Disease and Surgery of the Equine Lens.

Examination of the lens is critical, particularly when evaluating horses with visual impairment or performing prepurchase examinations. To adequately evaluate the lens, the pupil must be pharmacologically dilated. A cataract is any lens opacity. The size, density, and position of a cataract determine the impact on vision. Cataracts may be congenital or inherited or occur secondary to trauma or equine recurrent uveitis. Surgical removal is the only treatment option for vision impairing cataracts, but careful selection of surgical candidates is critical for successful outcomes.

The Significance of the Discordant Occurrence of Lens Tumors in Humans versus Other Species.

PURPOSE: The purpose of this study was to determine in which species and under what conditions lens tumors occur. DESIGN: A review of databases of available human and veterinary ocular pathologic material and the previously reported literature. PARTICIPANTS: Approximately 18 000 patients who had ocular surgical specimens submitted and studied at the University of Wisconsin School of Medicine and Public Health between 1920 and 2014 and 45 000 ocular veterinary cases from the Comparative Ocular Pathology Laboratory of Wisconsin between 1983 and 2014. METHODS: Material in 2 major archived collections at the University of Wisconsin medical and veterinary schools were studied for occurrence of lens tumors. Tumor was defined as a new growth of tissue characterized by progressive, uncontrolled proliferation of cells. In addition, cases presented at 3 major eye pathologic societies (Verhoeff-Zimmerman Ophthalmic Pathology Society, Eastern Ophthalmic Pathology Society, and The Armed Forces Institute of Pathology Ophthalmic Alumni Society) from 1975 through 2014 were reviewed. Finally, a careful search of the literature was carried out. Approval from the institutional review board to carry out this study was obtained. MAIN OUTCOME MEASURES: The presence of tumors of the lens. RESULTS: The database search and literature review failed to find an example of a lens tumor in humans. In contrast, examples of naturally occurring lens tumors were found in cats, dogs, rabbits, and birds. In the veterinary school database, 4.5% of feline intraocular and adnexal neoplasms (234/5153) were designated as feline ocular posttraumatic sarcoma, a tumor previously demonstrated to be of lens epithelial origin. Similar tumors were seen in rabbit eyes, a bird, and in a dog. All 4 species with lens tumors had a history of either ocular trauma or protracted uveitis. The literature search also revealed cases where lens tumors were induced in zebrafish, rainbow trout, hamsters, and mice by carcinogenic agents (methylcholanthrene, thioacetamide), oncogenic viruses (SV40, HPV-16), and genetic manipulation. CONCLUSIONS: Our results suggest that lens tumors do not occur in humans. In contrast, after lens capsule rupture, a lens tumor can occur in other species. We hypothesize that a genetic mechanism exists that prevents lens tumors in humans.

Bilateral lens luxation and intracapsular lens extractions in a Matshchie's tree kangaroo.

An adult, female, captive, Matshchie's tree kangaroo was diagnosed with an anterior lens luxation in the right eye and a lens subluxation in the left eye. Both eyes were treated surgically with intracapsular lens extractions. A 360° rhegmatogenous retinal detachment was diagnosed 6 months postoperatively in the left eye. Aphakic vision was maintained in the right eye 9 months postoperatively. Based on family history and the lack of antecedent ocular disease, the lens luxations were presumed to be inherited and veterinarians should be aware of this condition within the captive tree kangaroo population.

Intraocular sarcoma associated with a rupture lens in a rabbit (Oryctolagus cuniculus).

This case report describes the clinical manifestations and ocular pathology of an intraocular sarcoma in a spayed female 7-year-old rabbit that developed clinical signs consistent with phacoclastic uveitis at 6 months of age, which was left untreated for most of the next 6 years. Ophthalmologic examination confirmed pupillary occlusion, aqueous flare, fibrin, and lens debris within the anterior chamber of the right eye. The right eye was blind and phthisical. The tentative clinical diagnosis was chronic phacoclastic uveitis, and a routine transconjunctival enucleation of the right eye was completed. The globe was formalin-fixed and submitted for histologic examination. Light microscopic examination revealed a ruptured cataractous lens, uveitis, retinal detachment, and an intraocular sarcoma centered around the lens. Immunohistochemical (IHC) staining was positive for smooth muscle actin and vimentin and negative for Desmin and cytokeratin intermediate filaments.

Histopathologic evaluation of the anterior segment of eyes enucleated due to glaucoma secondary to primary lens displacement in 13 canine globes.

