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