title: Refractive states of eyes and associations between ametropia and age, breed, and axial globe length in domestic cats.
abstract: OBJECTIVE
  To determine the refractive states of eyes in domestic cats and to evaluate correlations between refractive error and age, breed, and axial globe measurements.
  
  
  METHODS
  98 healthy ophthalmologically normal domestic cats.
  
  
  METHODS
  The refractive state of 196 eyes (2 eyes/cat) was determined by use of streak retinoscopy. Cats were considered ametropic when the mean refractive state was ≥ ± 0.5 diopter (D). Amplitude-mode ultrasonography was used to determine axial globe length, anterior chamber length, and vitreous chamber depth.
  
  
  RESULTS
  Mean ± SD refractive state of all eyes was -0.78 ± 1.37 D. Mean refractive error of cats changed significantly as a function of age. Mean refractive state of kittens (≤ 4 months old) was -2.45 ± 1.57 D, and mean refractive state of adult cats (> 1 year old) was -0.39 ± 0.85 D. Mean axial globe length, anterior chamber length, and vitreous chamber depth were 19.75 ± 1.59 mm, 4.66 ± 0.86 mm, and 7.92 ± 0.86 mm, respectively.
  
  
  CONCLUSIONS
  Correlations were detected between age and breed and between age and refractive states of feline eyes. Mean refractive error changed significantly as a function of age, and kittens had greater negative refractive error than did adult cats. Domestic shorthair cats were significantly more likely to be myopic than were domestic mediumhair or domestic longhair cats. Domestic cats should be included in the animals in which myopia can be detected at a young age, with a likelihood of progression to emmetropia as cats mature.
authors.affiliation: Comparative Veterinary Ophthalmology, Eye Care For Animals, Pasadena, CA 91106, USA. kkonrade@eyecareforanimals.com
authors.forename: Kricket A
authors.initials: KA
authors.lastname: Konrade
authors.forename: Allison R
authors.initials: AR
authors.lastname: Hoffman
authors.forename: Kelli L
authors.initials: KL
authors.lastname: Ramey
authors.forename: Ruby B
authors.initials: RB
authors.lastname: Goldenberg
authors.forename: Terry W
authors.initials: TW
authors.lastname: Lehenbauer
mesh_terms: D000375:Aging; D000818:Animals; D002371:Cat Diseases / Q000235:genetics / Q000473:pathology*; D002415:Cats; D005123:Eye / Q000033:anatomy & histology*; D005260:Female; D008297:Male; D009799:Ocular Physiological Phenomena; D012029:Refraction, Ocular / Q000502:physiology*; D012030:Refractive Errors / Q000235:genetics / Q000662:veterinary*