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The eye of the domesticated sheep with implications for vision

Published online by Cambridge University Press:  02 September 2010

D. Piggins
Affiliation:
Department of Psychology
C. J. C. Phillips
Affiliation:
School of Agricultural and Forest Sciences, University of Wales, Bangor, Gwynedd, North Wales
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Abstract

The eyes of eighteen female sheep (Ovis aries) were refracted and details of inter ocular distance, pupil size, shape and fundus presence recorded. The sheep eyes generally possessed very low hyperopia with little astigmatism, such physiological optics being expected to produce a well focused retinal image for objects in the middle and long distance. No evidence was found for accommodation, which would have produced a well focused ocular image for near objects. A further 10 sheep had their monocular and binocular visual fields measured. The estimated visual field suggests the existence of at least binocular vision, if not the presence of stereopsis. Given the lack of accommodation and a wide inter-ocular distance, it is likely that some degree of stereopsis exists in the animal's middle and long distance vision, but is absent in near vision. These findings support those taken from the animal's neurophysiology and observations of its visually guided behaviour.

Type
Research Article
Copyright
Copyright © British Society of Animal Science 1996

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