from mitomycin C application has been reported (8). Other causes such as severe coughing, argon laser suture lysis, especially if a bleb leak was produced, or even argon laser trabeculoplasty have been reported (1,9 –14). The incidence of hypotony following argon laser suture lysis has been reported in 21% (12), but resolved with conservative management in 12 of the 13 patients affected. The authors noted a decreased risk of hypotony when the suture lysis was delayed after the surgery. The usual recommendation is to wait at least a week before performing argon laser suture lysis if antimetabolites, particularly mitomycin C, have been used in order to prevent hypotony in the early postoperative period (15,16). However, this is not always practical with lysis often performed from day 2 onwards (17). Another condition that may, rarely, predispose to hypotony maculopathy is pseudotumor cerebri. One report has suggested that an imbalance between low IOP following trabeculectomy and raised intracranial pressure may result in a translaminar pressure differential that results in optic disc swelling as well as macular changes (18). The underlying reason why some patients with hypotony develop maculopathy and others do not remains unclear, although it is suspected that varying degrees of scleral rigidity may contribute, with patients having less scleral rigidity being more predisposed to maculopathy. Similarly, the presence of a choroidal effusion has been reported to be associated with lower risk of macular changes (19).

3.

DIAGNOSIS

Hypotony maculopathy is diagnosed clinically and with the aid of intravenous fluorescein angiography. Gass (5) published an early description of hypotony maculopathy, and was the first to use the term, although he stated that it could more accurately be called “hypotony chorioretinopathy,” as the entire fundus is affected. Gass described choroidal folds radiating away from the fovea, most marked nasal to the optic disc, with overlying retinal folds (Fig. 26.2). There may be elevation of the optic disc margin. Findings seen [email protected]

Hypotony Maculopathy

249

Figure 26.2 Intravenous fluorescein angiogram—note choroidal folds with no leakage of dye from the vessels.

with fluorescein angiography include alternating bands of hyper and hypofluorescence due to the choroidal folding, and leakage from the optic nerve but not from retinal capillaries.

4.

INCIDENCE

The reported incidence of hypotony maculopathy after filtration surgery (as opposed to simple hypotony) varies, ranging from ,1% to as high as 25% (3,20 – 24). Major risk factors include younger age, myopia, and the use of intraoperative antimetabolites (20,25). Filtration surgery in younger myopes should always include consideration of the risks of hypotony maculopathy.

5.

RISK FACTORS

The risk of hypotony maculopathy is higher with mitomycin C than with 5-fluorouracil (23,26), but does not correlate with increased concentrations or exposure times (15,20). Other reported risk factors include high preoperative IOP, younger age, myopic refractive error, preoperative use of oral carbonic anhydrase inhibitors, and possibly a higher rate in white patients than in black (20,21,25,27,28). A large case–control study with over 200 cases showed significant risk factors to be young age, male gender, and myopia. The same report showed a protective effect from diabetes and the presence of choroidal effusions (19), whereas a smaller case–control study suggested that patients younger than 60 years of age were more likely to develop maculopathy with hypotony than were patients over 60 (6).

6.

MANAGEMENT

The best management is prevention. Surgeons should be careful to produce tight scleral closure, especially in young myopes in whom antimetabolites have been used. Meticulous [email protected]

250

Birt and Trope

closure of the conjunctival flap is also important. If hypotony maculopathy is diagnosed, therapy is best aimed at the underlying cause of the hypotony. Simple treatment of the IOP, such as with repeated filling of the anterior chamber with viscoelastics, is rarely sufficient (2). Hyung and Jung (24) recommend a stepwise approach, from medical management to blood injection to bleb and flap revision, finding a 79% success rate in 24 treated eyes with this approach. These more advanced management options are discussed subsequently. 1.

2.

3.

4.

5.

The bleb should be repaired if leaking, or revised if overfiltering (29). Repair of an overfiltering bleb has been shown to improve IOP in a good proportion of patients, in the range of 86% (30). The actual surgical techniques for management of the leaking or overfiltering bleb are covered in other chapters. Potential treatments other than full surgical repair have also been tried and successfully performed. Several authors have reported the use of subconjunctival intrableb or peribleb autologous blood injection (31). The usual technique is to withdraw 0.1–0.3 mL of whole blood from the antecubital vein, and slowly inject it either into the bleb itself or around it. The technique involves inserting the needle under the conjunctiva starting at least 3 mm from the edge of the bleb. A sterile 30-gage needle is advanced under the conjunctiva into the center of the bleb area and the bleb is filled with blood. Autologous blood can also be used with compression sutures over the bleb (32,33). A risk with introducing a large subconjunctival hemorrhage into the bleb site is the tracking of blood through the scleral flap and surgical ostomy into the anterior chamber (34,35). Corneal blood staining, hyphema, and vitreous hemorrhage have all been reported with the use of autologous blood injections (36,37). Injecting behind and around the bleb may decrease the risk of intracameral extension, and may be equally effective at introducing fibroblasts into the area (33,38). Variations of the technique include use of a Nd:YAG laser to induce subconjunctival bleeding by puncturing a subconjunctival blood vessel, and a case report included the introduction of intracameral viscoelastic prior to the laser, with resolution of hypotony (34,35). The laser settings reported were 1.8 mJ per pulse, and two pulses per burst. Success rates, in small reported series, are 50– 60% (38). Care must be taken to avoid rupturing a thin walled bleb, and, although intracameral viscoelastic injection prior to the laser application can increase the resistance to blood flow into the eye, it can also increase the IOP and the risk of corneal blood staining if blood enters. Cryotherapy, and both YAG and argon laser energy have been used to incite a bleb reaction and decrease filtration, rather than to induce bleeding. A reported technique described topical anesthetic and rose bengal instillation over the bleb after light epithelial debridement. The laser settings used were a 100 mm spot size for 0.3 s duration at a power of 600– 800 mW over two sessions to shrink the bleb. This technique successfully raised the IOP from zero to 10 mmHg in a case report (39). The technique for cryotherapy to the bleb involves five applications of the cryo probe at – 808C for 25 s each (3). Typically, 5 –6 cryo treatments are applied under topical anesthesia to the bleb periphery until the patient “feels” the treatment—about 10– 15 s at 2808C. We have successfully used this technique on a number of cases. For all of these techniques, complications include undertreatment, with lack of effect; over-treatment, with fibrosis and subsequent inadequate filtration; and inadvertent bleb perforation. [email protected]

Hypotony Maculopathy

6.

7.

7.

251

Other surgical options include cataract extraction (40). A report has shown that clear corneal phacoemulsification surgery resulted in increased IOP and increased vision in seven of nine eyes with hypotony maculopathy (41). However, before cataract surgery is considered we primarily recommend exploration and suture of the scleral flap after identifying the leaking area. The conjunctiva should be closed in two layers. If the scleral flap is too thin or friable for suture closure, then a donor scleral flap should be sutured over the thin leaking area using 10-0 nylon. If a scleral patch is used, a pressure spike with pain should be expected after a few days. This should initially be dealt with using medical therapy, but repeat filtration surgery without antifibroblastic therapy may be needed if the pressure returns to a level above target for that patient. We have on occasion sealed a friable scleral flap with donor sclera followed by immediate trabeculectomy without mitomycin C at a distant site to prevent the expected pressure spike.

PROGNOSIS

Visual loss may be irreversible, but outcomes with a return of vision following resolution of the hypotony as late as 6 months, or even 7 years have been reported (34,42). As a rule, however, treatment of hypotony within a few weeks, is recommended to either prevent the development of maculopathy, or allow its resolution with an excellent chance of retaining or restoring vision (24,27,43).

ACKNOWLEDGMENT We would like to acknowledge the generosity of Dr. Peter Kertes in supplying the color and fluorescein photographs used in this chapter.

REFERENCES 1. 2. 3. 4. 5. 6. 7. 8. 9.

