Manual for Eye Examination and Diagnosis, 7th edition

Manual for Eye Examination and Diagnosis Seventh Edition

Cornea

Clear, front part of the eye

Iris

Colored diaphragm that regulates amount of light entering

Aqueous

Clear fluid in front part of the eye

Ciliary body

Produces aqueous and focuses lens

Lens

Clear, refracting media that focuses light

Vitreous

Clear jelly filling the back of the eye

Sclera

Rigid, white outer shell of the eye

Conjunctiva

Mucous membrane covering sclera and inner lids

Retina

Inner lining of the eye containing light-sensitive rods and cones

Macula

Avascular area of the retina responsible for the most acute vision

Fovea

A pit in the center of the macula corresponding to central fixation of vision

Choroid

Vascular layer between retina and sclera

Optic nerve

Transmits visual stimuli from retina to brain

Zonule

Fibers suspending lens from ciliary body

Manual for Eye Examination and Diagnosis Mark W. Leitman, St. Peter’s University Hospital New Brunswick, NJ 08901

SEVENTH EDITION

MD

©2007 Mark W. Leitman Published by Blackwell Publishing Blackwell Publishing, Inc., 350 Main Street, Malden, Massachusetts 02148-5020, USA Blackwell Publishing Ltd, 9600 Garsington Road, Oxford OX4 2DQ, UK Blackwell Publishing Asia Pty Ltd, 550 Swanston Street, Carlton, Victoria 3053, Australia The right of the Author to be identified as the Author of this Work has been asserted in accordance with the Copyright, Designs and Patents Act 1988. All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, except as permitted by the UK Copyright, Designs and Patents Act 1988, without the prior permission of the publisher. Third Edition 1988 Fourth Edition 1993 Fifth Edition 2001 Sixth Edition 2004 Seventh Edition 2007 1 2007 Library of Congress Cataloging-in-Publication Data ISBN: 978-1-4051-6822-9 Leitman, Mark W., 1946– Manual for eye examination and diagnosis / Mark W. Leitman. — 7th ed. p. ; cm. Includes index. ISBN: 978-1-4051-6822-9 1. Eye—Examination—Handbooks, manuals, etc. 2. Eye—Diseases—Diagnosis—Handbooks, manuals, etc. I. Title. [DNLM: 1. Eye Diseases—diagnosis—Handbooks. 2. Diagnostic Techniques, Ophthalmological—Handbooks. WW 39 L533m 2007] RE75.L44 2007 617.7’15—dc22

2007010760

A catalogue record for this title is available from the British Library Typeset by Aptara Inc. New Delhi, India Printed and bound in Singapore by Markono Print Media Pte Ltd Commissioning Editor: Martin Sugden Editorial Assistant: Robin Harries Development Editor: Laura Murphy Production Controller: Debbie Wyer For further information on Blackwell Publishing, visit our website: http://www.blackwellpublishing.com The publisher’s policy is to use permanent paper from mills that operate a sustainable forestry policy, and which has been manufactured from pulp processed using acid-free and elementary chlorine-free practices. Furthermore, the publisher ensures that the text paper and cover board used have met acceptable environmental accreditation standards. Blackwell Publishing makes no representation, express or implied, that the drug dosages in this book are correct. Readers must therefore always check that any product mentioned in this publication is used in accordance with the prescribing information prepared by the manufacturers. The author and the publishers do not accept responsibility or legal liability for any errors in the text or for the misuse or misapplication of material in this book.

Dedicated to Andrea Kase It is impossible to perform a good eye exam without a good support team. Andrea has enthusiastically led our team for 26 years as office manager, ophthalmic technician, and typist of all correspondence, including the last five editions of this book. By encouraging me to bring my collection of rocks and other objects from nature into the waiting room, she helped create a museum that my patients look forward to seeing and contributing to.

Contents

In sequence of eye examination

Lids 54 Lashes 58

Preface viii Medical History 1 Medical illnesses 3 Medications 4 Family history of eye disease 5 Measurement of Vision and Refraction 6 Visual acuity 6 Optics 7 Refraction 9 Contact lenses 12 Refractive surgery 19 Neuro-ophthalmology 23 Eye movements 23 Strabismus 25 The pupil 35 Visual field testing 39 Nystagmus 43 Circulatory disturbances affecting vision 45 External Structures 49 Lymph nodes 49 Lacrimal system 49

The Orbit 59 Exophthalmos 61 Enophthalmos 62 Slit Lamp Examination and Glaucoma 63 Cornea 63 Conjunctiva 68 Sclera 73 Glaucoma 74 Uvea 84 Vitreous 92 Cataracts 94 The Retina 100 Retinal anatomy 100 Fundus examination 102 Fluorescein angiography 103 Papilledema (choked disk) 104 White retinal lesions 106 Diseases of retinal vessels 106 Diabetic retinopathy 113 Macular degeneration 115 Common retinal diseases 117 Index 123

vii

Preface

The first edition of this book was started when I was a medical student 35 years ago during the allotted two-week rotation in the eye clinic. At that time, all introductory books were 500 pages or more and could not be read quickly enough to understand what was going on. With this in mind, each word of this manual was carefully chosen so as to allow the beginning eye care professional to understand the refraction and hundreds of the most commonly encountered eye diseases from the onset. They are discussed with respect to anatomy, instrumentation, differential diagnosis, and treatment in the order in which they would be uncovered during the eye exam. It is meant to be read in its entirety in a few hours and, hopefully, impart to you a strong foundation on which to grow and enjoy this beautiful and ever-changing speciality. The popularity of previous editions has resulted in translations into Spanish, Japanese, Indonesian, Italian, Russian, Greek, and an Indian reprint. My special appreciation goes to Johnson & Johnson’s eye care division, which provided a generous grant to distribute the previous edition to 40,000 students; and to Pfizer Pharmaceuticals, which contributed illustrations compliments of www.xalatan.com (Figs 96, 158, 164, 217, 226, 231, 236, 240, 242). M A R K W. L E I T M A N

viii

Medical history

The history includes the patient’s chief complaints, medical illnesses, current medications, allergies to medications, and family history of eye disease. Common chief complaints

Causes

Persistent loss of vision

1 Focusing problems are the most common complaints. Everyone eventually needs glasses to attain perfect vision, and fitting lenses occupies half the eye care professional's day 2 Cataracts are cloudy lenses that occur in everyone in later life. Unoperated cataracts are the leading cause of blindness worldwide. In the USA, over 2.8 million cataract extractions are performed each year 3 Diabetes affects 14 million Americans, increasing from 0.3% at age 20 to 10% of the population after age 70. Diabetic retinopathy is the leading cause of blindness in the USA in those under 65 years of age 4 Macular degeneration causes loss of central vision and is the leading cause of blindness over age 65. Signs are present in 25% of people over age 75 5 Glaucoma is a disease of the optic nerve that is worsened by elevated eye pressure. It usually occurs after age 35 and affects 2 million Americans, with black persons affected five times as often as white persons. Peripheral vision is lost first, with no symptoms until it is far advanced. Progression to blindness is uncommon if discovered early. This is why there are so many state-sponsored eye-pressure screenings

Transient loss of vision lasting less than –12 hour, with or without flashing lights

In younger patients, think of migrainous spasm of cerebral arteries. With aging, consider emboli from arteriosclerotic plaques

Floaters

Almost everyone will at some time see shifting spots due to suspended particles in the normally clear vitreous. They are usually physiologic, but may result from hemorrhage, retinal detachments, or other serious conditions

Continued on p. 2

1

Continued

Common chief complaints

Causes

Flashes of light

Sparks may be due to traction of the vitreous on the retina and are sometimes associated with the onset of a retinal hole or detachment. Insults to the visual center in the occipital cortex are usually ischemic and cause more organized jagged lines of light Nyctalopia usually indicates a need for spectacle change, but also commonly occurs with aging and cataracts. Rarer causes include retinitis pigmentosa and vitamin A deficiency

Night blindness (nyctalopia)

2

Double vision (diplopia)

Strabismus, which affects 4% of the population, is the condition where the eyes are not looking in the same direction. The binocular diplopia disappears when one eye is covered. In straighteyed persons, diplopia is caused by hysteria or a beam-splitting opacity in one eye which does not disappear by covering the other eye

Light sensitivity (photophobia)

Usually a normal condition treated with tinted lenses, but could result from inflammation of the eye or brain; internal reflection of light in lightly pigmented or albinotic eyes; or dispersion of light by mucus, lens or corneal opacities, or retinal degeneration

Itching

Most often due to allergy or dry eye

Headache

Headache patients present daily to rule out eye causes and to seek direction 1 Headache due to blurred vision or eye-muscle imbalance worsens with use of eyes 2 Tension causes 80–90% of headaches. It worsens with anxiety and is often associated with temple and neck pain 3 Migraine occurs in 10% of the population. There is a severe recurrent, pounding headache often accompanied by nausea, blurred vision, and flashing zigzag lights. It is relieved by rest 4 Sinusitis causes a dull ache about the eyes and occasional tenderness over the sinus. There may be an associated nasal stuffiness and a history of allergy relieved with decongestants 5 Menstrual headaches are cyclical 6 Giant-cell arteritis occurs in elderly persons and may cause headache, loss of vision, pain on chewing, temporal scalp tenderness, arthritis, loss of weight, and weakness. An erythrocyte sedimentation rate over 40 and a positive temporal artery biopsy confirms the diagnosis. Prompt high-dose systemic steroid therapy should be started since blindness or death can occur 7 Sharp ocular pains lasting for seconds are often referred from nerve irritations in the neck, nasal mucosa, or intracranial dura, which like the eye are also innervated by the trigeminal nerve 8 Headaches that awaken the patient and are prolonged or associated with focal neurologic symptoms should be referred for neurologic study

Visual hallucinations

Occurs in dementia, psychosis, brain disease, and from medications

MEDICAL HISTORY

Medical illnesses Record all systemic diseases. Diabetes and thyroid disease are two of the most common. Both may be first discovered in an eye examination. Diabetes mellitus 1 Diabetes may be first diagnosed when there are large changes in spectacle correction due to the effect of blood sugar changes on the lens of the eye. 2 Diabetes is one of the common causes of III, IV, and VI cranial nerve paralysis. It is due to closure of small vessels. The resulting diplopia may be the first symptom of diabetes. 3 Cataracts and glaucoma are more common in diabetics. 4 Retinopathy is the most serious complication. If discovered early, laser treatment may reduce visual complications by 50%. Therefore all diabetics should be examined yearly. Autoimmune (Graves’) thyroid disease This is a condition in which an orbitopathy may be present with hyper- but also hypo- or euthyroid disease. 1 It is the most common cause of bulging eyes, referred to as exophthalmos or proptosis, and is due to white-cell and mucopolysaccharide infiltration of the orbit. A small white area of sclera appearing between the lid and upper cornea is diagnostic of thyroid disease 90% of the time (Fig. 1). This exposed sclera may be a result of exophthalmos or thyroid lid retraction due to an overactive Müller’s muscle that elevates the lid. Severe orbitopathy may be treated with steroids, radiation, or surgical decompression of the orbit.

Fig. 1 Thyroid exophthalmos with exposed sclera at superior limbus.

MEDICAL HISTORY

3

Fig. 2 Computed tomography scan of thyroid orbitopathy showing infiltration of medial rectus muscle (M) and normal lateral rectus muscle (L). Courtesy of Jack Rootman.

Fig. 3 Bull’s-eye maculopathy due to Plaquenil.

2 Infiltration of eye muscles may cause diplopia and is confirmed by a computed tomography (CT) scan (Fig. 2). 3 Exophthalmos may cause excessive exposure of the eye in the day and an inability to close the lids at night (lagophthalmos), resulting in damage to the cornea. 4 Optic nerve compression could cause permanent loss of vision.

Medications Record patient medications. Below are listed commonly prescribed drugs causing ocular side effects.

Fig. 4 Phenothiazine maculopathy with pigment mottling of macula.

Plaquenil, used for autoimmune diseases and malaria, causes “bull’s-eye” maculopathy (Fig. 3). Ethambutol, used for tuberculosis, causes optic neuritis. Phenothiazine tranquilizers (Fig. 4), niacin, a lipid-lowering agent, and tamoxifen, used for breast cancer, could damage the macula. Corticosteroids cause cataracts and glaucoma and increase the incidence of herpes keratitis. Pilocarpine, used to treat glaucoma, can cause cataracts (Fig. 5).

4

MEDICAL HISTORY

Fig. 5 Cataract.

Xalatan, Lumigan, and Travatan are the most commonly prescribed glaucoma medications. All three may darken the iris and periorbital skin (eyelids) with lengthening and darkening of the eye-lashes (Fig. 6). Amiodarone (Cordarone, Pacerone) one of the most potent antiarrhythmic drugs and Sildenafil (Viagra), Tadalafil (Cialis) and Vardenafil (Levitra) used to treat erectile dysfunction have all been suspected of causing nonarteritic anterior ischemic optic neuropathy.

Fig. 6 Hyperpigmentation of periorbital skin (eyelids) and iris with darkening and lengthening of lashes.

Allergies to medications Inquire about drug allergies before eye drops are placed or medications prescribed. Neomycin, a popular antibiotic in eye drops, may cause conjunctivitis and reddened skin (Fig. 7).

Family history of eye disease Cataracts, refractive errors, retinal degeneration, and strabismus—to name a few—may all be inherited. In glaucoma, which normally affects 1% of the population, family members have a 10% chance of acquiring the disease. Eighty percent of people with migraine have a relative with the disease.

Fig. 7 Neomycin allergy occurs in 5–10% of population.

A special question should be directed to the smoking of cigarettes since it doubles the rate of cataracts and macular degeneration. It also worsens all the visual problems related to hypertension, diabetes, and Graves’ disease.

MEDICAL HISTORY

5

Measurement of vision and refraction

Visual acuity The patients read the Snellen chart (Fig. 8) from 20 ft with the left eye occluded first. Take the vision in each eye without and then with spectacles. Vision is expressed in a fraction-like form. The top number is the distance at which the patient reads the chart; the bottom number is the distance at which someone with normal vision reads the same line of the chart. Whenever acuity is less than 20/20, determine the cause for the decreased vision. The most common cause is a refractive error, i.e., the need for lens correction. If visual acuity is less than 20/20, the patient may be examined with a pinhole. Improvement of vision while looking through a pinhole indicates that spectacles will improve vision. Use an illiterate “E” chart with a young child or an illiterate adult.

Fig. 8 Snellen chart.

Ask the patient which way the $ is pointed. Near vision is checked with a reading card held about 14 inches away. If a refraction for new spectacles is necessary, perform it prior to other tests that may disturb the eye.

Examples of visual acuity

Measurement in feet (meters in parentheses)

Meaning

20/20 (6/6)

Normal. At 20 ft, patient reads a line that a normal eye sees at 20 ft

20/30–2 (6/9–2)

Missed two letters of 20/30 line

20/50 (6/15)

Vision required in at least one eye for driver’s license in most states Continued

6

Measurement in feet (meters in parentheses)

Meaning

20/200 (6/60)

Legally blind. At 20 ft, patient reads line that normal eye could see at 200 ft

10/400 (3/120)

If patient cannot read top line at 20 ft, walk him or her to the chart. Record as the “numerator” the distance at which the top line first becomes clear

CF/2ft (counts fingers at 2 ft)

If patient is unable to read top line at 3 ft, have the patient count fingers at maximal distance

HM/3 ft (hand motion at 3 ft)

If at 1 ft patient cannot count fingers, ask him or her direction of hand motion

LP/Proj. (light perception with projection)

Light perception with ability to determine position of the light

NLP

No light perception: totally blind

Record vision as follows

 s¯

c¯ 

Key

OD OS

20/70 + 1 LP/Proj.

V s¯ c¯ OD

Vision Without spectacles With spectacles Right eye

OD OS

20/20 LP/Proj.

OS OU

Left eye Both eyes

Optics Emmetropia (no refractive error) In an emmetropic eye (Fig. 9), light from a distance is focused on the retina.

Ametropia In this disorder, light is not focused on the retina. Four types are hyperopia, myopia, astigmatism, and presbyopia.

Fig. 9 Emmetropic eye.

Hyperopia Parallel rays of light are focused behind the retina (Fig. 10). The patient is farsighted and sees more clearly at a distance than near, but still might require glasses for distance.

Fig. 10 Hyperopic eye.

MEASUREMENT OF VISION AND REFRACTION

7

A convex positive lens is used to correct hyperopia (Fig. 11). The power of the lens is expressed in diopters (D). A positive 1 D lens converges parallel rays of light to a focus 1 meter from the lens (Fig. 12). The total refracting power of the eye is 60 D; 43 D from the cornea and 17 D from the lens.

Fig. 11 Hyperopic eye corrected with convex lens.

Myopia Parallel rays are focused in front of the retina (Fig. 13). The patient is nearsighted and sees more clearly near than at distance. Myopia often begins in the first decade and progresses until stabilization at the end of the second or third decade. One in four Americans are myopic. It is often inherited and may be made worse with increasing amount of near work.

Fig. 12 Parallel rays focused by 1 D lens.

A concave negative lens (Fig. 14), which diverges light rays, is used to correct this condition. Refractive myopia is due to increased curvature of the cornea or the human lens, whereas axial myopia is due to elongation of the eye. In axial myopia the retina is sometimes stretched so much that it pulls away from the optic disk (see Fig. 299) and may cause retinal thinning (see Fig. 300) with subsequent holes or detachments.

Fig. 13 Myopic eye.

Astigmatism In this condition, which affects 85% of people, the rays entering the eye are not refracted uniformly in all meridians. Regular astigmatism occurs when the corneal curvature is uniformly different in meridians at right angles to each other. It is corrected with spectacles. For example, take the case of astigmatism in the horizontal (180°) meridian (Fig. 15). A slit beam of vertical light (AB) is focused on the retina, and (CD) anterior to the retina. To correct this regular astigmatism, a myopic cylindrical lens (Fig. 16) is used that diverges only CD.

8

Fig. 14 Myopic eye corrected by concave lens.

Fig. 15 Myopic astigmatism.

MEASUREMENT OF VISION AND REFRACTION

Irregular astigmatism is caused by a distorted cornea, usually resulting from an injury or a disease called keratoconus (see Figs 168 and 169). Presbyopia This is a decrease in near vision, which occurs in all people at about age 43. The normal eye has to adjust +2.50 D to change focus from distance to near. This is called accommodation (see Fig. 243). The eye’s ability to accommodate decreases from +14 D at age 14 to +2 D at age 50.

Fig. 16 Myopic astigmatism corrected with a myopic cylinder, axis 90°.

Middle-aged persons are given reading glasses with plus lenses that require updating with age: 40–45 years 50 years Over 55 years

+1.00 to +1.50 D +1.50 to +2.00 D +2.00 to +2.50 D

The additional plus lens in a full reading glass (Fig. 17) blurs distance vision. Half glasses (Fig. 18) and bifocals (Fig. 19) are options that allow for clear distance vision when looking up. No-line bifocals are more attractive, but more expensive.

Refraction

Fig. 17 Full reading glass blurs distance vision.

Fig. 18 Half glasses.

Refraction is the technique of determining the lenses necessary to correct the optical defects of the eye.

Trial case and lenses The lens case (Fig. 20) contains convex and concave spherical and cylindrical lenses and prisms. The diopter power of spherical lenses and the axis of cylindrical lenses are recorded on the lens frames.

Fig. 19 Bifocals.

Trial frame The trial frame (Fig. 21) holds the trial lenses. Place the strongest spherical lenses in the

MEASUREMENT OF VISION AND REFRACTION

9

Fig. 20 Lens case with red concave and black convex lenses.

Fig. 21 Trial frame.

compartment closest to the eye because the effective power of the lens varies with its distance from the eye. Place the cylindrical lenses in the compartment farthest from the eye so that the axis can be measured on the scale of the trial frame (0–180°).

Streak retinoscopy (“flash”) This objective means of determining the refractive error is used to prescribe glasses to infants and illiterate persons who cannot give adequate subjective responses. Hold the retinoscope (Fig. 22) at arm’s length from the eye and direct its linear beam onto the pupil. To determine the axis of astigmatism, rotate the beam until it parallels the pupillary reflex (Fig. 23), then move it back and forth at that axis, as demonstrated in Fig. 24.

Fig. 22 Streak retinoscope.

Fig. 23 Retinoscopic determination of axis of astigmatism.

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MEASUREMENT OF VISION AND REFRACTION

If the reflex moves the same way that the retinoscope beam is moving (“with motion”), a plus (+) lens is added to the trial frame. If the reflex moves in the opposite direction (“against motion”), a negative (-) lens is needed. Absence of “with motion” or “against motion” indicates the endpoint. Add -1.50 D to the above findings to approximate the refractive error of that meridian. Rotate the beam 90° to refract the other axis.

Fig. 24 Pupillary reflex with motion and against motion.

Manifest A manifest is the subjective trial of lenses. Place the approximate lenses, as determined by the old spectacles or retinoscopy, in a trial frame. Occlude one of the patient’s eyes, and refine the sphere by the addition of (+) and (-) 0.25 D lenses. Ask which lens makes the letters clearer. Next, refine the cylinder axis by rotating the lens in the direction of clearest vision. Test the cylinder power by adding (+) and (-) cylinders at that axis. Large changes in cylinder or axis may improve vision, but partial corrections are sometimes given to adults, since they find it difficult to adjust. Children are given the full cylinder. In presbyopes, determine the reading “add” after distance correction. The following abbreviations are used to record the results of the refraction: W, old spectacle prescription as determined in a lensometer; F, “flash,” the refractive error by retinoscopy; M, manifest, the subjective correction by trial and error; Rx, final prescription, usually equal to M. A bifocal prescription for a farsighted presbyope with astigmatism is written as follows:

Rx

+2.50

-1.50 ¥ 80°

add

+1.50 in bifocal lens for reading axis of cylinder

power of cylinder in diopters power of sphere in diopters

MEASUREMENT OF VISION AND REFRACTION

11

Plastic lenses are typically prescribed because they are lighter and have less chance of shattering, especially in children. Glass is heavier, but has the advantage of not scratching as easily. For photophobia, grey tints are often prescribed because they distort all colors equally. Photochromic glass lenses and Transitions plastic lenses darken in sunlight. Ultraviolet filters reduce the incidence of skin cancer, cataracts, and macular degeneration.

