title: Preschool children's vision screening in New Zealand: a retrospective evaluation of referral accuracy.
abstract: OBJECTIVE
  To assess the accuracy of preschool vision screening in a large, ethnically diverse, urban population in South Auckland, New Zealand.
  
  
  METHODS
  Retrospective longitudinal study.
  
  
  METHODS
  B4 School Check vision screening records (n=5572) were compared with hospital eye department data for children referred from screening due to impaired acuity in one or both eyes who attended a referral appointment (n=556). False positive screens were identified by comparing screening data from the eyes that failed screening with hospital data. Estimation of false negative screening rates relied on data from eyes that passed screening. Data were analysed using logistic regression modelling accounting for the high correlation between results for the two eyes of each child.
  
  
  METHODS
  Positive predictive value of the preschool vision screening programme.
  
  
  RESULTS
  Screening produced high numbers of false positive referrals, resulting in poor positive predictive value (PPV=31%, 95% CI 26% to 38%). High estimated negative predictive value (NPV=92%, 95% CI 88% to 95%) suggested most children with a vision disorder were identified at screening. Relaxing the referral criteria for acuity from worse than 6/9 to worse than 6/12 improved PPV without adversely affecting NPV.
  
  
  CONCLUSIONS
  The B4 School Check generated numerous false positive referrals and consequently had a low PPV. There is scope for reducing costs by altering the visual acuity criterion for referral.
authors.affiliation: Department of Ophthalmology, Counties Manukau District Health Board, Auckland, New Zealand.
authors.forename: Miriam A
authors.initials: MA
authors.lastname: Langeslag-Smith
authors.affiliation: Ko Awatea, Counties Manukau District Health Board, Auckland, New Zealand Faculty of Health and Environmental Sciences, Auckland University of Technology, Auckland, New Zealand.
authors.forename: Alain C
authors.initials: AC
authors.lastname: Vandal
authors.affiliation: Ko Awatea, Counties Manukau District Health Board, Auckland, New Zealand.
authors.forename: Vincent
authors.initials: V
authors.lastname: Briane
authors.affiliation: Department of Optometry and Vision Science, The University of Waterloo, Waterloo, Ontario, Canada School of Optometry and Vision Science, The University of Auckland, Auckland, New Zealand.
authors.forename: Benjamin
authors.initials: B
authors.lastname: Thompson
authors.affiliation: School of Optometry and Vision Science, The University of Auckland, Auckland, New Zealand.
authors.forename: Nicola S
authors.initials: NS
authors.lastname: Anstice
mesh_terms: D002675:Child, Preschool; D005188:False Negative Reactions; D005189:False Positive Reactions; D005260:Female; D006801:Humans; D016015:Logistic Models; D008137:Longitudinal Studies; D008297:Male; D009520:New Zealand; D011237:Predictive Value of Tests; D012017:Referral and Consultation / Q000592:standards*; D012189:Retrospective Studies; D012574:Schools; D014786:Vision Disorders / Q000175:diagnosis*; D015351:Vision Screening / Q000592:standards*; D014792:Visual Acuity