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 assess the refractive state of eyes in various breeds of dogs to identify breeds susceptible to ametropias.
Animals—1,440 dogs representing 90 breeds.
Procedures—In each dog, 1 drop of 1% cyclopentolate or 1% tropicamide was applied to each eye, and a Canine Eye Registration Foundation examination was performed. Approximately 30 minutes after drops were administered, the refractive state of each eye was assessed via streak retinoscopy. Dogs were considered ametropic (myopic or hyperopic) when the mean refractive state (the resting focus of the eye at rest relative to visual infinity) exceeded ± 0.5 diopter (D). Anisometropia was diagnosed when the refractive error of each eye in a pair differed by > 1 D.
Results—Mean ± SD refractive state of all eyes examined was −0.05 ± 1.36 D (emmetropia). Breeds in which the mean refractive state was myopic (≤ −0.5 D) included Rottweiler, Collie, Miniature Schnauzer, and Toy Poodle. Degree of myopia increased with increasing age across all breeds. Breeds in which the mean refractive state was hyperopic (≥ +0.5 D) included Australian Shepherd, Alaskan Malamute, and Bouvier des Flandres. Astigmatism was detected in 1% (14/1,440) of adult (≥ 1 year of age) dogs; prevalence of astigmatism among German Shepherd Dogs was 3.3% (3/90). Anisometropia was detected in 6% (87/1,440) of all dogs and in 8.9% (8/90) of German Shepherd Dogs.
Conclusions and Clinical Relevance—Refractive states of canine eyes varied widely and were influenced by breed and age. In dogs expected to have high visual function (eg, performance dogs), determination of refractive state is recommended prior to intensive training.