title: Numerical confusion errors in ishihara testing: findings from a population-based study.
abstract: OBJECTIVE
  To describe the prevalence of numerical confusion errors in Ishihara testing in a representative sample of Australian children.
  
  
  METHODS
  Cross-sectional, population-based study.
  
  
  METHODS
  The Sydney Myopia Study examined a representative stratified random cluster sample of 1,741 children (aged 6 years) attending 34 schools in Sydney, Australia (response rate, 78.9%), including color vision tests in 1,735 children. Those with any color vision defects (n = 33; 1.9%; 97% boys) were excluded. Responses for each Ishihara plate were recorded.
  
  
  RESULTS
  Numerical confusion errors were made by 75.8% of children with normal color vision; there was no gender difference. Plates 3 and 7 were particularly prone to numerical confusion errors; 48.4% and 40.8%, respectively, of children misread these plates.
  
  
  CONCLUSIONS
  Numerical confusion errors in the Ishihara test were relatively common in children with normal color vision. The frequency of such errors could indicate an inherent deficiency in this commonly used test.
authors.affiliation: Department of Ophthalmology, Centre for Vision Research, Westmead Hospital, Australia.
authors.forename: Michael
authors.initials: M
authors.lastname: Cosstick
authors.forename: Dana
authors.initials: D
authors.lastname: Robaei
authors.forename: Kathryn
authors.initials: K
authors.lastname: Rose
authors.forename: Elena
authors.initials: E
authors.lastname: Rochtchina
authors.forename: Paul
authors.initials: P
authors.lastname: Mitchell
mesh_terms: D002648:Child; D003118:Color Perception; D003119:Color Perception Tests / Q000295:instrumentation*; D003117:Color Vision Defects / Q000175:diagnosis / Q000453:epidemiology; D003430:Cross-Sectional Studies; D003951:Diagnostic Errors; D005260:Female; D006801:Humans; D008297:Male; D009517:New South Wales / Q000453:epidemiology; D015995:Prevalence; D015203:Reproducibility of Results