Bardak Y, Cuypers MH, Tilanus MA, Eggink CA. Ocular hypotony after laser suture lysis following trabeculectomy with mitomycin C. Int Ophthalmol 1997; 21:325– 330. Pederson JE. Ocular hypotony. In: Ritch R, Shields MB, Krupin T, eds. The Glaucomas. 2nd ed. St Louis: Mosby, 1996; Chap. 18. Costa VP, Wilson RP, Moster MR et al. Hypotony maculopathy following the use of topical mitomycin C in glaucoma filtration surgery. Ophthalmic Surg 1993; 24:389 – 394. Kee C, Kaufman PL. Profound long-term hypotony without maculopathy after trabeculectomy with antimetabolite. Acta Ophthalmol (Copenh) 1994; 72:388 – 390. Gass JD. Hypotony maculopathy. In: Bellows JC, ed. Contemporary Ophthalmology, Honoring Sir Stewart Duke-Elder. Baltimore: Williams & Wilkins, 1972. Stamper RL, McMenemy MG, Lieberman MF. Hypotonous maculopathy after trabeculectomy with subconjunctival 5-fluorouracil. Am J Ophthalmol 1992; 114:544 – 553. Zacharia PT, Deppermann SR, Schuman JS. Ocular hypotony after trabeculectomy with mitomycin C. Am J Ophthalmol 1993; 116:314 –326. Nuyts RM, Felten PC, Pels E et al. Histopathologic effects of mitomycin C after trabeculectomy in human glaucomatous eyes with persistent hypotony. Am J Ophthalmol 1994; 118:225–237. Shaikh A, Ahmado A, James B. Severe cough: a cause of late bleb leak. J Glaucoma 2003; 12:181 – 183. [email protected]

252 10. 11. 12. 13. 14. 15.

16. 17. 18. 19. 20. 21. 22. 23. 24. 25. 26.

27. 28. 29. 30. 31. 32. 33. 34.

35.

Birt and Trope Keller C, To K. Bleb leak with hypotony after laser suture lysis and trabeculectomy with mitomycin C. Arch Ophthalmol 1993; 111:427 – 428. Kennedy CJ, Roden DM, McAllister IL. Suprachoroidal effusion following argon laser trabeculoplasty. Aust N Z J Ophthalmol 1996; 24:279 – 282. Morinelli EN, Sidoti PA, Heuer DK et al. Laser suture lysis after mitomycin C trabeculectomy. Ophthalmology 1996; 103:306– 314. Savage JA, Condon GP, Lytle RA, Simmons RJ. Laser suture lysis after trabeculectomy. Ophthalmology 1988; 95:1631– 1638. Schwartz AL, Weiss HS. Bleb leak with hypotony after laser suture lysis and trabeculectomy with mitomycin C. Arch Ophthalmol 1992; 110:1049. Shields MB, Scroggs MW, Sloop CM, Simmons RB. Clinical and histopathologic observations concerning hypotony after trabeculectomy with adjunctive mitomycin C. Am J Ophthalmol 1993; 116:673 – 683. Geijssen HC, Greve EL. Mitomycine, suterelysis and hypotony. Int Ophthalmol 1992; 16:371 – 374. Macken P, Buys Y, Trope G. Glaucoma laser suture lysis. Br J Ophthalmol 1996; 80:398 – 401. Faingold D, Francis CJ, Buys YM. Hypotony maculopathy and papilledema after trabeculectomy in a patient with pseudotumor cerebri. J Glaucoma 2003; 12:374– 378. Fannin LA, Schiffman JC, Budenz D. Risk factors for hypotony maculopathy. Ophthalmology 2003; 110:1185 – 1191. Bindlish R, Condon GP, Schlosser JD et al. Efficacy and safety of mitomycin-C in primary trabeculectomy: five-year follow-up. Ophthalmology 2002; 109:1336– 1341. Costa VP, Moster MR, Wilson RP et al. Effects of topical mitomycin C on primary trabeculectomies and combined procedures. Br J Ophthalmol 1993; 77:693 – 697. Perkins TW, Gangnon R, Ladd W et al. Trabeculectomy with mitomycin C: intermediate-term results. J Glaucoma 1998; 7:230– 236. Skuta GL, Beeson CC, Higginbotham EJ et al. Intraoperative mitomycin versus postoperative 5-fluorouracil in high-risk glaucoma filtering surgery. Ophthalmology 1992; 99:438– 444. Hyung SM, Jung MS. Management of hypotony after trabeculectomy with mitomycin C. Korean J Ophthalmol 2003; 17:114 – 121. Hong C, Hyung SM, Song KY et al. Effects of topical mitomycin C on glaucoma filtration surgery. Korean J Ophthalmol 1993; 7:1– 10. Kitazawa Y, Suemori-Matsushita H, Yamamoto T, Kawase K. Low-dose and high-dose mitomycin trabeculectomy as an initial surgery in primary open-angle glaucoma. Ophthalmology 1993; 100:1624 – 1628. Stamper R. Bilateral chronic hypotony following trabeculectomy with mitomycin-C. J Glaucoma 2001; 10:325 – 328. Suner IJ, Greenfield DS, Miller MP et al. Hypotony maculopathy after filtering surgery with mitomycin C. Incidence and treatment. Ophthalmology 1997; 104:207– 214. Schwartz GF, Robin AL, Wilson RP et al. Resuturing the scleral flap leads to resolution of hypotony maculopathy. J Glaucoma 1996; 5:246 –251. van de Geijn EJ, Lemij HG, de Vries J, de Waard PW. Surgical revision of filtration blebs: a follow-up study. J Glaucoma 2002; 11:300 –305. Wise JB. Treatment of chronic postfiltration hypotony by intrableb injection of autologous blood. Arch Ophthalmol 1993; 111:827 –830. Haynes WL, Alward WL. Combination of autologous blood injection and bleb compression sutures to treat hypotony maculopathy. J Glaucoma 1999; 8:384 – 387. Okada K, Tsukamoto H, Masumoto M et al. Autologous blood injection for marked overfiltration early after trabeculectomy with mitomycin C. Acta Ophthalmol Scand 2001; 79:305–308. Ascaso FJ, Loras E, Cristobal JA. Combination of Nd:Yag laser-induced subconjunctival bleeding and intracameral viscoelastic injection to treat hypotony maculopathy. Ophthalmic Surg Lasers 2002; 33:504– 507. Bettin P, Carassa RG, Fiori M, Brancato R. Treatment of hyperfiltering blebs with Nd:YAG laser-induced subconjunctival bleeding. J Glaucoma 1999; 8:380– 383.

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Hypotony Maculopathy 36.

37. 38. 39.

40. 41. 42. 43.

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Ayyala RS, Urban RC Jr, Krishnamurthy MS, Mendelblatt DJ. Corneal blood staining following autologous blood injection for hypotony maculopathy. Ophthalmic Surg Lasers 1997; 28:866 – 868. Flynn WJ, Rosen WJ, Campbell DG. Delayed hyphema and intravitreal blood following intrableb autologous blood injection after trabeculectomy. Am J Ophthalmol 1997; 124:115 – 116. Leen MM, Moster MR, Katz LJ et al. Management of overfiltering and leaking blebs with autologous blood injection. Arch Ophthalmol 1995; 113:1050– 1055. Akova YA, Dursun D, Aydin P et al. Management of hypotony maculopathy and a large filtering bleb after trabeculectomy with mitomycin C: success with argon laser therapy. Ophthalmic Surg Lasers 2000; 31:491– 494. Sibayan SAB, Igarashi S, Kasahara N et al. Cataract extraction as a means of treating postfiltration hypotony maculopathy. Ophthalmic Surg Lasers 1997; 28:241– 243. Doyle JW, Smith MF. Effect of phacoemulsification surgery on hypotony following trabeculectomy surgery. Arch Ophthalmol 2000; 118:763 – 765. Delagdo MF, Daniels S, Pascal S, Dickens CJ. Hypotony maculopathy: Improvement of visual acuity after 7 years. Am J Ophthalmol 2001; 132:931– 933. Schnyder CC, Shaarawy T, Ravinet E et al. Free conjunctival autologous graft for bleb repair and bleb reduction after trabeculectomy and nonpenetrating filtering surgery. J Glaucoma 2002; 11:10 – 16.

