Small Animal Ophthalmology E-Book

Heidi Featherstone

• Herausgeber: John Wiley & Sons
• Kategorie: Fachliteratur
• Serie: What's Your Diagnosis?
• Sprache: Englisch

Seitenzahl: 385

Veröffentlichungsjahr: 2011

Beschreibung

Small Animal Ophthalmology: What's Your Diagnosis? is one of the first books in an exciting new series that combines problem-based learning, case studies, and questions and answers. Designed specifically for veterinarians and students, the series aims to present material in a format to enhance critical thinking and understanding.

Adopting a case-based approach, chapters are built around common ophthalmic presentations and are directed by questions to test the reader's ability to interpret clinical history, ophthalmic photographs and diagnostic results in order to provide differential diagnoses, diagnostic plans and treatment options.

For veterinary students, this book is an ideal guide to how ophthalmology cases are handled in the clinical setting. For veterinary practitioners, it is an innovative and interesting way to increase their knowledge and skills in clinical ophthalmology.

Leseprobe

Table of Contents

Cover

Table of Contents

Title page

Copyright page

Foreword

Preface

Acknowledgements

List of Abbreviations

CHAPTER 1 Abnormalities of Globe Size and Position

Introduction

CASE STUDY 1

CASE STUDY 2

CASE STUDY 3

CASE STUDY 4

CHAPTER 2 Eyelid Abnormalities

Introduction

CASE STUDY 1

CASE STUDY 2

CASE STUDY 3

CHAPTER 3 Abnormalities of the Third Eyelid

Introduction

CASE STUDY 1

CASE STUDY 2

CASE STUDY 3

CHAPTER 4 Ocular Discharge

Introduction

CASE STUDY 1

CASE STUDY 2

CASE STUDY 3

CHAPTER 5 The Painful Eye

Introduction

CASE STUDY 1

CASE STUDY 2

CASE STUDY 3

CHAPTER 6 The Red Eye

Introduction

CASE STUDY 1

CASE STUDY 2

CASE STUDY 3

CHAPTER 7 The Opaque Eye

Introduction

CASE STUDY 1

CASE STUDY 2

CASE STUDY 3

CHAPTER 8 Corneal Opacities

Introduction

CASE STUDY 1

CASE STUDY 2

CASE STUDY 3

CASE STUDY 4

CHAPTER 9 Abnormalities of the Iris

Introduction

CASE STUDY 1

CASE STUDY 2

CASE STUDY 3

CASE STUDY 4

CHAPTER 10 The Abnormal Pupil

Introduction

CASE STUDY 1

CASE STUDY 2

CHAPTER 11 The Blind Eye

Introduction

CASE STUDY 1

CASE STUDY 2

CASE STUDY 3

CASE STUDY 4

CASE STUDY 5

CHAPTER 12 Ocular Trauma

Introduction

CASE STUDY 1

CASE STUDY 2

CASE STUDY 3

APPENDIX 1  Practical Tips for An Ophthalmic Examination

Pupillary light reflex (PLR)

Examination with a focal light source

Purkinje images (or Purkinje-Sanson images)

Tapetal reflection (or tapetal reflex, fundic reflex)

Dazzle reflex

Tear film break-up time (TBUT)

Normal references ranges

APPENDIX 2  Further Reading

Glossary

Index

This edition first published 2011 by Blackwell Publishing Ltd

© 2011 by Heidi Featherstone and Elaine Holt

Blackwell Publishing was acquired by John Wiley & Sons in February 2007. Blackwell’s publishing program has been merged with Wiley’s global Scientific, Technical and Medical business to form Wiley-Blackwell.

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Library of Congress Cataloging-in-Publication Data

Featherstone, Heidi

 Small animal ophthalmology : what’s your diagnosis? / Heidi Featherstone, Elaine Holt.

p. ; cm.

 Includes bibliographical references and index.

 ISBN 978-1-4051-5161-0 (pbk. : alk. paper)

 1. Veterinary ophthalmology. 2. Pet medicine. I. Holt, Elaine. II. Title.

[DNLM: 1. Eye Diseases–veterinary–Case Reports. 2. Eye Diseases–veterinary–Problems and Exercises. 3. Animals, Domestic–Case Reports. 4. Animals, Domestic–Problems and Exercises. 5. Diagnosis, Differential–Case Reports. 6. Diagnosis, Differential–Problems and Exercises. SF 891]

 SF891.F43 2011

 636.089'77–dc22

2010041328

A catalogue record for this book is available from the British Library.

