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Author (up) Harman, A.M.; Moore, S.; Hoskins, R.; Keller, P. doi  openurl
  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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