Contact lenses Plastic contact lenses, invented in 1947, are now worn by 34 million Americans, usually as an alternative to spectacles, to correct myopia, hyperopia, astigmatism, and presbyopia (Fig. 25)

Fig. 25 Plastic contact lens.

Other uses of contact lenses include the following: • Correction of vision in cases of an irregularly shaped cornea • Tinted and colored lenses for cosmetic effect (see Fig. 34) and for reducing photophobia • Prosthetic artificial eyes to cover a disfigurement or enucleated socket (see Fig. 263) • Bandage lenses relieve discomfort due to blinking associated with corneal abrasions and edema

Candidates for contact lenses Soft lenses make up the vast majority of lenses fit. However, hard and rigid gas permeable contacts may be preferred for certain cases of dry eye, astigmatism, and irregularly shaped corneas such as occur in keratoconus (see Figs 168 and 169). Because harder lenses are used less frequently, and because they are difficult to fit, this beginner's manual will limit the discussion to soft lenses. The patient usually helps to determine whether the individual should be fitted with contact lenses, which type of lens should be prescribed, the type of care products to prescribe, and whether difficulties with lens wear may be expected. It is important to know if the patient has ever failed at wearing 12

Fig. 26 Wake up and see with extended wear lenses.

MEASUREMENT OF VISION AND REFRACTION

contacts and why. Their occupation, hobbies, and unusual visual requirements may also foretell potential problems. Allergies may reduce contacts lens success due to discomfort and excess mucus production. Similarly many medications that dry the eye surface may limit success. Most wearers enjoy their contacts during the day only ("daily wear") or less often on an overnight schedule ("extended wear") (Fig. 26). Others enjoy lens wear on a part-time basis for sports or social occasions (Fig. 27). Lenses may be replaced yearly but are more commonly disposed of every two weeks to three months ("frequent replacement") or on a daily basis ("disposable").

Fig. 27 Contacts are great for almost every sport.

The frequency of replacement often depends on comfort and the rate of mucus accumulation (Fig. 28).

Fig. 28 Mucus deposits on contact lenses. Contraindications to contact lens wear: • lack of motivation • significant allergies • lid margin infection • conjunctivitis • dry eyes • insensitive corneas • work or play in unsuitable environments • difficulty handling lenses • poor personal hygiene

Tests for fitting contact lenses Keratometry (Fig. 29) After the refraction for spectacles, the corneal curvature is measured with a keratometer or corneal topographer. This determines whether to fit a flatter or steeper lens (see Fig. 39). The keratometer also reveals distortion of the cornea from unhealthy contact lens wear (Fig. 30).

Fig. 29 Keratometer.

MEASUREMENT OF VISION AND REFRACTION

13

Fig. 31 Fluorescein staining of the cornea.

Fig. 30 Circular images projected on a damaged cornea have distorted keratometric readings.

Slit lamp examination 1. Integrity of cornea and tear film Fluorescein dye when placed in the eye and illuminated with the cobalt blue light normally reveals an even green fluorescence. Damaged corneal epithelial cells take up the dye and appear brighter (Fig. 31). Fluorescein dye is also used in the tear film break-up time test to evaluate for dry spots. If the tear film breaks up quickly after a blink, it could foretell a potential problem with drying of the contact lens surface, deposit formation, and discomfort.

Fig. 32 Papillary conjunctivitis with characteristic whitish elevations of conjunctiva.

2. Conjunctival examination The upper and lower lids should be everted to examine the conjunctiva covering the underside of the lids (palpebral conjunctiva) (see Fig. 189). The upper palpebral conjunctiva is the area most often irritated by contact lenses. Called papillary conjunctivitis (Fig. 32), it is often due to excessive contact lens deposits, especially in allergic individuals. It responds well to more frequent lens replacements.

Fig. 33 Limbal injection from a tightfitting lens.

The bulbar conjunctiva surrounding the cornea reddens when the cornea is being compromised or with tight-fitting lenses (Fig. 33). Another sign of a tight-fitting lens is an air bubble getting trapped beneath it.

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MEASUREMENT OF VISION AND REFRACTION

Fig. 35 Typical package markings of contact lenses.

Fig. 34 Colored contact lenses.

Iris The iris color should be noted for consideration of possible enhancement with transparent tinted soft lenses or for color change with opaque tinted soft lenses (Fig. 34).

General rules for fitting soft lenses Power (P), base curvature (BC), and diameter (DIA) are the three basic variables that are usually required to order all types of soft lenses (Fig. 35).

Determination of lens power The power of a contact lens is not always the same as the patient’s spectacle correction. With powers greater than 4 diopters, this difference between spectacle and contact lens powers becomes significant enough to consider. The difference increases with the power of the lens and the increasing vertex distance of the spectacle from the eye. Vertex charts are available which take the power of the lens and vertex distance into account. This gives you the power of a trial contact lens to place on the eye. This then is refined with an over-refraction.

MEASUREMENT OF VISION AND REFRACTION

15

Fig. 36 Place contact lens directly on the cornea using the tip of the index finger for the contact, the middle finger to hold lower lid down, and the finger of the other hand to lift upper lid.

Fig. 37 Remove lens by sliding it off cornea onto sclera and then gently pulling it off using thumb and index finger.

Determination of diameter and curvature of lens 1. Centering A trial lens of approximate power is placed on the eye and allowed to settle for at least 5 minutes (Fig. 36). The lens should be initially comfortable to wear. If discomfort is present, the lens may have a speck of debris and should be removed and rinsed (Fig. 37).

Fig. 38 Contact lens properly overlapping limbus.

The lens should completely cover the cornea and extend just beyond the entire limbus (corneal-conjunctival junction) (Fig. 38). If adequate centration is not achieved, a different base curve may be tried. Base curves generally range from 8.2 to 9.1 mm (Fig. 39). If a change in base curve does not solve the centration problem, a larger lens diameter, if available, may be tried. Typical diameters are in the range of 13.5 to 14.5 mm, and many brands are available in only one fixed diameter (Fig. 40). If changing the base curve, diameter, or both does not solve the lens centration problem, a different lens design (brand) should be evaluated.

16

Fig. 39 (a) Steep base curve 8.2 mm. (b) Flat base curve 9.1 mm.

Fig. 40 (a) 13.5 mm diameter. (b) 14.5 mm diameter.

MEASUREMENT OF VISION AND REFRACTION

2. Movement A lens should move 0.5–1.0 mm on each blink. If adequate lens movement is not achieved, a flatter base curve may be tried. If a lens moves too much, a steeper base curve is placed. If a change in base curve does not solve the movement problem, a larger lens diameter will usually tighten this lens and a small diameter will loosen a lens on the eye.

Fig. 41 Lens properly aligned on eye with center marking at 180°.

Fitting spherical, astigmatic, bifocal, and extended-wear contact lenses Spherical soft lenses correct myopia and hyperopia with small amounts of astigmatism of 0.75 diopters or less. Astigmatic lenses are preferred for refractive errors of 0.75 or more. They are elliptical in shape with markings at 90° or 180° axis (depending on the brand) (Fig. 41). When placed on the eye, these lines should line up close to those axes. If the lens settles on the eye off the desired axis (Fig. 42), for example rotated 10° counterclockwise, 10° must be subtracted from the spectacle astigmatic correction. If rotated 10° clockwise, add 10°. Companies use different methods to prevent rotation of the lenses. The lower portion of the lens could be made thicker or the top and the bottom could be thinner. Presbyopic bifocal contact lenses may be very successful for motivated patients—often over age 40—who have problems focusing up close (Figs 43 and 44). In fitting this lens, allow 20 minutes for the patient to adapt before testing vision. An alternative to a bifocal contact lens in correcting a presbyopic patient is to use a standard spherical contact lens, making one eye focused for near and the other focused for distance. This is called monovision. Usually, the eye with the clearest vision is chosen for distance. Caution the patient about driving and possibly give a distance glass to wear over the contacts when driving.

Fig. 42 Lens settled on to eye rotated 10° counterclockwise.

Fig. 43 Acuvue bifocal contact lens with concentric zones of alternating near and far vision.

Fig. 44 Vision with bifocal contact lens.

MEASUREMENT OF VISION AND REFRACTION

17

Fig. 46 Contact lens solutions.

Fig. 45 Wash hands for at least 15 seconds before inserting lenses.

Extended-wear lenses may be slept with overnight for 1 week to 1 month depending on the brand. These lenses are associated with a 5 times greater rate of infection than daily-wear lenses, so caution these patients to be even more careful in handwashing (Fig. 45) and to watch for signs of infection such as red, uncomfortable eyes. Teach them the “Yamane Triad” of being alert to whether they see, look, and feel good. Patients should also be instructed to only wear the lenses overnight if they were having no problems with lens wear during the initial daily wearing experience. No patient should leave the office without feeling adept at lens insertion and removal; realizing the importance of good handwashing techniques, and having knowledge about the use and differences between disinfecting, cleaning, and rinsing (saline) solutions (Fig. 46).

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MEASUREMENT OF VISION AND REFRACTION

Refractive surgery The refractive power of the eye may be altered by surgically reshaping the cornea, thereby eliminating the need for distance correction. Refractive surgery began twenty-five years ago in Russia with the radial keratotomy technique (Fig. 47). In this procedure, the cornea is flattened with 4-8 radial incisions through 90% of the corneal depth. It has lost popularity due to slow healing, the inability to accurately predict the amount of correction, variable vision throughout the day, glare, halos, infection, and corneal perforation with secondary cataract formation. The three newest surgical procedures used to correct myopia, hyperopia, and astigmatism utilize an excimer laser to remove corneal stroma. The three techniques vary in the way the surface epithelium is removed prior to laser ablation. 1. Laser in situ keratomileusis (LASIK—Figs 48–52) is the most commonly used technique with over 1 million procedures done in the USA in 2005. A flap of epithelium, Bowman’s membrane, and stroma is created with a blade or femtosecond laser. Then, a different laser called an excimer is used to ablate the underlying stromal bed.

Fig. 47 Rare instance of traumatic rupture of radial keratotomy wound. Courtesy of Leo Bores.

Epithelium Stroma

Bowman's membrane

Fig. 48 Normal cornea.

Excimer laser beam

Fig. 49 LASIK—Flap of epithelium, Bowman’s membrane, and stroma is created with blade or laser. Then, an excimer laser ablates the stroma.

Fig. 51 Excimer laser used to remove a layer of central corneal stroma. Courtesy of Summit Technology, Inc.

Fig. 50 Sculpted cornea after LASIK with remaining Bowman’s membrane.

MEASUREMENT OF VISION AND REFRACTION

19

Excimer laser beam

Fig. 52 LASIK surgery showing flap being lifted with spatula and laser beam on central cornea ablating stroma.

A disadvantage of LASIK is a resulting decrease in ocular rigidity. This is due to loss of ablated stromal bed and decreased effectiveness of stroma remaining in the flap since it never completely heals. Up to six years later, the flap can still be lifted with a forceps. In eyes with over 8 diopters of myopia that require a lot of stromal ablation, this combined thinning becomes excessive and could result in irregular bulging of the cornea (ectasia) called keratoconus. Rarely, it may necessitate a corneal transplant. Also, LASIK cuts through more corneal stroma due to the flap thus destroying more nerve tissue resulting in increased dry eye complaints.

Fig. 53 PRK laser ablation of Bowman’s membrane and stroma after mechanical debridement of epithelium.

Fig. 54 Sculpted cornea after PRK or epi-LASIK.

Fig. 55 Epi-LASIK. Creation of epithelial flap with blade followed by laser ablation of stroma.

2. An alternative procedure, photorefractive keratectomy (PRK— Figs 53 and 54), removes the epithelium by mechanically creating a central corneal abrasion. The advantage is it leaves more functioning stroma. The disadvantage is significant post-operative pain and prolonged visual haze. 3. The newest technique, called epi-LASIK (Figs 54 and 55) creates an epithelial flap that includes no stroma.

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MEASUREMENT OF VISION AND REFRACTION

Therefore, there will be more stroma remaining to contribute to ocular rigidity. However, the epithelial flap heals more slowly than the LASIK flap so that vision takes longer to recover. It heals faster and has less pain than PRK where there is a total corneal abrasion after surgery. All three laser techniques usually yield good results, but may be complicated by infection, glare, halos, dry eye, over- or under-correction of refractive error, and unknown long-term effects. Although LASIK is still by far the most popular technique because of its quick healing, there is a movement toward epiLASIK because it minimizes dry eye and stromal flap complications.

Fig. 56 Intac ring. Courtesy of Dimitri Azar, MD.

Intac is a less used technique for correcting small amounts of myopia and keratoconus. It involves the placement of a plastic ring in the peripheral cornea (Fig. 56). Proponents argue that unlike LASIK, it is safer because it doesn’t involve surgery on the central visual axis. Large amounts of hyperopia (over 4 diopters) and myopia (over 8 diopters) are difficult to correct with reshaping the cornea because it becomes too thin and unstable. Intraocular lenses can be inserted inside the eye (Fig. 57) to correct these larger refractive errors, but have all the inherent risks associated with intraocular surgery.

Fig. 57 Phakic 6H2 anterior chamber intraocular lens to correct refractive errors. Courtesy of Oii Inc.

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21

Fig. 58 Illustration of conductive keratoplasty (CK) for correction of hyperopia and presbyopia. Images courtesy of Refractec, Inc.

Fig. 59 Heated tissue shrinks.

Conductive keratoplasty (Figs 58–60) Near Vision CK is the only FDA-approved treatment for improving near vision in presbyopic patients. It reshapes the cornea with 8–16 non-laser radio-frequency energy applications in a circular pattern to the peripheral cornea. The shrinkage of tissue results in a constrictive band (like tightening of a belt) causing steepening of the cornea. It corrects hyperopia at distance and, at the same time, increases depth of focus to improve near vision. It may be used in patients who have already had LASIK or cataract surgery, and may have to be repeated. It is a relatively safe procedure, but there are risks of infection, inflammation, astigmatism, and over- or under-correction.

22

Fig. 60 Photograph of conductive keratoplasty.

MEASUREMENT OF VISION AND REFRACTION

Neuro-ophthalmology

Six muscles move each eye around 3 axes. They are innervated by the III, IV, and VI cranial nerves.

Eye movements

Fig. 61b The eye rotates around three different axes coordinated by the action of six extraocular muscles.

Fig. 61a Lateral orbital view: adduction and abduction are around vertical axis superiorinferior.

Fig. 62 Superior orbital view. Elevation and depression are on the horizontal axis nasal–temporal passing from the nasal to temporal side of the eye. Torsion is on the anterior–posterior axis.

23

Six extraocular muscles that rotate the eye

Muscle

Actions

Neural control

Medial rectus

Adducts

Oculomotor nerve (CN III)

Inferior rectus

Mainly depresses, also extorts, adducts

Oculomotor nerve (CN III)

Superior rectus

Mainly elevates, also intorts, adducts

Oculomotor nerve (CN III)

Inferior oblique

Mainly extorts, also elevates, abducts

Oculomotor nerve (CN III)

Superior oblique

Mainly intorts, also depresses, abducts

Trochlear nerve (CN IV)

Lateral rectus

Abducts

Abducens nerve (CN VI)

CN, cranial nerve.

Nerves to ocular structures

Optic nerve Cranial nerve (CN) II Oculomotor nerve (CN III)

Motor (1–5)

Parasympathetic (6–7)

Trochlear nerve (CN IV)

The axon of the retinal ganglion cell which transmits visual impulse from the eye to the brain Innervates

Causes

1. Medial rectus muscle

Adducts

2. Inferior rectus muscle

Mainly depresses, also extorts, adducts

3. Superior rectus muscle

Mainly elevates, also intorts, adducts

4. Inferior oblique muscle

Mainly extorts, also elevates, abducts

5. Levator palpebrae muscle

Elevates upper lid

6. Pupil constrictor muscle

Responds to light and near focus

7. Ciliary muscle

Focuses lens for near

Superior oblique muscle

Mainly intorts, also depresses, abducts

CN V1 … Eye, upper lid, orbit, and nose

Sensory

Trigeminal nerve

CN V2 … Lower lid Abducens nerve (CN VI)

Lateral rectus muscle

Abducts

Facial nerve (CN VII)

Orbicularis muscle

Closes upper and lower lids

1. Müller’s muscle

1. Elevates upper lid

2. Pupil dilator muscle

2. Opens pupil in response to stress, “fight-or-flight,” and adrenergic drugs

3. Skin of lid

3. Sweat glands

Sympathetic nerve

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NEURO-OPHTHALMOLOGY

Strabismus Strabismus refers to the nonalignment of the eyes such that an object in space is not visualized simultaneously by the fovea of each eye. Phoria refers to the potential for an eye to turn. Once it turns it is called a tropia.

Phoria If one eye is occluded while both eyes are fusing, the occluded eye may turn in (esophoria, noted with the letter E) or out (exophoria, X). Small phorias are usually asymptomatic. Phorias degenerate into tropias as the amount of turn increases and the patient’s ability to correct it decreases. This occurs with tiredness later in the day and from any stimulus that dissociates the eyes, such as poor vision in one eye. Absence of a phoria (perfectly straight eyes) is termed orthophoria.

Complications of strabismus 1. Amblyopia Also called lazy eye, amblyopia is decreased vision due to improper use of an eye in childhood. The two common causes are an eyeturn (strabismic amblyopia) or a refractive error (refractive amblyopia), uncorrected before Types of tropias

Esotropia (ET)

Deviation of eye nasally

Exotropia (XT)

Deviation of eye outward (temporally)

Hypertropia (HT)

Deviation of eye upward

Intermittent tropia

A phoria that spontaneously breaks to a tropia; indicate with parentheses. Example: R (ET) = right intermittent esotropia

Constant monocular tropia

Present at all times in one eye. Example: RXT, constant right exotropia. Often associated with loss of vision, if onset in childhood

Alternating tropia

Either eye can deviate. Vision is usually equal in both eyes

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25

age 8. In strabismus, children unconsciously suppress the deviated eye to avoid diplopia. Strabismic amblyopia is treated by patching the good eye (Fig. 63), thereby forcing the child to use his amblyopic eye. The better eye is patched fulltime—one week for each year of age. It is repeated until there is no improvement on two consecutive visits. Refractive amblyopia is treated by correcting the refractive error with glasses and patching the better eye. Both types must be treated in early childhood because after age 5, it is difficult to improve vision. After age 8, improvement is almost impossible, but should be tried.

Fig. 63 Patching for amblyopia.

2. Poor cosmetic appearance Tropias that cannot be corrected with spectacles may be cosmetically unacceptable and the patient may desire surgery. 3. Loss of fusion Fusion occurs when the images from both eyes are perceived as one object, with resulting stereopsis (three-dimensional vision). Many patients with tropias never gain the ability to fuse. Finer grades of fusion are assessed by using the Wirt stereopsis test.

Wirt stereopsis test

Fig. 64 Wirt stereopsis.

(Fig. 64)

While wearing polarized glasses, the patient views a special test card. The degree of fusion is determined by the number of pictures correctly described in three dimensions.

Near point of convergence (NPC) (Fig. 65) The NPC is the closest point at which the eyes can cross to view a near object. It is measured by having the patient make a maximal effort to fixate on a small object as it is moved toward his or her eyes. The distance at which

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NEURO-OPHTHALMOLOGY

Fig. 65 Near point of convergence.

the eyes stop converging and one turns out is recorded as the NPC. Convergence insufficiency must be considered if the NPC is greater than 8 cm. These patients may complain of diplopia or other difficulties while reading. Exercises or prism glasses may help.

Accommodative esotropia (Figs 66 and 67) When the lens of a normal eye focuses, it simultaneously causes the eyes to converge. Hyperopes not wearing glasses must focus the lens of their eye (accommodation) to see clearly near and far. This focusing stimulates the accommodative reflex causing convergence of the eyes. When the ratio of convergence to accommodation is abnormally high, an esotropia results, which corrects with lenses.

Fig. 66 Accommodative esotropia.

Fig. 67 Accommodative esotropia corrected with hyperopic lenses.

Nonaccommodative esotropia This is due to a defect in the brain not related to the accommodative reflex. It is corrected by surgically weakening the medial rectus muscle by recessing its insertion posteriorly on the sclera (Fig. 68) or by tightening the lateral rectus muscle by resecting part of it (Fig. 69). Less often, botulinum toxin is injected to weaken eye muscles.

Fig. 68 Recession to weaken muscle.

Fig. 69 Resection to strengthen muscle.

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27

An epicanthal skin fold connects the nasal upper and lower lids (Fig. 70) and is common in infants and Asians. It gives the false impression of a cross-eye called pseudostrabismus.

Measurement of the amount of eye-turn with prisms Ocular deviations are measured in prism diopters. When light passes through a prism, it is bent toward the base of the prism. One prism diopter (1 D) displaces the image 1 cm at a distance of 1 meter from the prism. Do not confuse prism diopters (D) with lens diopters (D).

Fig. 70 Epicanthal folds causing false impression of cross-eye (pseudostrabismus)

In right esotropia, the right fovea is turned temporally. To focus the light on the right fovea, a prism (apex in) is placed in front of the right eye (Fig. 71). For an exotropia, use apex out. Rule: point prism apex in the direction of the tropia.

Prism cover test for measurement of eye-turn (Fig. 72)

Fig. 71 Right esotropia neutralized with prism (apex-in).

The patient fixates on an object at 20 ft. When the fixating eye is occluded, the deviated eye must move to look at the target. Increasing amounts of prism are placed in front of the deviated eye until no movement is noted when the cover is moved back and forth over each eye.

Hirschberg’s test When the cover test is difficult to perform on young children, the angle of strabismus can be estimated by using Hirschberg’s test (Figs 73–75). As the child fixates on a point source of light, the position of the corneal light reflexes is noted. Each 1 mm of deviation from the center of the cornea is equivalent to approximately 14 D of deviation. A reflex 2 mm temporal to the center of the cornea indicates an esotropia of approximately 28 D. 28

NEURO-OPHTHALMOLOGY

Fig. 72 Prism cover test.

Fig. 73 Hirschberg: esotropia.

Causes of strabismus 1 Paralytic strabismus is due to cranial nerve (III, IV, or VI) disease or eye-muscle weakness from thyroid disease, traumatic contusions, myasthenia gravis, or orbital floor fractures. 2 Nonparalytic strabismus is due to a malfunction of a center in the brain. It is often inherited and begins in childhood. Fig. 74 Hirschberg: exotropia.