PURPOSE To describe histologic anterior segment changes in eyes affected with primary lens displacement (PLD) and secondary glaucoma. METHODS Histologic sections stained with H&E from canine eyes enucleated because of PLD and secondary glaucoma were examined. RESULTS Thirteen eyes from 12 patients were evaluated. Four dogs were castrated males and eight spayed females. Median age was 8 years of age (range 3-13). Breeds included seven terriers and five other breeds. All eyes examined demonstrated varying degrees of inflammation involving the iris and cleft. Mononuclear and melanophagic infiltration of the cleft was found in all specimens. Four globes also showed polymorphonuclear infiltrate. Pre-iridal fibrovascular membranes were clearly identified in 10 of 13 eyes. Total inflammatory score was significantly greater in all globes examined compared with an age-matched group of normal dogs. The posterior pigmented iris epithelium demonstrated a consistent pattern of hyperplasia and/or hypertrophy and cystic degeneration, more prominent in the more central regions. In some cases, hyperplasia was of greatest severity in the mid-iris and associated with thinning or flattening of the pupillary region. CONCLUSIONS These results suggest that lens instability may be associated with chronic inflammation and secondary glaucoma. Mechanical irritation from an unstable lens may result in hypertrophy and/or hyperplasia of the posterior pigmented iris epithelium and subsequent cellular exfoliation and release of melanin. An inflammatory reaction directly or indirectly related to melanin release may obstruct the outflow pathways ultimately leading to glaucoma and loss of vision. Use of topical steroids may be warranted in dogs with PLD.

Evidence of enhanced bacterial invasion during Diplostomum spathaceum infection in European grayling, Thymallus thymallus (L.).

Farmed grayling, Thymallus thymallus (L.), are susceptible to atypical Aeromonas salmonicida (aAS) infections. Interactions between bacteria and parasites were studied using grayling subjected to concomitant exposure to aAS bacteria and the digenean parasite Diplostomum spathaceum. Atypical AS was detected from fish by a combination of bacterial cultivation and polymerase chain reaction techniques. A detection level of 17 aAS cells per 100 mg intestine tissue sample was obtained. Concomitant bacterial exposure did not enhance the severity of grayling eye rupture and nuclear extrusion induced by D. spathaceum, but D. spathaceum invasion into grayling increased the proportion of fish carrying aAS in their heart tissue. However, the number of aAS cells detected in heart tissue was low. Atypical AS did not cause acute disease or mortality during 15 days post-exposure. There was a higher prevalence of aAS in grayling heart samples than in intestinal samples, indicating that the intestine is not favoured by aAS. We suggest that heart tissue would be a good organ from which to isolate aAS when tracing latent carrier fish. We conclude that penetrating diplostomids can enhance bacterial infections in fish and that diplostomids can cause serious eye ruptures in grayling.

Feline lens disorders.

The lens is the second most powerful structure for refraction in the eye, and is important in the fine-focusing ability in individual species. Specific disorders of the feline lens are frequent in clinical practice and include: congenital anomalies, nuclear sclerosis, cataracts, lens subluxations and luxations, intraocular sarcomas, and anterior lens displacement associated with aqueous misdirection glaucoma. Clinical signs and current therapeutic options are discussed for the general practitioner. A close working relationship with the regional veterinary ophthalmologist is advised.

First cases of animal diseases published since 2000. 2. Cats.

In this second article of a series of papers listing first case reports of animal diseases published since 2000, the following nine cases of cat diseases are discussed: Congenital spongiform change in the brain stem nuclei. Enterococcus hirae enteropathy. Focal cerebral angiomatosis. Glomus tumor. Intraocular extramedullary plasmacytoma. Lens epithelial neoplasias. Phaeohyphomycosis due to Fonsecaea pedrosoi. Pulmonary lymphomatoid granulomatosis. Systemic amyloidosis in a Devon rex. After a short introduction, the bibliographical data, the abstract of the author(s) and some additional information derived from the article are given. The article will be regularly updated adding overlooked as well as new first reports.

Staphyloma in a cat.

A unilateral scleral staphyloma in an 18-month-old, female spayed Domestic Short-haired cat was treated with excision, primary closure and fascial graft. Other ocular abnormalities noted on examination included iris coloboma, anterior cortical cataract, focal lens equator flattening and retinal dysplasia. The staphyloma was presumed to be congenital in origin.

Aldose reductase activity and glucose-related opacities in incubated lenses from dogs and cats.

OBJECTIVE: To determine responses of canine and feline lenses to incubation in a medium with a high glucose concentration. SAMPLE POPULATION: Lenses from 35 dogs and 26 cats. PROCEDURE: Glucose concentrations were measured in paired lenses from 25 dogs and 17 cats after incubation for 14 days in high-glucose (30 mmol of glucose/L) or control (6 mmol of glucose/L) medium. Aldose reductase activity was measured spectrophotometrically in the incubated lenses and in freshly frozen lenses from 10 dogs and 9 cats. Two lenses of each group were studied histologically. RESULTS: Canine and feline lenses in high-glucose medium developed glucose-specific opacities of variable localization and extent. Canine lenses developed equatorial vacuoles, but severity of the lesions was not associated with the age of the dog. Lenses from young cats (< or = 4 years old) developed extensive posterior cortical opacities, whereas those from older cats (> 4 years old) did not. Glucose concentrations were similar in all lenses incubated in high-glucose medium; however aldose reductase activity was significantly lower in lenses from older cats, compared with lenses from young cats and from dogs. CONCLUSIONS AND CLINICAL RELEVANCE: High aldose reductase activity and glucose-related opacities suggest a central role for this enzyme in the pathogenesis of diabetic cataracts in dogs and cats. Because onset of diabetes mellitus usually occurs in cats > 7 years of age, low activity of aldose reductase in lenses of older cats may explain why diabetic cataracts are rare in this species despite hyperglycemia.

