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in Journal of the American Veterinary Medical Association

Abstract

Objective—To evaluate the usefulness of high-resolution ultrasonography (HRUS) for measurements of anterior segment structures in canine eyes.

Animals—4 clinically normal Beagles.

Procedure—Images were obtained from 8 eyes with a handheld 20-MHz transducer. Eleven anterior segment structures on each image were measured 5 times by 2 independent observers. Coefficients of variation (CVs) for measurements were used to assess intraobserver reliability. Interobserver reliability was assessed by comparing measurements obtained by the 2 observers from the same images. Five images were sequentially obtained from 2 locations (ie, superior and temporal) to evaluate image reproducibility. Anterior segment structures were measured once on each image; image reproducibility was assessed by use of the CV for each parameter measured. Imaging location was assessed by comparison of CV for measurements from each location.

Results—CVs were < 10% for observer A for all measurements except the ciliary cleft area (11.63%). The CVs were > 10% for observer B for measurements of the angle recess area (18.51%) and ciliary cleft width (17.44%) and area (16.01%). Significant differences in measurements between observers were found for 5 of 11 anterior segment structures. Imaging the superior aspect of the globe provided the most reproducible images, although image reproducibility was still somewhat variable, with the highest and lowest CVs for measurements of 33.01% and 11.32%, respectively, in the superior position.

Conclusions and Clinical Relevance—High-resolution ultrasound images can be used to reliably measure various anterior segment structures. Clinically relevant findings in the anterior segment of canine eyes may be detectable by use of HRUS. (Am J Vet Res 2005;66:1775–1779)

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in American Journal of Veterinary Research

Abstract

Objective—To determine the effect of 0.005% latanoprost solution on intraocular pressure (IOP) of eyes of clinically normal horses and establish the frequency of adverse effects of drug administration.

Animals—20 adult clinically normal horses.

Procedure—IOP was recorded (7, 9, and 11 AM; 3, 5, and 7 PM) on days 1 and 2 (baseline), days 3 to 7 (treatment), and days 8 to 9 (follow-up). Latanoprost was administered to 1 randomly assigned eye of each horse every 24 hours during the treatment period, following the 7 AM IOP recording. Pupil size and the presence or absence of conjunctival hyperemia, epiphora, blepharospasm, blepharedema, and aqueous flare were recorded prior to IOP measurement.

Results—IOP was reduced from baseline by a mean value of 1.03 mm Hg (5%) in males and 3.01 mm Hg (17%) in females during the treatment period. Miosis developed in all treated eyes and was moderate to marked in 77% of horses, with the peak effect observed 4 to 8 hours after drug administration. Conjunctival hyperemia, epiphora, blepharospasm, and blepharedema were present in 100, 57, 42, and 12% of treated eyes, respectively, 2 to 24 hours following drug administration. Aqueous flare was not observed at any time point.

Conclusions and Clinical Relevance—Although IOP was reduced with every 24-hour dosing of latanoprost, the frequency of prostaglandin-induced adverse events was high. Because recurrent uveitis appears to be a risk factor for glaucoma in horses, topical administration of latanoprost may potentiate prostaglandin-mediated inflammatory disease in affected horses. (Am J Vet Res 2001;62:1945–1951)

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in American Journal of Veterinary Research

Abstract

OBJECTIVE

To compare single and triplicate applanation tonometry values across previous intraocular pressure (IOP) studies in dogs.

ANIMALS

116 ophthalmologically normal dogs.

PROCEDURES

Triplicate IOP readings (n = 1432) from studies evaluating effect of anesthetic protocols were analyzed to estimate a range of probable differences between averaged triplicate and first, averaged and lowest, and first and lowest IOPs. The decrease in variability with triplicate measurements and the magnitude of effects on statistical power were quantified.

RESULTS

The 2.5th to 97.5th interpercentile range for differences of averaged triplicate values minus first IOP readings was –3 to 2.7 mm Hg; for averaged minus lowest: 0 to 3.7 mm Hg; for first minus lowest: 0 to 5 mm Hg. The 95% prediction interval for differences in study group means (n = 160 groups, n = 5 to 11 eyes per group) based on averaged minus first measurements was –1.0 to 0.9 mm Hg with associated SDs reduced by 4% on average. Analysis of previous studies using averaged instead of first IOP values resulted in minimal decreases in SEs of 3–9% (0.03 to 0.09 mm Hg). Of 11 comparisons found significant with averaged data, 2 (18%) were found nonsignificant with first measurements. Of 96 comparisons found nonsignificant with averaged data, 3 (3%) were found significant with first measurements.

CLINICAL RELEVANCE

With applanation tonometry in ophthalmologically normal dogs, no clinically meaningful difference was found between the first, lowest, or averaged triplicate IOP measurements, but the first reading has a larger variance and hence will result in lower statistical power.

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in American Journal of Veterinary Research

Abstract

Case Description—A great horned owl of estimated age < 1 year that was captured by wildlife rehabilitators was evaluated because of suspected cataracts.

Clinical Findings—Nuclear and incomplete cortical cataracts were evident in both eyes. Ocular ultrasonography revealed no evidence of retinal detachment, and electroretinography revealed normal retinal function.

Treatment and Outcome—For visual rehabilitation, cataract surgery was planned and intraocular lens design was determined on the basis of values obtained from the schematic eye, which is a mathematical model representing a normal eye for a species. Cataract surgery and intraocular lens placement were performed in both eyes. After surgery, refraction was within −0.75 diopters in the right eye and −0.25 diopters in the left eye. Visual rehabilitation was evident on the basis of improved tracking and feeding behavior, and the owl was eventually released into the wild.

Clinical Relevance—In raptors with substantial visual compromise, euthanasia or placement in a teaching facility is a typical outcome because release of such a bird is unacceptable. Successful intraocular lens implantation for visual rehabilitation and successful release into the wild are achievable.

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in Journal of the American Veterinary Medical Association