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D. Management of Bleb Infection

27 Blebitis and Bleb-Associated Endophthalmitis: Diagnosis and Treatment Fani Segev University Health Network and University of Toronto, Toronto, Ontario, Canada

Allan R. Slomovic and Graham E. Trope University of Toronto, Toronto Western Hospital, Toronto, Ontario, Canada

1. 2. 3. 4.

Definitions Risk Factors Incidence Diagnosis 4.1. Blebitis 4.2. Bleb-Associated Endophthalmitis 5. Microorganisms 6. Prognosis 6.1. Treatment 6.2. Prevention References

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Bleb-related infections are potentially catastrophic complications of filtration surgery. Early recognition and management are key to bleb survival and preservation of vision.

1.

DEFINITIONS

The two types of bleb-related infections are blebitis and bleb-associated endophthalmitis. Blebitis is a term used to describe an isolated bleb infection. This is characterized by varying degrees of localized conjunctival hyperemia, associated with a mucopurulent infiltrate identified within the bleb or within the peri-bleb area, giving the appearance of a “white on red” conjunctiva. Blebitis may be associated with mild to moderate inflammation of the anterior segment, but typically there is no vitritis. It has been suggested that blebitis may represent a prodromal event of endophthalmitis or a limited form of endophthalmitis (1). 255

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Bleb-associated endophthalmitis by definition refers to an infected bleb with associated intraocular infection. This is characterized by a hypopyon, a vitritis, and/or a positive vitreous culture. Bleb-associated endophthalmitis occurs early or late in the postoperative period. Acute endophthalmitis usually occurs within the first 2 weeks following surgery. Late-onset bleb-associated endophthalmitis, typically occurs months to years postoperatively.

2.

RISK FACTORS

The major risk factor for infection is a leaking bleb (2). Other risk factors include chronic bacterial blepharitis or conjunctivitis, keratitis sicca, the use of contaminated eye drops or bottle tips, and contact lens wear (2). In addition, inferiorily placed trabeculectomies carry an increased risk of bleb-associated endophthalmitis compared with superior blebs (3). Inferior blebs are poorly protected by the lower lid, and may be exposed to chronic mechanical irritation by the lid margin during blinking. This results in a more friable conjunctival epithelium over the bleb. In addition, these blebs are exposed to both the bacteria-rich inferior tear film meniscus and the bacterial flora of lower eyelid margin. Several authors have reported an increased risk of blebitis and bleb-associated endophthalmitis after filtering surgery with mitomycin C and 5-fluorouracil (3 –6). This is attributed to the fact that these blebs are more likely to be thin, avascular, and cystic. Several histopathological studies of blebs after trabeculectomy with mitomycin have demonstrated irregularities in the conjunctival epithelium, breaks in the basement membrane, conjunctival and subconjunctival hypocellularity (7 – 10). Each of these findings predispose towards a late-onset bleb leak. Trabeculectomies combined with adjunctive 5-fluorouracil have a higher incidence of bleb leaks, and trabeculectomies performed with mitomycin have an even higher rate of bleb leaks (11,12). Soltau et al. (13), reported that eyes with bleb-related infections are 26 times more likely to have a concomitant bleb leak, than eyes without bleb-related infections. Patients undergoing combined cataract surgery and trabeculectomy are less likely to develop bleb-related infections compared with patients who have a trabeculectomy procedure alone (14). This is due to the fact that the blebs in eyes following combined procedures tend to be thicker and therefore less susceptible to bleb leaks with secondary infection. The intermittent or chronic use of topical antibiotics, beyond the early postoperative period, is also associated with an increased risk of bleb-related infections (14). It is possible that the prolonged use of topical antibiotics may select for more virulent and antibiotic resistant bacteria. Other risk factors implicated as having a causal role in bleb-related infections include nasolacrimal duct obstruction, releasable sutures, dementia (poor hygiene), poor follow-up, the use of systemic corticosteroids, juvenile glaucoma, the use of epinephrine drops, bleb-needling, bleb remodeling, and trauma (14 –16). Early postoperative complications such as early wound leak, flat anterior chamber (AC), and suprachoroidal hemorrhage are associated with an increased incidence of late-onset bleb-related infections (14).

3.

INCIDENCE

The incidence of acute- and late-onset bleb-related infections ranges from 0.4% to 6.9%. In contrast, the reported incidence of acute postoperative endophthalmitis after other types [email protected]

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of intraocular surgery is significantly lower at 0.05% (17,18). Several studies have reported that the incidence of bleb-related infections ranges from 1.1% to 1.6% per year and it is postulated that this figure is increasing because of the increased use of adjuvant antifibrotic agents (3,4,12).

4.

DIAGNOSIS

It is very important to differentiate between blebitis, which is considered a “localized bleb infection” without involvement of intraocular contents, and the more serious blebassociated endophthalmitis. The treatment and prognosis for these two entities are different. 4.1.

Blebitis

Symptoms associated with blebitis include tearing, photophobia, ocular injection, foreign body sensation, and discharge. Patients present with a mucopurulent discharge and severe ciliary and conjunctival hyperemia. This is mostly localized around the infiltrated opalescent filtering bleb that has a milky-white appearance with loss of clarity (Fig. 27.1). Seidel test is often positive. Some patients with leaking blebs may have hypotony and even a shallow or flat AC. High intraocular pressure is also possible due to obstruction of the sclerostomy site with purulent debris. 4.2.

Bleb-Associated Endophthalmitis

Patients with bleb-associated endophthalmitis have a rapidly progressive deterioration in their clinical presentation, characterized by worsening pain, discharge, reduction of vision, marked hyperemia, and increasing AC reaction with or without a hypopyon. A positive Seidel test is common. In contrast to patients with blebitis, patients with bleb-associated endophthalmitis have vitreous involvement which may range from just a few vitreous cells detectable on slit lamp examination with a dilated pupil to frank intravitreal abscess formation obscuring visualization of the fundus. In cases of poor posterior pole visibility B-scan ultrasonography is a useful method to detect vitreous involvement.

Figure 27.1 vessels.

Avascular infiltrated opalescent filtering bleb surrounded by congested conjunctival

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MICROORGANISMS

Early-onset bleb-related infections (blebitis and bleb-associated endophthalmitis) are reported to have a similar spectrum of causative bacterial organisms as that of acuteonset endophthalmitis postcataract surgery. In blebitis (early and late), the most commonly cultured organisms are Staphylococcus epidermidis and Propriobacterium acnes, which are considered to be part of the normal flora of the ocular surface (1,19 – 21). Other studies have reported an increased association between blebitis and Staph. aureus (22). The diagnosis of blebitis should be established as soon as possible based on clinical presentation. The use of conjunctival cultures should be obtained if possible, before instituting appropriate antibiotic treatment (23). However, a positive bleb culture does not always differentiate a bleb infection from normal conjunctival colonization. Intraocular cultures from patients with blebitis are limited because these patients typically have a good response to topical and systemic antibiotic treatment, thereby obviating the need for further invasive diagnostic procedures. In early-onset bleb-associated endophthalmitis, the most commonly isolated organisms are Staph. epidermidis and P. acnes (1). Unlike early and late blebitis as well as early bleb-associated endophthalmitis, the most common organisms isolated from late-onset bleb-associated endophthalmitis, are Streptococcus species (accounting for 41– 57% of culture positive cases) and gram-negative organisms (23 –31%) such as Hemophilus influenzae, followed by staphylococcal species (1,4,19,24 –27). To explain this discrepancy in causative organisms between early- and late-onset bleb-associated endophthalmitis, it has been suggested that the perioperative introduction of normal host ocular flora is responsible for early-onset bleb-associated endophthalmitis. Late bleb-associated endophthalmitis is likely caused by transconjunctival migration of transiently present aggressive bacteria from the ocular surface. They gain access to the intraocular contents through thin walled and leaking blebs (1,24). It has also been suggested that patterns of causative organisms have changed over the past decade, with staphylococcal infections becoming more common (28). This may be due to the increased use of intraoperative mitomycin C that has led to more bleb leaks with infection caused by organisms that do not require transconjunctival migration. The relationship between conjunctival and intraocular cultures in late-onset blebassociated endophthalmitis is equivocal. Mandelbaum et al. reported that in the majority of cases (72%), the organism cultured from the intraocular contents (aqueous and vitreous) was different from the organism isolated from the ocular surface. They reported that direct swabbing of the bleb does not improve the ability to identify the intraocular organism. They recommended that cultures obtained from the bleb surface not to be used as a guide for the selection of appropriate antibiotic therapy in bleb-associated endophthalmitis (24). Several studies have shown that cultures obtained from the AC in patients with blebitis and bleb-associated endophthalmitis are often negative, both in aphakic eyes and in eyes that have undergone posterior capsulotomy (24,25). If the vitreous is clinically not involved, then vitreous cultures are not required. However, when the vitreous is involved with cells and/or infiltrates, it is the intraocular site with the highest yield for microbial isolation.

