(BQ) Part 1 book “Basic ophthalmology” has contents: Embryology and anatomy, physiology of vision, neurology of vision, examination of the eye, errors of refraction, the conjunctiva, the cornea, the sclera, the uveal tract, the lens.
Basic Ophthalmology Basic Ophthalmology FOURTH EDITION Renu Jogi MBBS MS Ex Associate Professor MGM Medical College, Indore (MP) Pt Jawahar Lal Nehru Memorial Medical College Raipur, Chhattisgarh, India ® JAYPEE BROTHERS MEDICAL PUBLISHERS (P) LTD New Delhi • Ahmedabad • Bengaluru • Chennai Hyderabad • Kochi • Kolkata • Lucknow • Mumbai • Nagpur Published by Jitendar P Vij Jaypee Brothers Medical Publishers (P) Ltd Corporate Office 4838/24 Ansari Road, Daryaganj, New Delhi - 110002, India, Phone: +91-11-43574357 Registered Office B-3 EMCA House, 23/23B Ansari Road, Daryaganj, New Delhi - 110 002, India Phones: +91-11-23272143, +91-11-23272703, +91-11-23282021, +91-11-23245672 Rel: +91-11-32558559, Fax: +91-11-23276490, +91-11-23245683 e-mail: jaypee@jaypeebrothers.com, Website: www.jaypeebrothers.com Branches 2/B, Akruti Society, Jodhpur Gam Road Satellite Ahmedabad 380 015, Phones: +91-79-26926233, Rel: +91-79-32988717 Fax: +91-79-26927094, e-mail: ahmedabad@jaypeebrothers.com 202 Batavia Chambers, Kumara Krupa Road, Kumara Park East Bengaluru 560 001, Phones: +91-80-22285971, +91-80-22382956, 91-80-22372664 Rel: +91-80-32714073, Fax: +91-80-22281761, e-mail: bangalore@jaypeebrothers.com 282 IIIrd Floor, Khaleel Shirazi Estate, Fountain Plaza, Pantheon Road Chennai 600 008 Phones: +91-44-28193265, +91-44-28194897, Rel: +91-44-32972089 Fax: +91-44-28193231, e-mail: chennai@jaypeebrothers.com 4-2-1067/1-3, 1st Floor, Balaji Building, Ramkote Cross Road Hyderabad 500 095, Phones: +91-40-66610020, +91-40-24758498, Rel: +91-40-32940929 Fax:+91-40-24758499, e-mail: hyderabad@jaypeebrothers.com No 41/3098, B and B1, Kuruvi Building, St Vincent Road Kochi 682 018, Kerala, Phones: +91-484-4036109, +91-484-2395739, +91-484-2395740 e-mail: kochi@jaypeebrothers.com 1-A Indian Mirror Street, Wellington Square Kolkata 700 013, Phones: +91-33-22651926, +91-33-22276404, +91-33-22276415 Rel: +91-33-32901926, Fax: +91-33-22656075, e-mail: kolkata@jaypeebrothers.com Lekhraj Market III, B-2, Sector-4, Faizabad Road, Indira Nagar Lucknow 226 016, Phones: +91-522-3040553, +91-522-3040554, e-mail: lucknow@jaypeebrothers.com 106 Amit Industrial Estate, 61 Dr SS Rao Road, Near MGM Hospital, Parel Mumbai 400 012, Phones: +91-22-24124863, +91-22-24104532, Rel: +91-22-32926896 Fax: +91-22-24160828, e-mail: mumbai@jaypeebrothers.com “KAMALPUSHPA” 38, Reshimbag, Opp Mohota Science College, Umred Road Nagpur 440 009 (MS), Phone: Rel: +91-712-3245220, Fax: +91-712-2704275, e-mail: nagpur@jaypeebrothers.com USA Office 1745, Pheasant Run Drive, Maryland Heights (Missouri), MO 63043, USA, Ph: 001-636-6279734 e-mail: jaypee@jaypeebrothers.com, anjulav@jaypeebrothers.com Basic Ophthalmology © 2009, Renu Jogi All rights reserved No part of this publication should be reproduced, stored in a retrieval system, or transmitted in any form or by any means: electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the author and the publisher This book has been published in good faith that the material provided by author is original Every effort is made to ensure accuracy of material, but the publisher, printer and author will not be held responsible for any inadvertent error(s) In case of any dispute, all legal matters are to be settled under Delhi jurisdiction only First Edition: 1994 Second Edition: 1999 Third Edition: 2003 Fourth Edition: 2009 ISBN 978-81-8448-451-9 Typeset at JPBMP typesetting unit Printed at Ajanta Offset and Packagins Ltd., New Delhi Dedicated to our beloved Anusha Preface to the Fourth Edition The eye is the lamp of the body If your eyes are good, your whole body will be full of light The Bible The need for a textbook for undergraduate medical students in ophthalmology dealing with the basic concepts and recent advances has been felt for a long-time Keeping in mind the changed curriculum this book is intended primarily as a first step in commencing and continuing the study for the fundamentals of ophthalmology which like all other branches of medical sciences, has taken giant strides in the recent past While teaching the subject I have been struck by the avalanche of queries from the ever inquisitive students and my effort therefore has been to let them find the answers to all their interrogatories It is said that revision is the best testimony to the success of a book In the