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: [email protected], 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: [email protected] 202 Batavia Chambers, 8 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: [email protected] 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: [email protected] 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: [email protected] 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: [email protected] 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: [email protected] Lekhraj Market III, B-2, Sector-4, Faizabad Road, Indira Nagar Lucknow 226 016, Phones: +91-522-3040553, +91-522-3040554, e-mail: [email protected] 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: [email protected] “KAMALPUSHPA” 38, Reshimbag, Opp. Mohota Science College, Umred Road Nagpur 440 009 (MS), Phone: Rel: +91-712-3245220, Fax: +91-712-2704275, e-mail: [email protected] USA Office 1745, Pheasant Run Drive, Maryland Heights (Missouri), MO 63043, USA, Ph: 001-636-6279734 e-mail: [email protected], [email protected] 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 do 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. xzkáa p :iL; eq[kL; “kksHkk] çR;{kcks/kL; p gsrq Hkwre~! rfeL=-fnd-deZlq ekxZnf”kZ] us=a ç/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 1. Embryology and Anatomy ................................................................................................ 1 2. Physiology of Vision .......................................................................................................... 9 3. Neurology of Vision .......................................................................................................... 15 4. Examination of the Eye .................................................................................................... 22 5. Errors of Refraction .......................................................................................................... 47 6. The Conjunctiva ................................................................................................................ 71 7. The Cornea .......................................................................................................................107 8. The Sclera .........................................................................................................................153 9. The Uveal Tract ...............................................................................................................161 10. The Lens ...........................................................................................................................205 11. The Vitreous .....................................................................................................................246 12. Glaucoma ...........................................................................................................................258 13. The Retina.........................................................................................................................300