Histologic Basis of Ocular Disease in Animals

Bruce Grahn, DVM, Diplomate ACVO, ABVP, is Professor Emeritus of Veterinary Ophthalmology at the Western College of Veterinary Medicine, Prairie Ocular Pathology Service, University of Saskatchewan in Saskatoon, Saskatchewan, Canada.Robert Peiffer, DVM, PhD, Diplomate ACVO, is Professor Emeritus of Ophthalmology and Pathology, School of Medicine at the University of North Carolina in Chapel Hill, North Carolina, USA.Brian Wilcock, DVM, PhD, Honorary Diplomate ACVO, is Professor Emeritus of Pathology, Ontario Veterinary College at the University of Guelph and Owner of Histovet Surgical Pathology in Guelph, Ontario, Canada.

• Foreword xiiiAcknowledgements xv1 Fixation and processing of ocular tissues 1Fixatives 1Fixation and sectioning artifacts 2Fixation techniques 3Trimming the fixed globe 5Electron microscopy 13References 142 General pathology of the eye 15Adaptations characterized by changes in cell size, number, or appearance 15Neoplasia 19Nomenclature 23Distinguishing benign from malignant 25Prognostication 27Unsuccessful adaptation: cellular degeneration, necrosis, and apoptosis 27Calcification, pigmentation, and cystic change 30Ocular inflammation 32Ocular manifestations of acute inflammation 34Chronic inflammation 39Ocular manifestations of chronic inflammation 39Immune privilege 41Lymphocytic–plasmacytic endophthalmitis 42The sequelae of intraocular inflammation and other injuries 43Limited regenerative ability 43Susceptibility to scarring 43Further reading 463 Congenital anomalies 49Introduction 49Defective organogenesis 50Defective early organogenesis 50Anophthalmos and cystic globe 53Anophthalmos and microphthalmos 54Cyclopia and synophthalmos 56Congenital anomalies of lens 56Congenital retinal nonattachment 63Aniridia – iridal hypoplasia or aplasia 63Coloboma 63Defective later organogenesis 64Neurectodermal defects 64Multifocal retinopathies 71Multiple ocular anomalies (MOA) in Rocky Mountain horses 71Anomalies of surface ectodermal origin that develop during later organogenesis 73Congenital adnexal cysts 73Dermoids 73Defects of neural crest migration and mesenchymal differentiation that develop in later organogenesis 73Congenital corneal disease 73Congenital disorders of neurocrest and mesenchymal tissues that manifest in the uvea during later organogenesis 74Persistent pupillary membranes (PPMs) 74Congenital glaucoma 75Uveal hypoplasia 78Collie eye anomaly (CEA) and related defects 78Persistence of embryonic vasculature 81References 834 Histopathology of ocular trauma 89Perforating and penetrating wounds of the globe and ocular tissues 89Perforating wounds of the globe 89Traumatic intraocular hemorrhage 89Expulsive subchoroidal hemorrhage 90Sequelae of intraocular hemorrhage 90Posttraumatic inflammation 95Phacoclastic endophthalmitis and traumatic cataract 95Infectious endophthalmitis 95Trauma to individual ocular tissues 95Orbit and optic nerve 95Cornea/sclera 95Uvea 100Lens 101Vitreous and retina 101Globe as a whole 101Reaction to foreign materials 101Complications of ocular surgery 102Chemical and thermal burns 102Effects of radiant energy 103References 1035 Diseases of the eyelid, conjunctiva, lacrimal, and nasolacrimal systems 105Eyelids 105Structural disorders 105Dermoids 105Hamartomas 105Subconjunctival fat prolapse 105Entropion, ectropion, and medial canthal pocket syndrome 105Distichiasis, districhiasis, and ectopic cilia 106Inflammatory disease 108Pyogranulomatous (granulomatous) blepharitis 108Juvenile sterile granulomatous dermatitis and lymphadenitis (juvenile cellulitis) 110Chalazion 110Medial canthal erosion syndrome 111Proliferative pox virus blepharitis in birds 111Parasitic eyelid disorders 111Demodicosis 111Cnemidocoptes pilae (scaly beak) infestation of avian species 113Eyelid tumors and neoplasms 113Cystic apocrine hyperplasia (hidrocystomas, sudoriferous cysts, and apocrine cysts) 113Granular cell tumor 113Meibomian (tarsal gland) adenoma 115Melanocytoma and melanoma 115Histiocytoma 118Mast cell tumor 118Peripheral nerve sheath tumors 118Equine sarcoid 121Squamous cell carcinoma 122Diseases of the conjunctiva 123General pathology of the conjunctiva 124Congenital conjunctival abnormalities 124Infectious conjunctivitis 126Herpesvirus 126Chlamydophila (chlamydia) 126Rickettsia rickettsi 126Moraxella bovis 126Parasitic conjunctivitis 126Noninfectious inflammatory disease 127Episclerokerataconjunctivitis 127Lipogranulomatous conjunctivitis of cats 127Eosinophilic conjunctivitis 128Miscellaneous conjunctival disorders 128Conjunctival overgrowth in rabbits (pseudopterygium) 128Membranous (ligneous) conjunctivitis 129Conjunctival neoplasms 129Conjunctival lymphoma 129Conjunctival mast cell tumors 130Conjunctival melanoma and melanocytoma 130Viral papillomas 133Conjunctiva squamous papilloma 133Conjunctival squamous cell carcinoma 133Conjunctival vascular neoplasia 133Miscellaneous neoplasms of the third eyelid 133Lacrimal and nasolacrimal disorders 136Neoplasms of the gland of the third eyelid 136Prolapsed gland of the third eyelid 138Keratoconjunctivitis sicca (KCS) 138Dacryops and canaliculops 138References 1386 Diseases of the cornea 143Corneal wound healing 143Epithelial wound healing 143Stromal wound healing 147Endothelial wound healing 149Epithelial and fibrous ingrowth 151Healing of corneal grafts 152Nonspecific corneal responses to insult 152Corneal vascularization 152Corneal pigmentation 154Corneal edema 154Keratitis 154Epithelial alterations of keratitis 154Stromal alterations of keratitis 156Endothelialitis 158Specific inflammatory corneal disease 159Immune‐mediated nonulcerative keratitis 159Immune‐mediated ulcerative keratitis 159Superficial punctate keratitis (punctate erosive corneal dystrophy) 159Chronic superficial keratitis (pannus) 159Eosinophilic keratitis 161Miscellaneous corneal disorders: corneal sequestrum, indolent corneal ulceration, corneal dystrophy, corneal lipid infiltrates, and corneal degeneration 161Corneal sequestrum 161Indolent ulceration (boxer ulcer, spontaneous corneal epithelial defects) 164Corneal dystrophies, corneal lipid infiltrates, and corneal calcific/lipid degeneration 165Miscellaneous corneal disease 167Corneal neoplasia 172References 1777 Diseases of the episclera and sclera 181Primary episcleral and scleral inflammatory disorders: a brief introduction 181Secondary scleritis 181Scleral neoplasia 182Limbal melanocytoma 184Episcleritis (episclerokeratitis, episclerokeratoconjunctivitis) 185Scleritis and necrotizing scleritis a continuum or separate conditions? 189Non‐necrotizing scleritis 193Necrotizing scleritis 195Parasitic episcleral disease (onchocerca vulpis/lienalis) 195References 1968 Histologic manifestations of disorders of the uvea 197Normal aging changes 203Degenerative diseases of the uvea 205Uveal atrophy 205Uveal cysts 205Cystoid degeneration of the pars plana ciliary epithelium 205Pre‐iridal fibrovascular membranes (PIFMs) 208Heterotopic bony metaplasia of the ciliary body in guinea pigs 208Uveitis 210The nomenclature of uveitis 210The intraocular events of uveitis 210The etiologic implications of inflammatory exudates 216Immune privilege 218Consequences of uveitis 218Histologic basis of the common infectious, idiopathic, and immune‐mediated uveitis syndromes in domestic animals 221Lens‐induced uveitis 221Phacolytic uveitis 223Phacoclastic uveitis 224Equine recurrent uveitis 227Feline lymphocytic–plasmacytic uveitis 231Pigmentary uveitis/pigmentary glaucoma of dogs 231Equine heterochromic iridocyclitis with secondary keratitis 233Vogt–Koyanagi–Harada‐like or uveodermatologic syndrome in dogs 233Uveal xanthogranuloma in miniature schnauzers 235Uveitis associated with specific infectious agents 235Viruses 235Feline infectious peritonitis 235Canine adenovirus‐associated uveitis 238Canine distemper virus‐associated uveitis 239Bovine malignant catarrhal fever (MCF)‐associated uveitis 239Bovine viral diarrhea mucosal disease‐associated uveitis 239Ovine bluetongue 239Equine viral arteritis (EVA)‐associated uveitis 239West Nile‐associated avian uveitis 239Hog cholera 239Bacteria 240Fungi 241Other infectious causes for endophthalmitis 245Algal endophthalmitis 246Protozoan endophthalmitis 246Metazoan parasitic uveitis 246References 2509 Histologic basis of glaucoma 255Introduction 255The gross, subgross, and histologic lesions of elevated IOP 255Retinal changes 257Optic nerve changes 262Classification of canine glaucoma and introduction to open and closed angles 266Congenital glaucoma 267Primary glaucoma 270Open angle glaucoma of beagle dogs 274Primary (congenital) glaucoma in New Zealand white rabbit 274Secondary glaucoma 274Pre‐iridal Fibrovascular Membrane 274Posterior Synechia with Pupillary Block 275Vitreous degeneration, syneresis, and anterior chamber prolapse 275Trabecular obstruction by tumor 278Other causes of secondary glaucoma in dogs 278Glaucoma in cats 283Glaucoma in horses 284References 28610 Histologic manifestations of acquired and inherited diseases of the lens 289Embryology and anatomy of the lens 289Physiology of the lens 292Pathology of the lens 292Aging changes 294Cataract 294The classification of cataracts 294The histopathology of cataract 294The pathogenesis of