competitive market of medical text publishing, only successful books survive Any textbook, more so, a medical one such as this, needs to be updated and revised from time to time Yet the very task of revising Basic Ophthalmology presents a dilemma: how does one preserve the fundamental simplicity of the work while incorporating crucial but complex material lucubrated from recent research, investigations and inquiries in this ever expanding field In essence, Basic Ophthalmology is both a ‘textbook’ and a ‘notebook’ that might as well have been written in the student’s own hand The idea is for the student to relate to the material; and not merely to memorize it mechanically for reproducing it during an examination It is something I wish was available to me when I was an undergraduate student not too long ago The past few years have witnessed not only an alarming multiplication of information in the field of ophthalmology, but more significantly, a definite paradigmatic shift in the focus and direction of ophthalmic research and study The dominant causes of visual disabilities are no longer pathological or even genetic in nature, but instead a direct derivative and manifestation of contemporary changes in predominantly modern urban lifestyles The student will thus find a new section devoted to a discussion on Visual Display Terminal Syndrome (VDTS) that is an outcome of excessive exposure of the eyes to the computer monitor as well as the use of contact lenses Two additional sections deal with the Early Treatment for Diabetic Retinopathy Study (ETDRS) classification and Scheie’s classification for hypertensive retinopathy that replaces the pre-existent taxonomy prevalent for little less than seven decades With posterior chamber intraocular lenses establishing themselves as the primary modality in the optical rehabilitation of patients undergoing cataract surgery, the emphasis has shifted from just visual rehabilitation to an early, perfect optical, occupational and psychological rehabilitation When I initiated this project I scarcely realized that it only had toil, sweat and hard work to offer Whenever anyone reminded me that I was working hard, my answer always was; I am trying to create something very enduring viii Basic Ophthalmology To conclude, for me, this has really been a trabalho coracao a phrase which does not have a correct synonym in English but when literally translated from Portuguese would mean “a work of the heart” In truth, it is a vivid reflection of my long lasting concern and affection for my students All books are collaborative efforts and I would like to take this opportunity to thank all the people who have advised and encouraged me in this project: specially my husband Shri Ajit Jogi, my son Aishwarya, Amit and Dr Nidhi Pandey I offer special thanks to my publisher Shri JP Vij, Chairman and Managing Director of M/s Jaypee Brothers Medical Publishers (P) Ltd., Mr Tarun Duneja, Director (Publishing) and his staff namely Mrs Yashu Kapoor, Mr Manoj Pahuja, Mr Arun Sharma, Mr Akhilesh Kumar Dubey and Mrs Seema Dogra By the grace of the Almighty God and with the continuing support of the teachers, I am happy to present the fourth updated edition of my book xzkỏa p :iL; eq[kL; kksHkk] ỗR;{kcks/kL; p gsrq Hkwre~! rfeL=-fnd-deZlq ekxZnfkZ] us=a ỗ/kkua ldysfUnz;k.kke~A An eye can perceive forms, it adorns the face; it is a source of direct knowledge; it is a guide to avoid wrong deeds; hence the eye is most important of all the sense organs Renu Jogi Contents Embryology and Anatomy Physiology of Vision Neurology of Vision 15 Examination of the Eye 22 Errors of Refraction 47 The Conjunctiva 71 The Cornea 107 The Sclera 153 The Uveal Tract 161 10 The Lens 205 11 The Vitreous 246 12 Glaucoma 258 13 The Retina 300 14 The Optic Nerve 341 15 Injuries to the Eye 361 16 The Ocular Motility and Squint (Strabismus) 375 17 The Lids 403 18 The Lacrimal Apparatus 424 19 The Orbit 437 20 General Therapeutics 448 21 The Causes and Prevention of Blindness 458 22 Ophthalmic Instruments 469 Index 489 The Lens 231 Sclero-corneal tunnel incision—It consists of three components: • Extenral scleral incision: A 1/3 or 1/2 thickness external groove is made 1.5 - mm behind the limbus It varies from 5.5 - mm in length depending on the size of the nucleus It may be straight or semi-circular in shape • Sclero-corneal tunnel: It is made with a crescent knife It usually extends - 1.5 mm into the clear cornea • Internal corneal incision: It is made with a sharp 3.2 mm angled keratome Side-port entry is made at