title: Negative predictive value of a population-based preschool vision screening program.
abstract: BACKGROUND
  The Enhanced Vision Screening Program is a population-based vision screening program that has, at present, examined 59,782 children. Its main goal is to detect amblyopia, strabismus, and high refractive errors. An average of 11,910 4 1/2- to 5 1/2-year-old children are screened yearly. The current study determines the negative predictive value of the screening program: For a subject having passed the vision screening test, what is the probability of not having amblyopia, strabismus, or high refractive errors?
  
  
  METHODS
  Of the 11,734 subjects who passed the vision screening, 200 were randomly chosen to undergo a strictly defined gold standard examination by an orthoptist and an ophthalmologist.
  
  
  RESULTS
  Of the 200 randomly chosen subjects, 157 underwent the gold standard evaluation. The negative predictive value of the Enhanced Vision Screening Program was 97.6% for any potentially vision-threatening ocular condition. It was 98.7% if we considered only the visually significant ocular problems that the test was designed to detect.
  
  
  CONCLUSIONS
  Because the negative predictive value of the Enhanced Vision Screening Program is not 100%, some children with amblyopia, strabismus, or refractive errors are missed. Occasionally, a rare, potentially vision-threatening condition may go undetected. Parents should be made aware of this when they receive the results of the vision screening.
authors.affiliation: Department of Ophthalmology, Dalhousie University, Halifax, Nova Scotia, Canada.
authors.forename: I
authors.initials: I
authors.lastname: De Becker
authors.forename: H J
authors.initials: HJ
authors.lastname: MacPherson
authors.forename: G R
authors.initials: GR
authors.lastname: LaRoche
authors.forename: J
authors.initials: J
authors.lastname: Braunstein
authors.forename: R
authors.initials: R
authors.lastname: Cottle
authors.forename: L L
authors.initials: LL
authors.lastname: McIntyre
authors.forename: V
authors.initials: V
authors.lastname: Kozousek
mesh_terms: D002648:Child; D002675:Child, Preschool; D005188:False Negative Reactions; D005260:Female; D006801:Humans; D008297:Male; D009674:Nova Scotia / Q000453:epidemiology; D011237:Predictive Value of Tests; D011336:Probability; D011897:Random Allocation; D014786:Vision Disorders / Q000453:epidemiology / Q000517:prevention & control*; D015351:Vision Screening / Q000592:standards*; D014787:Vision Tests / Q000379:methods