Ophthalmic disease and its management.

A variety of ocular disorders occur with increased frequency in aging patients. There are those, such as lens-induced uveitis, which simply represent the end stages of chronic disease. There are lesions of the orbit, eyelid, and uveal tract that epitomize the geriatric penchant for neoplasia. Calcific degeneration and endothelial dystrophy are among the disorders representing the degenerative side of the aging eye. Vision loss accompanies cataracts and retinal detachments. Though each of these disorders is potentially blinding, advances in medical and surgical management have improved the likelihood of lifelong vision in our veterinary patients.

Ligneous conjunctivitis in four Doberman pinschers.

Ligneous conjunctivitis (LC) was diagnosed in four unrelated Doberman pinschers. Thick, opaque membranes of the palpebral conjunctivae and nictitating membranes were present bilaterally. Three dogs had concurrent signs of multisystemic disease. A thick, amorphous, eosinophilic, hyaline-like material in the substantia propria of the conjunctiva--containing a moderate, mononuclear cell infiltrate--was evident on histological examination. A predominance of T lymphocytes, few macrophages, and weak positive staining for immunoglobulin G (IgG) and immunoglobulin A (IgA) were evident by immunohistochemical staining. The clinical and histological appearance of LC in Doberman pinschers and humans is similar.

Ophthalmic corticosteroid therapy: systemic effects in the dog.

Degenerative myopathy suggestive of glucocorticoid-induced myopathy was diagnosed in a 10-year-old female Poodle X Pekingese dog with a history of progressive lameness. Electromyography revealed bizarre high-frequency discharges. Evidence of adrenal suppression was obtained in response to exogenous ACTH. The predominant source of corticosteroid was an ophthalmic preparation used in the management of keratoconjunctivitis sicca. Considering the apparent adverse effects of the corticosteroid in this case, a study was undertaken to determine the systemic effects, if any, induced by long-term ophthalmic administration of 0.1% dexamethasone suspension in healthy adult dogs. Dogs in one group (n = 5) were treated 4 times daily for 8 weeks, and dogs in another group (n = 5) were treated 4 times daily for 16 weeks. All dogs remained healthy throughout the study, but dexamethasone-treated dogs developed marked adrenal suppression, beginning the second week of treatment and intensifying throughout the treatment period. Histopathologic changes in the liver of dexamethasone-treated dogs included scattered foci of vacuolated hepatocytes, increased hepatocytic glycogen content, and ballooning degeneration of hepatocytes. Muscle specimens were histologically, histochemically, and electromyographically normal.

Uveitis associated with Ehrlichia platys infection in a dog.

Bilateral anterior uveitis, nonregenerative anemia, and thrombocytopenia were found in a 9-month-old Chow Chow infected with Ehrlichia platys. Diagnosis was based on the finding of basophilic inclusions in platelets and an E platys antibody titer. The dog was treated orally with tetracycline, topically with antibiotic/corticosteroid, and topically with a mydriatic.

Effects of radiofrequency hyperthermia on the healthy canine cornea.

Radiofrequency hyperthermia was used to induce axial corneal lesions in the eyes of 10 dogs. Clinical observations were continued for up to 6 months, using biomicroscopy and indirect ophthalmoscopy. Eyes were harvested at intervals for light and electron microscopic evaluation. Clinical alterations included immediate corneal opacification and epithelial disruption at the site of electrode contact. Ulcerative keratitis persisted for 4 to 6 days, accompanied by anterior uveitis. Additional corneal changes included stromal thinning, edema, and vascularization. Final evaluation revealed negligible alterations in corneal contour or clarity 6 months after treatment. Microscopically, epithelial and superficial stromal necrosis preceded epithelial loss. Stromal alterations included edema (associated with focal endothelial detachments), vascularization, and inflammatory cell infiltration. Recovery was characterized by keratocytic hyperplasia and hypertrophy, epithelial proliferation, and stromal condensation.

Immunoglobulin levels in tears and aqueous humor of horses before and after diethylcarbamazine (DEC) therapy.

A quantitative investigation of equine tear and aqueous humor immunoglobulins was done using normal horses and ponies as well as horses and ponies infected with Onchocerca cervicalis. The equine immunoglobulin isotypes IgGa, IgM, IgA and IgG(T) were quantitated by either single radial immunodiffusion (SRID) or radioimmunoassay (RIA). Tear immunoglobulin levels for IgGa (128 +/- 151 micrograms/ml), IgA (1,664 +/- 1,038 micrograms/ml) and IgM (106 +/- 74 micrograms/ml) were measured, while IgG(T) was not detectable. In horses with ocular inflammation the IgGa was 18-fold higher in the tears, 2,269 +/- 3,077 micrograms/ml. Aqueous humor obtained by paracentesis of the normal equine eye under anaesthesia, resulted in values for IgGa (45.2 +/- 20.0 micrograms/ml), IgG(T) (5.2 +/- 2.0 micrograms/ml), IgM (1.3 +/- 4.8 micrograms/ml) and IgA (0.8 +/- 1.0 micrograms/ml). A pooled sample of normal aqueous fluid obtained from over 100 horses at an equine abbatoir in Indiana gave values of 1,150 micrograms/ml for IgGa, 65 micrograms/ml for IgG(T), 2.5 micrograms/ml for IgA and 3.0 micrograms/ml for IgM. In animals infected with 0. cervicalis and treated with Diethylcarbamazine (DEC), there was a marked elevation of IgGa and IgG(T) in the tears and aqueous humor while IgA and IgG(T) were also elevated slightly in the aqueous. The findings of elevated immunoglobulin isotypes in the aqueous humor may not be related to the DEC treatment and 0. cervicalis infections but rather to repeated paracentesis and the development of acute inflammation of the equine eye as a result of the trauma of paracentesis. The elevations in equine immunoglobulin isotypes in the tears after DEC treatment are not subject to the same caveat. The preferential elevation in IgGa and IgG(T) in the tears precedes the development of corneal opacities observed in the same horses. The concentration of specific antimicrofilarial antibody in these tears remains to be determined but may well account for a major share of the total immunoglobulins detected.