6.

PROGNOSIS

Early bleb-related infections tend to have a favorable prognosis with patients retaining relatively good visual acuity. This is attributable to the less virulent nature of these [email protected]

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organisms, and their high susceptibility to antibiotic therapy (1,19). In contrast, late-onset bleb-associated endophthalmitis tends to be caused by more virulent bacteria, (Streptococcus spp. and gram-negative bacteria such as H. influenzae) and is therefore often associated with a poor visual prognosis, occasionally culminating in evisceration or enucleation (1,24,27,29,30). A visual acuity of 20/400 or better is expected in 41% of eyes with bleb-associated endophthalmitis. This drops to 33% of eyes with streptococcal blebassociated endophthalmitis (1,3,24,26,29). 6.1.

Treatment

Unlike postcataract endophthalmitis, to date there has been no randomized controlled clinical trial conducted to establish recommended guidelines for the management of bleb-related infections. This is partly due to the fact that bleb-related infections represent a spectrum of disease from localized blebitis to endophthalmitis with different infecting organisms. Isolated blebitis, without an AC reaction, should be treated aggressively with intensive broad-spectrum topical antibiotics against the pathogens known to be associated with blebitis. Stains and culture results of conjunctival exudates, although equivocal, may help direct further antibiotic therapy (22,23,31). Reynolds et al. conducted a survey to investigate practice patterns in the management of isolated blebitis among members of the American Glaucoma Society (32). Treatment of blebitis varied among glaucoma subspecialists. Out of 319 physicians, 204 responded. Fifty-one percent (104/204) responded that they treat isolated blebitis with a topical fluoroquinolone alone as the primary empirical treatment. Another 23% use a topical fluoroquinolone in combination with one or two other topical antibiotics (half used a combination of an unfortified aminoglycoside or trimethoprim –polymixin combination or equivalent, and half used one or two fortified antibiotics). Twenty-one percent preferred a combination of fortified topical antibiotics as initial treatment (half of these used fortified cephalosporins with a fortified aminoglycoside, and half used fortified vancomycin in some combination with another topical agent). Subconjunctival and oral antibiotics were used infrequently (32). Fourth generation fluoroquinolones such as moxifloxacin, gatifloxacin, grepafloxacin, and trovafloxacin are now available for topical and/or systemic treatment. Their spectrum of activity covers many of the gram-positive and gram-negative pathogens, including bacteria most frequently implicated in blebitis and bleb-associated endophthalmitis (Staph. epidermidis, Staph. aureus, Streptococcus pneumonia, Strep. pyogenes, H. influenzae ). In addition, they have excellent activity against atypical pathogens such as Mycoplasma, Chlamydia species, and anaerobic microorganisms such as P. acnes (33,34). This generation of fluoroquinolones, achieves high intravitreal concentration well above the MIC90 for the specific microorganisms frequently implicated in blebrelated infections, is well tolerated and is reported to achieve excellent bioavailability with oral administration (33,34). Moreover, the intraocular penetration of these antibiotics is higher in eyes that are infected or inflamed (35). As blebitis may be a precursor to endophthalmitis, aggressive antibiotic treatment at this early stage of the infection is recommended to prevent progression to endophthalmitis (1,21). At least three studies have suggested that oral antibiotics might be effective in preventing the progression of blebitis to bleb-associated endophthalmitis (1,21,26). With the lack of specific evidence-based guidelines, most clinicians (80%) treat blebitis as a precursor of endophthalmitis (32). Our recommendation for the treatment of isolated blebitis without an AC reaction is the use of the newer topical 4th generation fluoroquinolones such as 0.5% moxifloxacin [email protected]

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or 0.3% gatifloxacin (if not available 0.5% levofloxacin 3rd generation fluoroquinolone can be used) every 15 min for the first hour and then hourly around the clock until clinical improvement is seen. Alternately, fortified cefazolin (50 mg/mL) or vancomycin (25 –50 mg/mL) and fortified tobramycin (14 mg/mL) or gentamycin (14 mg/mL) alternating every 2 h can be used (Table 27.1). The patient’s clinical status, especially symptoms of increasing pain or decreasing vision needs to be monitored very carefully over the first 24 h. Oral antibiotics may not be necessary as bactericidal concentrations are obtained with intensive topical therapy (36). Admission to hospital may not be necessary if the patient is compliant with drops and can be seen daily. In more advanced cases of blebitis, where there is a mild-to-moderate AC reaction, the patient should be treated with intensive topical antibiotic drops around the clock, as described earlier. We recommend the addition of a systemic 4th generation fluoroquinolone, for example, oral gatifloxacin or moxifloxacin 400 mg twice a day as a loading dose for the first day followed by 400 mg daily thereafter (if not available, other fluoroquinolone can be used) (37 –39). When a 4th generation fluoroquinolone is not available, intravenous vancomycin (1 g twice daily) combined with intravenous ceftazidime (1 – 2 g every 8 h) merits consideration, despite the endophthalmitis vitrectomy study (EVS)

Table 27.1 Symptoms Red eye Irritation Foreign body sensation Discharge, tearing Photophobia Pain

Blebitis Signs

Investigation

Treatment

Mucopurulent discharge Localized severe conjunctival hyperemia Bleb infiltrate in a cystic bleb +Bleb leak (Seidel positive) +Conjunctival epithelial defect

Conjunctival stains and cultures

(A) Isolated blebitis (no AC reaction): † Topical antibiotic drops – 4th generation fluoroquinolone (0.5% moxifloxacin, 0.3% gatifloxacin): 1 drop every 15 min in first hour, then q1h around the clock or – Fort. cephazoline (50 mg/mL) or vancomycin (25 –50 mg/mL) and tobramycin or gentamycin (14 mg/mL). A drop of each q15 min in first hour, then alternate drops q2h † Topical steroids—only after infection has been eradicated (B) Advanced blebitis (with mild to moderate AC reaction): † Topical antibiotic drops (as earlier) † Topical steroids—only after leak and infection has been eradicated † Systemic antibiotic – 4th generation fluoroquinolone (oral 0.5% moxifloxacin, 0.3% gatifloxacin): 400 mg P.O. bid as a loading dose-first day, than 400 mg P.O. qd until the infection is controlled or – IV vancomycin (1 g) bid and ceftazidime (1– 2 g) tid

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finding that adding systemic antibiotic treatment (intravenous amikacin and ceftazidime) to intravitreal antibiotic injections for postcataract endophthalmitis did not improve outcomes when compared with using intravitreal injections alone. This was attributable to the very poor intravitreal penetration of amikacin (1,21,40– 42). Vancomycin penetrates the blood-ocular barrier and was not tested in the EVS. Furthermore, ceftazidime provides good coverage for gram-negative organisms that were found to be infrequent in the EVS, but are more prevalent in late-onset bleb-associated endophthalmitis (42 – 44). Hospital admission is advisable. Patients where the ocular inflammation progresses, despite the earlier measures, or patients who present initially with blebitis associated with severe AC reaction (i.e., heavy cellular reaction with fibrin) hypopyon and/or vitreous cells should be treated as blebrelated endophthalmitis. Bleb-related endophthalmitis should be treated in a manner similar to acute postoperative endophthalmitis (40). If on presentation, the visual acuity is better than light perception, this is managed by performing a vitreous tap for cultures and stains and simultaneous intravitreal injection of vancomycin (1.0 mg/0.1 mL) and ceftazidime (2.25 mg/0.1 mL) or amikacin (400 mg/0.1 mL). In addition, the patient should be started on topical fortified antibiotic drops on an hourly or half hourly basis [e.g., vancomycin (25 –50 mg/mL) or cefazolin (50 mg/mL) combined with an aminoglycoside e.g., tobramycin (14 mg/mL)] (Table 27.2). Patients with vision of light perception or less at the time of diagnosis should have an immediate pars plana vitrectomy, as visualization permits, with injection of intravitreal fortified antibiotics (27). The use of concomitant topical or intravitreal corticosteroids is controversial. Currently, there is no evidence-based support in the literature which demonstrates their effectiveness in this setting. It is believed that their beneficial effect is to reduce the inflammatory component and the resultant destructive damage to ocular tissue. If the use of topical steroids is considered to reduce inflammation in the bleb, it should be started only after the leak and infection have been treated (36). If intravitreal corticosteroids are given, dexamethasone (400 mg/0.1 mL) is administered (36).