This book is published in the following electronic formats: ePDF 9781444340013; ePub 9781444340020

Foreword

Welcome to one of the most useful and informative ophthalmology text-books to have been published in recent years. The authors are to be commended on creating a reference book that is unlike any other currently on the market. They are medical educators that have drawn from a wealth of private practice knowledge and experience to create a highly practical guide to some of the most common presentations of ophthalmic disease. This highly utilitarian and functional approach is exemplified by their overall organizational approach. Rather than assuming the traditional ‘front to back’ approach taught in most classroom settings, the purpose of this text can be first best reflected in its chapters’ titles, whereby they encompass the most frequently encountered small animal patient complaints such as ocular discharge, the painful eye, the opaque eye, the abnormal pupil, blindness, and ocular trauma (to name just a few). The strength of this textbook is evident that all major topic areas have been presented using actual cases, which are both beautifully photodocumented and carefully organized. In addition to the numerous high quality coloured photographs, are clear illustrations, the results of advanced imaging modalities which in some cases utilize 3D reconstruction, and histopathology – all which dramatically strengthen the calibre of each case presentation.

The book will appeal to veterinary clinicians at all stages of the educational process, ranging from veterinary students and new graduates to board-certified ophthalmic specialists. The employment of case-based examples prompts the reader to hone his/her clinical acumen by working through relevant questions pertaining to differential diagnoses and the selection of appropriate diagnostic tests. Diagnosis, treatment, prognosis, and discussion are clearly provided. Importantly, the authors recognize that, depending on the reader’s level of experience, different diagnostic and therapeutic strategies may, at times, be equally successful to those provided and thus ample opportunities for additional reading is provided by way of several appendices, glossaries, and extensive bibliographic material. As I have, I believe you will find this text one of the most enjoyable, informative, and ‘user-friendly’ practical approaches to small animal ophthalmology to have been published in many years.

Elizabeth A. Giuliano, DVM, MS

Diplomate, American College of Veterinary Ophthalmologists

Preface

Veterinary ophthalmology is a visual discipline – not because the eye is the organ of vision but because the evidence that is required to diagnose ocular disease in animals is often highly visible. In other veterinary specialities a problem typically requires extensive investigation, but in veterinary ophthalmology a thorough ocular examination and a few routine tests may well result in an accurate diagnosis. The challenge is to know what to look for, and then to interpret the clinical signs correctly. Techniques such as electroretinography and advanced diagnostic imaging have their place, but only in a small number of cases.

There are numerous textbooks in both the human and veterinary fields containing comprehensive information on all aspects of ophthalmology, from anatomy and physiology to the treatment of clinical disease. The aim of this book is to offer the reader a practical guide to diagnosis using a case-based, systematic approach. It is intended for anyone with an interest in veterinary ophthalmology, including the general practitioner and the veterinary student.

We are veterinary ophthalmologists working in busy referral practices, with experience in general practice and in undergraduate and postgraduate teaching. We have sought to provide a pragmatic approach to the diagnosis and management of ocular disease in small animals, and to share our thought processes, drawing on the broad spectrum of examples in our daily case loads, from extreme forms of common conditions to more complex ocular disease. Practical recommen­dations are supported by extensive photodocumentation, and an appendix of tips for interpreting the information obtained from ophthalmic examination.

Heidi Featherstone & Elaine Holt

Acknowledgements

As with any book, the finished work is possible only with the help of many people. We are indebted to numerous colleagues, not only for generously contributing case material, but also for their time and advice. For their ophthalmology expertise, we thank Peter Renwick, Christine Heinrich, John Mould, Mike Rhodes, Barbara Braus, Sue Manning, Elizabeth Giuliano, Ellison Bentley, Marnie Ford and David Gould. Peter Renwick and Christine Heinrich deserve special thanks for their generosity in sharing their library of photographs, built up over many years. John Mould also deserves special thanks for his exceptional photographic skills, and for his readiness to share his photographs. With respect to imaging, we are grateful to Paul Mahoney for his tireless help and advice on advanced imaging techniques, and to Ruth Dennis and Rob White for sharing their case material. Emma Scurrell has provided invaluable expertise, along with enthusiasm, on ophthalmic pathology, supported by excellent gross and histological photographs. Simon Scurrell has worked skilfully and painstakingly on the annotated diagrams. Photographing the eyes of conscious dogs and cats is a challenge that requires excellent handling skills and patience: special thanks to David Hindley, Stephanie Ascott, Tom Buckley, Nicola Millington, Lou Hadley and the nursing team at Willows Veterinary Centre and Referral Service. Sue Jenkins’ non-veterinary editing expertise has been invaluable throughout.

Not least, we would like to thank the animals, their owners, and the referring veterinary surgeons, without whom this book would not have been possible.

