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  • Author or Editor: Michael G. Davidson x
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Abstract

Objective—To evaluate the outcome of thermokeratoplasty for treatment of ulcerative keratitis and bullous keratopathy secondary to corneal endothelial disease in dogs.

Design—Retrospective study.

Animals—13 dogs.

Procedures—Medical records from 1994 to 2001 for dogs evaluated because of ulcerative keratitis and bullous keratopathy and treated with thermokeratoplasty were reviewed.

Results—There were 7 spayed females, 5 castrated males, and 1 sexually intact male, ranging from 6 to 16 years of age. Ten dogs had endothelial degeneration, and 3 dogs had breed-related endothelial dystrophy. All dogs had bullous keratopathy, characterized by microbullae formation that was detected via biomicroscopy. Recurrent or nonhealing corneal ulcers were detected unilaterally in 5 dogs and bilaterally in 8 dogs. Mean ± SD duration from thermokeratoplasty until ulcerations were healed for all dogs was 2.2 ± 1.1 weeks. All dogs that underwent thermokeratoplasty for nonhealing corneal ulceration secondary to endothelial disease and corneal edema had epithelial wound healing and resolution of corneal ulceration. Mean duration of treatment (ie, topical treatment required until resolution of ulceration) was significantly less after thermokeratoplasty than duration of treatment (with multiple treatments) prior to referral.

Conclusions and Clinical Relevance—It may be necessary to perform thermokeratoplasty of the entire cornea to prevent recurrence of ulcerations in areas that have not been treated with thermokeratoplasty. (J Am Vet Med Assoc 2003;222: 607–612)

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in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate the use of an intravitreal sustained-release cyclosporine (CsA) delivery device for treatment of horses with naturally occurring recurrent uveitis.

Animals—16 horses with recurrent uveitis.

Procedures—Horses with frequent recurrent episodes of uveitis or with disease that was progressing despite appropriate medication were selected for this study. Additional inclusion criteria included adequate retinal function as determined by use of electroretinography, lack of severe cataract formation, and no vision-threatening ocular complications (eg, retinal detachment, severe retinal degeneration, and posterior synechia). Sustained-release CsA delivery devices (4 µg of CsA/d) were implanted into the vitreous through a sclerotomy at the pars plana. Reexaminations were performed 1, 3, 6, and 12 months after implantation, then continued annually. Ophthalmic changes, number of recurrent episodes of uveitis, and vision were recorded.

Results—The rate of recurrent episodes after device implantation (0.36 episodes/y) was less than prior to surgery (7.5 episodes/y). In addition, only 3 horses developed episodes of recurrent uveitis after surgery. Vision was detected in 14 of 16 affected eyes at a mean follow-up time of 13.8 months (range, 6 to 24 months).

Conclusions and Clinical Relevance—This intravitreal sustained-release CsA delivery device may be a safe and important tool for long-term treatment of horses with chronic recurrent uveitis. (Am J Vet Res 2001;62:1892–1896)

Full access
in American Journal of Veterinary Research

Abstract

Objective—To determine histologic and immunohistochemical characteristics of the multifocal adherent plaques that commonly develop on the internal surfaces of the anterior and posterior lens capsules in dogs with cataracts.

Sample Population—31 anterior and 4 posterior capsular specimens collected during lens extraction surgery in dogs with cataracts.

Procedure—Specimens were evaluated, using light and transmission electron microscopy. Immunohistochemical techniques were used to localize cytokeratin, vimentin, α-smooth muscle-specific actin, fibronectin, tenascin, and transforming growth factor- β (TGF-β) within plaques.

Results—Histologically, plaques comprised elongated spindle-shaped cells that formed a placoid mass. Cells were embedded in an extracellular matrix containing collagen fibrils, often with duplicated or split basement membranes. Immunohistochemically, normal lens epithelial cells and cells within plaques stained for vimentin. Most cells and some areas of the extracellular matrix within plaques stained for TGF-β and α-smooth muscle-specific actin. Fibronectin and tenascin were also detected in the extracellular matrix.