O’ clock position with a Stiletto or MVR (micro vitreal retinal) blade A valvular self sealing incision about mm wide is made at the limbus This helps in aspiration of the sub-incisional cortex and increasing the depth of anterior chamber Anterior capsulotomy—It can be either a ‘can-opener’, envelop shaped or continuous circular capsulotomy (CCC) However, a large sized CCC is preferred Hydrodissection is essential to separate cortico-nuclear mass from the posterior capsule Removal of nucleus i Prolapse of nucleus from the capsular bag into the anterior chamber is done during hydrodissection and completed by rotating the nucleus with Sinskey’s hook ii Delivery of nucleus through the corneo-scleral tunnel is done by • Irrigating wire vectis method It is used most commonly • Phacofracture technique • Phaco-sandwitch technique • Blumenthals technique • Fish hook • Visco expression Aspiration of the cortex is done by a two way irrigation and aspiration cannula from the main incision and side port entry A posterior chamber IOL is implanted in the capsular bag after filling it with viscoelastic substance (OVD) Viscoelastic substance is then removed thoroughly from the anterior chamber and capsular bag with the help of a two way irrigation aspiration cannula Wound closure—The anterior chamber is deepened with balanced salt solution or Ringer’s lactate (through side port entry) This results in self sealing the valvular incision The conjunctival flap is reposited back PHACOEMULSIFICATION Phacoemulsification is a sophisticated technique of extracapsular cataract extraction invented by Charles Kelman in 1967 It is the most popular method worldwide and has virtually replaced all other techniques in some well developed countries This technique consists of breaking down of cataractous lens by application of ultrasonic vibrations The machine is known as phacoemulsifier which has three functions: i Irrigation—It is done by a gravity flow system Balanced salt solution (BSS) is allowed to flow to the handpiece, which is controlled by foot switch ii Aspiration—The emulsified material is aspirated through peristaltic or venturi pump as irrigation maintains normal depth of the anterior chamber 232 Basic Ophthalmology Phacoemulsifier iii Fragmentation—It is performed through a piezo-electric ultrasonic mechanism which activates a hollow mm titanium needle, vibrating at the frequency of 40,000/sec (40 kilo- hertz ultrasonic energy) The amplitude of vibration is 0.038 mm from the resting point of the tip and the total to and fro motion is 0.076 mm (stroke length) Technique of Phacoemulsification The technique is constantly changing and has many variations The basic steps are described as follows: Phaco Incision i Scleral tunnel incision ii Clear corneal incision At present scleral tunnel approach is most popular Initially, incision is placed through half the scleral thickness, 1.5 to 2.0 mm away from the clear cornea The length of the incision is about mm Dissection is carried out in the sclera and upto atleast mm inside the cornea The incision heals quickly, ambulation is quick and there is no induced astigmatism Anterior Capsulotomy [Continuous Curvilinear Capsulorrhexis (CCC)] Continuous curvilinear capsulorrhexis of 4-6 mm is performed with bent needle cystitome or capsulorrhexis forceps after filling the anterior chamber with viscoelastic substance Capsulorrhexis Continuous curvilinear capsulorrhexis The Lens 233 is started by making a small cut at the centre of the lens, pulling directly towards the 12 O’clock position and curving towards the left This creates a central flap that tears in a circular pattern to the right The flap is folded over and pulled by forceps in a circular motion and capsulorrhexis is complete Hydroprocedures These procedures facilitate nucleus rotation and manipulation during phacoemulsification i Hydrodissection—It is the seperation of the capsule from the cortex by slowly injecting balanced saline solution between the two ii Hydrodelineation—A 26 gauze needle is inserted between the hard central nucleus and epinucleus and slowly balanced saline solution is injected Thus cleavage is done between nucleus and epinucleus Nucleus Emulsification The different densities of cataracts have created different methods of sculpting or breaking the nucleus in small fragments i In soft to moderately hard nucleus—A vertical ‘trench’ is sculpted and the procedure is called ‘trench divide and conquer’ (TDC) ii In moderately hard to very hard nucleus—A deep central crater is sculpted and the procedure