Table 27.2

Bleb-Associated Endophthalmitis

Symptoms Rapidly progressive presentation Red eye Visual loss Ocular pain Discharge Photophobia

Signs

Investigation

Treatment

Mucopurulent discharge Localized severe conjunctival hyperemia Bleb infiltrate in a cystic bleb +Bleb leak (Seidel positive) +Conjunctival epithelial defect Moderate to severe AC reaction (+hypopyon, fibrin) Vitreous cells and infiltrates

Stains and cultures from vitreous and aqueous

Vitreous tap/pars plana vitrectomy (visual acuity dependent) Broad-spectrum topical fortified antibiotic drops every half an hour to hourly (as described earlier for blebitis) Systemic antibiotics (same as for advanced blebitis earlier) Intravitreal antibiotics: vancomycin (1.0 mg/0.1 mL) and ceftazidime (2.25 mg/ 0.1 mL) or amikacin (400 mg/0.1 mL) If intravitreal corticosteroids are given: dexamethasone (400 mg/0.1 mL)

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6.2.

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Prevention

In light of the potentially devastating results associated with bleb-related endophthalmitis, it is advisable that patients who have undergone trabeculectomy, with or without antifibrotic agents, should be educated by their ophthalmologists to contact them immediately should they notice the onset of the following symptoms: redness, irritation, photophobia, discharge, or reduced vision. Excessive watering from the eye should be evaluated for a bleb leak. Such leaks should be surgically repaired, if conservative measures fail. Physicians should avoid prescribing prophylactic topical antibiotics for chronic postoperative use (9,14). The chronic prophylactic and subtherapeutic use of antibiotics (especially the fluoroquinolone family) can lead to an increase in antibiotic resistance and the selection of more virulent strains of bacterial and/or fungal infection. REFERENCES 1. 2. 3.

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Index

Acetazolamide adverse effects, 19 Acute angle closure, 105 Adrenaline failing bleb, 172 Advanced Glaucoma Intervention Study (AGIS), 4 Age failing bleb, 163 filtering surgery, 9 Ahmed glaucoma valve, 83– 91 Ahmed glaucoma valve plate placement, 85 Ahmed glaucoma valve with Pars Plana Clip, 84– 85 Ahmed implant, 64, 66 Ahmed valve ultrasound biomicroscopy, 126 Akinesia, 23 Alcaine-proparacaine hydrochloride, 102 Alfentanyl, 20 Amaurosis, 23 Amethocaine, 188 Anesthesia general filtering surgery, 19– 20 local care, 20– 21 filtering surgery, 20– 27 MAC, 20– 21 maximum doses, 24 retrobulbar, 22– 24 subconjunctival/sub-Tenon’s, 24– 26 topical, 26– 27

Angle closure failing bleb, 164 Angle closure glaucoma peripheral iridectomy, 102 –104 complications, 105 incision suturing, 104 iris return to anterior chamber, 104 results, 105 recurrence, 105 surgery, 101 – 105 Anterior chamber (AC) see also shallow/flat anterior chamber assessment, 237 formed high IOL, 135 – 137 low IOL, 137 IOL, 125 shallow with choroidal effusions treatment, 239 glaucoma implant, 77 – 79 glaucoma surgery differential diagnosis, 226 glaucoma suture lysis, 147 intraoperative prevention, 238 – 240 management, 235 – 244 with ocular massage, 142 Anterior lip sclerectomy full-thickness filtering glaucoma surgery, 99 Antibiotics trabeculectomy, 49 Antifibrotic agents wound healing, 32 Antimetabolite complications, 34 265

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Index

Antimetabolite intraoperative application, 35– 40 conjunctival clamp, 38 conjunctival closure, 39– 40 duration and washout, 39 incision/dissection, 35– 37 scleral flap, 38 scleral flap sutures, 39 sponge, 37– 38 Antimetabolite postoperative application, 40– 42 Anti-scarring agents applied directly to bleb site, 36 Anti-scarring regimen, 35 Aphakia failing bleb, 163 Apraclonidine, 188 Aqueous leaks external glaucoma suture lysis, 147 Aqueous misdirection, 137, 200 Atropine, 208 Autologous conjunctival graft leaking bleb, 221– 223 Avascular bleb, 229 Avascular filtering bleb, 257

Baerveldt implant, 64, 66, 84 Balanced salt solution (BSS), 64, 70 Beta-radiation applied directly to bleb site, 36 Bleb anti-scarring agents applied directly to, 36 assessment, 237 associated endophthalmitis, 255– 262 defined, 256 diagnosis, 257–258 prevention, 262 avascular, 229 avascular filtering, 257 cystic, 233 diffuse, 228– 229 treatment, 233 diffuse noncystic mitomycin-C (MMC), 41 digital pressure, 140, 142 dysmorphic, 226, 229– 230 elevated, 227– 228 compression sutures, 231– 233 mechanical ptosis, 228

nasal conjunctiva, 228 remodeling with compression sutures, 231 – 233 treatment, 230 – 233 encapsulation, 179 – 184 failing bleb, 169 needling, 183, 184 Tenon’s cysts, 183 failure corkscrew vessels, 166 – 168 preoperative risk factors, 162 – 164 signs, 171 fibrosis bleb failure, 166 –170 filtration, 137, 226 avascular, 257 ideal, 226 reflective, 122 remodeling, 225 – 234 ultrasound biomicroscopy, 126 focal cystic mitomycin-C (MMC), 37 height, 169 leaking, 169 – 170, 217 – 223 autologous conjunctival graft, 221 –223 natural history, 161 – 162 overlying functioning conjunctival microcysts, 170 reflective filtering, 122 survival needling, 191 sweating, 167 types, 226 – 230 vascularity, 166 – 168 wall thickness, 169 Blebitis, 255 – 262 defined, 255 – 256 diagnosis, 257 incidence, 256 – 257 microorganisms, 258 prognosis, 258 – 259 risk factors, 256 treatment, 259 – 261 Bleeding glaucoma implant, 77 Blocked tube glaucoma implant, 78 Bupivacaine, 21, 22 Buschmann’s echographic study, 201 Button hole glaucoma implant, 76

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Index

267

Carboxyfluorescein wound healing, 33 Cataract and glaucoma surgery combined, 107– 116 Cataract surgery failing bleb, 163 Chandler’s technique malignant glaucoma, 211 Chlorprocaine, 21, 22 Choroidal effusions assessment, 237 drainage, 243– 244 management, 235–244 Ciliary block glaucoma, 200 Ciliary processes, 124 Ciliolenticular block theory, 201 Cohen method releasable sutures, 154 Colchicine failing bleb, 172 Collaborative Initial Glaucoma Treatment Study (CIGTS), 5, 7, 8 Collaborative Normal Tension Glaucoma Study (CNTGS), 4 Combined cataract and glaucoma surgery, 107– 116 complications, 115– 116 contraindications, 107– 108 indications, 107– 108 informed consent, 108 one-site phacotrabeculectomy, 109– 113 patient information, 107– 108 postoperative care, 114 techniques, 109– 113 two-site phacotrabeculectomy technique, 113– 114 Combined surgery failing bleb, 164– 165 Compression sutures elevated bleb, 231– 233 Congenital glaucoma nonpenetrating glaucoma surgery, 53 Conjunctiva glaucoma implant, 71 surgical limbus, 13 Conjunctival (button hole) glaucoma implant, 76 Conjunctival advancement leaking bleb, 220 Conjunctival clamp antimetabolites intraoperative application, 38