Results of ophthalmologic screening examinations of German Pinschers in Finland--a retrospective study.

OBJECTIVE: To retrospectively review ophthalmologic findings in German Pinschers in Finland. ANIMALS STUDIED: One hundred and twenty-two German Pinschers that had ophthalmologic examination performed according to the Finnish Kennel Club's Eye Scheme before June 15, 1999. PROCEDURES: A total of 154 eye examination reports of 122 dogs were analysed and all described findings were reported. RESULTS: Persistent hyperplastic tunica vasculosa lentis (PHTVL) was diagnosed in 8.4% of all cases, and hereditary cataract (HC) in 6.5%. Even higher numbers of similar changes were reported by ophthalmologists; some of the dogs, however, were officially diagnosed as "free of symptoms" of inherited ocular diseases. A relatively high number (4.5%) of dogs had reported changes in Y sutures. A pedigree analysis suggests recessive inheritance for both diseases. Because of missing information about many dogs in the pedigree, an autosomal incomplete inheritance pattern cannot be ruled out in either case. CONCLUSIONS: Both HC and PHTVL are inherited diseases in German Pinschers. Further studies are needed to determine the importance of the changes found in Y sutures. Discrepancies between the official diagnosis and described changes are probably partially due to the lack of familiarity with the published literature concerning this breed. Further studies are needed to ascertain the inheritance pattern for both diseases. So far breeding with affected animals should be avoided.

Equine phacoclastic uveitis: the clinical manifestations, light microscopic findings, and therapy of 7 cases.

This retrospective clinical study describes the clinical manifestations, light microscopic findings, and diagnosis and treatment of acute and chronic lens rupture in the horse. Rupture of the lens capsule in the horse usually results in a chronic, blinding inflammation (phacoclastic uveitis) unless prompt surgical and medical therapies are implemented. The clinical manifestations of acute lens capsule rupture included: cataract; intralenticular displacement of iridal pigment; lens cortical fragments attached to the perforated lens capsule, iris, and corneal endothelium; miosis; aqueous flare; and usually a corneal or scleral perforation with ulceration or focal full thickness corneal edema and scarring. The clinical signs of chronic phacoclastic uveitis include blindness, phthisis bulbi, and generalized corneal opacification related to scarring, vascularization, pigmentation, and edema. In one horse, acute phacoclastic uveitis was successfully treated with phacoemulsification to remove the ruptured lens and medical therapy to control the accompanying inflammation. The affected eyes of the horses with chronic phacoclastic uveitis were enucleated because of persistent clinical signs of nonulcerative keratitis and uveitis, despite long-term medical management. The clinical manifestations and lack of improvement with medical therapy are similar in the horse, dog, cat, and rabbit. However, the histologic findings in equine phacoclastic uveitis differ significantly from those in the dog, and rabbit.

Establishment of the hereditary cataract rat strain (SCR) and genetic analysis.

The Shumiya cataract rat (SCR) and normal control rat strains of NC1 and NC2 were established. Mean cataract appearance in adult SCR rats was 66.7%, and embryo death rate was 25%. Genetic analysis of cataract formation in the SCR was studied by breeding experiments with strains such as NC1, BUF, ACI, AD3, and normal SCR rats. No sex-based differences in cataract appearance were observed in any of the progeny. These results confirmed our hypotheses that two autosomal genes, a recessive cataract gene (ctr1), and a normal allele of a dominant cataract gene with a recessive lethal trait (Ctr2(1)) for provisional designations participated in cataract genesis in SCR (ctr1/ctr1, Ctr2(1)/Ctr2) rats. One recessive cataract gene was maintained in normal SCR, NC1 and NC2 (ctr1/ctr1, Ctr2/Ctr2) rats. The same recessive cataract gene was retained in the albumin-deficient brown hooded rat strain AD3 (ctr1/ctr1, Ctr2/Ctr2).

[Lens-induced uveitis in a rabbit]. / Linseninduzierte Uveitis bei einem Kaninchen.

