Eye Muscle Problems in Children and Adults: A Guide to Understanding By Burton J. Kushner, MD The John W. and Helen Doolittle Professor of Ophthalmology University of Wisconsin Department of Ophthalmology and Visual Sciences, Madison Supported by an unrestricted grant from Research to Prevent Blindness, Incorporated, New York, NY Copyright © 2014 by Burton J. Kushner, MD Kushner Eye Muscle Problems/Acknowledgements/page-2 Dedication The gods split these creatures into two parts, creating male and female humans. The belief is that each one of us, on a deeply subconscious level, knows that something is missing within ourselves, and we seek wholeness. — Rephrased from Plato, The Symposium For Dale My missing half Kushner Eye Muscle Problems/Acknowledgements/page-3 Acknowledgements This book represents a substantial revision of the excellent monograph written in 1974 by Charles Windsor, M.D. and Jane Hurtt, R.N., A.A., Eye Muscle Problems in Childhood: a Manual for Parents — second edition. Although their booklet is now about 40 years old, it has remained the best guide available for informing parents, patients and primary care physicians about the complex subject of eye muscle problems. Both authors have generously given me permission to update and modify their publication. I would also like to thank the tens of thousands of patients who have entrusted me with their care over the past 40 years. Their questions inspired this book. There are no “dumb questions” when it comes to medical matters. If a question exists in a patient’s mind, it should be addressed. If that question remains unasked or unanswered, or if the answer is not understood, not only the doctor-patient relationship may suffer, but adverse medical consequences may follow. Kushner Eye Muscle Problems/page -4 Table of Contents Preface 5 Chapter 1: Your First Visit to the Eye Doctor 10 Chapter 2: How Our Eyes Work 19 Chapter 3: Teamwork of the Two Eyes 32 Chapter 4: About Strabismus and Why Eyes Are Sometimes Misaligned 40 Chapter 5: Amblyopia (“Lazy Vision”) 47 Chapter 6: The Treatment of Strabismus (Non-Surgical) 57 Chapter 7: Surgical Treatment of Strabismus 75 Chapter 8: Eye Muscle Problems in Adults 87 Chapter 9: Eye Exercises (Orthoptic Treatment) 90 Chapter 10: Glasses in the Management of Strabismus 91 Chapter 11: The Psychological Effects of Strabismus 95 Chapter 12: The Eye as it Relates to Reading Disabilities 97 Chapter 13: Special Forms of Strabismus 99 Chapter 14: Glossary: Some Important Terms to Understand 105 About the Author 111 Kushner Eye Muscle Problems/Preface/page -5 Preface Why Have I Written This Book? In recent decades patients have assumed a more active role in understanding their medical conditions and in making informed decisions about their health care. I assume you are reading this book because you, your child, or someone you care about has an eye muscle disorder. Perhaps your doctor did not satisfactorily answer your questions. Possibly you had questions you did not ask. Maybe you are just seeking a better grasp of what you were told at the doctor’s office in order to better evaluate the treatment options you were given. Alternatively, you are just seeking confirmation that you, or your child, are being treated properly. The purpose of this book is to help you understand the complex subject of eye muscle disorders and to address your unasked or unanswered questions, so that you can make informed decisions regarding treatment choices. In the following pages, I will attempt to explain the perplexing and mysterious subject of the lazy eye in a patient-friendly way that can be easily understood. If knowledge is power, one of its powers is to enable us to make wise and informed decisions that influence our future. Hopefully after reading this book you will feel more empowered to make considered choices regarding the treatment of your child, yourself, or your loved one. Let this book be an adventure of discovery about a pair of eyes, and how they should work together. Let it be an exploration that simulates a visit to the office of a caring and understanding physician who has unlimited time to answer questions and explain treatment options in a clear and understandable fashion. I wrote this book because, regrettably, not everyone is fortunate enough to be under the care of such an idealized doctor. Kushner Eye Muscle Problems/Preface/page -6 How to Use This Book Because people differ in the amount of technical information they desire, I have followed a layered approach to presenting this material. Basic Information: Information that is considered basic and important for you to read in order to understand a given topic is accompanied by the symbol of stacked books. If you limit your reading to the basic material for a particular topic, you will have sufficient grasp of the subject to understand related