Elevation Based Corneal Tomography Second Edition Editors: Michael W. Belin, MD, FACS Stephen S. Khachikian, MD Renato Ambrósio Jr., MD, PhD An Editorial Branch of Jaypee Brothers Medical Publishers (P) Ltd. PRODUCTION Production Director: Kayra Mejia Digital Composition: Laura Duran, Erick Navarro Art Director: Eduardo Chandeck International Communications: Joyce Ortega MARKETING Director Sales & Marketing Latin America: Srinivas Chaubey Customer Service: Miroslava Bonilla Sales Manager: Tomas Martinez © Copyright, English Edition, 2012 for Jaypee - Highlights Medical Publishers, Inc. All rights reserved and protected by Copyright. No part of this publication may be reproduced, stored in retrieval system or transmitted in any form by any means, photocopying, mechanical, recording or otherwise, nor the illustrations copied, modified or utilized for projection without the prior, written permission of the copyright owner. Due to the fact that this book will reach ophthalmologists from different countries with different training, cultures and backgrounds, the procedures and practices described in this book should be implemented in a manner consistent with the professional standards set for the circumstances that apply in each specific situation. Every effort has been made to confirm the accuracy of the information presented and to correctly relate generally accepted practices. The authors, editors, and publisher cannot accept responsibility for errors or exclusions or for the outcome of the application of the material presented herein. There is no expressed or implied warranty for this book or information imparted by it. Any review or mention of specific companies or products is not intended as an endorsement by the authors or the publisher. Belin, Michael W., MD, FACS; Khachikian, Stephen S., MD; Ambrosio Jr., Renato, MD, PhD “ELEVATION BASED CORNEAL TOMOGRAPHY” Second Edition ISBN: 978-9962-678-53-3 Published for: Jaypee - Highlights Medical Publishers, Inc. City of Knowledge International Technopark, Bldg. 237 Gaillard Highway, Clayton Panama Rep. of Panama Phone: (507) 301-0496 / 97 - Fax: (507) 301-0499 E-mail: [email protected] Worldwide Web: www.jphmedical.com ii Editors Michael W. Belin, MD., FACS Professor of Ophthalmology & Vision Science University of Arizona & Southern Arizona Veterans Administration Health Care System Tucson, Arizona (USA) Stephen S. Khachikian, MD Black Hills Regional Eye Institute Rapid City, South Dakota (USA) Renato Ambrósio Jr., MD, PhD Instituto de Olhos Renato Ambrósio Rio de Janeiro Corneal Tomography and Biomechanics Study Group Assistant Professor of Ophthalmology Federal University of São Paulo Brazil iii Contributing Authors Renato Ambrósio Jr., MD, PhD Frederico P. Guerra, MD Instituto de Olhos Renato Ambrósio Brazilian Study Group of Artificial Intelligence Rio de Janeiro Corneal Tomography and Corneal Analysis (BrAIn), Brazil and Biomechanics Study Group Instituto de Olhos Renato Ambrósio & Assistant Professor of Ophthalmology Rio de Janeiro Corneal Tomography and Federal University of São Paulo, Brazil Biomechanics Study Group, Rio de Janeiro, Brazil Luana P. N. Araújo, MD Brazilian Study Group of Artificial Intelligence Stephen S. Khachikian, MD and Corneal Analysis (BrAIn), Brazil Black Hills Regional Eye Institute Universidade Federal de Alagoas, Rapid City, South Dakota (USA) Maceió, Brazil Michael W. Belin, MD., FACS Joerg Iwanczuk, Dipl Ing (FH) Professor of Ophthalmology & Vision Science Product Manager University of Arizona & OCULUS Optikgeräte, GmbH Southern Arizona Veterans Administration Wetzlar, Germany Health Care System Tucson, Arizona (USA) Shuning Li, MD, PhD Beijing Ophthalmology & Edmondo Borasio, MedC, BQ, FEBO Visual