The lens-induced uveitis is a diagnostic as well as a therapeutic challenge for the veterinarian. In most cases the ocular structures have already been irreversibly damaged, so that the therapy can only bring relief, but does not lead to full recovery. This is a review of the pathophysiology and the resulting diagnostic consequences of the lens-induced uveitis. One case is discussed and recommendation for medical treatment is given.

Update on llama medicine. Ophthalmology.

Review of the limited literature on camelid eyes suggests they are anatomically similar to those of domestic livestock species, except they lack meibomian glands and have iridial folds (rather than corpora nigra). The microbial flora of the healthy camelid conjunctival sac also appears to be similar to those of domestic livestock and pets, except that no Mycoplasma have been isolated from camelids. Ocular diseases for which camelids are presented to veterinarians are numerous and varied. The most frequently presented conditions are ocular trauma and congenital abnormalities. Trauma to cornea, conjunctiva, eyelids, and sclera has been reported. Therapies for these injuries are the same as for other animals. Most congenital abnormalities are cataracts and optic nerve colobomas, but congenital eyelid defects, conjunctival cysts, and multiple ocular defects have been reported. Although these conditions are not demonstrably hereditary, breeding of animals with congenital ocular defects is strongly discouraged. Intraocular inflammatory diseases are seen commonly in camelids. Uveitis and chorioretinitis may cause permanent visual loss, usually with no indication of cause. Equine herpesvirus 1 has been isolated from camelids with severe ocular inflammation and is a known cause of chorioretinitis and neurologic abnormalities. Systemic aspergillosis causes severe chorioretinitis in alpacas. More research is needed to improve our understanding of ocular physiology and pathology in camelids. Genetic studies also are needed to establish hereditary patterns of ocular maldevelopment. Additional information from researchers and practitioners should improve our ability to recognize and treat ocular disease in camelids.

Diagnosis and treatment of lens diseases.

The lens represents a unique tissue in light of its embryologic development, retention of old cells and nuclear make-up, transparent nature, immune privileged status, and metabolic restrictions. Disorders of malformation and malposition occur, but cataract development is the most common and significant problem for owners and animals. Technologic and pharmacologic advances have allowed surgical removal of equine cataracts to become an acceptable alternative, capable of returning a visually impaired horse to a functional status. Uveal inflammation represents the greatest threat to successful surgical cataract removal. Veterinarians should consult with those versed in ophthalmology for assistance in diagnosis, prognosis, peroperative treatment, surgical intervention, and follow-up on lens disorders.

Lenticular lesions in harbour seals (Phoca vitulina).

Lenticular lesions were found in 21 of 44 mainly younger harbour seals investigated during the epidemic caused by phocine distemper virus (PDV) in 1988/89. Malformations and cataracts varied in quality and degree and were histologically characterized by proliferative and/or degenerative lenticular alterations. Except for two animals, both eyes were affected symmetrically. For that reason, local exogenous causes are improbable. There was very little evidence for infectious agents isolated from the seals investigated (viruses, in particular PDV, bacteria, mycoplasma, parasites). Environmental, dietary and hereditary aspects were also considered, but no final conclusions could be made as to the involvement of these factors in the genesis of lens lesions in harbour seals.

Spontaneous ophthalmic lesions in young Sprague-Dawley rats.

Eight hundred eight Sprague-Dawley rats were examined for ophthalmic abnormalities during a pretest period in various preclinical safety assessment studies. Persistent pupillary membrane, corneal crystal, healed minor trauma, synechia, coloboma of the iris, lens luxation, cataract, persistent hyperplastic primary vitreous, vitreous hemorrhage, coloboma of the optic disc or choroid, remnant of hyaloid arterial system, retinal hemorrhage, retinal detachment, retinal folding and choroidal defect were observed. The incidences of corneal crystal, synechia, and nuclear cataract in this survey were higher than those reported previously. On the other hand, retinal folding in this survey was less common than that reported previously. These results suggest that background data of eye problems in albino rats should be accumulated in each own laboratory colony. In addition, since spontaneous eye problems are common in young albino rats, elimination of rats with ophthalmic abnormalities from study groups by an ophthalmic examination during a pretest period would facilitate to evaluate toxicity potential of test compounds in safety assessment studies.

Cataracts and optic nerve hypoplasia in turkey poults.

Newly hatched commercial turkey poults culled because of grossly visible cataracts were studied. A total of 43 affected and 23 unaffected control poults at various ages were necropsied, and the ocular changes in affected poults were compared with those of aged-matched controls. Affected poults had consistent cataracts coupled with a marked depletion in retinal inner plexiform, ganglion cell, and optic nerve fiber layers, with a resultant reduction in the size of the optic nerves. Lesions were seen in 1-day-old poults. Lens changes included microphakia and lens fiber degeneration throughout the lens, with nuclear liquefaction. The depletion in the numbers of retinal ganglion cells did not appear to progress over several weeks time. The ganglion cell depletion was not uniform within the retina. The cause for these ocular changes is unknown.