Demonstration of paralytic strabismus In paralytic strabismus, the amount of deviation is greatest when gaze is directed in the field of action of the weakened muscle. To demonstrate underaction of any of the 12 external ocular muscles, the patient fixates on an object moved into each of the six cardinal fields of gaze (Fig. 76). Each position tests one muscle of each eye (e.g., position 3 tests the right inferior rectus and the left superior oblique muscles). In addition to observing for underaction or overaction of the muscles, ask

Fig. 75 Hirschberg: hypotropia.

Comparison of paralytic and nonparalytic strabismus

Paralytic

Nonparalytic

Age of onset

Usually in older persons

Usually starts before 6 years of age

Complaint since

Diplopia

Cosmetic eye-turn; less diplopiachild suppresses deviated eye

Eye-turn

Largest deviation in field of action of affected muscle

No one muscle is underactive; deviation similar in all directions

Vision

Not affected

Deviated eye may have loss of vision (amblyopia)

Plan

Neurologic workup

Ophthalmic workup

Fig. 76 The six cardinal fields of gaze.

NEURO-OPHTHALMOLOGY

29

the patient where diplopia is greatest. For exact measurements, use the prism cover test. Most often the cause for CN III, IV, and VI paralysis cannot be confirmed, since it is due to ischemia from small-vessel closure. Testing is done to rule out causes such as multiple sclerosis, aneurysms, neoplasms, and other rarer conditions, especially in younger individuals where vessel closure is not likely. Ischemia from diabetes is the most common cause and often resolves within 10 weeks.

Fig. 77 Right CN III paralysis. In straight gaze, eye turns down and out with dilated pupil and ptosis.

Oculomotor nerve (CN III) CN III paralysis (Figs 77–79) results in underaction of the inferior oblique and medial, inferior, and superior rectus muscles, resulting in an eye turned down and out. Since this nerve also innervates the levator palpebral muscle, which elevates the lid and the pupillary constrictor muscle, the lid is drooped and the pupil is dilated. CN III paralysis due to diabetes often spares the pupil. Always examine for a dilated pupil after head trauma. CN III parallels the posterior communicating artery (see Fig. 112) so that ruptured aneurysms in the circle of Willis are a common cause of CN III paralysis with a dilated pupil and pain. Also, CN III passes under the tentorial ridge in the brain and is highly susceptible to uncal herniation of the brain. Herniation may follow increased intracranial pressure from cerebral edema, hematoma, tumor, abscess, or cerebral spinal fluid obstruction. Although a dilated pupil is a more common ominous sign after head injury, small or unequal pupils could indicate serious insults to other parts of the brain.

Fig. 78 Inability of right eye to look to the left due to medial rectus paralysis.

Fig. 79 Inability of right eye to look up to right due to superior rectus paralysis. Courtesy of David Taylor.

Trochlear nerve (CN IV) The trochlear nerve (CN IV) innervates the superior oblique muscle. Since this muscle acts as a depressor when the eye is rotated nasally, it causes patients to have vertical diplopia when looking down to read. Since intorsion is this muscle’s main action, there is a head tilt to the opposite shoulder so that the eye doesn’t have to be intorted (Fig. 80). If the doctor

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NEURO-OPHTHALMOLOGY

Fig. 80 Left superior oblique paralysis. To avoid diplopia, head is tilted to the opposite shoulder. Courtesy of Joseph Calhoun.

forces the patient’s head straight (Fig. 81), the superior rectus must act as an intorter. Since the superior rectus also elevates the eye as it intorts, vertical diplopia occurs. A common cause of superior oblique muscle dysfunction is trauma since it passes through the trochlea (see Fig. 61a), where it is accessible to injury due to its location just under the superior nasal orbital rim. All patients with a head tilt should be checked for trochlear nerve dysfunction.

Fig. 81 Paralytic left superior oblique with vertical diplopia in primary gaze. Note: sclera visible below left cornea.

Abducens nerve (CN VI) The abducens nerve (CN VI) innervates the lateral rectus muscle that abducts the eye. Loss of function causes diplopia and a cross-eye (Figs 82–84). As this nerve may be damaged from increased intracranial pressure, one should be alert to an associated headache, nausea, and papilledema.

Fig. 82 Right lateral rectus paralysis in right gaze. Courtesy of Elliot Davidoff.

Trigeminal nerve (CN V) The trigeminal nerve (CN V) is the sensory nerve of the head and face (Fig. 85).

Fig. 83 Right lateral rectus paralysis, straight gaze.

Fig. 85 The trigeminal nerve. SO, supraorbital; ST, supratrochlear; L, lacrimal; IT, infratrochlear; IO, infraorbital; EN, external nasal.

Fig. 84 Right lateral rectus paralysis, left gaze.

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31

V1: ophthalmic branch—sensory to upper lid, eye, and nose. V2: maxillary branch—sensory to lower lid and cheek. V3: mandibular branch—no ocular action. Injury may cause an anesthetic effect, as occurs in an orbital blow-out fracture or pain as occurs in herpes zoster dermatitis (Fig. 86) or trigeminal neuralgia (tic douloureux). Herpes zoster dermatitis (shingles) is caused by the virus also responsible for chickenpox. It often affects the ophthalmic division of CN V. There may be an associated iritis, keratitis, a fever, and adenopathy. Rx: Valacyclovir (Valtrex) 1000 mg PO TID ¥ 7 days. The treatment for iritis is similar to the treatment for other causes of iritis.

Fig. 86 Herpes zoster dermatitis. Think of shingles when the dermatitis follows the distribution of CN V and doesn't cross the facial midline.

Facial nerve (CN VII) The facial nerve (CN VII) innervates the orbicularis oculi muscle, which closes the lid, and also the muscles that control facial expression (Fig. 87). It also stimulates lacrimal secretion. The common CN VII paralysis in adults is called Bell’s palsy and is usually due to ischemia or a virus (Fig. 88).

Fig. 87 Facial nerve to orbicularis oculi and oris muscles.

Minor eyelid spasms of the orbicularis muscle which the patient senses as a twitching of the muscles of the lid, and usually unnoticed by an observer, is called myokymia. It may be related to stress, fatigue, or too much caffeine, and often disappears in weeks. Blepharospasm (Fig. 89) is a more severe spasm of the orbicularis muscle causing the eyelids to close involuntarily. The first-line treatment is to give six injections of Botulinum toxin (Botox) into the muscles around the eye every 3–4 months. Severe cases may require surgical removal of the muscle or seventh nerve.

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NEURO-OPHTHALMOLOGY

Fig. 88 Right CN VII paralysis causes decreased blinking and inability to close lids completely (see Fig. 180).

Optic nerve (CN II) The optic nerve (CN II) is made up of 1.2 million retinal ganglion cell axons which transmit the visual message from the eye to the brain. The nerve begins at the optic disk (papilla) as the ganglion cell axons exit the eye. When the intraocular ganglion cells or the extraocular optic nerve are damaged, the normal pink or orange optic disk may turn chalk white (Fig. 91).

Fig. 89 Blepharospasm.

In the case of glaucoma, the pallor is associated with excavation (cupping) of the disk (Fig. 92).

Fig. 90 Schematic cross section of retina. The ganglion cell fibers on the surface of the retina become covered with a myelin sheath at the optic disk and this continuation of these fibers outside the eye is then called the optic nerve.

Fig. 91 Optic atrophy resulting from ischemia, transection, toxicity, or inflammation.

Fig. 92 Optic atrophy with cupping due to glaucoma.

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33

Intraocular causes for loss of optic nerve fibers Glaucoma—a disease of the optic nerve aggravated by high intraocular pressure—is the most common cause of optic neuropathy. Therefore, a whole section is devoted to it (p. 74). Retinal ischemia due to retinal artery and vein occlusion or diabetic closure of capillaries may cause loss of ganglion cells and result in pallor of the disk. Thinning of the ganglion cell layer also occurs in high myopia, retinitis pigmentosa, chorioretinitis, and numerous less common retinal diseases.

Extraocular causes for loss of optic nerve fibers When the nerve near the optic disk is inflamed (optic neuritis), you may see papillitis with an ophthalmoscope. Signs of papillitis include flame hemorrhages around the disk, cells in the overlying vitreous, and a blurred disk margin (Fig. 93). Optic neuritis could cause dimming of vision, reduced central vision, decreased pupil reaction to light, reduced color vision, and pain with eye movement. When light is shined in a normal eye, both pupils constrict. This is called a consensual light reflex. Damage to the optic nerve (CN II) reduces direct pupillary constriction to light. The diseased eye will constrict well when light shines on the other eye due to the normal consensual reflex. Shining a light back and forth between eyes, called the swinging light test (Fig. 94), reveals the eye with optic atrophy to be dilating as the light shines on it since the stronger consensual reflex is wearing off. This is called a Marcus Gunn pupil and is helpful in diagnosing optic neuritis. Also in optic neuritis the patient claims the light is dimmer in the diseased eye as it is shined back and forth.

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NEURO-OPHTHALMOLOGY

Fig. 93 Optic neuritis with papillitis.

(a)

(b) Fig. 94 Swinging light test. (a) Both pupils constrict when light shines in normal right eye due to consensual reflex. (b) Left pupil in eye with optic neuritis dilates as light shines on it, since consensual stimulation wears off.

Fifty percent of cases of optic neuritis are due to multiple sclerosis. Multiple sclerosis is a chronic relapsing condition with a usual onset between the third and fifth decades. It is due to multiple areas of demyelination in the central nervous system (Fig. 95). Diplopia due to CN III, IV or VI paralysis or decreased vision is often the first symptom of the disease. In multiple sclerosis, optic neuritis often occurs without papillitis due to the more posterior involvement of the nerve. The next most common cause is ischemic optic neuropathy due to arteriosclerosis, diabetes, or giant cell arteritis. Less common etiologies are drug or tobacco or alcohol toxicity, folic acid or vitamin B12 deficiency, trauma, compression from orbital inflammations, tumors, or thyroid disease. Infections such as mumps, measles, and influenza rarely may be associated. Once the cause is determined, a specific treatment can be instituted.

Fig. 95 Magnetic resonance imaging (MRI) of the brain. Areas of high intensity correspond to demyelinating plaques, which are present in 90% of known multiple sclerosis cases. MRI of orbit could show thickening of optic nerve when optic neuritis is present.

The pupil Both pupils are equally round and approximately 3–4 mm in diameter. Anisocoria refers to a difference in pupil size, and 4% of normal people may have as much as 1 mm of difference. Miosis is a constricted pupil, and mydriasis is a dilated pupil. Pupil size is determined by a dilator muscle controlled by the sympathetic nerve and a constrictor muscle that has cholinergic innervation via CN III (Fig. 96).

Fig. 96 Radial fibers of dilator muscle and ring of constrictor muscle near pupillary margin.

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35

Müller's muscle

Hypothalamus

Carotid a. 1st-order neuron Superior cervical ganglion

3rd-order neuron

C8-T2

2nd-order neuron Lung Fig. 97 Sympathetic pathway.

Sympathetic nerve The iris dilator muscle and the Müller’s muscle that elevates the lid are both stimulated by the sympathetic nerve that begins in the hypothalamus (Fig. 97) and descends down the spinal column. At C8–T2 it synapses and then exits and passes over the apex of the lung. It ascends in the neck until it synapses, and follows the carotid artery into the skull and orbit. It dilates the pupil in response to the “fight or flight” stimulus. Damage to this nerve causes Horner’s syndrome (Fig. 98): miosis, ptosis, and decreased sweating (anhidrosis).

Pupillary light reflex

(Fig. 99)

Light shining on the retina stimulates the optic nerve and then the optic chiasm and optic tract. Here, it exits from the visual pathway to stimulate the Edinger–Westphal nucleus in the midbrain. The pupillary fibers leave the nucleus and travel with CN III until 36

NEURO-OPHTHALMOLOGY

Fig. 98 Right Horner’s syndrome. Associated pain on the same side is highly suggestive of a dissection of the wall of the carotid artery and should be referred immediately to the emergency room for vascular imaging. If caught early, anticoagulation may prevent a stroke.

Causes of Horner’s syndrome

Neuron I Neuron II Neuron III

Spinal chord trauma, tumors, demyelinating disease, syringomyelia Apical lung tumors, goiter, neck injury, or surgery Carotid aneurysms, migraine, cavernous sinus, or orbital disease (Fig. 116)

Fig. 99 Pupillary light reflex.

it synapses at the ciliary ganglion in the orbit. It innervates the iris sphincter muscle. Light shining in one eye causes that pupil and the pupil of the other eye to simultaneously constrict. The latter is referred to as the consensual light reflex. Both pupils also constrict when the eye accommodates from distance to near. This normal state may be noted as PERRLA—pupils equally round and reactive to light and accommodation.

Argyll Robertson pupil In syphilis, the pupils may be irregularly constricted with a decreased or absent response to light, but a normal near reflex. The pupil dilates poorly with mydriatics. Adie’s pupil (tonic pupil) This is a dilated pupil with a reduced direct and consensual light reflex. It reacts slowly NEURO-OPHTHALMOLOGY

37

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NEURO-OPHTHALMOLOGY

Morphine

Histamine release from inflammation

Aldomet

Reserpine

Iritis

Horner’s syndrome

Pilocarpine drops used for glaucoma

Irritation to constrictor muscle

Ø Sympathetic

Miosis

≠ Cholinergic

Causes of irregular pupils

Cocaine

Antihistamines

Decongestants

Anxiety

Epinephrine

Phenylephrine

≠ Sympathetic

Adie’s pupil

CN III paralysis

Atropine

Ø Cholinergic

Trauma (especially common with hyphemas)

High eye pressure >40 mmHg

Damaged constrictor muscle

Mydriasis

to accommodation, and eventually becomes smaller and stays smaller than the other eye, hence the name tonic pupil. It is due to a benign defect in the ciliary ganglion. Resulting denervation hypersensitivity causes the tonic pupil to constrict intensely compared with the other eye in response to one drop of weak pilocarpine 1/10%.

Ptosis Ptosis is a drooping lid that rests more than 2 mm below the corneal margin. Most commonly, it is an aging change due to laxity of the upper lid. It may also be a congenital defect visible at birth. However, one must be alert to a new onset of paralysis to either of the lid elevator muscles, i.e., the levator palpebral muscles innervated by cranial nerve III or Müller’s muscle innervated by the sympathetic nerve. A ptosis occurring by itself, or with diplopia, may be the first sign of myasthenia gravis, which is a myoneural junction disorder. In myasthenia gravis, the ptosis may worsen when tired, or after a provocative test such as asking the patient to look up for several minutes (Figs 100 and 101).

Fig. 100 Myasthenia gravis: no ptosis.

Fig. 101 Myasthenia gravis: ptosis after looking up for 5 minutes.

Visual field testing The field of vision of each eye extends to 170° in the horizontal and 130° in the vertical meridian. Routine testing of vision with a Snellen chart recorded as 20/20 only means that the central few degrees corresponding to the macula are normal. 1 Amsler grid. This hand-held black crosshatched card tests the central 20° of the visual field. Hold the card at 14 inches and ask the patient if he or she loses the central white dot, continuity of lines, or the corners of the square. Waviness of lines is called metamorphopsia, and is characteristic of a wrinkled retina from macular disease (Fig. 102).

Fig. 102 Amsler grid. Distortion in macular degeneration.

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39

2 A tangent screen is a sheet of black felt (Fig. 103). It measures the central 60° of field. The patient is seated 1 or 2 meters from the screen, with one eye occluded. The examiner moves a small white ball centrally until the patient first sees it. Areas blind to this small object are tested with progressively larger objects. 3 Hemisphere perimeters (Fig. 104) test the entire 170° of horizontal field and 130° of vertical field. Automated perimeters are expensive but save examiners’ time and gives record of field. Static perimeters project increasingly intense stimuli at one location until it is first seen. 4 Confrontation testing is used when instruments aren’t available. The patient is seated opposite the examiner. The patient closes his or her right eye; the examiner closes his or her own left eye, and each fixates on the other’s open eye. The examiner moves an object in from the periphery and it should be seen simultaneously by both individuals. This technique compares patient’s and examiner’s field.

Fig. 104 Automated hemisphere perimeter tests central and peripheral fields.

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Fig. 103 Tangent screen central 60°. It is useful when patients cannot perform the more difficult automated perimetry.

Scotomas due to ocular and optic nerve disease A scotoma is loss of part of the field. Relative scotomas are areas of visual field blind to small objects, but able to perceive larger stimuli. Absolute scotomas are totally blind areas.

Fig. 105 Normal blind spot.

The normal blind spot is an absolute scotoma located 15° temporal to central fixation, which corresponds to the normal absence of rods and cones on the optic disk. It is plotted first (Fig. 105). If the blind spot cannot be located, the test is considered unreliable. Central scotomas (Fig. 106) occur in macular degeneration. Central and paracentral scotomas (Fig.107) are most characteristic of optic nerve disorders.

Fig. 106 Central scotoma.

Arcuate scotomas around central fixation are most typical of glaucoma (Fig. 108). Unilateral altitudinal scotomas are defects above or below the horizontal meridian and are caused by an occlusion of a superior or inferior retinal artery or vein and retinal detachments (Fig. 109).

Fig. 107 Paracentral scotoma.

Fig. 108 Arcuate scotoma.

Fig. 110 Lesions of the visual pathway.

Fig. 109 Altitudinal scotoma.

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41

Scotomas due to brain lesions Field defects help to localize the site of brain lesions. Light focused on the temporal retina passes through the optic nerve and stimulates the occipital cortex on the same side, whereas fibers carrying impulses from the nasal retina cross over in the optic chiasm and stimulate the brain on the opposite side (Fig. 110). Therefore, defects at or posterior to the chiasm cause loss of vision in both eyes. The scotomas respect the vertical meridian and are called hemianopsias. The term homonymous refers to having the same defect in both eyes as in the homonymous hemianopsia shown below.

1 In the optic chiasm the nasal axons from each eye cross over. Pituitary tumors press on these fibers and cause a bitemporal hemianopsia.

2 Optic tract lesions cause incongruous hemianopsia, that is, unequal in each eye.

3 Optic radiation defects are often partial because the fibers are so widespread. A parietal lobe tumor damages the superior half of the left radiation, causing a right homonymous inferior quadrantopsia.

4 Occipital cortex lesions usually cause a partial homonymous hemianopsia that is often vascular in origin, but tumors, trauma, and abscesses are also common.

Color vision Color vision depends on the ability to see three primary colors: red, green, and blue. Partial defects are inherited in 7% of males

42

NEURO-OPHTHALMOLOGY

and 0.5% of females and are detected using Ishihara or American optical pseudoisochromatic plates. Loss of color vision could limit one’s ability to become an electrician, airline pilot, or other profession requiring color discrimination. Acquired color defects may be due to retinal or visual pathway disease, the most common of which is optic neuritis. In acquired cases, test each eye separately and look for differences.

Nystagmus This is an involuntary rhythmic movement of the eyes in a horizontal, vertical, or rotary fashion. Pendular nystagmus means equal motion in each direction, while the jerky type has a quicker movement in one direction than the other.

Normal types Optokinetic nystagmus is a jerky type of movement, as occurs when one watches scenery go by while riding in a car (Fig. 111). End-point nystagmus is a jerky type occurring in extreme positions of gaze. Vestibular nystagmus is due to stimulation of the semicircular canals of the ear, either by rotating the body or placing cold or hot water in the ear.

Fig. 111 Optokinetic drum that stimulates optokinetic nystagmus when rotated. Hysterics and malingerers faking total blindness cannot help but move their eyes.

Abnormal types Gaze nystagmus occurs in certain fields of gaze. It is caused by drugs such as Dilantin or barbiturates, and in demyelinating diseases, cerebral vascular insufficiency, and brain tumors. Congenital nystagmus is a pendular nystagmus starting at birth and usually causes reduced vision. If there is a position of gaze with less movement (null angle), eye muscle surgery or prisms may be tried to move this position to a straight-ahead gaze.

NEURO-OPHTHALMOLOGY

43

44

NEURO-OPHTHALMOLOGY

Fig. 112 Blood is supplied to the brain by two vertebral arteries and two carotid arteries. The circle of Willis (dark red) is a cerebral arterial circle connecting the carotid to posterior cerebral arteries. It allows collateral flow if one vessel narrows. Eighty percent of ischemic strokes originate from the carotid and 20% from the vertebral or basilar circulation.

Spasmus nutans is a unilateral or bilateral pendular nystagmus beginning at about 6 months of age and often ending by 2 years of age. It may be associated with head nodding. Blindness that begins early in life may result in pendular nystagmus.

Circulatory disturbances affecting vision (Refer to Fig. 112) The blood supply to the brain originates from the two carotid arteries in the anterolateral neck and the two vertebral arteries passing through the cervical vertebrae. Transient loss of vision in those persons younger than age 50 is often due to a migrainous spasm of a cerebral artery. This causes scintillating scotomas (Fig. 113), which are brief flashes of light and/or zigzag lines that may precede a headache. It may progress to a homonymous hemianopsia lasting for 15–20 minutes. If neurologic symptoms persist, they should go to the emergency room. In older persons, the transient blurring is more often due to arteriosclerosis and is referred to as a transient ischemic attack (TIA). These visual obscurations—also called ministrokes—are caused by cholesterol, fibrin, or calcific emboli liberated from the plaques. Symptoms occur as these emboli pass through the eye or visual cortex of the brain and usually last less than a half hour but could last up to 24 hours. If it lasts longer, it could turn into a permanent obstruction called a stroke.

Fig. 113 Scintillating scotoma from migraine progressing to a homonymous hemianopsia.

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45

If the symptoms have already cleared by the time the patient reaches your office, they should be cautioned about the risks of a permanent stroke and advised to see a neurologist within a short time. Five percent of TIAs go on to develop a stroke within a month. If the TIA is still occurring after your examination, they should be sent directly to the emergency room since it could progress to a stroke. There, they can be thoroughly evaluated to see if they meet the stringent guidelines to receive tissue plasminogen activator (tPA). There is a three hour therapeutic window from the onset of ischemic symptoms to administer this thrombolytic drug which could increase the chance of recovery from a stroke by 30–50%.