Science Key Lab, Consultant Ophthalmic Surgeon Beijing Tongren Eye Center, Moorfields Eye Hospital, Dubai Beijing Tongren Hospital, Capital Medical University, Beijing, China Isaac Carvalho de Oliveira Ramos, MD Anterior Segment Fellow at Hospital Nossa Senhora da Saúde Allan Luz, MD, PhD (Gamboa), Rio de Janeiro, Brazil Doctorate Fellow at Federal University of São Paulo Cornea Department of Dilraj Grewal, MD Hospital de Olhos de Sergipe Department of Ophthalmology São Paulo, Brazil Northwestern University Chicago, Illinois, (USA) iv João Marcelo Lyra, MD, PhD Guilherme Ribeiro, MD Professor of Post-Graduation in Brazilian Study Group of Artificial Intelligence Artificial Intelligence and Ophthalmology and Corneal Analysis (BrAIn), Brazil Alagoas Federal University Universidade Federal de Alagoas, Member of Brazilian Study Group of Maceió, Brazil Artificial Intelligence and Corneal Analysis (BrAIn), Maceió, Brazil Marcella Salomão, MD Clinical Director of Femtolaser-RIO Aydano P. Machado, MSc, PhD Rio de Janeiro, Brazil Brazilian Study Group of Artificial Intelligence and Corneal Analysis (BrAIn), Brazil Universidade Federal de Alagoas, Satinder Pal Singh Grewal, MD Maceió, Brazil Grewal Eye Institute Chandigarh, India Naoyuki Maeda, MD Department of Ophthalmology Bruna V. Ventura, MD Osaka University Brazilian Study Group of Artificial Intelligence Graduate School of Medicine and Corneal Analysis (BrAIn), Brazil Yamadaoka, Japan Universidade Federal de Alagoas, Maceió, Brazil Leonardo N. Pimentel, MD Cornea Department of Federal University of Rio Grande do Norte Natal, Rio Grande do Norte, Brazil Isaac Ramos, MD Brazilian Study Group of Artificial Intelligence and Corneal Analysis (BrAIn), Brazil Instituto de Olhos Renato Ambrósio & Rio de Janeiro Corneal Tomography and Biomechanics Study Group, Rio de Janeiro, Brazil v Preface PREFACE TO THE SECOND EDITION (2012) by Michael W. Belin, MD Tucson, Arizona (USA) It’s been over three years since the first edition went to press. In the intervening period the technology has improved and numerous maps/displays have been added. In the second edition every chapter has been updated and new chapters have been added to reflect the expanded clinical use of Scheimpflug imaging. As in the first edition, we have attempted to keep the reading easy and hopefully, for some, enjoyable. PREFACE TO FIRST EDITION (2008) by Michael W. Belin, MD Albany, New York (USA) The last thing I wanted to do is write a book. There is a saying “Those who can… Do .. and Those who can’t … Teach.” I feel about the same about writing text books. It is a thankless job that usually means you have too much free time or nothing better to do. I wish that was the case. Constant nagging by my current research and clinical fellow (Stephen S. Khachikian, MD) about the need for a book on elevation topography and promises that it would not be that much work eventually wore me down. Well, in hindsight, he was half right. Elevation based topography (or Tomography) is a new and comprehensive way of looking at the cornea, its structure, shape and performance. For many practitioners used to relying on anterior curvature analysis it may initially appear foreign. It is the authors’ belief, however, that cross-sectional Scheimpflug analysis offers significant advantages in treatment, diagnosis and patient safety. We tried to make the book easy to read and comprehend and filled it with numerous color figures. Each chapter was designed to stand on its own, though for those with time and inclination the chapters are arranged in an orderly progression. We hope we have met our goal. The book was made possible in part by an unrestricted educational and research grant from the Sight Society of Northeastern New York, Inc and the Lions Eye Bank at Albany (New York). The authors are indebted to their continued support. vii Contents CHAPTER 1 Introduction and Overview.............................................................................. 