title: The range and variability of ophthalmological parameters in normal children aged 4 1/2 to 5 1/2 years.
abstract: BACKGROUND
  Some standards for childhood ophthalmological variables exist. However, for most parameters, the range of variation found in normal children remains poorly defined.
  
  
  METHODS
  We have determined the range of normal function for a number of commonly measured ophthalmological variables in 162 children, classified normal by Gold Standard ophthalmological examination. This group is representative of almost 12,000 normal children aged 4 1/2 to 5 1/2 in Nova Scotia.
  
  
  RESULTS
  In 56.8% of eyes the visual acuity was 6/4.5. The use of a chart with crowding bars was more discriminating between differences in higher levels of acuity and highlighted differences in acuity between the two eyes. Randot stereoacuity showed a uniform, non-Gaussian distribution of scores. Cycloplegic refractive errors were distributed about a modal value of between +0.5 and +1.0 diopter. Forty percent of eyes had no detectable astigmatism. Ninety-seven percent of subjects had no heterophoria. Fusional vergence data are presented.
  
  
  CONCLUSIONS
  Our results document the complete normal range for selected ophthalmological parameters in normal preschoolers. The values obtained were in general better than expected.
authors.affiliation: Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: S R
authors.initials: SR
authors.lastname: Lam
authors.forename: G R
authors.initials: GR
authors.lastname: LaRoche
authors.forename: I
authors.initials: I
authors.lastname: De Becker
authors.forename: H
authors.initials: H
authors.lastname: Macpherson
mesh_terms: D001251:Astigmatism / Q000503:physiopathology; D002675:Child, Preschool; D015331:Cohort Studies; D003290:Convergence, Ocular / Q000502:physiology*; D003867:Depth Perception / Q000502:physiology*; D005133:Eye Movements / Q000502:physiology*; D005260:Female; D005425:Flicker Fusion / Q000502:physiology*; D006801:Humans; D008297:Male; D012016:Reference Values; D012030:Refractive Errors / Q000503:physiopathology; D014792:Visual Acuity / Q000502:physiology*