Conjunctival closure antimetabolites intraoperative application, 39 – 40 Conjunctival flap full-thickness filtering glaucoma surgery, 95, 98 suturing trabeculectomy, 49 trabeculectomy, 46 Conjunctival incision glaucoma implant, 64 Conjunctival microcysts overlying functioning bleb, 170 Conjunctival pedicle flap leaking bleb, 221 Conjunctival perforation glaucoma suture lysis, 147 Conjunctival repair leaking bleb, 220 Conjunctival scarring filtering surgery, 9 Conjunctival sutures buried knots, 113 Conjunctival transparency failing bleb, 169 Conjunctival wound leak combined cataract and glaucoma surgery, 116 Conjunctival wound position failing bleb, 164 Corkscrew vessels bleb failure, 167 – 169 Corneal decompensation glaucoma implant, 80 Corneal-scleral trephining full-thickness filtering glaucoma surgery, 98 – 99 Corticosteroids failing bleb, 171 Crescent blade peritomy, 110 Cyclodialysis cleft ultrasound biomicroscopy, 128 Cystic bleb, 233 Cystic macular edema (CME) combined cataract and glaucoma surgery, 116 Deep sclerectomy with collagen implant, 125 nonpenetrating glaucoma surgery, 54– 57 Descemet’s membrane detachment nonpenetrating glaucoma surgery, 60 DeWecker scissors, 103, 112

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268

Index

Dexamethasone failing bleb, 171 Diabetes failing bleb, 164 Diclofenac failing bleb, 172 Diffuse bleb, 228–229 noncystic mitomycin-C (MMC), 41 treatment, 233 Diplopia glaucoma implant, 80 Direct lens block angle closure, 200 Diurnal variations filtering surgery, 7 –8 Double plate Molteno implant insertion, 72 Dry eye filtering surgery, 9 Dysmorphic bleb, 226, 229– 230 Elevated bleb, 227– 228 mechanical ptosis, 228 nasal conjunctiva, 228 remodeling with compression sutures, 231– 233 treatment, 230– 233 Encapsulated bleb, 179– 184 complications, 183–184 histology, 180 incidence, 181– 182 needling, 183, 184 pathophysiology, 180– 181 risk factors, 181– 182 signs and symptoms, 180 slit lamp photography, 180 surgery, 183 Tenon’s cysts, 183 treatment, 182– 183 Endophthalmitis combined cataract and glaucoma surgery, 116 Epinephrine adverse effects, 19 Etidocaine, 21, 22 Exfoliative glaucoma nonpenetrating glaucoma surgery, 53 Express glaucoma shunt glaucoma implant, 72– 73 External aqueous leaks glaucoma suture lysis, 147 Extraocular rectus muscle, 15 Eyedrops topical anesthesia, 27

Failing bleb, 160 – 173 intervening, 171 –172, 173 late, 170 risk factors perioperative, 164 – 165 postoperative, 165 –170 Fellow eye malignant glaucoma, 212 – 213 Fentanyl, 20 Filter blood in, 125 Filtration bleb, 137, 226 remodeling, 225 –234 ultrasound biomicroscopy, 126 Filtration surgery, 3– 11 anesthesia, 17 – 28 evolution, 18 diurnal variations, 7– 8 early postoperative complications, 135 – 138 early surgery, 8 5-FU, 10 general anesthesia, 19 – 20 indications, 3 – 8 lifestyle, 6 – 7 local anesthesia, 20 – 27 planning, 15 preoperative evaluation, 9 preoperative filtration, 18 – 19 prognosis, 196 progression risk factors, 5 – 6 quality of life, 6 – 7 suprachoroidal hemorrhage, 193 – 196 clinical picture, 194 diagnosis, 194 predisposing factors, 193 – 194 prevention, 194 – 195 surgical limbus, 13 – 15 surgical outcomes, 9 – 10 target pressures, 3 – 5 treatment, 195 – 196 ultrasound biomicroscopy, 121 – 122 Fistula and iridectomy full-thickness filtering glaucoma surgery, 95 – 96 Flaps failing bleb, 172 Flat anterior chamber see shallow/ flat anterior chamber Fluoroquinolone blebitis, 259 5-Fluorouracil (5-FU) applied directly to bleb site, 36

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Index

269

failing bleb, 172, 173 injected through viscoelastic wall, 41 needling, 189 postoperative injection, 40–43 wound healing, 32 Fluorouracil Filtering Surgery Study (FFSS), 10, 162–163, 172 Focal cystic bleb mitomycin-C (MMC), 37 Formed anterior chamber high IOL, 135– 137 low IOL, 137 Fornix dissection, 37 Full-thickness filtering glaucoma surgery, 93– 99 closure, 97– 99 sclerectomy, 99 subscleral Scheie procedure, 94 subscleral trephine, 99 technique, 94– 97, 98– 99

Gatifloxacin blebitis, 259 General anesthesia filtering surgery, 19– 20 General health status filtering surgery, 9 Glaucoma see also primary open angle glaucoma (POAG) ciliary block, 200 congenital, 53 exfoliative, 53 malignant, 199– 213 neovascular, 53 failing bleb, 164 pigmentary, 53 surgical anatomy, 13– 15 Glaucoma drainage implant (GDI) surgery, 83, 84 pars plana results and complications, 90– 91 Glaucoma implant, 63– 73 anesthesia, 64 complications intraoperative complications, 76– 77 management, 75– 81 conjunctival incision, 64 drainage failure, 79 express glaucoma shunt, 72– 73 flat anterior chamber, 77– 79 late postoperative complications, 79– 81 patch graft, 66– 72 plate attachment, 64– 65

technique, 64 – 77 tube preparation, 66– 72 valve priming, 66 Glaucoma medication compliance, 6 failing bleb, 163 – 164 Glaucoma shunt glaucoma implant, 72 –73 Glaucoma surgery see also nonpenetrating glaucoma surgery (NPGS) anatomy, 13 – 15 angle closure, 101 – 105 combined with cataract surgery, 107 – 116 full-thickness filtering, 93 – 99 low IOP and shallow AC differential diagnosis, 226 postoperative management needling, 187 –191 ultrasound biomicroscopy, 119 – 129 Glaucoma suture lysis, 145 –148 complications, 147 – 148 external aqueous leaks, 147 indications, 145 laser settings, 147 outcome, 147 timing, 145 – 146 Goniopuncture Nd:YAG after nonpenetrating glaucoma surgery, 57 – 58 Grepafloxacin blebitis, 259 Grieshaber hooks, 111 Haemophilus influenzae blebitis, 258 Harms forceps glaucoma implant, 64, 65 High IOL anterior chamber, 135 – 137 High myopia nonpenetrating glaucoma surgery, 52 – 53 Hoskin forceps, 103 Hydrodissection combined cataract and glaucoma surgery, 115 Hyoscine (scopolamine), 208 Hypertensive phase glaucoma implant, 78 Hyphema glaucoma suture lysis, 148

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270

Index Johnstone’s technique, 155, 156

Hypotony glaucoma suture lysis, 147 nonpenetrating glaucoma surgery, 59 Hypotony maculopathy, 247–251 causes, 248 defined, 247 diagnosis, 248– 249 incidence, 249 prognosis, 251 risk factors, 249 treatment, 249– 251

Kolker’s modification, 155 Krupin implant, 64 Kuglin hooks, 111

Ideal filtration bleb, 226 Implant insertion see specific type Indiana Bleb Appearance Grading Scale, 166, 167 Inflammation nonpenetrating glaucoma surgery, 59 Informed consent combined cataract and glaucoma surgery, 107– 108 Infusion port pars plana vitrectomy, 86 Intraocular inflammation assessment, 237 Intraocular pressure (IOP), 4, 94 assessment, 237 low glaucoma surgery differential diagnosis, 226 nonpenetrating glaucoma surgery, 59 postoperative increase, 59 Intraoperative antimetabolites application technique, 35– 42 Intrascleral obstruction failing bleb, 165– 166 Intravenous medications, 20 adverse effects, 21 Iridectomy full-thickness filtering glaucoma surgery, 95– 96 peripheral, 105, 112 angle closure glaucoma, 102– 104 trabeculectomy, 48 Iridocorneal endothelial (ICE) syndrome, 84 Iris incarcerations glaucoma suture lysis, 148 with ocular massage, 142 Iritis glaucoma implant, 78– 79

