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Juan I Seva, Manuel Sanes, Francisco Martinez-Gomariz, Matteo Lo Sapio, Juan Bueno; Ocular Refractive State In Fighting Bulls. Invest. Ophthalmol. Vis. Sci. 2013;54(15):2343.
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Fighting bulls are bred free range on extensive farms under similar experimental conditions, well-defined manipulation procedures and hardly human contact. Although they are genetically selected for a certain combination physical energy and aggressiveness, their behavior usually differs among animals during bullfighting. It is believed that bulls present some lateral preferences and sometimes they do not have a correct (near or far) vision. We investigate whether differences in the ocular refractive state (RS) might be part of this lateralized visual processing.
One-hundred and fifty eyes from 75 fighting bulls were involved in the study. Animals were obtained from a local bullfighting arena. They were raised in different farms distributed all across the country and ages ranged from 48 to 70 months. Enrolment was preceded by a veterinarian examination to rule out the presence of any physical factor likely to interfere with the usual fighting. The RS of each eye was assessed via streak retinoscopy with trial lenses in the horizontal meridian immediately after the regular bullfighting took place. Before assessment we ensured the eyes kept their optical properties intact.
RS values varied between -1.25 and 2.5 D, with a mean of +0.65 D (SD=+/-0.80 D). Although both eyes were highly correlated (R=0.79), left eyes tend to be less ametropic. 8% of eyes (12/150) were myopic (refraction < -0.5 D). Anisometropia (difference in RS in a pair of eyes > 0.5 D) was detected in 35 animals (23%). RS was not correlated with either age or weight. No significant differences in RS among the animals coming from different farms were found.
RS values of fighting bulls varied widely, although they tend to be slightly hyperopic. This RS could explain their behavior when stimuli are presented at different locations, especially at short distances. Moreover, the existence of a certain degree of anisometropy between pairs of eyes might be a factor contributing to a possible visual lateralization, and might help to understand differences in the behavior when the stimulus is presented in front of an eye or the other.
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