is called ‘crater divide and conquer (CDC) The other common methods are ‘chip and flip technique’ and ‘phaco chop technique’ The nucleus is finally emulsified and aspirated Nucleus emulsification by Divide and Conquer Technique (Four quadrant cracking) Aspiration of the Residual Cortex It is performed using the irrigation aspiration handpiece with a 0.3 mm aspiration port The posterior capsule is polished with the same handpiece using very low aspiration pressure The incision is then enlarged to a width sufficient to introduce the lens implant into the capsular bag 234 Basic Ophthalmology Intraocular Lens Implantation The intraocular lenses which may be used after phacoemulsification are, i Single piece PMMA IOL—The rigid IOL used in phacosurgery should have an optic diameter of 5.5 mm or less ii Foldable IOL is made of soft acrylic, hydrogels or silicone materials The design can be either piece lenses or single piece plate haptic design Presently, the piece lenses are used and plate haptic design is used for toric IOLs to correct astigmatism of < D Complications Immediate Complications i Excessive bleeding from conjunctiva during preparation of conjunctival flap It is managed by gentle cautery ii Damage to superior rectus muscle while passing bridle suture may occur iii Incision related complications depend on type of cataract surgery being performed a In conventional ECCE, irregular incision leading to defective coaptation of wound b In phacoemulsification • Button holing of the anterior wall of the tunnel due to superficial dissection of the sclera flap Re-entry at a deeper plane from the other side may be done • Premature entry into the anterior chamber due to deep dissection may occur New dissection can be started at a lesser depth at the other end of the tunnel • Scleral disinsertion due to very deep groove incision may occur There is complete separation of inferior sclera from the sclera superior to the incision It is managed by radial sutures iv Complications related to anterior capsulorhexis The capsulorhexis may sometimes escape, become very small or very large or may sometimes become eccentric v Injury to cornea, iris and lens may occur vi Iridodialysis may occur during intraoperative manipulations vii Rupture of the posterior capsule—This is dreaded complications of any extracapsular cataract surgery and more so with phacoemulsification viii Zonular dehiscence may give rise to sunset and sunrise syndrome after implantation of an intraocular lens ix Vitreous loss—This is a serious complication which may occur following accidental rupture of posterior capsule during any technique of ECCE x Nucleus drop into vitreous cavity—This occurs more frequently with phacoemulsification It is a dreaded complication which occurs due to sudden and large posterior capsular rupture The case must be referred to a vitreoretinal surgeon without making any attempts to fish out the nucleus xi Posterior loss of lens fragments—This may occur after zonular dehiscence or posterior capsule rupture It is a potentially serious complication because it may result in galucoma, chronic The Lens 235 uveitis, retinal detachment and chronic cystoid macular oedema This complication is more commonly associated with phacoemulsification than conventional ECCE The patient should be referred to a vitreoretinal surgeon after controlling any uveitis or raised intraocular pressure xii Posterior dislocation of IOL—This is a rare but serious complication and has to be managed by pars plana vitrectomy, with repositioning or exchange of IOL xiii Expulsive choroidal haemorrhage—This is one of the most dramatic and serious complications of open chamber surgery There is bleeding into suprachoroidal space which may result in extrusion of intraocular contents (expulsive haemorrhage) Although the exact cause is not known, contributing factors include advanced age, glaucoma, systemic cardiovascular disease and vitreous loss Postoperative Complications I Early postoperative (within first few days to weeks) i Hyphaema—Collection of blood in the anterior chamber may occur from conjunctival or scleral vessels It usually resolves spontanously ii Iris prolapse—This may occur after conventional ECCE due to inappropriate suturing iii Striate keratopathy—This occurs due to endothelial cell damage during surgery It is characterized by mild corneal oedema with Descemet’s membrane folds iv Flat or shallow anterior chamber—The incidence has decreased due to improved wound closure It may be due to a Wound leak—This is associated with hypotony