title: Amblyopia treatment outcomes after preschool screening v school entry screening: observational data from a prospective cohort study.
abstract: OBJECTIVE
  Preschool screening for amblyopia has controversially been abandoned in some localities within the United Kingdom, on the basis that there is no clear evidence of benefit to support its continuation. Data collected within a birth cohort study were used to examine visual outcomes at 7(1/2) years in children who did or did not receive preschool vision screening.
  
  
  METHODS
  Monocular logMAR visual acuity with and without a pinhole was assessed by orthoptists. Contemporary records were used to identify children who had been offered and/or received preschool screening.
  
  
  RESULTS
  Of 6081 children, 24.9% had been offered preschool screening and 16.7% had attended. The prevalence of amblyopia was approximately 45% lower in the children who received preschool screening than in those who did not (1.1% v 2.0%, p = 0.05). The mean acuity in the worse seeing eyes after patching treatment was better for amblyopic children who received preschool screening than for those who did not; 0.14 v 0.20 logMAR (p <0.001). These effects did not persist in an intention to screen analysis.
  
  
  CONCLUSIONS
  Preschool screening at 37 months was associated with an improved treatment outcome for individuals with amblyopia. However, the improvement was clinically small and disappeared when considering all children offered screening rather than only those who received it. Further research is needed into improving the effectiveness of vision screening for preschool children, while in the interim these data do not conflict with current recommendations for school entry screening by orthoptists.
authors.affiliation: Division of Child Health, University of Bristol, Bristol, UK. Cathy.Williams@bristol.ac.uk
authors.forename: C
authors.initials: C
authors.lastname: Williams
authors.forename: K
authors.initials: K
authors.lastname: Northstone
authors.forename: R A
authors.initials: RA
authors.lastname: Harrad
authors.forename: J M
authors.initials: JM
authors.lastname: Sparrow
authors.forename: I
authors.initials: I
authors.lastname: Harvey
mesh_terms: D000367:Age Factors; D000550:Amblyopia / Q000175:diagnosis / Q000628:therapy*; D002648:Child; D002675:Child, Preschool; D004739:England; D005260:Female; D006801:Humans; D008137:Longitudinal Studies; D008297:Male; D011446:Prospective Studies; D013223:Statistics as Topic; D016896:Treatment Outcome; D015351:Vision Screening / Q000458:organization & administration*; D014792:Visual Acuity