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Author | Harman, A.M.; Moore, S.; Hoskins, R.; Keller, P. | ||||
Title | Horse vision and an explanation for the visual behaviour originally explained by the 'ramp retina' | Type | Journal Article | ||
Year | 1999 | Publication | Equine veterinary journal | Abbreviated Journal | Equine Vet J |
Volume | 31 | Issue | 5 | Pages | 384-390 |
Keywords | Animals; Behavior, Animal; Cell Count; Eye/*anatomy & histology; Ganglia, Sensory/cytology; Horses/*physiology; Refractive Errors/veterinary; Retina/cytology/*physiology; Vision/*physiology; Visual Acuity; Visual Fields | ||||
Abstract | Here we provide confirmation that the 'ramp retina' of the horse, once thought to result in head rotating visual behaviour, does not exist. We found a 9% variation in axial length of the eye between the streak region and the dorsal periphery. However, the difference was in the opposite direction to that proposed for the 'ramp retina'. Furthermore, acuity in the narrow, intense visual streak in the inferior retina is 16.5 cycles per degree compared with 2.7 cycles per degree in the periphery. Therefore, it is improbable that the horse rotates its head to focus onto the peripheral retina. Rather, the horse rotates the nose up high to observe distant objects because binocular overlap is oriented down the nose, with a blind area directly in front of the forehead. | ||||
Address | Department of Psychology, University of Western Australia, Nedlands, Australia | ||||
Corporate Author | Thesis | ||||
Publisher | Place of Publication | Editor | |||
Language | English | Summary Language | Original Title | ||
Series Editor | Series Title | Abbreviated Series Title | |||
Series Volume | Series Issue | Edition | |||
ISSN | 0425-1644 | ISBN | Medium | ||
Area | Expedition | Conference | |||
Notes | PMID:10505953 | Approved | no | ||
Call Number | refbase @ user @ | Serial | 836 | ||
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