Table of Contents

Contents

Section 1 General Anatomy and Physiology of the Horse Eye
Introduction 3
Some Helpful Hints 3
Anatomy
Orbit 4
Eyelids 6
Nictitans 8
Conjunctiva 8
Anterior Segment 8
Precorneal Tear Film 8
Cornea, Limbus, Sclera 9
Iridocorneal Angle 11
Uvea 11
Iris 11
Pupil 12
Ciliary Body 13
Choroid 13
Lens 13
Posterior Segment 14
Vitreous Chamber 14
Retina 14
Optic Nerve 15

Section 2 Examination of the Eye of the Horse
History 18
Ophthalmic Examination 18
Reflex Testing 18
Diagnostic Testing 19
What does the Horse See? Visual Capabilities of the Horse 33
Ocular Problems in the Foal 36

Section 3 The Equine Orbit
Orbital Diagnostic Techniques 48
Orbital Trauma, Contusion and Periorbital Fractures 50
Foreign Bodies can lead to Orbital Abscesses 52
Orbital Tumors 52
Suture Line Periostitis 54
Treatment of Equine Orbital Disease 54

Section 4 The Eyelids, Conjunctiva and Lacrimal System
Traumatic Eyelid Lacerations 60
Neoplasia of the Lids 65
The Conjunctiva 72
Nictitans 76
The Nasolacrimal System 77
Keratoconjunctivitis Sicca (KCS) 78
Dacryocystitis 79

Section 5 Corneal Ulceration
Corneal Ulceration 86
Proteinases in the Tear Film 112
Corneal Sensitivity in Foals and Adult Horses 113
Corneal Healing in the Horse 114
The Equine Corneal Microenvironment 115
Medical Therapy 118
Antibiotics 119
Collagenolysis Prevention 119
Treat Uveitis 120
Adjunctive Surgical Therapy 120
**Important Concepts** 127
Corneal Lacerations/Perforations 128
Fungal Ulcers in Horses 130
Iris Prolapse in the Horse 131
Corneal Stromal Abscesses 132

Section 6 Other Corneal Problems
Corneal Edema 154
Squamous Cell Carcinoma and other Corneal Tumors 154
Corneal Foreign Bodies 156
Endothelial Detachment following Blunt Trauma 158
Nonulcerative Keratouveitis (NKU) 158
Nonulcerative Interstitial Keratitis (NIK) 158
Eosinophilic Keratoconjunctivitis 160
Herpes and Viral Keratitis 162
Burdock Pappus Bristle Keratopathy 164
Calcific Band Keratopathy 164

Section 7 Cataracts, Glaucoma and Uveal Problems in the Horse
Cataracts 170
Equine Cataract Surgery 175
Extracapsular Cataract Surgery 175
Phacoemulsification Cataract Surgery 175
Intracapsular Cataract Surgery 179
Postoperative Cataract Surgery Therapy and Results 179
Aphakic Vision in Horses 180
Equine Glaucomas 181
Contraindications/Possible Interactions 189
Tips on Tonometry for Evaluation of Intraocular Pressure (IOP) in Horses 189
The Uveal Tract 190
Heterochromia Iridis 190
Aniridia/Iris Hypoplasia/Enlarged Corpora Nigra/Iris Colobomas 191
Iris and Ciliary Body Cysts 191
Equine Recurrent Uveitis (Periodic Ophthalmia, Moon Blindness, Iridocyclitis 192
ERU Therapy 200
Some Horses require Life-Long Therapy! 200
Alternative Therapy for ERU 203
Surgical considerations for ERU 203

Section 8 Retinopathies and Ocular Manifestations of Systemic Diseases in the Horse
Retinopathies 208
Chorioretinitis 208
Congenital Stationary Night Blindness 211
Equine Motor Neuron Disease Retinopathy 211
Retinal Detachments 211
Optic Neuropathies 213
Bacterial Infections 219
Viral Infections 221
Chlamydial Infections 223
Fungal Infections 223
Protozoan Infections 224
Neoplasia 224
Unknowns 225
Eye Diseases associated with Specific Horse Breeds 226
Links 229
Electroretinography 229
Lavage Treatment Systems 231
Glossary of Selected Veterinary Ophthalmic Terms 232
Treatment Plans/Practice Tips 240
Index 255