A retinoscopic survey of donkeys and goats.

Abstract

PURPOSE: Assess the refractive states of donkeys and goats. METHODS: Forty-two donkeys and 28 goats were enrolled. The mean&#x2009;&#xb1;&#x2009;SD ages were 7.68&#x2009;&#xb1;&#x2009;7.33&#x2009;years for donkeys and 4.26&#x2009;&#xb1;&#x2009;2.33&#x2009;years for goats. Seven donkeys and one goat were <6&#x2009;months old. Retinoscopy was performed in alert animals, following cycloplegia in goats but not in donkeys. Normality was determined using the Kolmogorov-Smirnov test. The two primary meridians and two eyes were compared using Pearson's correlation and paired Student's t-tests. The association between refractive states and age was examined using one-way ANOVA in donkeys and a paired Student's t-test in goats. One-sample t-tests were conducted to assess if the refractive error distributions were significantly different from "0". RESULTS: The mean&#x2009;&#xb1;&#x2009;SD spherical equivalent (SE) refractive errors of the right and left donkey eyes were -0.80&#x2009;&#xb1;&#x2009;1.03 D and -0.35&#x2009;&#xb1;&#x2009;0.95 D, respectively. The majority (86%) of the donkeys had an astigmatic refraction and eight (19%) had anisometropia. The mean SE refractive errors of the right and left goat eyes were -0.15&#x2009;&#xb1;&#x2009;1.1 D and -0.18&#x2009;&#xb1;&#x2009;1.2 D, respectively. The majority (54%) of the goat eyes had an astigmatic refraction and five (18%) had anisometropia. The right and left eye SE refractive errors were positively correlated in both species (both p&#x2009;=&#x2009;.9). Age was not correlated with refractive error in both donkeys (p&#x2009;=&#x2009;.09) and goats (p&#x2009;=&#x2009;.6). CONCLUSIONS: Both goats and donkeys are emmetropic.