Recent Advances in Ophthalmology—8 HV Nema, Nitin Nema
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1Recent Advances in Ophthalmology—82
3Recent Advances in Ophthalmology—8
Editors HV Nema MS Former Professor and Head Department of Ophthalmology Banaras Hindu University Varanasi, India Nitin Nema MS DNB Assistant Professor Department of Ophthalmology Sri Aurobindo Institute of Medical Sciences Indore, India Editorial Board Jorge L Alio MD PhD Alicante, Spain Lingam Gopal MS FRCS Chennai, India Frank Goes MD Antwerp, Belgium Devinder Sood MD New Delhi, India Suresh Chandra MD Madison, USA
4Published by
Jitendar P Vij
Jaypee Brothers Medical Publishers (P) Ltd
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Recent Advances in Ophthalmology—8
© 2006, HV Nema, Nitin Nema
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 authors and the publisher.
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To
Pratibha
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Sandeep
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7Contributors 9Preface
Recent Advances in Ophthalmology-8, like its previous volumes, contains new information in the field of refractive surgery, glaucoma and dry eye disease.
Laser in situ keratomileusis (LASIK) has become an outstanding successful refractive surgical procedure over the past decade. It changes the refractive power of the eye by altering the corneal shape. LASIK surgery in myopia changes the shape of the cornea from prolate to oblate, while in hyperopia increases its prolateness. Although the surgery often successfully reduces the refractive error, it does so at the cost of increasing corneal surface irregularities. The predictability and stability of LASIK are reduced in high hyperopia. Dr Goes has traced the chronological developments in refractive surgery from past to present with a future optimism.
Surgical correction of presbyopia poses a challenge to the refractive surgeon. Though not ideal, monovision may be obtained by cataract surgery, LASIK, PRK and conductive keratoplasty. Creation of bifocal or multifocal cornea by excimer laser can correct presbyopia. Accommodation may be restored after cataract surgery by implantation of accommodative lenses. The axial movement of the lens is referred as pseudoaccommodation (since forward movement of the lens is one of the components of accommodation, partial accommodation seems to be a better term than pseudo). CrystaLens and Akkommodative1CU are designed to maximise anterior movement of the lens to obtain good uncorrected distant and near vision but a significant number of patients with these lenses may feel difficulty in reading and need near correction. Two other lenses; the SmartLens and the Light Adjustable Lens (LAL) designed for correction of presbyopia are under clinical investigation. Prof. Alio discussed the various theories of accomodation and the surgical correction of presbyopia in great details.
Glaucoma is a leading cause of blindness worldwide. Several risk factors for the development of glaucoma are identified. The importance of decreased corneal thickness, as a risk factor, has recently been recognized. Is the presence of peripapillary atrophy (PPA) a risk factor for POAG or Normal Pressure Glaucoma? PPA occurs more frequently and more extensively in the glaucomatous eye than in normal ones. The extent and location of PPA correlate well with the visual field defects. Dr Park demonstrated that the measurement of PPA is helpful in differentiating between a normal optic nerve head and the disc of normal tension glaucoma.
The medical treatment of the developmental glaucoma has a limited value; the choice of management is mostly surgical. Goniotomy or tabeculotomy is a preferred primary surgical procedure. When it fails to control IOP, trabeculectomy with or without antifibrotic agent (mitomycin or 5 FU) should be preferred. Dr Mandal and co-authors emphasized that the long-term prognosis of patients with developmental glaucoma has greatly improved with early surgical intervention, periodic follow-up and effective management of postoperative complications.
In spite of a notable ocular hypotensive effect, none of the currently available drug is capable of reversing the glaucomatous neuropathy. The 10present goal of medical therapy of POAG is to lower IOP to a target pressure (usually 20% reduction from baseline pressure) that is unlikely to cause further damage to the optic nerve. However, this reduction in IOP does not guarantee that further nerve damage will not occur in future. Therefore, in the event of IOP fluctuations, visual field progression, and optic nerve head changes, the target pressure must be further reduced. Drs Bansal and Tsai have comprehensively reviewed the current advances in the medical treatment of POAG.
Phacoemulsification is a safe and well established procedure to deal with cataract. However, in patients with complicated cataract, like uveitic cataract, pre- and intra-operative precautionary measures are needed to prevent postoperative complications and to regain good visual acuity. Dr Venkatesh and co-authors have well elaborated these measures.
Children are different from adults in many aspects. Therefore, age, weight, growth, immunological status and allergic predisposition must be taken into consideration before starting medical therapy. An excellent review article — Ophthalmic Medications in Pediatric Patients by Myers et al. from the Journal of Comprehensive Ophthalmology Update is reprinted in this volume for the benefit of our readers.
The development of Retinopathy of Prematurity (ROP) is inversely correlated with gestational age and birth weight. Screening and documentation, treatment modalities and prognosis of ROP in Indian scenario are well described by Drs Azad and Chandra.
Since the National Eye Institute Industry Workshop in 1992 proposed a diagnostic classification of dry eye, more and more interest is generated in the study of this disorder. Dr Vinay Agrawal has described the anatomical and physiological basis of tear formation and succinctly detailed the diagnostic tests and management of dry eye disease.
Several aspects of the obstruction of the lacrimal drainage system have been well studied. The age of the patient and site and characteristic of obstruction need to be identified before planning the management strategies. Drs Mahatme and Pande described in great details the old and new surgical approaches to deal with the drainage obstruction.
Recent advances and innovations in ophthalmology have significantly improved the visual outcome and quality of life patients. It is our sincere hope that the book will assist the postgraduate students in ophthalmology, general ophthalmic practitioners and clinicians and, ultimately our patients with eye diseases receiving better care and the treatment.
We wish to record our grateful thanks to all the contributing authors for their timely and outstanding contributions. Mr Jitendar Vij, Chairman and Managing Director, Jaypee Brothers Medical Publishers Pvt. Ltd. and staff especially Mr Tarun Duneja, Managing Director, Publishing, deserve our sincere thanks for their continued interest in the publication of the Recent Advances in Ophthalmology series.
HV Nema
Nitin Nema