List of Abbreviations

ACTH

adrenocorticotrophic hormone (adrenocorticotropin)

ALT

alanine aminotransferase

AP

alkaline phosphatase

CCT

corneoconjunctival transposition

CDV

canine distemper virus

CNS

central nervous system

CT

computed tomography

CTT

corneal touch threshold

DIM

diffuse iris melanoma

EOM

extraocular polymyositis

ERG

electroretinography

FCV

feline calicivirus

FeLV

feline leukaemia virus

FHV-1

feline herpesvirus-1

FIV

feline immunodeficiency virus

FNA

fine-needle aspiration

H&E

haematoxylin and eosin

HF-UBM

high-frequency ultrasound biomicroscopy

ICLE

intracapsular lens extraction

IMR

immune-mediated retinitis

IOP

intraocular pressure

IVIg

intravenous therapy with human immunoglobulin

KCS

keratoconjunctivitis sicca

LIU

lens-induced uveitis

MMM

masticatory muscle myositis

MRI

magnetic resonance imaging

Nd : YAG

neodymium-doped yttrium aluminium garnet

NGE

nodular granulomatous episclerokeratitis

NSAID

non-steroidal anti-inflammatory drug

OD

oculus dextor, right eye

OS

oculus sinister, left eye

OU

oculi unitas, both eyes

PCR

polymerase chain reaction

PDT

parotid duct transposition

PHPV

persistent hyperplastic primary vitreous

PLR

pupillary light reflex

PPM

persistent pupillary membrane

PRA

progressive retinal atrophy

prcd

progressive rod-cone degeneration

q

quisque, every, e.g. q4 hours means ‘every four hours’ (six times daily)

RPE

retinal pigment epithelium

RPED

RPE dystrophy

SARDS

sudden acquired retinal degeneration syndrome

SFT

swinging flashlight test

STT

Schirmer tear test

TEL

third eyelid

TBUT

tear film break-up time

TPA

tissue plasminogen activator

UBM

ultrasound biomicroscopy

VOR

vestibulo-ocular reflex

CHAPTER 1

Abnormalities of Globe Size and Position

Introduction

It can be a challenge to differentiate between a change in size and a change in position of the eye. An abnormally small eye (microphthalmos) may be confused with a normal-sized eye that is recessed in the orbit (enophthalmos); an enlarged eye (buphthalmos) may have a similar appearance to a normal-sized eye that is anteriorly displaced (exophthalmos). Assessing the size of the palpebral fissure, position of the third eyelid (TEL) and corneal diameter, looking at the eye from different angles, careful comparison with the other eye and concurrent clinical signs are helpful in differentiating between these conditions.

CASE STUDY 1

History

A 12-year-old female neutered domestic shorthaired cat is presented because of a sudden redness in the right eye. The left eye had looked abnormal for several weeks but appeared comfortable. The cat has recently lost weight and is lethargic.

Questions

1. Describe the abnormalities in Figs. 1.1a, b, and c.

Fig. 1.1a

Fig. 1.1b

Fig. 1.1c

2. What differential diagnoses should be considered for this presentation?

3. What tests could you perform to make the diagnosis?

Answers

1. What the Figures Show

Fig.1.1a The left eye appears larger than the right eye; a wide palpebral fissure, increased corneal diameter and clearly visible medial and lateral regions of the limbus are consistent with buphthalmos. There is a generalised corneal opacity which is most dense axially; a tapetal reflection is not visible. In the right eye, the green tapetal reflection is obstructed ventrally by a red/black irregular opacity which appears to be in front of the iris, and there is a similar coloured opacity overlying the iris at the 9 o’clock position. The pupil is moderately dilated.

Fig.1.1b In the left eye, the Purkinje images are disrupted. There is generalised corneal vascularisation and a stippled area of fluorescein stain uptake axially. The conjunctival vessels overlying the sclera on the lateral aspect of the globe are congested. The iris is difficult to see well but appears darker (medially) and possibly thickened. In the right eye, there is hyphaema; the regions of the iris that are visible appear normal.

Fig.1.1c Oblique view from the lateral aspect of both eyes. In the left eye there is an irregular contour and anterior protrusion of the cornea (OS > OD). There is increased exposure of the sclera and conjunctiva, and episcleral congestion. The anterior chamber is obliterated by abnormal iris tissue which appears to be displaced anteriorly. In both eyes fluorescein dye is visible on the periocular hair at the medial canthus.

2. Differential Diagnoses

Given the history and the appearance of the left eye, the following conditions should be considered:

Chronic glaucoma In contrast to the dog, primary glaucoma in the cat is rare, and secondary glaucoma is more common. The most common causes of secondary glaucoma in the cat are chronic idiopathic lymphocytic-plasmacytic uveitis and primary intraocular neoplasia, most notably diffuse iris melanoma. Typical clinical signs include buphthalmos, conjunctival and episcleral congestion, corneal oedema, mydriasis, and impaired or absent vision. Buphthalmos can be difficult to discern in the cat and assessment of the size of the palpebral fissure can be helpful because it becomes wider as the size of the eye increases. Glaucoma in cats is typically insidious in onset and is often difficult to recognise. This is in contrast to canine primary glaucoma which is characterised by peracute pain, episcleral congestion, marked corneal oedema, mydriasis and blindness ( ).