Tests for decreased circulation Patients with symptoms of transient uniocular loss of vision may be screened in the office with ophthalmodynamometry (Fig. 114). This determines the relative pressure in the retinal arteries. Pressure is applied to the anesthetized sclera until the retinal arteries on the optic disk collapse. Differences of 20% in the two eyes are evidence for carotid narrowing on one side. Listen with a stethoscope for a carotid bruit in the neck which could indicate narrowing.

Fig. 114 Ophthalmodynamometry.

If stenosis still is suspected, a non-invasive Duplex ultrasonography could show carotid stenosis and decreased blood flow. Magnetic resonance angiography (MRA) may be ordered if more detail is needed. Invasive arterial catheter angiography is infrequently used since there is a 1% chance of procedurerelated stroke (Fig. 115). The right and left cavernous sinuses in the brain drain the superior and inferior ophthalmic veins from the orbit and face. Passing through the sinuses are the internal carotid artery, cranial nerves III–VI, and the sympathetic nerve (Fig. 116). Fig. 115 Internal carotid artery narrowing.

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NEURO-OPHTHALMOLOGY

Visual disturbances due to circulation

Carotid circulation

Posterior cerebral circulation

Cause

Cardiac abnormalities or carotid atheromas cause emboli to the retina (see Fig. 328)

Neck disorders affecting vertebral artery or emboli from atheroma

Symptoms

Unilateral curtain lasting a few minutes (amaurosis fugax): rarely headache, confusion, contralateral hemiparesis

Hemianopsia in both eyes: usually history of headache, dizziness, diplopia, drop attacks, or ringing in ears

Tests

Ultrasound, MRA of carotid, ophthalmodynamometry, bruit over carotid artery in neck, cardiac evaluation

CT scan and MRI of brain (Fig. 118) with cardiac evaluation

Rx

Immediate thrombolysis (tPA), anticoagulants or balloon angioplasty, stent, or endarterectomy if 50% narrowing

Immediate thrombolysis (tPA), anticoagulants or stent

Carotid-cavernous fistulas usually result from trauma to an aneurysm of the carotid artery in the cavernous sinus (Figs 116 and 117). It connects high-pressure arterial to low-pressure venous circulation causing a pulsating exophthalmos with a bruit over the eye, and tortuous—”corkscrew”—conjunctival vessels. It must be distinguished from a cavernous sinus thrombosis which causes a non-pulsatile exophthalmos. The latter is often due to infection carried to the sinus via the superior and inferior ophthalmic veins. A carotid-cavernous fistula and a cavernous sinus thrombosis are two causes of exophthalmos that can mimic orbital cellulitis (see Fig. 154). What both conditions have in common with orbital cellulitis are conjunctival vascular engorgement and chemosis (see Fig. 190); lids that are often swollen shut; and possible involvement of cranial nerves III–VI and the sympathetic nerve. Orbital cellulitis is usually unilateral; cavernous sinus thrombosis is commonly bilateral; and carotid-cavernous fistula is unilateral unless there are large connections between the right and left sinuses. Intracranial aneurysms most often occur in arterial junctions in the circle of Willis (Fig. 112 and 116). Pressure on the third NEURO-OPHTHALMOLOGY

47

Carotid artery

Superior ophthalmic vein

Posterior communicating artery Aneurysm

Ophthalmic artery Retinal artery

III IV V VI

Cranial nerves III-VI

Orbit

Abnormal carotidcavernous fistula

Inferior ophthalmic vein

Venous cavernous sinus Sympathetic nerve

Fig. 116 Structures passing through the venous cavernous sinus are the internal carotid artery, cranial nerves (CN) III-VI, sympathetic nerve, superior and inferior ophthalmic veins, retinal and ophthalmic arteries. Note the two abnormalities. 1. carotid-cavernous fistula and 2. the posterior communicating artery with its aneurysm pressing on the cranial nerve III.

cranial nerve from an aneurysm at the junction of the posterior communicating and carotid artery may cause slowly progressive pain and signs of paralysis. Rupture of the aneurysm could result in sudden severe symptoms, including coma.

Fig. 117 Carotid cavernous fistula.

Fig. 118 The earliest tissue damage following a stroke can be demonstrated with an MRI. Note in the image above an area of increased signal intensity (white) in the occipital cortex. However, a CT scan is usually performed first in the emergency room to be sure there is no bleeding. Only then can tPA be safely administered. Courtesy of Salim Samuel, MD.

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NEURO-OPHTHALMOLOGY

External structures

Begin with the four Ls: lymph, lacrimal, lashes, and lids.

Lymph nodes Lymphatics from the lateral conjunctiva drain to the preauricular nodes just anterior to the ear. The nasal conjunctiva drains to the submandibular nodes (Fig. 119). Enlarged or tender nodes help to distinguish infectious from allergic lid and conjunctival inflammations.

Lacrimal system

Fig. 119 Lymph drainage from the eye.

The tear film is made up of an outer oily component, a middle watery layer, and a deep mucous layer (Fig. 120). With most external eye infections, the tear film is highly infectious. In AIDS, only bloody tears are so far considered infectious. In any case, wash your hands between patient examinations.

Type

Source

Oily

Meibomian glands at edge of eyelid

Watery

Constant secretion by conjunctival glands and reflex secretion by the lacrimal gland in response to ocular irritation or emotion. In this reflex, CN V is the afferent pathway and CN VII is the efferent pathway

Mucous

Conjunctival goblet cells

Fig. 120 Tear film.

49

With each blink acting as a lacrimal pump, the tear is moved nasally, where it enters the puncta and flows through the canaliculus, lacrimal sac, and the nasolacrimal duct (NLD) into the nose (Fig. 121). All eye drops are more effective and have less systemic side effects if patients press on the puncta and close the eyes for 60 seconds. This minimizes flow into the nose.

Fig. 121 Lacrimal system.

Dry eye Tear production normally decreases with age and could result in a symptomatic dry eye (keratoconjunctivitis sicca). Dryness may also occur from medications such as anticholinergics, tranquilizers, antihistamines, diuretics, or vitamin A deficiency. The latter may occur due to poor diet or malabsorption, which is increasing in incidence with the surging popularity of gastric bypass surgery used to treat obesity. Loss of vision from vitamin A deficiency may result from dessication of the cornea due to dryness or from decreased function of the rod receptors in the retina, which requires this vitamin to produce the visual pigment rhodopsin. Dry eye also occurs in autoimmune diseases such as rheumatoid arthritis, lupus, and Sjögren's syndrome (dry eye, arthritis, dry mouth). In these cases, the lacrimal gland is immunologically damaged. Patients with dry eye complain of a gritty sensation with an occasional gush of tears from 50

EXTERNAL STRUCTURES

the lacrimal gland in response to the irritated eye. The Schirmer test measures tears on the surface of the eye. A drop of anesthetic is instilled and a strip of folded filter paper is placed inside the lateral lid (Fig. 122). Less than 10 mm of moist paper in 5 minutes is presumptive of a dry eye. Dry eye is treated in the daytime with artificial tears and at night with ointments. There are many on the market. They vary mostly by their viscosity and whether they have preservatives. The patient often decides which one is best. In severely dry eyes, the puncta may be closed with punctal plugs (Fig. 123) or cautery to conserve tears. Room humidifiers may be tried and oral flaxseed oil has been shown to be of value. Restasis (cyclosporine ophthalmic emulsion) 0.05% eye drops used twice a day may increase tear production in patients with keratoconjunctivitis sicca (chronic dry eye) whose tear production is suppressed due to inflammation of the goblet cells or lacrimal gland.

Fig. 122 Schirmer test.

Fig. 123 Punctal plug. Courtesy of EagleVision.

Tearing (epiphora) Tearing is a very common complaint and often is minor enough so as not to require the work-up and treatment discussed below. There are two causes of epiphora (tearing): 1 increased tear production due to emotion or eye irritation; or 2 normal tear production that cannot flow properly into the nose.

Tearing due to failure of drainage system Once emotion and irritation are ruled out as the cause of tearing, an evaluation is made of the patency of the ducts leading into the nose. An obstruction is presumed if fluorescein dye placed on the conjunctiva (Fig. 124) disappears slowly and asymmetrically from one eye, or runs over the lid onto the cheek.

Fig. 124 (a) Fluorescein in both eyes. (b) Obstruction prevents exit of dye in left eye.

EXTERNAL STRUCTURES

51

Next, determine if the obstruction is in the puncta, canaliculus, or NLD.

A - Tearing due to punctal and canalicular obstructions 1. Ectropion (see Fig. 148)—Tear film is not in contact with everted punctum. Rx: Repair lid. 2. Visibly narrowed puncta—It may be dilated using dilator (Fig. 125b) or scissor snip. 3. Narrowed canaliculi are often due to medications and aging. The narrowed canaliculi and puncta can be dilated with progressively wider diameter punctal probes (Fig. 125a). If the lumen is still inadequate, a self-retaining bicanalicular stent (Fig. 126) can be inserted in the office with topical anesthetic and be left in place for three months. Traumatic laceration of the canaliculus can lead to an obstruction. Carefully repair tears using a pigtail probe (Figs 125c and 127a). The probe is passed through the upper puncta toward the laceration. A silicone tube is threaded onto it and it is withdrawn. The probe is then passed through the lower puncta and the other end of the silicone tube is threaded onto it and it is withdrawn forming a continuous lumen to heal over the tube. 4. Rarely, the canaliculus can be obstructed from Actinomyces israelii infection. In this case, incise canaliculus; remove sand-like concretions; and instill erythromycin ointment.

B - Tearing due to nasolacrimal duct obstructions In adults, it is often due to chronic nasal inflammation or aging. In infants, the distal opening of this duct in the nose—called the valve of Hasner—fails to open at birth. It is usually treated at 6 months to 1 year of age in infants by irrigating through the puncta to the nose (Fig. 127b) Additionally, a puncta probe can be passed through the puncta into the nose (Fig. 128). The same technique can be used in adults. If it is still narrowed, a balloon catheter may be used to widen the

52

EXTERNAL STRUCTURES

Fig. 125 (a) Punctal probe. (b) Punctum dilator. (c) Pigtail probe.

canaliculus

lacrimal sac

Fig. 126 Bicanalicular stent–for puncta stenosis or canalicularconstriction. Courtesy of FCI Ophthalmics.

Fig. 127a Repair of canalicular tear.

passage, and/or a silicone stent may be inserted through the puncta, canaliculus, and nasolacrimal duct into the nose (Fig. 129) and left in place for 4–5 months.

Fig. 127b Irrigation of nasolacrimal duct.

If it still remains closed, a new surgical opening in the nasal bone is created and the mucosa of the lacrimal sac is sutured to the nasal mucosa (dacryocystorhinostomy). Besides tearing, an additional motivation for performing the latter surgical procedure is recurring infections of the lacrimal sac (dacryocystitis; Fig. 130) caused by stagnant tear flow.

Fig. 128 Probing of nasolacrimal duct.

Fig. 129 Transnasal lacrimal stent used to dilate entire system from puncta into nose. Courtesy of FCI Ophthalmics.

Fig. 130 Dacryocystitis.

EXTERNAL STRUCTURES

53

Signs of dacryocystitis are swelling and tenderness over the lacrimal sac with pus exuding from the puncta when pressure is applied to the sac. Rx: massage the sac; nasal decongestant; local and systemic antibiotics; then a dacryocystorhinostomy to open the NLD.

Fig. 131 Shriveled skin following allergy.

Lids Lid swelling is commonly due to allergy, in which case the edema clears with a telltale shriveling of the skin between episodes (Fig. 131). Dependent edema caused by body fluid retention affects the lids on awakening and the ankles later in the day. Hypothyroidism (myxedema) and orbital venous congestion due to orbital masses or cavernous sinus thrombosis or fistulas are less common causes of edematous lids. Dermatochalasis is loose skin (Fig. 132) due to aging, and is aggravated by recurrent bouts of lid edema. There may be palpable orbital fat that herniated through the orbital septum (see Fig. 156). A surgical blepharoplasty is performed for cosmetic reasons or if resulting drooping of the lid (ptosis) obstructs vision. Lid-margin lacerations must be carefully approximated to prevent notching. Pass a 4-0 silk suture through both edges of the tough tarsal plate using the gray line for accurate alignment (Fig. 133).

Fig. 133 Lid margin. The gray line delineates the mucocutaneous junction.

54

EXTERNAL STRUCTURES

Fig. 132 Dermatochalasis.

Fig. 134 Xanthelasma.

Common skin conditions The lesions in Figs 134–138 are electively removed for cosmetic reasons. Xanthelasmas (Fig. 134) are irregular, yellowish plaques on the medial side of the upper and lower lids. They are often inherited and sometimes associated with hypercholesterolemia.

Fig. 135 Verrucas.

Verrucas (warts) (Fig. 135) are cauliflower-like growths of viral etiology; cauterize the base. Seborrheic keratosis (Fig. 136), which is common with aging, is a benign, brown, rough-surfaced growth appearing stuck on like clay thrown against a wall. Epidermoid inclusion cysts (Fig. 137) are intracutaneous benign, smooth, glistening, white balls filled with cheesy substance.

Fig. 136 Seborrheic keratosis.

Nevi (Fig. 138) are benign, nonpigmented or pigmented, well-demarcated growths from early childhood. Suspect malignancy in the following cases: growing, irregular edges, inflamed, satellites, irregular pigment, ulcerated, or bleeding. Keratoacanthoma (Fig. 139) is a benign growth that resolves spontaneously. Rolled edges with umbilicated center filled with keratin make it difficult to distinguish from squamous carcinoma, so a biopsy is sometimes indicated. Cavernous hemangiomas (Fig. 140) appear at or shortly after birth and spontaneously regress by 2–3 years of age. Usually, they are a cosmetic problem, but may cause the lid to block vision. Intralesion injection of corticosteroids, excision, or laser may be used, especially if it causes visual loss.

Fig. 137 Epidermoid inclusion cyst.

Fig. 138 Nevus.

EXTERNAL STRUCTURES

55

Fig. 140 Cavernous hemangioma. Fig. 139 Keratoacanthoma.

The lids are a common location for basal and, less often, squamous cell carcinoma of the skin (Fig. 141). All chronic, hard, nodular, umbilicated, ulcerated, vascularized lesions demand a biopsy. Cutaneous horns (Fig. 142) are keratinized overgrowths of seborrheic keratosis, verruca, or squamous or basal cell carcinoma; therefore, a biopsy of the base is indicated.

Fig. 141 Carcinoma.

Blepharitis is inflammation of the lid margin with redness and flaking (Fig. 143). It is often chronic and may be associated with allergy, seborrheic dermatitis (dandruff), or acne rosacea (Fig. 144). Infection and ulceration may result in loss of lashes. Toxins from Staphylococcus bacteria can cause marginal corneal ulcers. Rx: routine cleansing of lashes with baby shampoo and/or topical antibiotic with or without steroid. Meibomian glands may be squeezed between a sterile cotton applicator and your finger. Gland obstruction may lead to a chalazion. Chalazions are internal to the lashes and are caused by infections of meibomian glands on the lid (Fig. 145). They can become chronic granulomas. Rx: hot soaks, topical antibiotic, and sometimes local steroid. A chalazion is often incised and drained.

Fig. 142 Cutaneous horn.

Styes are pimples on the lid margin external to the lashes due to infection (Fig. 146). Rx: hot soaks, local antibiotics, incision. Systemic antibiotics are indicated if there is significant surrounding cellulitis. Lid cellulitis is a diffuse infection often due to a sty, chalazion, bug bite, or cut. Lids are red

56

EXTERNAL STRUCTURES

Fig. 143 Blepharitis.

Fig. 145 Chalazion. Fig. 144 Blepharoconjunctivitis in acne rosacea. This chronic condition is associated with engorged vessels and pustules on the nose, forehead, cheeks, and chin.

and tender (Fig. 147). There may be adenopathy and fever. Rx: topical and systemic antibiotics. Shriveled skin as in Fig. 131 is an initial indication that lid cellulitis is responding to treatment. An ectropion (Fig. 148) is an outturned lid. It is often caused by senile relaxing of the lid. This is aggravated in patients who chronically dab their tears or apply eye drops since both cause downward tugging and weakening of lid tissue. Less common causes are CN VII paralysis or traction of scarred skin on the lower lid. Correct with surgery.

Fig. 146 Sty.

An entropion (Fig. 149) is an inturned lid margin. It may be due to contraction of scarred conjunctiva, senile lid laxity, or spasm of the orbicularis oculi muscle. It is corrected with surgery. Fig. 147 Lid cellulitis.

Fig. 148 Ectropion.

Fig. 149 Entropion.

EXTERNAL STRUCTURES

57

Lashes Trichiasis (inturned lashes) (Figs 149 and 179) causes corneal irritations, and may be the result of an entropion (inturned lid), or trauma to the lid margin. Lashes can be epilated (pulled out), or the lash follicles can be destroyed with electrolysis or cryosurgery. Lashes sometimes grow under the skin (Fig. 150) and may be removed after injection of local anesthetic.

Fig. 150 Ingrown lash.

Lice on lashes cause blepharitis and conjunctivitis (Fig. 151). Rx: Kwell shampoo. Loss of lashes may be due to skin disease, drugs, thyroid disease, radiation and surgical trauma, infection, and epilation due to psychiatric reasons (trichotillomania).

Fig. 151 Crab lice (Phthirius pubis) on lashes.

58

EXTERNAL STRUCTURES

The orbit The orbit is a cone-shaped vault (Figs 152 and 153). At its apex are three orifices through which pass the nerves, arteries, and veins supplying the eye.

Fig. 152 Side view of orbit.

Fig. 153 Front view shows the apex of the orbit.

59

Clues that may indicate disease of the orbit A. Proptosis (exophthalmos)—forward bulging of the eye. B. Enophthalmos—sunken eye. C. Swollen lids (sometimes totally shut); redness and engorgement of conjunctival vessels; clear fluid under conjunctiva (chemosis). D. Loss of eye movement (ophthalmoplegia) due to involvement of cranial nerves III, IV, and VI or local damage to extraocular muscles.

Fig. 154 Orbital cellulitis with chemosis and ophthalmoplegia, causing inability to look up.

Orbital cellulitis causes the lids to be swollen shut (Fig. 154). The globe may not move (ophthalmoplegia) and there is chemosis, fever, adenopathy, and exophthalmos. It is most often due to sinusitis, but also occurs with tooth, facial or lid infections. An orbital septum connecting the lid tarsal plates to the orbital rim (see Fig. 152) acts as a barrier protecting the orbit from lid infections. Beware of the rare breakthrough. Orbital cellulitis can spread to the cavernous sinus through the superior and inferior ophthalmic veins that drain the orbit and part of the face. This could cause thrombosis and death. Rx: hospitalize the patient and treat with systemic antibiotics. Orbital fat may migrate under the conjunctiva (Fig. 155) or herniate through the septum under the skin (Fig. 156). This is only a cosmetic problem.

60

THE ORBIT

Fig. 155 Orbital fat under conjunctiva.

Fig. 156 Prolapsed fat through septum is palpable under skin.

Exophthalmos Exophthalmos (proptosis) is a protrusion of the eyeball caused by an increase in orbital contents. It is measured with an exophthalmometer (Fig. 157). In adults, unilateral and bilateral cases are most often due to thyroid disease. In children, unilateral cases are most often due to orbital cellulitis. Other causes are metastatic tumors, orbital hemorrhage, cavernous sinus thrombosis or fistulas, sinus mucoceles, or the following primary orbital tumors: 1 hemangioma; 2 rhabdomyosarcoma; 3 pseudotumor; 4 lipoma; 5 dermoid; 6 lacrimal gland tumor; 7 glioma of the optic nerve; 8 lymphoma (Fig. 158); 9 meningioma. Computed tomography (CT) scans are usually the radiologic technique of choice to evaluate orbital diseases such as fractures (Fig. 159), foreign bodies, thyroid disease (see Fig. 2), optic canal changes, and sinusitis.

Fig. 157 Exophthalmometer.

Fig. 158 Axial computed tomography (CT) of orbital lymphoma.

THE ORBIT

61

Enophthalmos Enophthalmos is a retracted globe. The most common cause is a blow to the orbit that raises intraorbital pressure, causing the thin roof of the maxillary sinus to fracture (Fig. 159). This is called a “blow-out” fracture. Associated signs may include subconjunctival hemorrhage, entrapment of the inferior rectus muscle in the fracture causing restriction of upward gaze, and vertical diplopia (Fig. 160). Hypesthesia of the cheek is due to infraorbital nerve damage. Rx: surgical insertion of silicone implant in the floor of the orbit if diplopia or enophthalmos persists.

Fig. 159 Computed tomography (CT) scan of orbital blow-out fracture (arrow).

Fig. 160 Restriction of upward gaze due to blow-out fracture.

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THE ORBIT

Slit lamp examination and glaucoma

The slit lamp projects a beam of light onto the eye, which is viewed through a microscope (Fig. 161). The long wide beam is useful in scanning surfaces such as lids, conjunctiva, and sclera. The short narrow beam is used to study fine details (Figs 162 and 163).

Cornea The cornea is the avascular, transparent, anterior continuation of the sclera. The corneal–scleral junction is called the limbus. A slit beam cross section of a normal cornea reveals the following, as shown in Figs 164 and 165. 1 anterior band: epithelium on Bowman’s membrane; 2 cross section: through stroma; 3 posterior band: endothelium on Descemet’s membrane. Corneal inflammation (keratitis) and abrasions are very painful because of the extensive number of corneal sensory fibers. (Kerat—prefix used to refer to the cornea) Corneal abrasions (Figs 166 and 167) due to trauma present with pain and a “red” eye. The de-epithelialized area stains bright green with fluorescein and a cobalt blue light. Rx: topical

Fig. 161 Slit lamp.

I

C

L

A

V

Fig. 162 Slit lamp view of anterior segment. (C, cornea; A, anterior chamber; I, iris; L, lens; V, vitreous). Courtesy of Takashi Fujikado, MD.

Epithelial Cells

Bowman’s Membrane Stroma

Endothelial Cells

Descemet’s Membrane Anterior Chamber

Fig. 163 Slit lamp beams.

Fig. 164 Cross section of cornea.

