Analysis of the ocular refractive state in fighting bulls: Astigmatism prevalence

Abstract

The purpose of this study was to describe the ocular refractive state (ORS) of fighting bulls. The study consisted of 90 ophthalmological healthy animals (85 in post-mortem and 5 in living conditions, resp.). The ORS of the eyes (2 per animal) was determined using streak retinoscopy. In vivo animals were assessed at a fighting bull farm facility. Post-mortem measurements were carried out at a local arena. The ORS along the horizontal meridian ranged between-1.00 and +2.50 diopters (D), with a mean of +0.66±0.85 D in post-mortem animals. Values for in vivo conditions were similar (+0.75±0.46 D). Left and right eyes were highly correlated in both sets (p<0.001). A fairly good correlation was also observed when comparing living and post-mortem eyes in the same animals. Anisometropia ≥ 1.00 D was diagnosed in 3 animals. Astigmatism (≥+0.5 D) was detected in 93% of the eyes. To our knowledge, the ORS of the fighting bull has been reported for the first time. Although values vary among individuals, all eyes presented a marked astigmatism. Whereas the horizontal meridian was slightly hyperopic, the vertical meridian was always closer to emmetropia. These results represent a starting point to understand the ocular optics of this kind of animals, which might benefit the selection of animals at the farm before being sent to the bullfighting arena.