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Table 5 Definition and prevalence rate of amblyopia

From: Effectiveness of screening preschool children for amblyopia: a systematic review

Reference Definition of amblyopia
(Snellen acuity)
Prevalence*
(Intervention group)
Prevalence* (Control group) P-value
   Orthoptist Health Visitor  
  VA ≤6/9 1.1% (0.7–1.8%) 1.0% (0.6–1.5%) Not reported
Bray
1996 33
   GP  
    1.2% (0.8–1.9%) Not reported
Eibschitz-   Screening No screening  
Tsimhoni VA ≤5/10 1.0% 2.6% <0.01
2000 27 VA ≤5/15 0.1% 1.7% <0.001
Rasmussen   Preschool screening No preschool screening  
2000 34 VA not specified 0.0% 0.1% Not reported
Williams   Intensive screening Less intensive screening  
2002 31,32 Inter-ocular difference ≥ 2 lines 1.5% 2.7% 0.06
  VA <6/12 0.6% 1.8% 0.02
Williams   Preschool screening No preschool screening  
2003 28,29,30 Inter-ocular difference ≥ 2 lines 1.1% 2.0% 0.05 (0.24)
  VA ≤6/9 1.9% 3.4% 0.01 (0.16)
  VA <6/12 0.7% 1.3% 0.11 (0.55)
  1. VA = Visual acuity.
  2. * In brackets: 95% confidence interval, if reported in the publication.
  3. Adjustment for confounding factors like sex, highest level of maternal education, birth weight, family history of strabismus/amblyopia and duration of breastfeeding.