63

Fig. 166 Corneal abrasion. Fig. 165 Slit beam cross section of a cornea. A  epithelium, B  stroma, C  endothelium

cycloplegic (Cyclogel) 1%, topical broad-spectrum antibiotic and an oral analgesic with a pressure patch (two patches) or for chronic cases a bandage contact lens, which has the advantage of not restricting vision. A mild abrasion (Fig. 167) does not require as aggressive treatment as a severe one (Fig. 166). Most abrasions clear within 24–48 hours.

Fig. 167 Linear abrasions from trichiasis or particle under lid.

Topical proparacaine 0.5% anesthetizes the cornea within 20 seconds and lasts a few minutes. Never prescribe it for relief of pain since continued use damages the cornea. It is used to facilitate examination of a painful eye, prior to tonometry, and for removal of corneal foreign bodies. To remove a corneal foreign body, use a sterile needle and patch with antibiotic drops. Keratoconus (Figs 168 and 169) is a bilateral central thinning and bulging (ectasia) of the cornea to a conical shape. It is associated with folds in Descemet’s membrane. It begins between ages 10 and 30, often in allergic persons. The resulting irregular type of astigmatism corrects poorly with glasses and may need contact lenses to obtain clearer vision. Ten to twenty percent eventually require a corneal transplant. It is one of the dreaded complications of LASIK surgery. Corneal transplantation (keratoplasty) (Fig. 170) is used to replace an opaque or visiondistorting cornea with a donor cornea. Forty thousand operations a year are performed in the USA by ophthalmologists specializing in this procedure. There is a 90% success rate. 64

Fig. 168 Keratoconus.

Fig. 169 Munson’s sign: cornea indents lid when looking down. Courtesy of Michael P. Kelly.

S L I T L A M P E X A M I N AT I O N A N D G L A U C O M A

Fig. 170 Corneal transplant.

Fig. 171 Marginal corneal ulceration.

Corneal ulceration is usually due to a bacterial infection, but occasionally to a viral and rarely a fungal infection. It follows abrasions, blepharitis, or conjunctivitis. Over 50% result from contact lens wear, especially lenses worn during sleep. There is a white patch of inflammatory cells with surrounding corneal edema and conjunctivitis. Treat vigorously on an emergency basis since it almost always scars and, in the case of Pseudomonas, may perforate within one day. Marginal ulcers (Fig. 171) are most common and may be due to infection or an immune reaction to staphylococcal toxins from associated chronic blepharitis. Rx: topical hourly broad-spectrum antibiotics.

Fig. 172 Central corneal ulcer with secondary hypopyon.

Central ulcers (Fig. 172) are most ominous. Cultures are always needed, with topical broad-spectrum antibiotics used up to every 15 minutes. Hypopyon is a level of white blood cells in the anterior chamber, which is the space bounded anteriorly by the cornea and posteriorly by the iris and lens. It results from a sterile or infectious intraocular inflammation (endophthalmitis). Infectious endophthalmitis (Fig. 173) is a serious complication of intraocular surgery or a penetrating intraocular injury. A culture of the aqueous and vitreous and topical, subconjunctival, intravitreal, and systemic broad-spectrum antibiotics are started immediately to save the eye and prevent blindness.

Fig. 173 Endophthalmitis with hypopyon following cataract surgery.

A vitrectomy is often performed to prevent formation of membranes that cause vitreoretinal traction. Herpes keratitis (Fig. 174) presents with a gritty ocular sensation, conjunctivitis, and an

Fig. 174 Herpes keratitis.

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occasional fever sore on the lip. There may be small vesicles on the skin of the lids (Fig. 175). These often crust and then disappear within three weeks. On the cornea, there are linear, branching lesions called dendrites that are almost impossible to see without fluorescein dye and a slit lamp. Herpes keratitis should be treated quickly since it usually scars and could penetrate the stroma, causing a more chronic keratitis and iritis that might require the addition of topical steroids. Recurrences are common. Rx: trifluridine (Viroptic) 1% every 2 hours. Valtrex 500 mg PO BID for 5 days may be added in resistant cases. Localized superficial corneal edema (Fig. 176) has a translucent appearance, unlike an ulcer, which is opaque. In the common condition, called recurrent corneal erosion, a small patch of edema develops where the epithelium does not adhere well to Bowman’s membrane. This often follows injury, but may be spontaneous. Patients awake in the morning with pain when cells slough off, usually just below the center of the cornea. The abrasion is treated with a patch and an antibiotic. The edematous epithelium is treated with hypertonic 2% or 5% sodium chloride solution (Muro 128 2% or 5%) in the daytime and sodium chloride 5% ophthalmic ointment (Muro 128 ointment 5%) at bedtime. If sloughing continues, roughing up Bowman’s membrane with a needle (stromal puncture) increases adhesiveness of cells. Superficial punctate keratitis (SPK) (Fig. 177) is diffuse epithelial edema, which appears as punctate hazy areas that stain with fluorescein (Fig. 178). Burning pain and conjunctival redness may result. Traumatic causes include improper contact lens wear, trichiasis (Fig. 179), rubbing of eyes, ultraviolet injury from a welder’s torch, sunlamp, snow blindness, chemical injury, staphylococcal toxins, or a reaction to eye drops. SPK due to epithelial desiccation occurs with dry eyes or exposure associated with thyroid exophthalmos, over-correction in cosmetic blepharoplasty surgery, or CN VII paralysis with inability to close the eye during the day or night (lagophthalmos) (Fig. 180). 66

Fig. 175 Herpes dermatitis.

Fig. 176 Recurrent corneal erosion with localized epithelial edema.

Fig. 177 Superficial punctate keratitis, (SPK).

Fig. 178 Superficial punctate keratitis (SPK) stained with fluorescein.

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Fig. 179 Superficial punctate keratitis (SPK) from trichiasis.

Fig. 180 Lagophthalmos is a condition in which the lids don’t close completely.

Fig. 181 Severe corneal edema.

Fig. 182 Corneal edema with stria.

Full-thickness corneal edema results from diffuse and severe damage to the epithelium or endothelium, which are both responsible for maintaining stromal clarity. Endothelium is most commonly damaged during cataract surgery and less often by iritis or high intraocular pressure. Epithelial cell injury is usually due to mechanical or chemical trauma. There may be epithelial cysts, called bullous keratopathy, in severe cases (Fig. 181), or folds in Descemet’s membrane (stria; Fig. 182). Corneal edema causes the patient to see halos around lights, which is a classic symptom of angle-closure glaucoma. Rejection of lenses implanted during cataract surgery may cause permanent diffuse corneal edema and is one of the most common reasons for corneal transplant surgery. Chemical injuries with basic substances, such as lye, are the most ominous since they immediately penetrate the epithelium and scar (Figs 183 and 184). Acid burns usually do not penetrate stroma or scar. Rx: irrigate all chemical injuries immediately and profusely.

Fig. 183 Sodium hydroxide injury minutes later.

Fig. 184 Sodium hydroxide injury 3 months later.

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Corneal vascularization is a response to injury. Superficial vessels are most commonly a response to poorly fitting contact lenses (Fig. 185), but also grow into areas damaged from ulcers, lacerations, or chemicals (see Fig. 184). Deeper stromal vessels occur with congenital syphilitic interstitial keratitis. Epidemic keratoconjunctivitis (Fig. 186) is a common highly infectious condition due to one of the adenoviruses that cause the common cold. There may be a severe conjunctivitis lasting up to 3 weeks associated with photophobia, fever, cold symptoms, and an adenopathy. The main problem is the keratitis, which can last for months and, rarely, years. It does not scar but does restrict use of contact lenses until it clears. Arcus senilis is a narrow white band of lipid infiltration separated from the limbus by a clear zone (Fig. 187). It occurs in almost everyone by age 80. Its occurrence in those younger than 40 warrants measuring blood lipids, which may be elevated. Dermoid tumors (Fig. 188) are benign congenital growths often having protruding hairs. They are most common at the corneal limbus or in the orbit and may grow during puberty. They are removed if vision is threatened or for cosmetic reasons.

Fig. 185 Superficial vascularization often due to poorly fitting contact lenses. Courtesy of Michael Kelly.

Fig. 186 Epidemic keratoconjunctivitis with characteristic white punctate subepithelial opacities.

Conjunctiva The conjunctiva is a mucous membrane. The bulbar conjunctiva covers the sclera and ends at the corneal limbus. The palpebral conjunctiva lines the lids (Fig. 189). Fluid within the conjunctiva is called chemosis (Fig. 190) and is commonly seen in allergy and in rare cases of orbital venous congestion. To examine the inner surface of the upper lid, first warn the patient, then “flip the lid” as follows: 1 have the patient look down with eyes open; 2 grasp eyelashes of upper lid at their bases; 3 pull out and up on lashes while pushing in and down on upper tarsal margin 68

Fig. 187 Arcus senilis.

Fig. 188 Corneal dermoid.

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Fig. 190 Chemosis. Fig. 189 Bulbar and palpebral conjunctiva.

Fig. 192 Pinguecula.

Fig. 191 Pterygium.

(patient should continue to look down during examination); 4 to return lid to normal position, have the patient look up. A pterygium (Fig. 191) is a triangular growth of vascularized conjunctiva encroaching on the nasal cornea. Two causes are wind and ultraviolet light. It may be excised for cosmetic, comfort, or visual reasons. Recurrences of up to 30–40% are reported.

Fig. 193 Inflamed pinguecula.

A pinguecula (Fig. 192) is a common, benign, yellowish elevation of the 180° conjunctiva, usually nasal but also temporal. It is composed of collagen and elastic tissue. It occasionally becomes red, especially with allergies (Fig. 193), and, rarely, may be removed if it is chronically inflamed, if it interferes with contact lens wear, or if it is a cosmetic problem. Subconjunctival hemorrhages (Fig. 194) may be spontaneous, or result from rubbing of the eye, vomiting, coughing, elevated blood pressure, or, rarely, bleeding disorders. Recommend no rubbing, and no exercise or bearing down.

Fig. 194 Subconjunctival hemorrhage.

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Conjunctivitis causes redness with a gritty sensation. Common causes are tired eyes, pollutants, wind, dust, dryness, allergy, or infection (Fig. 195). If there is pain, it usually indicates corneal or intraocular involvement. Vascularized elevations of the palpebral conjunctiva, called papillae (Fig. 196), are a reaction to an inflamed eye most unique to giant papillary conjunctivitis and vernal conjunctivitis. Giant papillary conjunctivitis (GPC) is the most common cause for rejecting soft contact lenses. Large papillae develop under the lids, which are an immune reaction usually to mucous debris on the lenses. Rx: change to a soft contact lens that is disposed of more frequently, i.e., every two weeks or even on a daily schedule; decrease wearing time; and keep lenses especially clean. Vernal conjunctivitis is an allergic condition in which large papillae under the upper lid abrade the cornea. It occurs in the first decade and may last for years. Both GPC and vernal conjunctivitis may be treated with a topical mast-cell inhibitor such as Alamast and less often with steroid drugs. White lymphoid elevations of the conjunctiva (Fig. 197) called follicles occur as a reaction to conjunctival irritation, especially from viruses, Chlamydia, and drugs. 1 Trachoma is a severe keratoconjunctivitis due to an infection by Chlamydia trachomatis. It affects 146 million people worldwide and is responsible for blindness in 6 million people outside the USA. It begins with papillae and follicles on the superior palpebral conjunctiva. Conjunctival shortening may result in an entropion, which causes trichiasis. Inflammation of the cornea leads to superior vascularization (pannus), occasional corneal scarring, and loss of vision (Fig. 198). Rx: oral azithromycin. 2 Inclusion conjunctivitis in adults is a follicular conjunctivitis with occasional keratitis. It is also due to Chlamydia trachomatis of a different serotype than that causing trachoma. This organism is the most common sexually transmitted pathogen—and, therefore, must be ruled out in sexually active people. It is the most common cause of conjunctivitis in newborns, who acquire it passing through the birth 70

Fig. 195 Conjunctivitis.

Fig. 196 Papillae of the palpebral conjunctiva.

Fig. 197 Follicles of the palpebral conjunctiva.

Fig. 198 Corneal inflammation from trachoma.

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canal. Confirm with smear or culture. Rx: oral azithromycin, erythromycin ophthalmic ointment; treat sexual partners. Bacterial conjunctivitis often has a white– yellow discharge and is often due to Staphylococcus aureus, Streptococcus pneumoniae, and Haemophilus influenzae. It is usually treated without cultures (Figs 199 and 200). Inexpensive generic eye drops are used to treat simple infections of the conjunctiva and lids. Examples are gentamycin*, tobramycin*, sulfacetamide*, and 3rd generation fluoroquinolones such as ofloxacin and ciprofloxacin (*also comes in ointments). Newer, 4th generation fluoroquinolones, such as Zymar and Vigamox are preferred for more serious corneal ulcers and intraocular injuries and surgeries. The only fluoroquinolone ointment is the brand of ciprofloxacin (Ciloxan). Popular combination drops are bacitracin/ neomycin/polymyxin B and polymyxin B/ trimethoprim. Ointments blur vision and are most useful for bedtime use, especially on the lid margins. Two antibiotics available only as ointments are bacitracin and erythromycin.

Fig. 199 Infectious conjunctivitis.

Fig. 200 Bacterial blepharoconjunctivitis.

Chronic bacterial conjunctivitis, styes, chalazions, and blepharitis commonly occur in acne rosacea (see Figs 144 and 200). This pustular dermatitis affects the forehead, cheeks, chin, and nose. Telangiectatic vessels and bumps, especially on the nose, are pathognomonic. Viruses cause half the infectious cases of conjunctivitis. There is usually a watery discharge associated with “cold symptoms” and a swollen preauricular node. It is often treated with antibiotics since it is difficult to be sure the infection is not bacterial and cultures are not usually practical. Antibiotic–steroid combinations, such as Tobradex, may relieve symptoms, but could aggravate an atypical herpes simplex infection.

Fig. 201 Kaposi’s sarcoma of conjunctiva.

Allergic conjunctivitis is a condition associated with itching, slight conjunctival injection, stringy mucous discharge, chemosis, and puffy lids. Treatment begins with avoidance of known irritants, discontinuing make-up, and applying cold compresses. Over-the-counter eye S L I T L A M P E X A M I N AT I O N A N D G L A U C O M A

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drops often bring sufficient relief. They may contain varying combinations of antihistamine, zinc astringent, and decongestant. The latter ingredient may dilate the pupil and cause an attack of angle-closure glaucoma in patients with an untreated narrow angle. Therefore, if decongestants are recommended, caution the patient to call if they experience eye pain, blurring of vision, or increased redness.

Fig. 202 Kaposi’s sarcoma of skin.

Zaditor (ketotifen) is one of a group of drugs that have antihistamine, mast cell stabilizer and eosinophil inhibitor actions. It is the first of the group to change from prescription to over-the-counter status and may be used one drop twice a day to relieve allergic symptoms. If symptoms still persist, a non-steroidal antiinflammatory (NSAID), such as Acular may be used. An anti-inflammatory steroid such as Alrex is usually used last for severe or recalcitrant cases. Kaposi’s sarcoma (Figs 201–203) is a malignancy seen most often in AIDS. There is a nontender purple nodule on the skin or conjunctiva. Rx: radiation or excision.

Fig. 203 Kaposi’s sarcoma of skin (Fig. 202) treated with radiation. Courtesy of Jerry Shields.

Conjunctival nevi (Fig. 204) are common. Malignant transformation of nevi to melanomas is rare. Malignant transformation is suggested by satellites, rapid growth, elevation, and inflammation (Fig. 205).

Fig. 204 Conjunctival nevus.

Conjunctivitis

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Viral

Bacterial

Allergic

Onset

Acute

Acute

Intermittent

Associated complaints

Often sore throat, rhinitis, fever

Often none

History of allergy; nasal or sinus stuffiness, dermatitis

Discharge

Watery

Thick, yellow

Stringy mucus

Preauricular node

Common

In nonpurulent

None

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Sclera The sclera is the white, fibrous, protective outer coating of the eye that is continuous with the cornea. The episclera is a thin layer of vascularized tissue that covers the sclera. Episcleritis is a localized, elevated, and tender inflammation of the episclera (Fig. 206). It lasts for weeks and may be suppressed with topical steroid if painful. It is a nonspecific immune response to surface irritants, but, infrequently, occurs in gout, syphilis, rheumatoid arthritis, and gastrointestinal disorders. Scleritis is a severe inflammation of the sclera that may cause blindness. It is often painful and is most commonly associated with systemic immune diseases such as lupus erythematosus or rheumatoid arthritis. Anterior scleritis is associated with visible engorgement of vessels deep to the conjunctiva (Fig. 207). Posterior scleritis causes choroidal effusions and even retinal detachments. Corticosteroids and antimetabolite therapy are often required.

Fig. 205 Conjunctival melanoma.

Fig. 206 Episcleritis.

A blue sclera is due to increased scleral transparency, which allows choroidal pigment to be seen. It occurs normally in newborns, and abnormally in osteogenesis imperfecta, or following scleritis in rheumatoid arthritis, in which case the sclera is so thin it could rupture—scleromalacia perforans (Fig. 208). A staphyloma is a localized ballooning of thinned sclera in rheumatoid arthritis, high myopia, glaucoma, or trauma (Fig. 209).

Fig. 208 Rheumatoid arthritis with thin sclera.

Fig. 207 Scleritis.

Fig. 209 Staphyloma in rheumatoid arthritis.

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Glaucoma Cornea Schlemm’s Canal

Glaucoma is a disease of the optic nerve most likely due to a compromised blood supply. The nerve can be damaged even more by elevated intraocular pressure pushing on the blood vessels supplying the nerve and causing a further reduction in blood flow. Intraocular pressure is maintained by a balance between aqueous inflow and outflow. The aqueous produced by the ciliary body passes from the posterior chamber (the space behind the iris) through the pupil into the anterior chamber (Fig. 210). It drains through the trabecular meshwork and out of the eye through the venous canal of Schlemm.

Trabecular Meshwork

Iris

Lens Ciliary Body

Fig. 210 Aqueous flow from ciliary body to Schlemm’s canal.

Glaucoma vs. glaucoma suspect Normal intraocular pressure is 10–20 mmHg and should be measured at different times of day as there is a diurnal rhythm. Pressure greater than 28 mmHg should be treated to prevent loss of vision. Treat pressures of 20–27 mmHg when there is loss of vision, damage to the optic nerve, or a family history of glaucoma. Patients with pressures of 20–27 mmHg without these findings are called glaucoma suspects and are followed, but not treated.

Fig. 211 Goldmann tonometer.

Infrequently, the optic nerve could be damaged even when the pressure is less than 20 mmHg (normal tension glaucoma) and must be further reduced to the low teens. Several instruments can be used to indirectly measure intraocular pressure by indenting the cornea. A Goldmann applanation tonometer (Fig. 211) is the most accurate. It is used in conjunction with a slit lamp, and requires the use of anesthetic drops and fluorescein dye. A Schiötz tonometer is a portable instrument (Fig. 212) that indents the anesthetized cornea and is used for bedside measurements. The air-puff tonometer tests the pressure by blowing a puff of air at the eye. It is used by 74

Fig. 212 Schiötz tonometer.

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technicians since it does not require eye drops or corneal contact. With all three instruments, the tonometric pressure reading is only an estimate of the real pressure. A thick cornea requires extra force to indent and, therefore, gives a falsely elevated reading, and the opposite is true with thin corneas. To better approximate the real pressure—especially in glaucoma suspects where exactitude is important—an ultrasonic pachymeter is used to measure corneal thickness. A conversion factor for corneal thickness then adjusts the tonometric reading upward or downward.

Fig. 213 Normal trabecular meshwork: grade 4 angle as seen with a goniolens.

The iridocorneal angle Aqueous exits from the eye through the trabecular meshwork (Fig. 213) which is the tan to dark brown band at the angle between the cornea and iris. The angle, normally 15–45%, can be estimated with a slit lamp (Figs 214 and 215) but a goniolens (Fig. 216) is more accurate. In open-angle glaucoma, the trabecular meshwork and the canal of Schlemm are obstructed, whereas in narrow-angle glaucoma, the space between the iris and cornea is too narrow so that aqueous cannot reach the trabecular meshwork. A narrow angle at risk of closing is graded 0–2. Angles of 3–4 are considered wide open with no chance of closing (Fig. 217).

Fig. 214 Narrow angle in short hyperopic eye.

Fig. 215 Deep anterior chamber with wide open angle in long myopic eye.

Fig. 216 Trabecular meshwork seen with goniolens.

Fig. 217 Grading angle by progressive widening from 0–4.

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Fig. 218 Schematic cross section of retina.

The Optic Disk In the center of the optic disk is a cup that is usually less than one-third the disk diameter, although larger cups can be normal. As the pressure damages the nerve (Figs 221–223). 1 cup/disk ratio increases; 2 cup becomes more excavated and often unequal in the two eyes; 3 vessels shift nasally; 4 disk margin loses capillaries, turns pale, with infrequent flame hemorrhage (Fig. 221); 5 diffuse loss of retinal nerve fiber layer (Figs 220 and 223).

Fig. 219 Drawing of retinal nerve fiber layer with 1.2 million ganglion cell axons converging to make up the optic nerve (ON).

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Fig. 220 “Red-free” photograph of glaucomatous cupping and loss of retinal nerve fiber layer (white arrows). The dark area with loss of striations is pathognomonic of fiber loss if it fans out and widens further from disk. Courtesy of Michael P. Kelly.

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Fig. 221 Optic cup/disk ratio. (a) C/D  0.25; (b) C/D  0.40; (c) C/D  0.70 with hemorrhage; (d) C/D  0.90.

The optic disk changes can be followed by accurate drawings or photographs. Recently introduced, laser scanning tomography is more expensive but more accurately measures the three-dimensional changes in the optic disk (Fig. 222). Scanning laser polarimetry

Fig. 222 Scanning laser optic disc topography with red color indicating progressive cupping over 3 year period. Courtesy of Heidelberg Engineering, Inc.

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Pilocarpine

Timolol and Dorzolamide

Cholinergic ≠Aqueous outflow

Combination*

Cosopt

Pilocar

Diamox

* Xalatan, Lumigan, or Travatan, combined with Timolol awaiting approval in USA.