Laser treatment Nd:YAG malignant glaucoma, 208 –209 Leaking bleb defined, 218 early, 218 incisional repair, 220 – 221 late, 218 – 219 nonincisional correction, 219 observation, 219 treatment, 217 – 223 Lens zonules malignant glaucoma, 202 Lidocaine (xylocaine), 21, 22, 26 – 27 Lifestyle filtering surgery, 6 –7 Local anesthesia filtering surgery, 20 – 27 MAC, 20 –21 maximum doses, 24 Malignant glaucoma, 199 – 213 aqueous humor misdirection, 201 –202 Chandler’s technique, 211 clinical diagnosis, 200 – 201 differential diagnosis, 204 –205 fellow eye, 212 – 213 glaucoma suture lysis, 148 laser treatment, 208 – 209 lens zonules, 202 management, 205 –213 pars plana vitrectomy, 209 – 210 pars plana vitrectomy success rate, 209 pathophysiology, 201 – 202 positive pressure phenomenon, 202 –204 pupillary block, 205 risk factors, 206 sequence of events, 203 suprachoroidal hemorrhage, 204 – 205 surgery, 209 – 210 terminology, 200 treatment, 206 – 208, 207 ultrasound biomicroscopy, 127 – 129 Marfan’s syndrome, 20 Massage, 139 – 143 complications, 142 –143 indications, 139 – 140 mechanism, 140 –141

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Index outcome, 143 patient technique, 142 surgeon technique, 141 technique, 140– 141 Mechanical ptosis elevated bleb, 228 Mepivacaine, 22 Microcysts failing bleb, 170 Migdal method releasable sutures, 153 Mitomycin-C (MMC) applied directly to bleb site, 36 diffuse noncystic bleb, 41 failing bleb, 162 focal cystic bleb, 37 wound healing, 32 Molteno implant, 64, 66, 84 double plate insertion, 72 Monitored anesthesia care (MAC) local anesthesia, 20– 21 Moorfields Safe Surgery System, 31– 42 antifibrotic agents, 32 application technique, 35– 42 Moxifloxacin blebitis, 259 Nasal conjunctiva elevated bleb, 228 Needles glaucoma implant, 65, 69 Needling adjunctive antimetabolite, 189 bleb survival, 191 complications, 190 encapsulated bleb, 183, 184 5-FU, 189 glaucoma surgery postoperative management, 187– 191 interval between surgery, 189 potential risk factors, 190 repeated, 189 take home message, 190– 191 technique, 188– 189 Neodymium:YAG goniopuncture after nonpenetrating glaucoma surgery, 57– 58 laser treatment malignant glaucoma, 208–209 Neovascular glaucoma failing bleb, 164 nonpenetrating glaucoma surgery, 53

271 Nonpenetrating glaucoma surgery (NPGS), 51 – 60 complications, 58 –60 contraindications, 53 indications, 52 – 53 Nd:YAG goniopuncture after, 57 – 58 open angle glaucoma, 52 pigmentary glaucoma, 53 results, 60 technique, 54 – 57 Nuclear cracking phacoemulsification, 111 Nuclear phacoemulsification combined cataract and glaucoma surgery, 115 Ocular explosion, 23 Ocular Hypertension Treatment Study (OSTS), 4 Ofloxacine, 188 Open angle glaucoma nonpenetrating glaucoma surgery, 52 Osher method releasable sutures, 154 Ostium hemorrhage with ocular massage, 142 Over filtration, 125 – 127 Paracentesis full-thickness filtering glaucoma surgery, 95 glaucoma implant, 69 trabeculectomy, 48 Pars Plana GDI complications, 90, 91 Pars Plana insertion, 83 –91 indications, 84 technique, 84 – 90 Pars Plana tube closure, 88 – 90 placement, 87 – 88 Pars Plana Vitrectomy (PPV), 86 – 87 malignant glaucoma, 209 – 210 success rate malignant glaucoma, 209 Patch trabeculectomy, 49 Patient information combined cataract and glaucoma surgery, 107 – 108 Penetrating ocular injuries wound healing, 160 – 161 Pericardium glaucoma implant, 67, 71

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272

Index

Peripheral anterior synechia nonpenetrating glaucoma surgery, 60 Peripheral iridectomy, 105, 112 angle closure glaucoma, 102– 104 trabeculectomy, 48 Peritomy crescent blade, 110 Phacoemulsification nuclear cracking, 111 Phacotrabeculectomy, 108 two-site technique combined cataract and glaucoma surgery, 113– 114 Phenylephrine, 188 Pigmentary glaucoma nonpenetrating glaucoma surgery, 53 Plate erosion glaucoma implant, 79– 80 Positive pressure phenomenon malignant glaucoma, 202– 204 Posterior lip sclerectomy full-thickness filtering glaucoma surgery, 99 Posterior sclerotomy, 243 Postoperative drops trabeculectomy, 49 Prednisolone failing bleb, 172 Procaine, 21, 22 Propofol, 20 Proprionibacterium acnes blebitis, 258 Pseudoexfoliation combined cataract and glaucoma surgery, 115 Pupil block, 137 Pupillary block malignant glaucoma, 205 Quality of life filtering surgery, 6 –7 Race failing bleb, 164 Radiation applied directly to bleb site, 36 Reflective filtering bleb, 122 Releasable sutures, 151– 157 with buried ends, 153– 154 Cohen method, 154 complications, 156–157 indications, 151

Migdal method, 153 Osher method, 154 techniques, 152 – 153 Releasable U-suture, 152 – 153 Remifentanyl, 20 Retinal detachment combined cataract and glaucoma surgery, 116 Retinal vascular occlusion, 23 Retrobulbar anesthesia, 22 – 24 complications, 23 –24 technique, 22 – 23 Retrobulbar hemorrhage, 23 Rootman technique, 152 Ropivacaine, 21, 22 Scarring risk factors, 34 Scheie procedure subscleral, 94 Schlemm’s canal, 55 Schocket GDI, 84 Scleral ectasia nonpenetrating glaucoma surgery, 60 Scleral flap antimetabolite intraoperative application, 37 – 38 closure trabeculectomy, 48 – 49 formation, 110 full-thickness filtering glaucoma surgery, 95, 98 repair, 244 sutures antimetabolites intraoperative application, 39 Scleral perforation, 23 Sclerectomy with collagen implant, 124 nonpenetrating glaucoma surgery, 54 – 57 Scopolamine, 208 Shallow/flat anterior chamber with choroidal effusions assessment, 236 – 238 treatment, 239 without leak, 239 –243 glaucoma implant, 77– 79 high IOL, 137 intraoperative prevention, 238 – 240 low IOL, 137 – 138 management, 235 –244 reforming, 240 – 243

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Index reinflating, 242 surgery, 240 Silicone tube glaucoma implant, 70 Skin color failing bleb, 164 Slit-lamp needle procedure malignant glaucoma after trabeculectomy in pseudophakic eye, 211– 212 Staphylococcus aureus blebitis, 258 Staphylococcus epidermidis blebitis, 258 Steroids trabeculectomy, 49 Streptococcus blebitis, 258 Subconjunctival/sub-Tenon’s anesthesia, 24– 26 complications, 25–26 technique, 25 Subscleral Scheie procedure, 94 Subscleral trephine full-thickness filtering glaucoma surgery, 97– 98 Sufentanyl, 20 Superonasal port pars plana vitrectomy, 87 Superotemporal port pars plana vitrectomy, 87 Suprachoroidal hemorrhage, 137 filtering surgery, 193– 196 malignant glaucoma, 204– 205 Supraciliary effusions, 127 Suramin wound healing, 32 Surgery. see also specific type combined failing bleb, 164– 165 Surgical iridectomy, 101– 105 Surgical limbus conjunctiva, 13 filtering surgery, 13– 15 Tenon’s Fascia, 13 Sutures compression elevated bleb, 231– 233 conjunctival buried knots, 113 glaucoma implant, 66 glaucoma suture lysis, 145– 148 releasable, 151– 157 releasable U-suture, 152– 153