It is diagnosed by Seidel’s test In this test, a drop of fluorescein is instilled in the lower fornix and the patient is asked to blink The incision is examined with slit lamp using cobalt-blue filter Fluorescein will appear to be diluted by aqueous at the site of leak b Cilio-choroidal detachment may or may not be associated with wound leak v Postoperative anterior uveitis—It may be induced by instrumental trauma, handling of uveal tissue, reaction to residual cortex or chemical reaction vi Endophthalmitis—Acute postoperative endophthalmitis is a devastating complication which occurs in 1:1000 surgeries approximately Causative organisms include staphylococci, pseudomonas and proteus sp Source of infection is often thought to be patient’s own external bacterial flora of the eyelids, conjunctiva and lacrimal drainage passages Prevention—The following measures may be beneficial a Preoperative treatment of pre-existing infection such as blepharitis, conjunctivitis, dacryocystitis etc b Povidone-iodine is instilled preoperatively as follows: Two drops of 5% betadine solution are instilled into the conjunctival sac several minutes prior to surgery The solution is also used to paint the skin of the eyelids prior to draping The eye is irrigated with saline solution prior to commencing surgery c Meticulous draping technique that ensures that the lashes and lid margins are isolated d Prophylactic antibiotics should be given e Postoperative injection of anterior sub-tenon antibiotics is commonly performed f Intraoperative irrigation of anterior chamber by adding antibiotics such as vancomycin into the infusion fluid may be efficacious 236 Basic Ophthalmology II Late postoperative (after one month to years) i Cystoid macular oedema—It commonly occurs after complicated surgery involving rupture of posterior capsule and vitreous prolapse There is collection of fluid in the form of cystic loculi in the Henle’s layer of macula ii Delayed chronic postoperative endophthalmitis It may occur when an organism of low virulence becomes trapped within the capsular bag iii Retinal detachment—Though uncommon following uneventful ECCE or phacoemulsification, it may sometime occur, specially in the presence of vitreous loss and high myopia iv Pseudophakic bullous keratopathy—It is usually a continuation of postoperative corneal oedema It is a common indication of penetrating keratoplasty The Lens 237 v Posterior capsular opacification (after or secondary cataract)—It is the most common late complication of uncomplicated cataract surgery It is the opacity which follows extracapsular extraction of the lens Advantages of Phacoemulsification Intraoperatively, phacoemulsification allows excellent control of each phase of the operation for cataract removal The small incision technique involving a self-sealing ‘no stitch’ or ‘sutureless’ incision produces very secure and stable wound There is rapid wound healing and shorter convalescence Removal of the nucleus occurs through a continuous circular capsulotomy (CCC) with the closed chamber Aspiration of the cortex also occurs within a closed anterior chamber, with low risks of damaging the endothelium, iris and posterior chamber Phacoemulsification and small incision surgery are compatible with small size implants, i.e foldable lenses There is minimum or no astigmatism with early return of binocular vision Disadvantages of Phacoemulsification It is a difficult technique to master It requires expensive instrumentation PHAKONIT It is a technique of phacoemulsification performed with a needle opening via an incision using the tip of a phacoprobe The size of the incision is only 0.9 mm and after surgery an ultrathin rollable IOL is inserted into the capsular bag The main advantage of this technique is that it is an astigmatism free cataract surgery LASER PHACOLYSIS In recent times laser phacolysis is under trial whereby it is possible to lyse the lens matter through the intact anterior capsule by excimer, ruby or other newer lasers OCULAR VISCOSURGICAL DEVICE (OVD) (Viscoelastic substance) Viscoelastic substance or OVD have been recently introduced in ophthalmology They are useful in various diagnostic procedures as well as during surgery These agents have high viscosity and elasticity Diagnostic Procedures i Gonioscopy ii Three mirror examination iii Laser procedures 238 Basic Ophthalmology In diagnostic procedures these agents create a required working space, lubricate the instruments as in gonioscopy, three-mirror examination or even in performing laser procedures for