A retinoscopic survey of donkeys and goats

Purpose: Assess the refractive states of donkeys and goats. Methods: Forty-two donkeys and 28 goats were enrolled. The mean ± SD ages were 7.68 ± 7.33 years for donkeys and 4.26 ± 2.33 years for goats. Seven donkeys and one goat were <6 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 ± SD spherical equivalent (SE) refractive errors of the right and left donkey eyes were −0.80 ± 1.03 D and −0.35 ± 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 ± 1.1 D and −0.18 ± 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 =.9). Age was not correlated with refractive error in both donkeys (p =.09) and goats (p =.6). Conclusions: Both goats and donkeys are emmetropic.