cataracts 299Etiologies of cataract 299Lens luxation 302Inherited lens zonular dysplasia 303References 30511 Acquired diseases of the vitreous 307Primary disorders of the vitreous 310Vitreous degeneration 310Asteroid hyalosis 315Posterior vitreous detachment 315Synchisis scintillans 315Uveal and neuroectodermal pigment and cysts within the vitreous and incidental parasitic encounters 317Neovascularization 317Conditions with secondary vitreous involvement 317Vitritis 317Vitreous hemorrhage 319References 32212 Histologic manifestations of retinal disease 325Introduction 325Retinal diseases by histologic pattern 328Retinal atrophy 329Inner retinal atrophies 329The pathogenesis of retinal degeneration secondary to glaucoma 329Retinal atrophy secondary to non‐glaucomatous optic nerve injury and vascular disease 335Optic nerve hypoplasia/aplasia 336Outer retinal (photoreceptor) atrophies 336Inherited photoreceptor dysplasias and degenerations 336Retinal detachment 340Toxic and nutritional retinopathies 346Fluoroquinolone‐induced retinal degeneration 346Vitamin A deficiency 347Vitamin E deficiency 347Taurine deficiency 347Light‐induced retinal degeneration 347Sudden acquired retinal degeneration (SARD) and immune mediated retinopathy (IMR) of dogs 352Diseases targeting the retinal pigment epithelium 352Retinal pigment epithelial dystrophy (central progressive retinal atrophy) 352Hereditary retinal pigment epithelial disorders (congenital stationary night blindness of briard dogs, multifocal retinopathies) 352Canine multifocal retinopathy 354Retinal pigment epithelial dysplasia in the royal college of surgeons rat 354Localized chorioretinal atrophy in rats 354Retinitis 354Bystander retinitis 356Retinitis as a manifestation of neurologic disease 356Histophilus somni (formerly Hemophilus somnus) infection in cattle 356Canine distemper 356Retinal lesions reflecting noninfectious systemic disease 357Retinal lesions of systemic hypertension 357Retinal lesions resulting from inborn errors in the intermediary metabolism (lysosomal storage diseases and others) 357Retinal injury from thermal energy 358Retinal neoplasms 358Medullopitheliomas 360Retinoblastoma 360References 36013 Acquired diseases of the optic nerve 367Intraocular disorders with associated optic neuropathy 367Glaucomatous optic neuropathy 367Endophthalmitis and ascending optic neuritis 372Canine distemper optic neuritis 372Orbital disorders that affect the optic nerve 372Proptotic optic neuropathy 372Orbital cellulitis/abscess with optic nerve sepsis 372CNS conditions that affect the optic nerve 372Optic nerve disorders 376Granulomatous meningoencephalitis 376Unilateral granulomatous optic neuritis 376Optic neuropathy in horses 376Feline optic neuropathies 376Other causes of optic neuritis 378Toxic optic neuropathy 378Vitamin A deficiency 379Primary optic nerve neoplasms 381Meningioma 381Optic nerve gliomas 382Peripapillary medulloepitheliomas 382Lymphosarcoma and other metastatic neoplasms 382References 38414 Acquired diseases of the orbit 387Introduction 387Inflammatory disease 387Extraocular myositis 388Lacrimal adenitis 389Orbital trauma/hematoma 390Zygomatic sialocoele 391Orbital cysts and post‐enucleation orbital mucocoeles 393Parasitic orbital disease 396Orbital neoplasia 396Multilobular tumor of bone (multilobular osteochondroma) 398Primary orbital osteoma and osteosarcoma 402Lacrimal adenoma and adenocarcinoma 404Harderian gland adenomas and adenocarcinomas 404Rhabdomyosarcoma 404Orbital myofibroblastic sarcoma 404Vascular anomalies 406References 40615 Intraocular neoplasia 409Non‐neoplastic hyperpigmented lesions 410Benign melanocytic neoplasia 410Uveal melanocytoma 410Uveal melanocytosis (melanosis) 415Malignant uveal melanomas 415Canine and feline uveal malignant melanoma 415Diffuse iris melanoma of cats 417Iris and ciliary epithelial neoplasia 422Medulloepithelioma and retinoblastoma (primitive neuroectodermal tumors) 426Primary ocular sarcomas of cats and rabbits 428Schwannomas of blue eyed dogs 430Osteosarcoma and chondrosarcoma 430Miscellaneous primary intraocular tumors 432Metastatic uveal neoplasia 433Lymphosarcoma 433Secondary intraocular neoplastic extension from primary nasal and orbital and adnexal neoplasms 435References 436Index 443

"Throughout this superbly illustrated textbook, the authors use a combination of histology, gross specimens, and many clinical examples to describe ocular diseases and their underlying pathophysiology...Overall, this book is a valuable and fairly priced resource for veterinary students, veterinarians, and pathologists." JAVMA, MAR 15, 2019, VOL 254, NO. 6