Conclusions and Clinical Relevance—Canine lens capsular plaques are histologically and immunohistochemically similar to posterior capsule opacification and subcapsular cataracts in humans, which suggests that the canine condition, like the human conditions, is associated with fibrous metaplasia of lens epithelial cells. Transforming growth factor-β may play a role in the genesis of capsular plaques. Because severity of plaques was correlated with stage of cataract development, earlier surgical removal of cataracts may be useful to avoid complications associated with plaque formation. (Am J Vet Res 2000;61:139–143)

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in American Journal of Veterinary Research

Abstract

Objective—To characterize clinical and clinicopathologic findings, response to treatment, and causes of systemic hypertension in cats with hypertensive retinopathy.

Design—Retrospective study.

Animals—69 cats with hypertensive retinopathy.

Procedure—Medical records from cats with systemic hypertension and hypertensive retinopathy were reviewed.

Results—Most cats (68.1%) were referred because of vision loss; retinal detachment, hemorrhage, edema, and degeneration were common findings. Cardiac abnormalities were detected in 37 cats, and neurologic signs were detected in 20 cats. Hypertension was diagnosed concurrently with chronic renal failure (n = 22), hyperthyroidism (5), diabetes mellitus (2), and hyperaldosteronism (1). A clearly identifiable cause for hypertension was not detected in 38 cats; 26 of these cats had mild azotemia, and 12 did not have renal abnormalities. Amlodipine decreased blood pressure in 31 of 32 cats and improved ocular signs in 18 of 26 cats.

Conclusions and Clinical Relevance—Retinal lesions, caused predominantly by choroidal injury, are common in cats with hypertension. Primary hypertension in cats may be more common than currently recognized. Hypertension should be considered in older cats with acute onset of blindness; retinal edema, hemorrhage, or detachment; cardiac disease; or neurologic abnormalities. Cats with hypertensioninduced ocular disease should be evaluated for renal failure, hyperthyroidism, diabetes mellitus, and cardiac abnormalities. Blood pressure measurements and funduscopic evaluations should be performed routinely in cats at risk for hypertension (preexisting renal disease, hyperthyroidism, and age > 10 years). Amlodipine is an effective antihypertensive agent in cats.(J Am Vet Med Assoc 2000;217:695–702)

Restricted access
in Journal of the American Veterinary Medical Association

Abstract

Objective—To determine appropriate intraocular lens (IOL) implant strength to approximate emmetropia in horses.

Sample Population—16 enucleated globes and 4 adult horses.

Procedures—Lens diameter of 10 enucleated globes was measured. Results were used to determine the appropriate-sized IOL implant for insertion in 6 enucleated globes and 4 eyes of adult horses. Streak retinoscopy and ocular ultrasonography were performed before and after insertion of 30-diopter (D) IOL implants (enucleated globes) and insertion of 25-D IOL implants (adult horses).

Results—In enucleated globes, mean ± SD lens diameter was 20.14 ± 0.75 mm. Preoperative and postoperative refractive state of enucleated globes with 30-D IOL implants was −0.46 ± 1.03 D and −2.47 ± 1.03 D, respectively; preoperative and postoperative difference in refraction was 2.96 ± 0.84 D. Preoperative anterior chamber (AC) depth, crystalline lens thickness (CLT), and axial globe length (AxL) were 712 ± 0.82 mm, 11.32 ± 0.81 mm, and 40.52 ± 1.26 mm, respectively; postoperative AC depth was 10.76 ± 1.16 mm. Mean ratio of preoperative to postoperative AC depth was 0.68. In eyes receiving 25-D IOL implants, preoperative and postoperative mean refractive error was 0.08 ± 0.68 D and −3.94 ± 1.88 D, respectively. Preoperative AC depth, CLT, and AxL were 6.36 ± 0.22 mm, 10.92 ± 1.92 mm, and 38.64 ± 2.59 mm, respectively. Postoperative AC depth was 8.99 ± 1.68 mm. Mean ratio of preoperative to postoperative AC depth was 0.73.

Conclusions and Clinical Relevance—Insertion of 30-D (enucleated globes) and 25-D IOL implants (adult horses) resulted in overcorrection of refractive error.

Full access
in American Journal of Veterinary Research