Acetazolamide

Azopt

Brinzolamide

Oral ØAqueous secretion

Trusopt

Dorzolamide

Carbonic anhydrase inhibitor Topical

Alphagan P

Brimonidine 0.2%

Alpha adrenergic agonist ØAqueous secretion ≠Aqueous outflow

Xalatan Travatan Lumigan

Latanoprost Travoprost Bimatoprost

Prostaglandin analogue ≠Aqueous outflow

Timoptic, Betimol 0.25% & 0.50% Timoptic-XE 0.25% & 0.50%

Timolol Timoptic gel

0.5 % and 2%

0.5–6.0%

250 mg 500 mg tablet

1% ophth sol

2% ophth sol

0.1% 0.15%

0.005% 0.004% 0.03%

0.25%

Betopic S

Betaxolol

Concentration

Beta-blocker ØAqueous secretion

Trade name

Generic name

Class and action

Common glaucoma medications and side effects

Could suppress bone marrow

Frequent allergy

Darkening and lengthening of eyelashes, with hyperpigmentation of iris and periocular (eyelid) skin (Fig. 6). Also iritis, macular edema, and conjunctivitis

Slows heart rate Aggravates respiratory conditions Betoptic is cardioselective with least systemic side effects

Comment

BID

QID

Convenient

Retinal detachment, cataracts, small pupil, brow ache

250 mg (QID) Could suppress 500 mg (BID) bone marrow

TID

TID

TID

HS

BID QD

BID

Dosage

measures changes in the thickness of the nerve fiber layer around the disk (Fig. 223). The latter test may be most useful for initial diagnosis. It is argued that if you wait for field defects before starting treatment, half the nerve fiber layer may already have been lost.

Healthy retinal nerve fiber layer

Visual field defects pathognomonic of glaucoma (Fig. 224) 1 Bjerrum’s scotoma extends nasally from the blind spot in an arc. 2 Island defects could enlarge into a Bjerrum’s scotoma. 3 Constricted fields occur before loss of central vision. 4 Ronne’s nasal step is loss of peripheral nasal field above or below horizontal.

Moderate retinal nerve fiber loss

Therapy for open-angle glaucoma

Severe retinal nerve fiber loss Thickness Map Legend (microns)

The goal is to lower pressure below 20 mmHg, or at least to a level where there is no further loss of visual field or increase in cupping. Each patient should have a target pressure we try to attain and it is lowest in severe glaucoma. If optic nerve damage continues to progress even when pressures are maintained in the high teens, it is referred to as normal-tension glaucoma. The pressure in these eyes must be further decreased to the low teens. It may require a combination of medications, one from each of the classes on the preceding page or the addition of a surgical procedure (Figs. 225–230).

0

20

40

60

80

100 120 140 160 180 200

Fig. 223 Color-coded GDx scanning laser polarimetry showing loss of thicker (yellow) nerve fiber layer over several years. It should be noted that the nerve fiber layer is normally thickest inferiorly then superiorly, followed by nasal, and then temporal. This can be remembered by the acronym ISN’T. Courtesy of Carl Zeiss Meditec, Inc.

Surgical procedures for openangle glaucoma If maximum medical therapy does not control the pressure, surgery can be performed to increase aqueous outflow or less often to reduce aqueous secretion. Argon laser

Fig. 224 Visual field defects in glaucoma.

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Trabeculectomy

C

Routes of aqueous flow

T

I P

Fig. 226 Surgical trabeculectomy showing aqueous flow from cilliary body through iridectomy and scleral tunnel. It exits eye under conjunctiva.

Fig. 225 Argon laser trabeculoplasty. Up to 100 burns (white discoloration) may be applied to the junction of the pigmented and nonpigmented trabecular meshwork around the entire 360 circumference. The pressure lowering effect is likely due to the contraction of tissue around the trabecular meshwork stretching open the drainage pores. C, cornea; T, trabecular meshwork; I, iris; P, pupil.

trabeculoplasty, which increases outflow, is often a first choice (Fig. 225). If pressure is still too high, a surgical hole is created at the limbus (trabeculectomy) to drain aqueous through the sclera and under the conjunctiva (Figs 226 and 227). The trabeculectomy could be repeated if the hole closes. If still unsuccessful, a tube could be implanted connecting the anterior chamber and subconjunctival space (Fig. 228). Usually, as a last resort, if the pressure is still too high, reduction of aqueous secretion may be achieved by destroying some of the ciliary processes. To accomplish this, transscleral cryotherapy or laser therapy may be applied externally 1.5 mm posterior to the limbus which is the area directly overlying the ciliary processes (Fig. 229). A newer technique called endoscopic cyclophotocoagulation is performed by entering the eye and has the advantage of destroying the ciliary processes with a laser under direct visualization (Fig. 230). However, it does have the added risk associated with intraocular surgery. 80

Fig. 227 Trabeculectomy: surgical fistula from anterior chamber to subconjunctival space.

Fig. 228 Ahmed glaucoma valve. Tube in anterior chamber drains aqueous to subconjunctional space. Courtesy of New World Medical, Inc.

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Limbus Cryoprobe

Ciliary processes

Fig. 229 Transscleral cryotherapy to partially destroy ciliary processes.

Ciliary process

Lens

Pars plana

Retina

Fig. 230 Endoscopic cyclophotocoagulation for partial destruction of aqueous secreting ciliary processes. One probe consisting of a light source, laser, and camera is usually inserted into the eye near the corneal limbus although a pars plana site may be used. Anywhere from 170–280 is usually treated.

Angle-closure glaucoma Angle-closure glaucoma usually occurs in hyperopic eyes that are short with crowded anterior segments. The iris in these eyes is closer to the cornea (see Figs 214–217). The resulting narrow angle becomes even more narrow when the pupil becomes mid-dilated. In this position, there is maximum contact between the iris and lens preventing the aqueous from reaching the anterior chamber and the trabecular meshwork. This ”pupillary block’’ traps aqueous behind the iris and pushes the iris forward even more until the angle is totally closed. The total closure of the angle causes a sudden elevation in pressure, often exceeding 60 mmHg. This pressure damages the pupil, causing it to remain fixed and dilated. S L I T L A M P E X A M I N AT I O N A N D G L A U C O M A

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Symptoms include pain, blurred vision, halos, and nausea. Signs include a mid-dilated nonreactive pupil, corneal edema, and a reddened conjunctiva (Figs 231 and 232). The pupil dilation precipitating this attack may be caused by catecholamine release associated with stress, or darkness, antihistamines, anticholinergics, sympathomimetics, and major tranquilizers. Treatment of angle-closure glaucoma first requires lowering of the pressure. It may require oral Diamox and topical drops always including pilocarpine 1% so the pupil constricts. If the pressure still remains too high, a short acting hyperosmotic agent such as mannitol 20% i.v. or oral glycerine 50% may be administered. Both draw fluid out of the eye by increasing the osmolarity of the blood. Once the attack is arrested, the corneal edema clears so that a laser iridotomy can be performed (Fig. 233). This allows aqueous to flow into the anterior chamber and bypass the pupillary block. It is often a permanent cure.

Fig. 231 Acute angle-closure glaucoma with dilated pupil.

Fig. 232 Angle-closure glaucoma: shallow anterior chamber and corneal edema.

Common types of glaucoma

Primary open-angle

Angle-closure

Occurrence

70% of all glaucomas

10% of all glaucomas

Etiology

Unknown obstruction in trabecular meshwork, usually inherited; increases with age

Closed angle increases with age and hyperopia

Symptoms

Usually asymptomatic

Red, painful eye; halos around lights; nausea

Signs

Elevated pressure Increased disk cupping Visual field defect

Markedly elevated pressure Steamy cornea Fixed, mid-dilated pupil Conjunctival injection

Treatment

Usually eye drops

Laser iridotomy

Contraindicated medications

Corticosteroids—high doses or long-term use mandate pressure testing

Pupil dilators such as adrenergics, anticholinergics, antihistamines, major tranquilizers*

*Patients may be treated with these medications once the laser iridotomy is performed. When in doubt, call their ophthalmologist.

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Less common types of glaucoma, called secondary open-angle glaucoma, could be caused by blockage of the trabecular meshwork by pigment (Fig. 234), hemorrhage, inflammatory cells (as in iritis), pseudoexfoliation (Fig. 235), or scarring from rubeosis iridis (Fig. 236). The trabecular meshwork may be covered with a membrane in the case of infantile glaucoma.

Fig. 233 Peripheral iridotomy at 2 o’clock.

Trauma could cause glaucoma by tearing the iris at its insertion on the ciliary body. Often, there is associated bleeding in the anterior chamber (Fig. 237) referred to as a hyphema. Complications of hyphema include rebleeds, associated retinal damage, and glaucoma. Rx: bilateral patch and absolute bedrest for 5 days.

Fig. 234 Pigmentary glaucoma.

Fig. 236 Rubeosis iridis. These abnormal iris blood vessels scar the angle of the eye. They most often result from ischemic retinal diseases such as proliferative diabetic retinopathy and central retinal artery or vein occlusion.

Fig. 235 Pseudoexfoliation is identified by white flakes seen on the anterior lens capsule, pupillary margin, zonules, and trabecular meshwork. It is relatively common and is associated with an increased incidence of glaucoma and weakened zonules which could complicate cataract surgery.

Fig. 237 Hyphema with large iris disinsertion (dialysis) from its root.

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Gonioscopy may reveal angle recession (Fig. 238) in which the iris insertion is shifted posteriorly, exposing a wide band of darkly pigmented ciliary body. Patients should be monitored indefinitely for glaucoma. One type of juvenile glaucoma is Sturge– Weber syndrome (Fig. 239) in which there is also angiomatosis of the face and the meninges with cerebral calcifications and seizures.

Uvea

(Figs 240 and 241)

Fig. 238 Angle recessed posteriorly following traumatic hyphema. The recessed angle is seen as a wide dark band between the cornea and the iris.

The uvea is composed of the iris, ciliary body, and choroid. All three are contiguous, and contain pigmented melanocytes. The ciliary body is made up of the pars plicata and the pars plana (Figs 242 and 243). The pars plicata is anatomically the root of the iris. It

Fig. 239 Sturge–Weber syndrome.

Fig. 240 The uvea is made up of the iris, ciliary body, and choroid. Fig. 241 Uvea. Courtesy of Stephen McCormick.

Fig. 242 Ciliary body.

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Fig. 243 Ciliary muscle focusing lens.

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comprises ciliary processes that secrete aqueous, and the ciliary muscle, which focuses the lens by decreasing the tension on the zonules (Fig. 243). The pars plana is the flat structure connecting the pars plicata with the retina. Because it is relatively avascular, it can be used as the site to enter the eye in vitreous and retinal surgery.

Malignant melanoma A melanocyte tumor is the most common primary intraocular malignancy. It is unilateral and develops from the choroid in 85% of cases, the ciliary body in 9%, and the iris in 6%. Choroidal lesions are elevated and usually slate gray, but may be white to black with yellow–gold and uneven pigmentation (Figs 244–246) unlike a benign nevus, which is usually a more uniform gray color and flat (Fig. 247). This must be distinguished from metastatic carcinoma to the eye, which is also most common in the choroid but is usually lighter in color. Most often the primary site is the breast or lung.

Fig. 244 Malignant choroidal melanoma.

Fig. 245 Gross section of malignant melanoma treated with removal of eye (enucleation). An alternative treatment for smaller lesions is the placement of an episcleral radioactive plaque under the tumor or infrared laser treatment called “transpupillary thermal therapy.” The latter two may preserve vision.

Sclera

Vitreous

Choroidal Melanoma

Fig. 246 B-scan ultrasound of a malignant choroidal melanoma showing typical domeshaped growth which helps to confirm the diagnosis. The scan also shows its size and whether it extends beyond the sclera which will determine the type of treatment. This eye, with this massive tumor, was enucleated.

Fig. 247 Benign choroidal nevus.

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Benign iris freckles (Fig. 248) and nevi are common, whereas malignant iris melanoma (Figs 249 and 250) is extremely rare. Lesions become more suspicious if they are growing, elevated, vascularized, distort the pupil, or cause inflammation, glaucoma, or cataracts. Rubeosis iridis is a serious condition in which abnormal vessels grow on the surface of the iris (Fig. 251) in response to ischemia associated with central retinal vein occlusion proliferative diabetic retinopathy, or carotid artery occlusive disease. Laser photocoagulation of the retina may cause regression of iris vessels. Untreated, the neovascularization causes a severe glaucoma.

Fig. 248 Benign iris freckle.

An iris coloboma (Fig. 252) is due to failure of embryonic tissue to fuse inferiorly. It may also involve the choroid, lens, and optic nerve.

Anterior uveitis This is an inflammation of the iris (iritis) and ciliary body (cyclitis). Cyclo- is a prefix referring to the ciliary body. It causes ocular pain, tearing, and photophobia. Signs include miosis (small pupil), perilimbal conjunctival injection (Fig. 253), and anterior chamber flare and cells (Fig. 254), Flare refers to the beam’s milky appearance due to elevated protein. With the slit lamp on high magnification and a short bright beam shining across the dark pupil, grade cells from barely visible (trace) to very many (4).

Fig. 251 Rubeosis iridis.

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Fig. 249 Malignant iris melanoma with elevated lesions and distorted pupil.

Fig. 250 Gonioscopic view of elevated iris melanoma. Courtesy of Michael P. Kelly.

Fig. 252 Iris coloboma.

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Keratitic precipitates are deposits of inflammatory cells and protein on the corneal endothelium (Figs 255 and 257). Cyclitis typically reduces eye pressure, since the ciliary body secretes the aqueous, but in severe iritis eye pressure may become elevated if cellular debris obstructs the trabecular meshwork. Another complication of uveitis is posterior synechiae. These are adhesions between the iris and the lens capsule (Fig. 255). To prevent this, the pupil is kept dilated and steroids are given to prevent a fibrinous sticky aqueous. Treatment for iritis includes a topical cycloplegic such as cyclogel 1% and a steroid such as Pred Forte 1%. Frequency and strength of medication depends on the severity of the condition. Besides dilating the pupil, the cycloplegic also relieves the pain due to ciliary spasm. This same action prevents accommodation of the lens, making this drug also useful in refracting children. Shorter acting anticholinergics are also used to dilate the pupil prior to retinal examination. Iritis or cyclitis is caused most often by intraocular surgery, blunt ocular trauma, and corneal ulcers, abrasions, and foreign bodies. Next in frequency of causation is the finding of human leucocytic antigen 27 (HLA-27) on blood tissue typing. It occurs in about 25% of patients with anterior uveitis and no associated disease. But HLA-27 is sometimes positive in patients with ankylosing spondylitis (males with arthritis of lower spine), juvenile

Fig. 253 Iritis (see Fig. 257).

Fig. 254 Slit-beam view of flare and cells in anterior chamber.

Fig. 255 Keratitic precipitates and posterior synechiae.

Anticholinergic

Action time

Primary use

Atropine 0.5–1%

±2 weeks

Prolonged or severe anterior uveitis

Scopolamine 0.25% (hyoscine 0.25%)

±4 days

Alternative when allergic to atropine

Homatropine 2–5%

±2 days

Anterior uveitis

Cyclopentolate (Cyclogel) 1–2%

±1 day

Cycloplegic retinoscopy; rapid onset (30 min)

Tropicamide (Mydriacyl) 0.5%

±6 hours

Often used with phenylephrine 2.5% for pupil dilation. This combination blocks the pupillary sphincter muscle and stimulates the dilator muscle.

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Iritis

Keratitic precipitates

Conjunctivitis

Angle-closure glaucoma Fig. 257 Characteristics of three causes of an inflamed eye

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rheumatoid arthritis, Reiter’s syndrome (young males with urethritis and conjunctivitis), and inflammatory bowel disease. HLA27 negative causes are toxoplasmosis, sarcoidosis, Lyme disease, influenza, lymphoma, AIDS, herpes simplex and zoster (shingles), and Behc¸et’s disease (ulcers in the mouth and genitals). There are other even rarer etiologies. Therefore, careful clinical judgement is needed in determining the timing and extent of the work-up, taking into consideration cost, severity, chronicity, and associated medical history.

Fig. 256 Band keratopathy.

Patients with juvenile rheumatoid arthritis and chronic iritis often develop a band of superficial corneal calcification known as band keratopathy (Fig. 256). It also occurs in sarcoidosis and hypervitaminosis D and may be removed with chelation. Characteristics to help distinguish iritis from two other important causes of a red eye are given in Fig. 257 on preceding page.

Posterior uveitis (choroiditis) (Fig. 258) Posterior uveitis is characterized by white exudates on the retina, sometimes obscured from view by cells extending into the vitreous. It leads to chorioretinal atrophy with pigment mottling (Fig. 259). Often no cause is found, but the following etiologies should be considered. 1 Bacterial: syphilis, tuberculosis. 2 Viral: herpes simplex, cytomegalovirus in 25% of AIDS patients. 3 Fungal: histoplasmosis, candidiasis. 4 Parasitic: Toxoplasma, Toxocara. 5 Immunosuppression: AIDS predisposes to several of above. 6 Autoimmune: Behçet’s disease (mouth and genital ulcers with dermatitis); sympathetic ophthalmia. Sympathetic ophthalmia refers to a traumatic or surgical injury to the uvea of one eye causing an immune uveitis in the uninvolved eye. A penetrating injury involving

Fig. 258 Toxoplasma gondii choroiditis often reactivates next to old lesion.

Fig. 259 Old toxoplasmosis scar: sclera visible through atrophic retina and choroid.

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Fig. 260 Fish hook in eye.

Fig. 261 Ruptured globe through sclera and cornea with prolapse of iris and ciliary body.

Fig. 263 Enucleated socket with scleral prosthesis.

Fig. 262 Penetrating injury through iris and lens capsule with secondary cataract.

the uvea is referred to as a ruptured globe (Figs 260–262). Handle the eye with minimal probing. Place the patient at rest with bilateral shields that exert no pressure and call the eye surgeon immediately. If the uvea or retina are extruded from the eye and it cannot be repaired, the eye is removed (enucleated). A spherical prosthesis is then placed in the orbit and covered with conjunctiva (Figs 263–265). A removable scleral prosthesis painted to match the other eye is placed on the conjunctiva. Enucleation should be performed within 10 days of the injury to prevent sympathetic ophthalmia. Treatment of choroiditis is directed at the specific cause if one can be found. 90

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Fig. 264 Silicone orbital implant with scleral prosthesis. Courtesy of Integrated Orbital Implants, Inc.

Fig. 265 Porous hydroxyapatite implant allows ingrowth of blood vessels to prevent migration or extrusion. Addition of the peg allows more normal movement, but has more complications. Courtesy of Integrated Orbital Implants, Inc.

Posterior uveitis (choroiditis) often requires subconjunctival, intravitreal, or systemic steroid, especially when it threatens the macula, optic nerve, or the associated vitritis is a potential source of membrane formation. Uveitis that does not respond to steroids is treated with antimetabolites. Aside from their use in uveitis, steroids are also commonly used to treat post-operative inflammation, conjunctivitis, keratitis, scleritis, episcleritis macular edema, giant cell arteritis, Grave’s orbitopathy, et al. They may be given orally, by eye drop, subconjunctival injection and intravitreal implant or injection. Choose the route and lowest dosage to minimize side effects. S L I T L A M P E X A M I N AT I O N A N D G L A U C O M A

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Local side effects of corticosteroids include cataracts, glaucoma, and activation of herpes keratitis. Systemic side effects include reduced immunity, osteoporosis, or exacerbation of diabetes or gastric ulcers. Topical nonsteroidal anti-inflammatory drops (NSAIDs) such as Xibrom, Acular, and Nevanac are less effective and may be used as an alternate treatment or added to steroid, especially in glaucoma patients since they don’t elevate eye pressure.

Fig. 266 Hazy view of toxoplasmosis choroiditis due to white cells in the vitreous.

Vitreous The vitreous is a clear gel made up of collagen fibrils. White cells in the vitreous (Fig. 266) are found in uveitis, endophthalmitis, or papillitis. Red cells are seen in vitreous hemorrhages, which occur most often with diabetic retinopathy. Retinal holes, detachments, and trauma are less common causes (Fig. 267). Fine reddish vitreous debris (“tobacco dust”) liberated by the retinal pigment epithelium may be seen with a slit lamp and should alert one to a possible retinal hole or detachment. The vitreous normally shrinks and liquifies with aging. This may cause a posterior vitreous detachment (Fig. 268a) and fibrillar opacities to form within the vitreous. Patients complain of shifting cobweb-like floaters in their field of vision. As the vitreous shrinks, it may create traction on the retina, especially where it is normally adherent to retina near the ora serrata and macula. This may cause a retinal hole and subsequent detachment. Therefore, in all patients with recent onset of floaters, a dilated retina examination is required. Less common causes of floaters are asteroid hyalosis (Fig. 268b), in which calcium phospholipid crystals deposit in the vitreous for no apparent reason, and synchysis scintillans, where similarly appearing crystals of cholesterol are suspended in the vitreous, often following severe ocular disease. Ophthalmoscopically, both of these appear like stars in the galaxy and are benign, requiring no treatment. 92

Fig. 267 Blunt trauma causing retinal hemorrhage referred to as commotio retinae. Hemorrhage may extend into vitreous.

Fig. 268a Posterior vitreous detachment.

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B-scan ultrasound is valuable in evaluating the status of the posterior segment of the eye when it cannot be visualized because of a cloudy cornea, lens, or vitreous hemorrhage (Fig 269). It is also used in determining whether an intraocular tumor or trauma has penetrated the sclera. A-scan ultrasound measures the length of the eye. This length, together with the corneal curvature as determined with a keratometer, is used to calculate the power of the intraocular lens implant used in cataract surgery. A-scan also measures corneal thickness for more accurate tonometry measurements in glaucoma.

Pars plana vitrectomy

Fig. 268b Slit lamp view of asteroid hyalosis, with lens seen on left and vitreous on right.

(Fig. 270)

Vitreous surgery is often performed using three sites of incision through the sclera and anterior pars plana. This avoids the highly vascular ciliary processes, attachments of the vitreous base, and the delicate retina. The entry sites are located on the sclera by measuring about 3.5 mm posterior to the limbus. One site is for endoillumination. The second is for irrigation with balanced saline to replace any vitreous removed. The third site is for instruments which can cut and remove vitreous; remove membranes, obtain tissue for cytology or culture, inject medications, gas, or silicone oil, cauterize or laser photocoagulate the retina, and forceps and magnets to remove foreign bodies. These procedures are performed while looking through a microscope with a contact lens on the cornea.

