title: Aging Dogs Manifest Myopia as Measured by Autorefractor.
abstract: OBJECTIVE
  Dogs, like humans, experience eye changes with aging: hardening and clouding of the lens and accumulated oxidative damage from UV sunlight. It has been debated whether such changes could be affecting the visual function of dogs. The objective of this study was to determine if autorefractometry could be used to measure visual function in dogs.
  
  
  METHODS
  Nine Beagle dogs (ages 1 to 14 years) were examined by a veterinary ophthalmologist and their eyes determined to be free of cataracts. Spherical equivalent refractive error was measured by handheld autorefractor (Welch Allyn SureSight) under both indirect and direct lighting conditions with five measurements per condition, per eye. Measures were repeated on three different days for each dog within six weeks. Nonparametric statistics were used to detect differences among lighting conditions and test days, and between eyes. Spearmen correlation assessed the visual measurement outcomes' association with age.
  
  
  RESULTS
  There was no difference for day-to-day or between-eye measurements. Significantly, the Beagles showed a myopic shift with aging (average spherical equivalent ranged from plano to -3.00 diopters), suggesting that dogs become more near-sighted as they age (r = -0.48 and -0.73 under direct and indirect lights; p<0.05 both). Younger dogs were able to make larger accommodation changes from indirect light to direct light conditions, indicating a more flexible lens (r = -0.50, p<0.05).
  
  
  CONCLUSIONS
  Although designed for humans, the hand-held autorefractor technique is applicable to dogs and sensitive to light conditions. The age-associated myopic shift could be expected to compromise dogs' visual functions.
authors: Nestlé Purina Research, St Joseph, Missouri, United States of America.
authors: Jerome
authors: J
authors: Hernandez
authors: Department of Veterinary Medicine and Surgery, University of Missouri, Columbia, Missouri, United States of America.
authors: Cecil
authors: C
authors: Moore
authors: Nestlé Research Center, St Louis, Missouri, United States of America.
authors: Xuemei
authors: X
authors: Si
authors: Ophthalmology, Captain James A Lovell Federal Health Care Facility, North Chicago, Illinois, United States of America.
authors: Stuart
authors: S
authors: Richer
authors: Nestlé Research Center, St Louis, Missouri, United States of America.
authors: Janet
authors: J
authors: Jackson
authors: Nestlé Research Center, St Louis, Missouri, United States of America.
authors: Wei
authors: W
authors: Wang
mesh_terms: D000065:Accommodation, Ocular; D000375:Aging; D000818:Animals; D004285:Dogs; D005123:Eye / Q000503:physiopathology; D005260:Female; D008027:Light; D008297:Male; D009216:Myopia / Q000175:diagnosis* / Q000503:physiopathology* / Q000662:veterinary; D009885:Ophthalmology / Q000379:methods*; D012029:Refraction, Ocular; D012030:Refractive Errors / Q000175:diagnosis; D012031:Refractometry; D014787:Vision Tests