glaucoma, after cataract and on the retina In Surgery i They are helpful in dissecting the tissues in the most atraumatic manner ii For creating and maintaining surgical space as during insertion of intraocular lens during catract surgery iii Protecting the endothelium from damage due to handling in keratoplasty and phacoemulsification The common viscoelastic substances are 1%, 2% hydroxy propyl methyl cellulose, 1% chondroitin sulphate, 1% sodium hyaluronate (Healon) and combinations of these like Viscoat (3% Sodium hyaluronate and 4% chondroitin sulphate) Sodium hyaluronate (1%, 1.4%, 5%) is obtained from rooster combs and most closely resembles the natural vitreous gel TREATMENT OF APHAKIA Correction by Spectacles Aphakia is treated by prescribing suitable spherical convex lens (+ 10 D approximately) and convex cylindrical lens (+1 to +2D at 180°) weeks after the operation, i.e when the corneo-scleral scar has healed completely and the refraction has become stable Advantages It is cheap, easy to handle and readily available Disadvantages • • • • • They are heavy and give a cosmetically poor appearance There is 25% retinal image magnification hence it causes diplopia in unilateral aphakia Spherical aberration can cause ‘pin-cushion’ effect There may be chromatic aberration This leads to visual distortion There is ‘jack in the box’ ring scotoma and reduction in peripheral visual field Physical invonvenience and cosmetic deficiency are usually present The Lens 239 Contact Lens Advantage There is minimum retinal image magnification therefore it is specially useful in case of unilateral aphakia It also looks good cosmetically Disadvantages • Daily cleaning and maintenance is essential • Their insertion and removal is cumbersome • Corneal epithelial oedema, erosion and vascularization may occur due to hypoxia • Conjunctivitis, intolerance and foreign body sensation are common complaints • Loss, breakage and deterioration of the contact lens leads to financial loss Intraocular Lens (IOL) Implant This is also known as ‘pseudophakia’ The modern trend is in favour of posterior chamber IOL implantation as it offers best optical rehabilitation following removal of a cataractous lens Biometry Removal of the crystalline lens substracts approximately 20D from the refracting system of the eye Modern cataract surgery therefore involves the implantation of an intraocular lens (IOL) Biometry offers calculation of the lens power likely to result in emmetropia or a desired postoperative refraction Two ocular parameters are involved in biometry i Keratometry—The curvature of anterior corneal surface (steepest and flattest meridians) ii Axial length—The anteroposterior dimension of the eye measured using A-scan ultrasonography SRK formula—It is the most commonly used mathematical formula to calculate the IOL power It was developed by Sanders, Retzlaff and Kraff and states that P = A – 2.5L – 0.9K, where; • P is the power of IOL • A is a constant, which is specific for each lens type • L is the axial length of eyeball in mm (A-scan ultrasonography) • K is the average corneal curvature (Keratometry) The ultrasound machine equipped with A-scan and IOL power calculation software is called Biometer The intraocular lens optic may be monofocal, toric or multifocal, but monofocal lenses with a separate pair of glasses for close work are most widely used Advantages There is minimum retinal image magnification and early return of binocular vision It also has cosmetic advantage Complications • Pupillary block glaucoma may result in raised tension 240 Basic Ophthalmology • • • Dislocation of IOL may occur in the vitreous or anterior chamber Sunset phenomenon occurs when posterior chamber IOL dislocates inferiorly Cystoid macular oedema, maculopathy and iridocyclitis Corneal endothelial dystrophy may occur with anterior chamber lens TREATMENT OF UNILATERAL CATARACT Unilateral cataract occurs commonly in cases of traumatic cataract and senile cataract Treatment of unilateral cataract is often difficult and unsatisfactory when the vision is good in the fellow eye It is best treated by extracapsular lens extraction with intraocular lens implantation (ECCE with IOL) Postoperative correction with spectacles causes intolerable diplopia due to difference in the size of retinal image (eyes can tolerate dioptric difference of to D) Binocular vision is only possible with: i Contact lens ii Intraocular lens implant TREATMENT OF ASSOCIATED RAISED TENSION Increased intraocular tension may be present in association with cataract in: i