L

VH R

S

Fig. 269 B-scan ultrasound of retinal detachment (R) with vitreous hemorrhage (VH), posterior surface of lens (L), and sclera (S).

Ciliary processes 3.5mm 3.5m

Retina

Pars plana

Fig. 270 Pars plana vitrectomy

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B D

A C

E

Fig. 271 Slit lamp view of lens: A-cornea, Banterior capsule, C-nucleus, D-posterior cortex, E-posterior capsule. Courtesy of Takashi Fujikado, MD.

Fig. 272 Anterior cortical spokes (cuneiform).

Cataracts The lens consists of an outside capsule surrounding a soft cortical substance and a hard inner nucleus (Fig. 271). A cataract is a cloudy lens. It should be suspected when the patient complains of blurry vision and there is a hazy view of the retina with an ophthalmoscope. The diagnosis is confirmed with a slit lamp and described in one of the following ways. 1 By etiology: usually aging, but may be hastened by steroids, radiation, ultraviolet light, diabetes, and trauma (especially perforation of capsule; see Fig. 262). There is twice the incidence in cigarette smokers. 2 By age of onset: congenital, juvenile, adult, senile. 3 By location in lens: cortex (Fig. 272). nucleus, or posterior subcapsule (often due to steroids; Fig. 273). 4 By color or pattern: cuneiform (spokes); zonular congenital type, involves one layer usually in or around the nucleus, and is often nonprogressive (Fig. 274), brunescent (brown), often hard and difficult to break up with phacoemulsification (Fig. 275). A cataract raises two questions. Is it responsible for the decreased vision? Is it ripe? Ripe is the layman’s term for whether surgery is indicated. In most cases, a surgeon waits for a

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Fig. 273 Posterior subcapsular cataract.

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Fig. 275 Brunescent cataract.

Fig. 274 Congenital (zonular) cataract surrounded by clear cortex.

reduction in vision of 20/50 or worse, but indications vary with the patient’s needs. Surgery is usually elective except in the case of a mature lens that might rupture or is already leaking (Fig. 276) or a dislocated lens in imminent danger of dropping into the vitreous or anterior chamber. Lens dislocation (Fig. 277). is due to rupture of the zonules. It occurs with trauma or may be associated with Marfan’s disease, homocystinuria, or syphilis. Cataract surgery is performed as an outpatient procedure using local anesthesia. The cornea is entered with a blade making a 3 plane incision to minimize chance of leakage and eliminate or decrease the number of sutures needed for closure (Fig. 278). The anterior lens capsule is then removed (Fig. 279). The hard nucleus is either extracted in one piece (Fig. 280) or liquified with a phacoemulsifier, which has a tip that vibrates 40,000 times per second (Fig. 281). Phaco- is a prefix referring to the lens. The advantage of phacoemulsification is that it causes a smaller wound, while its disadvantage is that it is difficult to perform and that the large amount of energy needed to emulsify a hard nucleus could damage the cornea or delicate posterior capsule. An alternative to phacoemulsification is manual phacofragmentation where a platform is placed under the hard nucleus and a chopper is placed on top. Pushing down divides the nucleus (Figs 282 and 283) into two pieces.

Fig. 276 Mature lens dislocated into the anterior chamber, obscuring pupil and iris.

Fig. 277 Superiorly dislocated lens.

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Bowman’s membrane Epithelial cells

Stroma

A

B

C

A

B C

Endothelial cells Anterior chamber

Descemet’s membrane

Fig. 278 A 3 plane corneal incision for entering the eye during cataract surgery. Blade A is guarded to create a uniform mid-depth incision approximately 3–6 mm in length. Blade B is crescent shaped for a 4 mm dissection of corneal lamellae. A downward motion with the keratome (blade C) enters the anterior chamber.

Fig. 279 Anterior capsulotomy: 50 punctures of anterior capsule prior to removal. Courtesy of Richard Tipperman and Stephen Lichtenstein.

Fig. 281 Removal of soft nucleus by phacoemulsification. Courtesy of Richard Tipperman and Stephen Lichtenstein.

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Fig. 280 Removal of hard nucleus in one piece. Courtesy of Richard Tipperman and Stephen Lichtenstein.

Fig. 282 Manual phacofragmentation of nucleus after dislocation into anterior chamber

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This technique is less expensive; requires a slightly larger wound; and gives the surgeon an option to choose a technique at which he is most skilled. After the nucleus is removed by either method, the soft cortex is aspirated (Fig. 284) and the eye is referred to as aphakic. A spectacle lens of about 12.0 D would be required to focus the eye, but it is thick and magnifies the image 33% larger than the normal eye, so that the two eyes cannot fuse. A contact lens that magnifies the image to a lesser degree than a spectacle lens can minimize the problem of image size disparity (aniseikonia) and allow binocular vision. However, contact lenses are sometimes impractical with elderly patients. Therefore, a lens implant of about 18.0 D is inserted into the eye to restore distance vision and the eye is then referred to as pseudophakic. It is usually placed behind the iris (Figs 285–287) unless the posterior capsule is torn

Fig. 283 After splitting the hard nucleus, (Fig. 282) it is removed in two pieces with toothed forceps. Note the white cortex still to be aspirated.

Fig. 284 Irrigation and aspiration of cortex. Courtesy of Richard Tipperman and Stephen Lichtenstein.

Fig. 285 Insertion of rigid lens through 6 mm incision. Courtesy of Richard Tipperman and Stephen Lichtenstein.

Fig. 286 Foldable implant inserted through 3.2-mm incision.

Fig. 287 Posterior chamber lens behind iris: preferred location.

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Fig. 288 Anterior chamber lens, sometimes used when the posterior capsule is damaged during surgery.

Fig. 289 ReSTOR multifocal intraocular lens with 12 concentric steps of focusing power which allows focus from far to near.

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Fig. 290 Eyeonics Crystalens utilizes natural action of the ciliary muscle during accommodation to move the optic of the implanted lens forward to focus for near.

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and can’t support it. In this case, it is placed in front of the iris (Fig. 288). This eye is now in focus for distance, but requires a spectacle for focus at near. Recently, multifocal lens implants that focus the eye for near and far have been introduced and can be used in selected patients so that they can be spectaclefree. One type has alternating rings with different refractive powers (Fig. 289) and the other changes its refractive power by shifting its position with accommodative stimulation to the ciliary body muscle (Fig. 290). The posterior capsule may opacify months to years later in 30% of cases and is called a secondary cataract (Fig. 291). It may be opened with a YAG laser (Fig. 292).

Fig. 291 Secondary cataract. Courtesy of Richard Tipperman and Stephen Lichtenstein.

Fig. 292 YAG laser capsulotomy for secondary cataract of posterior capsule. Courtesy of Richard Tipperman and Stephen Lichtenstein.

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The retina

Retinal anatomy The retina is the sensory layer of the eye extending from the optic disk to the ora serrata (Figs 293–297). Light stimulates the receptor cells, called rods and cones, which transmit the message to the ganglion cell on the retinal surface. The long ganglion cell axons make up the optic nerve, which synapses in the brain (Fig. 297).

Fig. 293 Posterior retinal landmarks.

The macula The macula is rich in cones and is the most sensitive area of the retina. The retinal vessels terminate at its margin, and in its center is a pit called the fovea, which produces a bright reflex. The fovea has the most dense concentration of cones and is responsible for the most acute vision. This reflex decreases with age, and its absence in a young individual with a visual disturbance could indicate a macular dysfunction. When the macula is destroyed, the best corrected vision is 20/200.

Fig. 296 Gross section of peripheral retina.

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Fig. 294 Posterior retina

Fig. 295 Peripheral retina

Fig. 297 Schematic cross section of retina.

The optic disk The optic disk is normally orange–red with a yellow cup at its center. The retinal artery and vein pass through the optic cup and bifurcate on the surface of the disk. Proliferated retinal pigment epithelium at the disk margin is a normal finding (Fig. 298). In axial myopia, the eye is increased in length and the retina may be dragged away from the optic disk margin, exposing the sclera. This is called a myopic conus or crescent (Fig. 299). In extremely myopic eyes often greater than 10 D, the retina is stretched so thin that it is absent in some areas, causing a loss of vision. There may be hemorrhage at the macula, called a Fuchs’ spot (Fig. 300).

Fig. 299 Normal myopic conus (crescent) at disk margin.

Fig. 298 Normal tigroid fundus with pigment around disk.

Fig. 300 Myopic degeneration.

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Another disk variation occurs when the myelin sheath that normally covers the optic nerve extends onto the retina, appearing like white flame-shaped patches obscuring the disk margin. It is benign (Fig. 301). The disk margin may also be obscured by drusen (Fig. 302) which are small, round, translucent bodies. They may damage nerve fibers and cause an enlarged blind spot.

Fig. 301 Myelination of the optic nerve.

The choroid The choroid is highly vascularized and nourishes the rod and cone layer and the retinal pigment epithelium. Unlike the tree-like branching of the retinal vessels, the choroidal circulation forms a criss-crossing network. As the retinal pigment epithelium loses pigment with age, the choroidal vasculaturè becomes more visible, resulting in a tigroid appearance (see Fig. 298).

Fundus examination The fundus refers to the inner part of the eye seen with ophthalmoscopy, that is, the retina, choroid, and disk. It is evaluated by first focusing on the optic disk and then on the retinal blood vessels and surrounding retina. The macula is examined last to minimize miosis and discomfort. A direct ophthalmoscope (Fig. 303) allows for monocular visualization of the posterior half

Fig. 303 Direct ophthalmoscope.

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Fig. 302 Disk drusen.

Fig. 304 Indirect ophthalmoscope.

of the fundus, where most retinal pathology is located. Use a negative lens (red) for myopic eyes, and a plus lens (black) for hyperopic eyes. Get as close to the eye as possible and minimize movement by resting your hand that is holding the ophthalmoscope on the patient’s cheek. A binocular indirect ophthalmoscope (Fig. 304) consists of a light source worn over the head and a hand-held lens, which allows the entire retina to be seen in three dimensions. Retinal holes and detachments at the ora serrata can be viewed by indenting the sclera with a small thimble worn on the index finger.

Fig. 305 Three-mirror contact lens.

A three-mirror contact lens (Fig. 305) used with a slit lamp gives a stereoscopic detailed view of the entire retina. It is useful in studying subtle changes in each layer of the retina, and to gauge optic cupping. Its disadvantage is the need for anesthetic drops and a solution on the eye.

Fluorescein angiography (Figs 306–308) Fluorescein dye is injected intravenously. As it passes through the retinal circulation, fundus

Fig. 306 Normal fluorescein angiogram.

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Fig. 307 Fluorescein angiogram of inferior retinal artery occlusion showing lack of perfusion inferiorly after 15.4 seconds.

photographs are made in a rapid sequence. This test is useful for evaluating retinal circulation. It demonstrates rate of flow, leakage from capillaries, staining of tissues, areas of nonperfusion, and neovascularization. Normally retinal blood vessels do not leak.

Papilledema (choked disk) (Figs 308–311) Papilledema is swelling of the optic disk, usually due to increased intracranial pressure, in which case it is eventually bilateral. Unilateral cases are due to increased pressure in one orbit, sometimes caused by a tumor. It begins with blurred disk margins and engorged disk veins. As it progresses, flame-shaped hemorrhages and cotton-wool spots develop in the peripapillary area (Fig. 309). Chronic, elevated intracranial pressure inevitably destroys the optic nerve, resulting in optic atrophy. In 80% of normal eyes, there are subtle pulsations of the retinal veins as they exit from the globe at the optic cup. If pulsations are not visible they can almost always be elicited by exerting slight pressure on the globe (through the lid). In papilledema, one cannot see spontaneous or elicited venous pul104

THE RETINA

Fig. 308 Fluorescein angiogram of papilledema with leakage of dye from disk.

Fig. 309 Papilledema with elevated disk, engorged veins, and flameshaped hemorrhages.

Fig. 310 An enlarged blind-spot can be plotted most accurately on a tangent screen.

sations. Swelling of the optic disk damages the surrounding retina and enlarges the blind spot, which helps confirm the diagnosis (Fig. 310). Elevated intracranial pressure that causes papilledema may also cause headache, nausea, and pressure on the CN VI, resulting in diplopia.

Differential diagnosis of papilledema A swollen disk caused by optic neuritis (see Fig. 93) is associated with a Marcus Gunn pupil and loss of vision, whereas in papilledema the pupil is normal and there is usually no loss of visual acuity unless edema extends to the macula, sometimes resulting in a macular star (Fig. 311). Early papilledema may be difficult to distinguish from drusen of the disk (Fig. 302) and myelinated nerve fibers (Fig. 301). All three blur the margin and cause an enlarged blind spot (Fig. 310). On fluorescein angiography, however, only papilledema has leakage of dye (Fig. 308). A hyperopic eye might have a small disk with blurred margin, but there is no leakage with fluorescein angiography. Like papilledema, central retinal vein occlusion (Fig. 321) may have venous engorgement, a blurred disk margin, and cotton-wool spots. In central retinal vein occlusion, however, the flame hemorrhages extend out to the periphery and there is usually more loss of vision. Malignant systemic hypertension can also cause a papilledema-like retinal appearance, which is easily distinguished by measuring blood pressure on all patients with blurred disk margins (Fig. 318).

Fig. 311 Papilledema with macular star (arrow).

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105

White retinal lesions (Figs 312–316)

Cotton-wool spots

(Fig. 312)

Ischemia of the superficial nerve fiber layer causes white, cloud-like lesions around the disk that obscure underlying retina. Causes include diabetes (Fig. 333), hypertension (Fig. 318), and papilledema. Up to 50% of AIDS patients may develop retinal microangiopathy with cotton-wool spots.

Inflammatory cells

(Fig. 313)

White-blood cells occur in posterior choroiditis (Fig. 258), retinitis, vasculitis (Fig. 327), or optic neuritis. Often there is an unclear view because of overlying vitritis. Cytomegalovirus or necrotizing retinitis occurs in 25% of AIDS patients, mainly in late stages, and is rapidly blinding if untreated. Culture of blood, urine, or lungs confirms diagnosis. Rx: intravitreal ganciclovir.

Hard (waxy) exudate

(Fig. 314)

Leaking fluid from vessels leaves behind a waxy, yellowish proteinaceous residue. It is seen most often in diabetes, but also in papilledema (Fig. 311) and hypertension.

Drusen

(Fig. 315)

This is a hyaline thickening of Bruch’s membrane of the retina (do not confuse with disk drusen). These are round, dull white, bilateral, and uniformly distributed, unlike asymmetric, yellow, irregular, waxy exudates. Drusen may progress to macular degeneration.

Diseases of retinal vessels Retinal vessel walls are normally transparent. The vessels are visualized because of the blood within them. In arteriosclerosis, as the vessel walls become hyalinized they develop 106

THE RETINA

Fig. 312 Cotton-wool spots in AIDS.







Fig. 313 White inflammatory cells in Cytomegalovirus retinitis. Courtesy of Joseph Walsh.



Choroid Sclera Fig. 316 Retinal cross section.

Fig. 314 Exudate in background diabetic retinopathy.

Fig. 315 Drusen in early macular degeneration due to thickening of Bruch’s membrane and degeneration of overlying retinal pigment epithelium.

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a dull “copper wire” and then a ”silver wire“ reflex, and the relative thickness of artery to vein decreases (Figs 317 and 319).

Hypertensive retinopathy Scheie classification

I

Thinning of retinal arterioles relative to veins

II

Obvious arteriolar narrowing with focal areas of attenuation

III

Stage II, plus cotton-wool spots, exudates, and hemorrhages

IV

Stage III plus swollen optic disk resembling papilledema

Stages I and II are similar to arteriosclerosis of aging

Stages III and IV are medical emergencies referred to as malignant hypertension. Ninety percent die in 1 year if not treated

At their junctions, the arteries and veins share a common sheath. Thickening of the arteriole causes indentation of the venule, referred to as A-V nicking (Fig. 319) inferior to the disk. This can lead to a retinal vein occlusion.

Fig. 317 Engorgement of distal vein with flame hemorrhages due to pressure from thickened arterial wall (A-V nicking). Also, as the wall thickens, the crossing changes from an acute to a right angle.

Fig. 318 Stage III malignant hypertension with cotton-wool spots, flame-shaped hemorrhages, and arteriolar narrowing.

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Fig. 319 Arteriosclerosis with partial vein occlusion demonstrated by engorged vein inferiorly and a secondary flame hemorrhage. “Silver wire” changes are noted at the superior disk margin and irregular narrowing of the artery is noted on the left superior side of the figure.

Retinal vein occlusion Retinal vein occlusions cause a painless decrease in vision with hemorrhages extending to the peripheral retina. Acutely, there are flame-shaped hemorrhages (Fig. 321) and dot and blot hemorrhages The flame hemorrhages clear in several months. Dot and blot hemorrhages (Fig. 322) may last for years. Cotton-wool spots and a poorly reactive pupil usually indicate an ischemic retina due to a total occlusion. Ischemia is confirmed with fluorescein angiography. The ischemia could stimulate secretion of vascular endothelial growth factor (VEGF) causing new blood vessel growth on the iris. Eventually, tortuous collateral vessels are sometimes seen on the optic disc. If macular edema occurs, it may be treated with localized laser to the retina and/or intravitreal steroid injection. THE RETINA

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Fig. 321 Central retinal vein occlusion with superficial flame-shaped hemorrhage following contour of nerve fiber layer.

Fig. 320 Preretinal hemorrhage between retina and vitreous.





Nerve fiber layer Sensory retina





RPE Choroid Sclera Fig. 324 Cross section of the retina.

Fig. 322 Deep retinal hemorrhage in partial central retinal vein occlusion.

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Fig. 323 Disciform macular degeneration with subretinal hemorrhage (under retinal pigment epithelium) more grayish in appearance.

Optical coherence tomography (OCT) is a new technology to obtain high-resolution cross-sectional images of the eye. It is analagous to ultrasound except uses light instead of sound. It is especially useful to monitor macular edema (Figs 325 and 326) and macular holes (Figs 353 and 354).

Depths of retinal hemorrhages (Figs. 320–324) Preretinal hemorrhages (Fig. 320) Preretinal hemorrhages occur between the vitreous and retina and may layer out to a boat shape. They are often caused by proliferative diabetic retinopathy with breakthrough into vitreous. Trauma and vitreous detachments are also common causes.

Superficial flame-shaped hemorrhages (Fig. 321) These occur in the nerve fiber layer radiating from the optic disk. They occur most commonly in central retinal vein occlusion, papilledema, diabetes, hypertension, and optic neuritis.

Deep retinal hemorrhages (Fig. 322) Dot and blot hemorrhages occur most often in diabetes, papilledema, and venostasis conditions, such as retinal vein occlusion.

Subretinal hemorrhages (Fig. 323) In disciform macular degeneration these lie under the retinal pigment epithelium (RPE) and are, therefore, darker red. Retinal vessels overlie subretinal hemorrhages.

Other retinal vessel wall changes Retinal blood vessels appear white when inflamed. Arteritis occurs in sarcoidosis

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111

NFL RPE macular edema

Fig. 325 OCT of retinal macular edema after retinal vein occlusion. RPE, retinal pigment epithelium; NFL, nerve fiber layer.

NFP

Fig. 326 OCT of resolved macular edema from retinal vein occlusion after intravitreal triamcinolone injection. Vision improved from 20/400 to 20/30. NFP, normal foveal pit. Courtesy of Jennifer Hancock.

(Fig. 327), cytomegalovirus retinitis, and lupus erythematosus. Phlebitis occurs in Eales disease, an inflammatory condition in young boys. Damaged vessels from choroiditis and vein and artery occlusions could develop a white fibrous sheathing (Fig. 330), or appear thread-like since there is no circulation. Abnormal capillaries may grow inside the eye in a misguided response to ischemia associated with retinal artery or vein occlusion and proliferative diabetic retinopathy. It is due to liberation of vascular endothelial growth factor (VEGF). The resulting iris neovascularization could cause severe secondary glaucoma. Panretinal laser photocoagulation is used to destroy large areas of the hypoxic retina which decreases the release of VEGF. 112

THE RETINA

Fig. 327 Sarcoidosis with vasculitis causing ”candle-wax” drippings on vessel. Courtesy of Joseph Walsh.

Fig. 328 Retinal artery occlusion with Hollenhorst plaque on disk with cherry-red macula.

Hypoxia in age-related macular degeneration may also cause abnormal choroidal neovascularization. Macugen (pegaptanib), or Lucentis (ranibizumab) are both anti-VEGF drugs, which may be injected into the vitreous cavity to decrease formation of these abnormal vessels. Ischemia is also the stimulus to the abnormal peripheral vascularization in retinopathy of prematurity (see Fig. 363).

Retinal artery occlusion Retinal artery occlusion (Fig. 328) causes sudden loss of vision. Carotid artery plaques (see Fig. 115) or heart disease such as arrhythmias, endocarditis, or valve disease may liberate fine platelets or larger cholesterol emboli (Hollenhorst plaque), which lodge in arterial bifurcations. Sludging of blood flow gives a boxcar appearance (Fig. 329). The resulting ischemic retina becomes edematous, giving the macula a cherry-red appearance. Irreparable loss of vision occurs within 1 hour. Eventually optic atrophy results (Fig. 330). Rx: breathe into a paper bag to elevate CO2 which dilates the artery. Lower eye pressure with oral or topical medications. Gently massage the eye to get embolus to move on. Call eye doctor immediately to tap anterior chamber which further lowers eye pressure. It is difficult to reverse if more than 12 hours old.

Fig. 329 Drawing of branch retinal artery occlusion showing box car sludging of blood flow, emboli on disc, and pale edematous retina causing the cherry-red macula.

Fig. 330 Late-stage retinal artery occlusion with optic atrophy and arteries that are thread-like and sheathed.

Diabetic retinopathy Diabetes causes microvascular complications in the retina which usually increase in severity with time. Twenty-five percent of eyes have changes after 10 years, 50% after 15 years, and 80% after 20 years. To minimize these changes, one should ideally keep the fasting blood sugar less than 110 mg/dL, blood pressure less than 120/80, exercise, stay thin, and keep blood glycosylated hemoglobin (HbA1c) levels less than 6.5% since there is a 50% reduction in risk for each percentage point lower. HbA1c gives an estimate of preceding 3 month control of blood sugar.

Approximate Equivalent

HbA1c (%) 4 5 6 7 8

. . . .