material. Advanced Information: A graduate identifies information that delves more deeply into the technical aspects of a topic, and which expands on the basic material to give you a more thorough understanding of a subject. If you do not wish to explore these more advanced aspects, you may skip over this information. I consider this material to be “extra credit” for those readers who have a greater interest in particular aspects of eye muscle problems. Important Point: A string around an index finger denotes an important point. This identifies a particularly useful fact or concept that is worth remembering. Frequently Asked Questions: A question mark will identify frequently asked questions. I encourage you to read all of them. During my 39 years in practice, certain questions re-occur. Perhaps you have these same questions. Perhaps they are ones you have not thought about yet, but would find the answers helpful. The answers to these frequently asked questions are of benefit to all readers. Myth: There are many myths and misconceptions that relate to the subject of the lazy eye. These represent misleading and incorrect information that will confuse your understanding of this subject. The trashcan is the appropriate place for these incorrect ideas. Try This Experiment: To help you understand certain subjects, I may suggest you perform simple experiments. These will be identified by this scientific symbol. Kushner Eye Muscle Problems/Preface/page -7 Regarding Unfamiliar Medical Terms Doctors tend to speak in their own language. They often use terms that may be unfamiliar to you. It is important that you become acquainted with some of these terms if you are going to learn about eye muscle problems and “lazy eye.” When an unfamiliar term appears for the first time in this book, a simple definition will be given. Each time the term subsequently appears, it will be written in italics. There is also a Glossary at the end of the book in which all italicized terms are listed alphabetically and definitions given (see Chapter 14, page 107). Feel free to refer to the Glossary if you come across an italicized word for which you may have forgotten the definition. Before you can start on this journey of discovery, there are two very important terms with which you should become familiar. Strabismus: This is the medical term to describe any type of misalignment of the eyes. If someone’s eye crosses (turns in), drifts outward toward the ear (is “wall-eyed”) or is misaligned vertically (points too high or too low), that person has strabismus. Substitute words that have the same meaning include “eye muscle imbalance” or “wandering eye.” Amblyopia: This refers to vision that is decreased because the eye has been ignored or “shut off.” A common slang term for amblyopia is lazy eye. With amblyopia, the vision is said to be “lazy,” because even with proper glasses (if needed), the vision initially is still not normal (however, it may normalize with treatment). The brain has not learned, or has forgotten, how to see with the eye. The most common cause of amblyopia is a misalignment of the eye (strabismus). However, the two conditions are not the same. As you will learn in Chapter V your child can have amblyopia without any misalignment of the eyes (without strabismus), or he may have misaligned eyes yet good vision (has strabismus but no amblyopia). Many people incorrectly use the term lazy eye to describe an eye that is misaligned or deviates. Strictly speaking, however, the term lazy eye should be reserved for describing lazy vision and not to describe a misaligned eye. Regarding Gender In order to avoid the complex use of gender-neutral pronouns such as (s)he or he/she, I arbitrarily will use either he or she, alternating back and forth equally. Regarding Eye Doctors In recent years, the differences in the scope of practice between ophthalmologists and optometrists (see page 109) have become less distinct, and this has resulted in some controversy. In this book, I wish to avoid that controversy. In most places I simply refer to “eye doctor” rather than specifying ophthalmologist or optometrist, unless the issue is one in which the distinction is clear. Kushner Eye Muscle Problems/Preface/page -8 Regarding Right and Left Eyes Throughout this book, when I refer to a “right eye” or a “left eye,” I will be describing the eye from the viewpoint of the person whose eye it is. The girl shown in the photograph below has a crossed eye. Although it is her right eye that is deviated, it is to your left as you look at her picture. In the chapters that follow, I would describe this situation as demonstrating a deviated right eye and a properly aligned left eye. Kushner Eye Muscle Problems/Preface/page -9 Topic Checklist You may wish to read this entire book to get a good general understanding of eye muscle problems.