1 Michael W. Belin, MD, FACS; Stephen S. Khachikian, MD CHAPTER 2 Evolution of Topographic / Tomographic Imaging........................................... 15 Stephen S. Khachikian, MD; Michael W. Belin, MD, FACS; Renato Ambrósio Jr., MD, PhD CHAPTER 3 Understanding Elevation Based Topography: How Elevation Data is Displayed....... 25 Michael W. Belin, MD, FACS; Stephen S. Khachikian, MD; Renato Ambrósio Jr., MD, PhD CHAPTER 4 The Importance of Understanding the Reference Surface............................... 47 Michael W. Belin, MD, FACS; Stephen S. Khachikian, MD; Renato Ambrósio Jr., MD, PhD CHAPTER 5 Suggested Set-up and Screening Guidelines..................................................... 57 Michael W. Belin, MD, FACS; Stephen S. Khachikian, MD; Renato Ambrósio Jr., MD, PhD CHAPTER 6 Normative Data for the Oculus Pentacam.......................................................... 71 Stephen S. Khachikian, MD; Michael W. Belin, MD, FACS; Renato Ambrósio Jr., MD, PhD CHAPTER 7 Comprehensive Pachymetric Evaluation............................................................ 81 Renato Ambrósio Jr., MD, PhD; Isaac Carvalho de Oliveira Ramos, MD; Allan Luz, MD; Frederico Guerra, MD; Marcella Salomão, MD ; Michael W. Belin, MD, FACS CHAPTER 8 Keratoconus / Ectasia Detection with a Modified (Enhanced) Reference Surface Belin / Ambrósio Enhanced Ectasia Display III............................................................. 93 Michael W. Belin, MD, FACS; Renato Ambrósio Jr., MD, PhD; Stephen S. Khachikian, MD viii CONTENTS CHAPTER 9 Keratoconus & Ectasia Detection: Asymmetric Keratoconus & Post LASIK Ectasia Study..................................... 105 Marcella Salomão, MD; Isaac Carvalho de Oliveira Ramos, MD; Allan Luz, MD; Frederico Guerra, MD; Leonardo N. Pimentel, MD; Renato Ambrósio Jr., MD, PhD CHAPTER 10 Applications of Artificial Intelligence Techniques for Improving Tomographic Screening for Ectasia................................................ 123 João Marcelo Lyra, MD, PhD; Aydano P. Machado, MSc, PhD; Bruna V. Ventura, MD; Guilherme Ribeiro, MD; Luana P. N. Araújo, MD; Isaac Ramos, MD; Frederico P. Guerra, MD; Renato Ambrósio Jr, MD, PhD CHAPTER 11 Elevation Topography Atlas............................................................................ 137 Stephen S. Khachikian, MD; Michael W. Belin, MD, FACS; Renato Ambrósio Jr., MD, PhD CHAPTER 12 Scheimpflug Images in Clinical Practice...................................................... 167 Michael W. Belin, MD, FACS; Renato Ambrósio Jr., MD, PhD; Stephen S. Khachikian, MD CHAPTER 13 BESSt 2 Formula for IOL Calculation........................................................ 185 Edmondo Borasio, MedC, BQ, FEBO CHAPTER 14 Evaluation of Corneal Optical Quality for Premium IOLs with Pentacam HR... 197 Naoyuki Maeda, MD CHAPTER 15 Scheimpflug Evaluation of Primary Angle Closure Glaucoma...................... 205 Shuning Li, MD CHAPTER 16 Other Displays................................................................................................ 211 Joerg Iwanczuk, Dipl Ing (FH); Michael W. Belin, MD, FACS CHAPTER 17 The Use of Pentacam in a Cataract Practice............................................... 229 Dilraj Grewal, MD; Satinder Pal Singh Grewal, MD CHAPTER 18 Glossary........................................................................................................... 247 Stephen S. Khachikian, MD; Michael W. Belin, MD, FACS; Renato Ambrósio Jr., MD, PhD ix