Phacomorphic glaucoma (swelling of the lens in intumescent stage of cataract) ii Phacolytic glaucoma (leakage of lens protein in hypermature cortical cataract) iii Associated simple glaucoma (primary angle closure or open angle glaucoma) Treatment i Raised tension is controlled medically before cataract surgery as it may result in expulsive haemorrhage during surgery due to increased pressure gradient Trabeculectomy is performed prior to or along with cataract surgery Iridectomy (peripheral buttonhole) alone may be done in case of narrow angle glaucoma Following this cataract extraction is done in the routine manner ii Alternatively, trabeculectomy and cataract extraction can be combined iii Recent advanced procedures such as Argon laser trabeculoplasty (ALT) or iridotomy or laser filtration may be done Precaution Following trabeculectomy, care is taken to make the corneo-scleral incision, i In the upper part of the cornea, in front of the drainage area or filtering bleb ii Alternatively in the lower temporal part of the cornea, i.e corneal section should be away from the bleb AFTER OR SECONDARY CATARACT After or secondary cataract is an opacity which persists or follows after extracapsular lens extraction or discission (needling) of the lens In both these operations, the posterior capsule and part of anterior capsule remains in situ Clinical Types Thin membrane—It may remain following extracapsular lens extraction even with modern suction and infusion devices The Lens 241 Ring of Sommerring—The new lens fibres are formed by the proliferation of anterior capsular cells These are enclosed within the two capsule layers It can get dislocated into the anterior chamber Clinical types of after cataracts Elschnig’s pearl—The subcapsular cells proliferate to form large balloon-like cells Fibrous membrane—It is usually formed when there is associated iritis Treatment After cataract has to be removed if the vision is markedly impaired Thin pupillary membrane is removed by: i Discission (needling), irrigation and aspiration ii Vitreous infusion suction cutter (VISC) iii YAG laser capsulotomy or pupillary reconstruction Elschnig’s pearls Thick pupillary membrane i It is cut into small pieces with Ziegler knife or vitreous scissors and is aspirated by VISC ii YAG laser capsulotomy or pupillary reconstruction Treatment of after cataract DISLOCATION OF LENS The lens is displaced from its normal position due to complete rupture of the zonule Etiology Congenital, e.g Marfan’s syndrome, homocystinuria, Marchesani’s syndrome, Weill-Marchesani syndrome, hyperlysinemia, sulphite oxidase deficiency, etc Traumatic dislocation may occur following blunt or perforating injury 242 Basic Ophthalmology Types i Complete dislocation—There is complete or total rupture of zonule hence the lens is dislocated, • In the vitreous or in the posterior chamber • In the anterior chamber • Under the conjunctiva • Expelled out from the eye ii Partial dislocation (subluxation)—Subluxation or tilting Subluxation of lens of the lens occurs due to partial rupture of zonule Symptoms There is blurred vision due to refractive error, i.e aphakia or astigmatism Uniocular diplopia may be present in cases of partial dislocation (subluxated lens) Signs Iridodonesis—Tremulousness (tremors) of iris is present in both subluxated and dislocated lens The edge of lens and zonule are visible in subluxation of lens by the ophthalmoscope and slit-lamp examination Dislocation into the anterior chamber Dislocation into the vitreous Dislocated lens is visible by naked eye or slit-lamp if it is in the anterior chamber The diagnosis can be confirmed by ultrasonography Complications Secondary glaucoma may occur in cases of dislocation into the anterior chamber due to the angle closure Posterior chamber dislocations may result in pupillary block or phacolytic glaucoma Treatment No treatment is required if the vision is good It is similar to the old technique of ‘couching’ Remove the lens if it is opaque and if there is associated secondary glaucoma CONGENITAL ABNORMALITIES OF LENS Coloboma of lens—A notch-shaped defect is seen in the inferior margin of lens Ectopia lentis—There is subluxation of lens usually ‘upwards’ or in the ‘up and in’ direction It is bilateral usually It is a hereditary condition It may be associated with Marfan’s syndrome and homocystinuria Lenticonus—The posterior surface of lens is conical, which Ectopia lentis results in myopia It is typically seen in Alport’s syndrome The Lens 243 MULTIPLE CHOICE QUESTIONS Lens capsule is thinnest at