273 scleral flap antimetabolites intraoperative application, 39 tube glaucoma implant, 68 Suturing conjunctival flap trabeculectomy, 49 Symblepharon filtering surgery, 9 Synechiae, 124 Systemic antifibrosis therapy failing bleb, 172 Tenon’s conjunctiva and sclera, 64 Tenon’s cysts encapsulated bleb, 183 failing bleb, 169 Tenon’s Fascia surgical limbus, 13 Tetracaine, 22 Tissue repair sequence of events, 33 Topical anesthesia, 26 – 27 with eyedrops, 27 Trabeculectomy, 45 – 50, 112, 160 anesthesia, 47 anterior chamber reformation, 49 conjunctival flap, 46 conjunctival flap suturing, 49 early postoperative complications, 136 globe positioning, 46 limbal incision, 47 paracentesis, 48 peripheral iridectomy, 48 postoperative care, 49 – 50 postoperative drops, 49 scleral flap closure, 48 –49 technique, 45 – 49 Trabeculo-Descemet’s membrane (TDM), 52 – 57 perforation, 58, 59 –60 Trabio wound healing, 32, 34 Trovafloxacin blebitis, 259 Tube complications glaucoma implant, 76 –77 Tube-corneal touch glaucoma implant, 78 Tube erosion glaucoma implant, 79

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274

Index

Tube stent glaucoma implant, 66 Tube suture glaucoma implant, 68 Tube trimming glaucoma implant, 68– 69 Two-site phacotrabeculectomy technique combined cataract and glaucoma surgery, 113– 114

Valve priming glaucoma implant, 66 Valves filtering surgery, 125 Viscocanalostomy, 124 nonpenetrating glaucoma surgery, 57 Vitreous loss glaucoma implant, 77

Ultrasound biomicroscopy, 120 Ahmed valve, 126 assessing filtration, 121– 125 clinical use, 120– 121 cyclodialysis cleft, 127 filtering bleb, 125 filtering surgery, 121– 124 glaucoma surgery, 119– 129 malignant glaucoma, 129 measuring ocular structure, 121 technique, 120– 121 U-suture releasable, 152– 153 Uttrata forceps, 111 Uveitis failing bleb, 164

Wound dehiscence glaucoma suture lysis, 147 Wound healing see Moorfields Safe Surgery System penetrating ocular injuries, 160 – 161 surgical technique, 161 Wound leaks, 138 flat anterior chamber, 238 – 239 nonpenetrating glaucoma surgery, 58 – 59

Xylocaine, 21, 22, 26 – 27 Xylocaine jelly trabeculectomy, 47

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Figure 2.2 Photograph of dissected 1/3 thickness scleral flap with anatomical landmarks.

Figure 4.1 Changes in technique leading to improvements in outcome following the use of antimetabolites.

Figure 4.2 Patient’s left eye treated with smaller area of mitomycin-c 0.4 mg/mL showing focal cystic bleb. Left eye treated with mitomycin-c 0.5 mg/mL and large area showing diffuse noncystic bleb. [email protected]

Figure 4.3 Fornix dissection to ensure large surface area of treatment.

Figure 4.4 Special clamp protecting conjunctiva while folded sponges are being inserted.

Figure 4.5 New adjustable sutures being adjusted through the conjunctiva using special finely machined forceps. For video, see http://www.ucl.ac. uk/ioo/research/khaw.htm [email protected]

Figure 4.6 Injection of 5FU being given through a viscoelastic wall.

Figure 4.7 Example of diffuse noncystic bleb with intraocular pressure of 12 mmHg 5 years after surgery using mitomycin 0.5 mg/mL and described techniques. This result may be possible for the majority of patients having filtration surgery with improvements of current techniques, and can lead to a dramatic reduction in complications.

Figure 6.1 Sclerectomy, ab externo trabeculectomy, deep sclerectomy. [email protected]

Figure 6.2 flap.

Dissection of superficial scleral

Figure 6.3 Dissection of deep flap, excision, and exposure of Schlemm’s canal.

Figure 6.4 Peeling of the innerwall of Schlemm’s canal and juxtacanalicular trabeculum.

Figure 6.5 [email protected]

Implantation of a collagen implant.

Figure 7.1 Needles preplaced through anterior needle holes. Supramid suture inserted from plate side.

Figure 7.2 Harms forceps used to insert plate.

Figure 7.3 Placing sutures through sclera 8 – 10 mm from limbus. [email protected]

Figure 7.4 Pericardium cut to cover tube from plate to limbus.

Figure 7.5 Pericardium retracted to side following insertion of preplaced sutures. Suture preplaced around silicone tube.

Figure 7.6 Cutting of tube with scissor blades facing upwards to ensure bevel of tube is facing up. [email protected]

Figure 7.7 Paracentesis with microsharp blade.

Figure 7.8 Use of 22 or 23 gage needle to create passage for silicone tube into anterior chamber.

Figure 7.9 Inserting silicone tube into anterior chamber. [email protected]

Figure 7.10 Testing patency of slits made in silicone tube by injecting BSS.

Figure 7.11 Pericardium sutured to sclera. Tube tied off with 70 Vicril at junction with plate.

Figure 7.12 Suturing conjunctiva to limbus and showing availability of supramid suture for removal at a later date. [email protected]

Figure 9.1 The Ahmed valve is primed with balanced salt solution.

Figure 9.2 The Ahmed valve is tucked underneath the limbral-based conjunctival flap.

Figure 9.3 The Ahmed valve is anchored to the episclera with interrupted 8/0 silk sutures through the eyelets on the receptacle plate. [email protected]

Figure 9.4 Sclerostomy is made with MVR blade 3 mm posterior to the limbus.

Figure 9.5 Set up for Pars Plana sclerostomy with Landers ring suture in place.

Figure 9.6 The tube of the Ahmed valve is inserted through the superotemporal sclerostomy. [email protected]

Figure 9.7 The Pars Plana ClipTM is anchored to the episclera with 8/0 silk sutures through the eyelets.

Figure 9.8 Half-thickness cornea graft is sutured to the episclera with interrupted 10/0 nylon sutures to cover the tube and the Pars Plana ClipTM .

Figure 9.9 Water-tight closure of Tenon’s capsule and conjuctival flap. [email protected]

Figure 13.3

A filtering bleb (B) contains clear spaces and low reflective episcleral tissue.

Figure 13.9 Ultrasound biomicroscopy image of Ahmed valve. The iris is partially obstructing the opening of the tube (arrow). [email protected]

Figure 13.12 Ultrasound biomicroscopy image of anterior chamber in malignant glaucoma. The anterior chamber (AC) is extremely shallow. C, cornea, L, lens.

Figure 13.13 Ultrasound biomicroscopic image in malignant glaucoma. The iris (I) and ciliary processes (CP) are rotated forward closing the angle. The lens is forward. There is a supraciliary effusion (E) present. C, cornea, S, sclera.

Figure 16.1 Visualization of scleral suture through Hoskins lens. [email protected]

Figure 18.2

The Moorfields bleb grading system.

Figure 19.1 Slit-lamp photograph of an encapsulated bleb, with its characteristic dome-shaped appearance and enlarged conjunctival vessels. [email protected]

Figure 19.2 Needling procedure. Under sterile conditions, a lid retractor is placed and a 30 gage bent needle is advanced into the cyst through a remote conjunctival entry; side-to-side movements of the needle are used to tear the wall of the cyst (A). At the end of the procedure, topical fluorescein 2% is applied to test for leakage (B).

Figure 23.1

Measuring the bleb.

Figure 23.2

Dissecting and raising the flap. [email protected]

Figure 23.3

A pericardial or scleral patch graft.

Figure 23.4

Edges trimmed as necessary and anchored to the limbus region.

Figure 26.1

Fundus photograph detailing choroidal folds. [email protected]

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