Mean non-fasting glucose (mg/dL)

. . . . . . . . . . . . .65 . . . . . . . . . . . .100 . . . . . . . . . . . .135 . . . . . . . . . . . .170 . . . . . . . . . . . .205

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113

Fig. 331 Stage 1. Background retinopathy with microaneurysms and exudates.

There are three progressive stages of diabetic retinopathy. 1 Non-proliferative or background retinopathy initially presents with microaneurysms (Fig. 331). These may leak (Fig. 332) and cause edema and proteinaceous exudates at the macula, which is the most common reason for loss of vision in diabetic retinopathy. Later, dot hemorrhages appear. The macular edema is usually treated with focal laser photocoagulation. If unsuccessful, one may try intravitreal triamcinolone (steroid) injections, vitrectomy surgery, or an intravitreal antivascular endothelial growth factor injection. 2 Preproliferative retinopathy (Fig. 333) is due to widespread capillary closure (Fig. 334) causing retinal ischemia. The clinical signs of this are cotton-wool spots, venous beading, larger blot hemorrhages, and the absence of blood flow on fluorescein angiography. 3 Proliferative diabetic retinopathy occurs when the ischemic areas of the retina stimulate the growth of abnormal capillaries on or around the disk (Fig. 335) and the iris. The former may bleed into the vitreous and cause fibrotic membranes (Fig. 336) that contract and cause retinal detachments. Panretinal photocoagulation destroys part of the ischemic retina, thus reducing the release of VEGF that causes neovascularization. Intravitreal antiVEGF causes regression of new vessels, but its clinical value is still being tested. This third 114

THE RETINA

Fig. 332 Leakage of fluorescein from microaneurysms. Normal retinal vessels do not leak.

Fig. 333 Stage 2. Preproliferative retinopathy with cotton-wool spot.

Fig. 334 Fluorescein angiogram showing neovascularization (↓) adjacent to dark area of capillary nonperfusion (↓↓).

stage often occurs late in the course of diabetes and is associated with other serious systemic vascular diseases and an associated 56% 5-year survival rate.

Macular degeneration Age-related macular degeneration is the leading cause of blindness in elderly persons. Twenty-five percent of 70-year-old persons have signs of the condition, and this number increases to 50% by age 90. In a normal retina (Fig. 337) the retinal pigment epithelium (RPE) has tight junctions protecting the sensory retina from leakage of more permeable choroidal capillaries. The RPE also metabolically supports the rods and cones and creates an adhesive force with the overlying neurosensory retina, which prevents retinal detachments. In dry macular degeneration, Bruch’s membrane degenerates by fragmenting in some areas and thickening with hyaline (drusen) in other areas (Fig. 338). The RPE on top of the drusen degenerates. The overlying sensory retina dependent on the RPE thins out, resulting in atrophic (nonexudative) macular degeneration (Fig. 339). This accounts for 80% of all cases of macular degeneration. If enough retina disappears, the underlying choroidal vasculature is easily visualized with an ophthalmoscope.

Fig. 335 Stage 3a. Proliferative retinopathy with neovascularization and preretinal hemorrhages.

Fig. 336 Stage 3b. Fibrous proliferation.

Fig. 337 Normal retina.

Fig. 338 Atrophic macular degeneration.

Fig. 339 Atrophic macular degeneration often has drusen and pigment mottling.

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115

RPE

Fig. 341 Hemorrhagic stage of disciform macular degeneration.

Sclera Fig. 340 Disciform (exudative) macular degeneration.

Ten percent of macular degeneration is the wet type called disciform (Fig. 340). This occurs when abnormal choroidal blood vessels (subretinal neovascularization) penetrate the damaged Bruch’s membrane. These vessels may bleed, causing a hemorrhagic detachment of the RPE, which appears dark red. When it breaks into the sensory retina, it appears bright red (Fig. 341). Eventually, the blood fibroses and forms a white scar (Fig. 342). A fluorescein angiogram may reveal subretinal vessels before they bleed (Fig. 343). If the neovascular membrane is more than 200 um from the fovea, it can be destroyed with argon laser photocoagulation. A side effect of this is damage to the surrounding retina. A newer technique called photodynamic therapy is safer. An injected intravenous dye concentrates in the choroidal vasculature. A low-energy laser is then aimed at the vessels, activating the dye—resulting in cell death only inside the vessel. Intravitreal steroid (triamcinolone) injection may reduce inflammation from the laser and improve the visual outcome. The newest treatment for wet macular degeneration is the addition of serial intravitreal injections of Macugen (pegaptanib) or Lucentis (ranibizumab). Both of these antagonize vascular endothelial growth factor (VEGF) causing regression of abnormal vessels. Both wet and dry macular degeneration have an onset after age 50. 116

THE RETINA

Fig. 342 Late-stage disciform scar. Courtesy of Leo Masciulli.

Fig. 343 Fluorescein angiogram of subretinal neovascular membrane.

Fig. 344 Central serous retinopathy.

Early signs of both are drusen, pigment mottling at the macula, loss of foveal reflexes, decreased central vision, and waviness of lines on Amsler grid testing. To protect the macula, avoid cigarettes, wear U-V filters, and eat fruits and vegetables. Supplements of Vitamins C, E, A, zinc, lutein, and zeaxanthin (Ocuvite, I Caps PreserVision) have been shown to reduce loss of vision by 25% once degeneration begins. The remaining 10% of macular degenerations are due to juvenile inherited types, chorioretinitis, infection, and staring at the sun. Reassure patients that they never go totally blind, but only lose central vision, often resulting in 20/400 vision.

Fig. 345 Fluorescein leakage through the RPE in central serous retinopathy.

Common retinal diseases Central serous retinopathy This is a macular disease in which a defect in the RPE allows choroidal fluid to leak into the sensory retina (Figs 344–346). It usually affects males ages 25–40 and may be triggered by stress. Symptoms are decreased and distorted vision. Wavy lines are demonstrated with an Amsler grid. Ophthalmoscopically, there is a clear oval elevation of retina. Eighty to ninety percent clear within a few months. Laser photocoagulation may be used if leakage continues for 6 months.

RPE

Fig. 346 Central serous retinopathy.

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117

Sensory retina

Fig. 347 Macular pucker. Courtesy of Jennifer Hancock.

Fig. 348 Retinal hole with detachment of sensory retina from pigment epithelium.

Macular pucker As you age, the vitreous normally shrinks. If there are adherences to the macula, it may cause scarring and wrinkling called macular pucker. This may cause blurred or distorted central vision. If severe enough, a vitrectomy may be performed to remove the traction and abnormal membrane (Fig. 347).

Fig. 349 Lattice degeneration with round hole. Courtesy of Leo Bores.

Retinal detachments These are separations of the neurosensory retina from the RPE (Fig. 348). They often begin with degeneration in the peripheral retina, such as myopic thinning or lattice degeneration. Lattice degeneration is seen with an indirect ophthalmoscope in 8% of eyes as a white meshwork of lines with black pigment near the ora serrata (Fig. 349). Holes may develop in these areas spontaneously or from trauma, cataract surgery, vitreous traction, or contraction of diabetic retinal membranes. Fluid then enters the holes and detaches the retina (Fig. 350). Not all holes cause problems. Small, round, asymptomatic holes may often be left untreated. Large horseshoe tears with vitreous traction and recent symptoms must be sealed. Symptoms include loss of vision, described as a “curtain,” with flashes and floaters. Ophthalmoscopically, an elevated, gray membrane is seen unless a vitreous hemorrhage obscures it. At surgery (Fig. 351) the subretinal fluid is 118

THE RETINA

Fig. 350 Retinal detachment with large hole.

Fig. 351 Surgical repair of retinal detachment.

drained through a scleral hole. The retinal hole and surrounding retina is then scarred to underlying choroid using laser, cryopexy, or diathermy. A scleral buckle is placed, which pushes the sclera against the retina. An alternative to a buckle is to inject gas or silicone oil which pushes the retina against the sclera until chorioretinal adhesions develop. If there are fibrous bands of vitreous tugging on the retina, a vitrectomy may also be necessary.

Fig. 352 Diabetic retinopathy with exudates and macular hole.

Holes in the macula (Fig. 352) do not usually lead to detachments, but if they are full thickness, central vision could drop to 20/400. A vitrectomy could be performed if the hole is due to vitreoretinal traction bands. Air is then injected into the vitreous and the patient is sent home to lie on their stomach for two weeks so that the air rises and tamponades the hole (Figs 353 and 354).

VRT NFL RPE

MH

Fig. 353 OCT scan of macular hole caused by vitreous traction. RPE - retina pigment epithelium; NFL - nerve fiber layer; MH - macular hole; VRT - vitreoretinal traction

NFP

Fig. 354 OCT scan of macular hole resolution after vitrectomy with injection of gas into the vitreous. NFP - normal foveal pit

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119

Fig. 356 Transilluminated iris.

Fig. 355 Albinotic fundus.

Albinism Albinism has many forms and refers to inherited hypopigmentation. Common findings in all types involving the eye are photophobia, hypopigmentation of the retina (Fig. 355), and transillumination of the iris with a pen-light at the limbus (Fig. 356). Additional findings may include nystagmus, a hypoplastic macula with absence of a foveal reflex, reduced vision, refractive errors, decreased immunity, and decreased pigmentation of the hair and skin (Fig. 357).

Retinitis pigmentosa

(Fig. 358)

This is a slowly progressive hereditary degeneration. Since it begins in the retinal periphery, the first loss is peripheral and night vision (Fig. 359) often sparing central visual acuity for many years. The retina has pigmentary changes resembling bone corpuscles. The diagnosis is confirmed with an electroretinogram.

Fig. 357 Albinotic hair and skin.

120

THE RETINA

Fig. 358 Retinitis pigmentosa.

Fig. 359 Constricted visual field in late-stage retinitis pigmentosa. Dark squares indicate absence of vision.

Preliminary findings show some gain in vision with implantation of a silicon microchip in the subretinal space. It contains 5000 solar cells to convert light energy into electrical current (Fig. 360).

Retinoblastoma

(Figs 361 and 362)

This is a malignant tumor of the retina often appearing by 2 years of age. Most occur from a genetic mutation that survivors may transmit as a mendelian dominant. The retina has one or more white elevated retinal masses, which are bilateral 30% of the time. Calcifications may be seen in the tumor with a CT scan. Removal of the eye is indicated for unilateral cases. When both eyes are involved, the worst eye may be enucleated and the other treated with chemo-, radio-, laser-, or cryotherapy.

Fig. 360 Silicone microchip in the subretinal space. Note black pigment clumping typical of retinitis pigmentosa. Courtesy of Alan and Vincent Chow.

THE RETINA

121

Fig. 362 Leukocoria (white pupil) due to retinoblastoma. Fig. 361 Retinoblastoma. Courtesy of David Taylor.

Retinopathy of prematurity (ROP) This disease of newborns occurs in premature infants weighing less than 2000 grams or having a gestational age of 28 weeks or less. It occurs more often when oxygen was administered. Normal vascularization of the retina progresses peripherally and is not normally completed until 1 month after birth. Oxygen given to newborns stops this normal vascularization process. When the oxygen is discontinued, the avascular peripheral retina stimulates new vessel growth (Fig. 363). These new vessels, however, are now abnormal and may bleed, resulting in vitreous hemorrhage with fibrous proliferation. It could drag the retina (Fig. 364), sometimes causing a retinal detachment. The ideal therapy is comprehensive prenatal care to reduce the number of premature births and careful monitoring of oxygen in the nursery. Unfortunately, ROP is becoming more prevalent because of advances in neonatal intensive care units causing an improvement in survival for very low birthweight infants. An eye doctor should check the peripheral retina at 6 weeks of chronological age or 32 weeks gestational age, whichever was earlier. Transscleral cryotherapy or laser photocoagulation may be used to scar the avascular retina in stage 3 when the demarcation line is elevated with fibrovascular proliferation. Rigid examination and treatment guidelines and frequent poor visual outcomes are causing a shortage of doctors willing to follow these infants and be exposed to high cost litigation. 122

THE RETINA

A

B Fig. 363 (a) Stage 3 retinopathy of prematurity with vascularized ridge demarcating normal from avascular retina. Note laser photocoagulation spots. (b) Scarred peripheral retinal two weeks post-laser. Photos taken by Leslie Mackeen, Toronto, Canada, with wide-angle RetCam camera. Masse Research Lab, Inc.

Fig. 364 Late stage of retinopathy of prematurity with disk and retinal vessels dragged peripherally on left side.

Index

Abducen’s nerve (CN VI) 24,31,44,48,59 Acne Rosacea 56, 57 AIDS (Acquired Immune Deficiency Syndrome) 49, 72, 89, 107 Albinism 120 Amblyopia 25, 26 Amsler grid 39, 117 Aneurysms 47, 48 Ankylosing spondylitis 87 Anterior chamber 74, 75, 87 Arcus senilis 68 Asteroid hyalosis 92, 93 Astigmatism 8, 17, 19 Band keratopathy 89 Basal cell carcinoma 56 Behçet’s disease 89 Bell’s palsy 32 Blepharitis 56 Blepharospasm 32, 33 Blow-out fracture of orbit 62 Bowman’s membrane 19, 20, 63 Brain 30, 42–47 Bruch’s membrane 106, 107, 115, 116 Carotid artery 36, 44–48, 113 Carotid-cavernous fistula 47, 48 Cataract 1, 4, 94–99 Cavernous hemangioma 56 Cavernous sinus 44, 46–48 Cavernous sinus thrombosis 47, 61 Central serous retinopathy 117 Chalazion 56, 57 Choroid 84, 85, 89–91, 102, 113, 115–117 Choroiditis (see Uveitis) Ciliary body (processes and muscle) 80, 83, 84–90 Circulation to visual centers 45–48, 100, 106–115 Color vision 42, 43

Computerized axial tomography (CT Scan) 4, 61, 62 Conjunctiva 14, 68–72 Chemosis (edema) 60, 69 Follicles 70 Hemorrhage 69 Papillae 14, 70 Conjunctivitis (Red, inflamed eye) 70, 72, 88 Allergic 71 Bacterial 71 Blepharoconjunctivitis 71 Inclusion 70 Papillary or Vernal 14, 70 Trachoma 70 Viral 68, 72 Contact lens fitting 12–18 Cornea 63 Abrasion 14, 64, 66 Curvature 13, 16 Edema 66, 67, 82 Endothelium 63, 67 Epithelium 14, 64–68 Inflammation (keratitis) 65–68 In contact lens wear 12–21 In refractive surgery 19–21 Keratitis (inflammation) 65–68 Transplantation 64–65 Ulceration 65 Cotton-wool spots 105–109, 114 Cutaneous horn 56 Cyclitis (See Uveitis) Dacryocystitis 53, 54 Dacryocystorhinostomy 54 Dermatochalasis 54 Dermoid tumor 68 Descemet’s membrane 63, 64, 67 Diabetes 1, 3, 113–115 Diabetic retinopathy 1, 113–115 INDEX

123

Diplopia 2, 26, 29–31 Drusen (2 different meanings) Optic disk 101, 104 Retinal 106, 107, 115, 117 Dry eye 50, 51 Ectropion 52, 57 Endophthalmitis 65 Enophthalmos 60, 62 Entropion 57 Enucleation 90 Epidermoid inclusion cyst 55 Episcleritis 73 Esophoria 25 Esotropia 25, 27, 28 Exophoria 25 Exophthalmos 3, 47, 60, 61 Exotropia 25, 28, 29 Facial nerve 24, 32 Floater 1, 118 Fluorescein angiography 103, 105, 114, 116, 117 Fusion 26 Ganglion cells 33, 34, 76, 79, 100, 110 Giant cell arteritis 2, 35 Glaucoma 1, 67, 74–84 Angle-closure 81, 82, 88 Infantile 83 Inflammatory 83, 87 Open angle 75–81 Pigmentary 83 Pseudoexfoliation 83 Rubeosis iridis 83, 86 Sturge-Weber syndrome 84 Traumatic iris recession 83, 84 Gonioscopy 84 Graves’ disease 3, 5, 15, 61 Headache 2, 31, 47, 105 Herpes simplex keratitis 65, 66, 89 Herpes zoster dermatitis (Shingles) 32, 89 Homonymous hemianopsia 42 Horner’s syndrome 36 Hyperopia (farsightedness) 7, 17, 19, 22, 82 Hyphema 83 Hypopyon 65 Hypotropia 29 124

INDEX

Inferior oblique muscle 24, 30 Inferior ophthalmic vein 46, 47, 48 Inferior orbital fissure 60 Inferior rectus muscle 24, 62 Infraorbital nerve 62 Internal carotid artery 44–48, 113 Iritis and Iridocyclitis (see Uveitis) Kaposi’s sarcoma 71, 72 Keratitic precipitates 87, 88 Keratitis (see Cornea) Keratoconus 9, 12, 20, 21, 64 Keratoacanthoma 55, 56 Keratometry 13 Lacrimal gland 50, 51 Lagophthalmos 4, 66, 67 Lateral rectus muscle 4, 24, 27, 31 Levator palpebral muscle 30, 39 Lice on eyelashes 58 Lid cellulitis 57 Limbus 16, 63, 68, 80, 93 Lymph nodes 49 Macula 4, 100, 120 Macular degeneration 1, 39, 41, 107, 110, 111, 115–117 Macular edema 109, 111, 112, 114 Macular pucker 118 Magnetic resonance imaging (MRI) 35, 48 Marcus Gunn pupil 34, 105 Meibomian glands 49, 56 Melanoma 73, 85, 86 Migraine 2, 5, 45 Müller’s muscle 3, 24, 36 Multiple sclerosis 35 Muscles (Extraocular) 23, 24, 27, 29–31 Myasthenia gravis 39 Myelinated nerve fibers 34, 102, 105 Myopia (nearsightedness) 8, 17, 19, 21, 101 Nasolacrimal duct 50, 52, 53 Near point of convergence 26 Nerves (extraocular) 24, 29–36, 39, 47, 48, 59 Nevi 55, 72, 86 Nystagmus 43, 45, 120

Oculomotor nerve 30 OCT (optical coherence tomography) 111, 112, 119 Ophthalmic artery 48 Ophthalmodynamometry 46, 47 Ophthalmoplegia 60 Ophthalmoscopy 102 Optic atrophy 33, 34 Optic chiasm 36, 42 Optic disc 77, 101 Optic nerve 4, 33–36, 41 Optic neuritis 4, 34, 35, 43, 105 Optic tract 36, 42 Ora serrata 100 Orbicularis oculi muscle 32 Orbit 3, 23, 48, 59–62 Orbital cellulitis 47, 60 Orbital fat 54, 60 Orbital septum 54, 60

PRK (photorefractive keratectomy) 20 Radial keratotomy 19 Reiter’s syndrome 89 Retina 100-122 Retinal artery 41, 48, 101, 104, 106, 108, 111–113 Retinal artery occlusion 113 Retinal blood vessel disease 106–115, 122 Retinal detachment 41, 73, 78, 93, 114, 118–119, 122 Retinal hemorrhages 111 Retinal hole 103, 118, 119 Retinal vein occlusion 105, 109–113 Retinitis pigmentosa 2, 120, 121 Retinoblastoma 121 Retinopathy of prematurity 113, 122 Rheumatoid arthritis 50, 73, 89 Rubeosis iridis 83, 86

Papilledema 104–106 Pars plana 81, 93 Phacoemulsification 95, 96 Photophobia (Light sensitivity) 2, 12, 86, 120 Pinguecula 69 Pituitary gland 41, 42 Posterior cerebral artery 44–47 Presbyopia 9, 12, 22 Prism testing 28 Proptosis (see exophthalmos) Pseudostrabismus 28 Pterygium 69 Ptosis 36, 39 Puncta 50–53 Pupil 30, 35, 38 Adie’s pupil 37 Argyll Robertson pupil 37 Constrictor muscle 35 Dilator muscle 35, 36 Light reflex 34, 36, 37 Marcus Gunn pupil 34

Sarcoidosis 89, 111 Sclera 73 Scleral staphyloma 73 Scleritis 73 Scotoma 41, 42, 45 Seborrheic keratosis 55 Shingles 32, 89 Sinus cavities (facial) 2, 60–62 Sjögren’s syndrome 50 Slit lamp 63 Squamous cell carcinoma 56 Strabismus 2, 25–29 Stroke 45–48 Sty 56, 57 Superior oblique muscle 24, 29, 30, 31 Superior ophthalmic vein 46, 47, 48, 60 Superior orbital fissure 60 Superior rectus muscle 24, 30 Surgery Cataract 94–99 Corneal transplant 20, 64, 67 Enucleation 90 Glaucoma 79–82 Refractive surgery 19–22 Retinal detachment 118 Strabismus 25 Vitrectomy 93, 114, 119 Sympathetic nerve 24, 36, 39, 48 Sympathetic ophthalmia 89, 90 Syphilis 37, 73, 89

Refraction 9–11 Refractive surgery 19–22 Conductive keratoplasty 22 Epi-LASIK 20 Intac 21 LASIK (Laser in situ keratomileusis) 19 Phakic implants 21

INDEX

125

Tarsus 54, 60 Tearing (Epiphora) 51–53 Thyroid disease 3, 35 Tonometers 74 Toxoplasmosis 89 Trabecular meshwork 74, 75, 80 Transient ischemic attack (ministroke) 45 Trauma Anterior uveitis 86–89 Dislocated lens 95 Hyphema 83 Ruptured globe 90 Vitreous hemorrhage 92, 93, 118, 122 Trichiasis 58, 66, 70 Trigeminal nerve 24, 31, 32 Trigeminal neuralgia 32 Trochlear nerve 24, 30, 31

Uveitis 86–92 Anterior (iritis, cyclitis) 86–89 Posterior (choroiditis) 89–92 Vascular endothelial growth factor (VEGF) 109, 112–114, 116 Verruca (warts) 55 Vertebral artery 44–47 Vision testing (central) 6 Visual cortex 45 Visual field testing (peripheral) 39–43 Visual pathway 36, 43 Vitrectomy 93, 114, 119 Vitreous 92, 93 Vitreous detachment 92, 111 Vitreous hemorrhage 92, 93, 118, 122 Wirt stereopsis test 26

Ultrasound 85, 93 Uvea (iris, ciliary body and choroid) 84

126

INDEX

Xanthelasma 55