the a centre anteriorly b laterally c superior pole d inferior pole Congenital cataract is associated with all EXCEPT a toxoplasmosis b Lowe’s syndrome c galactosaemia d glycogen storage disease Diminished vision in daylight is seen in a central cataract b peripheral cataract c zonular cataract d none of the above Cataracts are found in association with a parathyroid deficiency b myotonic dystrophy c dinitrophenol toxicity d all of the above White pupillary reflex is seen in the all EXCEPT a optic atrophy b retinoblastoma c total retinal detachment d after cataract Most common cause of blindness in India is a trachoma b vitamin deficiency c glaucoma d cataract Postoperative flat anterior chamber may be due to a pupillary block b leaking wound c choroidal detachment d all of the above Expulsive haemorrhage may occur following a blunt injury with hyphaema b perforating injury c lens extraction d panophthalmitis The etiology of complicated cataract includes all EXCEPT a disciform keratitis b iridocyclitis c retinitis pigmentosa d retinal detachment 10 Displaced lens is seen in all, EXCEPT a Marfan’s syndrome b Marchesani’s syndrome c Laurence-Moon-Biedl syndrome d Homocystinuria 11 The most common complication in exfoliation of the lens capsule is a iritis b conjunctivitis c glaucoma d optic neuritis 12 Ideal site for intraocular lens implantation is a in the anterior chamber b transfix in the pupillary margin c in the posterior chamber d behind the posterior lens capsule 13 Polyopia is a symptom of a cortical cataract b cupuliform cataract c radiation cataract d electrical cataract 244 Basic Ophthalmology 14 Ring of Sommerring is a type of a congenital cataract b complicated cataract c after cataract d traumatic cataract 15 Attack of acute congestive glaucoma can occur in a incipient stage of cortical cataract b intumescent stage c immature stage d mature stage 16 Burst Morgagnian cataract may cause a secondary glaucoma b iritis c both d none 17 Elschnig’s pearls arise from a anterior capsule of lens b posterior capsule of lens c cubical cells underneath lens capsule d none of the above 18 Diagnostic criteria of immature cataract includes a greyish lens b presence of iris shadow c black shadow visible against red d all of the above fundal glow 19 Which of the following congenital or developmental cataract can also be acquired a coronary b polar c suture d coralliform 20 Lens derives its nourishment from a air b aqueous humour c vitreous d perilimbal capillaries 21 After cataract is seen after following operations a lensectomy b extracapsular lens extraction c vitrectomy d intracapsular lens extraction 22 Intraocular lenses are generally made of a prolene b PMMA c HEMA d silicone 23 Rosette-shaped cataract is a feature of a traumatic cataract b diabetic cataract c coronary cataract d complicated cataract 24 Polychromatic lustre is typically seen in the following cataract a anterior polar cataract b complicated cataract c traumatic cataract d diabetic cataract 25 Lensectomy is an operation whereby a lens is removed b nucleus and anterior capsule are removed c lens and anterior vitreous phase is removed d none of the above 26 YAG laser is used in the treatment of a diabetic retinopathy b open angle glaucoma c after cataract d retinal detachment The Lens 245 27 Following are associated with zonular cataract EXCEPT b rickets a IUGR c dental anomalies d diabetes 28 After cataract operation, lenses are prescribed after a weeks b weeks c weeks d 12 weeks 29 Most common type of cataract following radiation is a anterior subcapsular b posterior subcapsular c diffuse cataract d tear drop cataract 30 Late complication of vitreous loss during cataract surgery a updrawn pupil b retinal detachment c corneal oedema d any of the above ANSWERS 1—a 6—d 11—c 16—c 21—b 26—c 2—d 7—d 12—c 17—c 22—b 27—d 3—a 8—c 13—a 18—c 23—a 28—c 4—d 9—a 14—c 19—b 24—b 29—b 5—a 10—c 15—b 20—b 25—c 30—d ... - 11 0002, India, Phone: + 91- 11- 43574357 Registered Office B-3 EMCA House, 23/23B Ansari Road, Daryaganj, New Delhi - 11 0 002, India Phones: + 91- 11- 2327 214 3, + 91- 11- 23272703, + 91- 11- 232820 21, ... frontal SOL d retinoblastoma ANSWERS 1 b 6—b 11 —b 16 —b 21 a 26—c 2—c 7—c 12 —a 17 —c 22—b 27—c 3—b 8—c 13 —c 18 —d 23—b 28—b 4—b 9—c 14 —b 19 —d 24—d 29—b 5—c 10 —d 15 —a 20—d 25—a 30—a ... India Phones: + 91- 11- 2327 214 3, + 91- 11- 23272703, + 91- 11- 232820 21, + 91- 11- 23245672 Rel: + 91- 11- 32558559, Fax: + 91- 11- 23276490, + 91- 11- 23245683 e-mail: jaypee@jaypeebrothers.com, Website: www.jaypeebrothers.com