title: Prevalence and causes of decreased visual acuity in Singaporean Chinese preschoolers.
abstract: OBJECTIVE
  To describe the prevalence and causes of decreased visual acuity (VA) in Singaporean Chinese children.
  
  
  METHODS
  A population-based survey of Singaporean Chinese children aged 6 to 72 months was conducted. Participants underwent an orthoptic evaluation, cycloplegic refraction and biometric measurements. A sub-group of children aged 30 to 72 months with presenting logMAR VA were included in this analysis. Retesting was performed on the same day or another day by predefined criteria with best refractive correction. Decreased VA was defined as worse than 20/50 (0.4 logMAR) for ages 30 to 47 months and worse than 20/40 (0.3 logMAR) for ages 48 to 72 months.
  
  
  RESULTS
  The study examined 3009 children (participation rate 72.3%) of which 2017 children aged 30 to 72 months were eligible for VA testing and completed in 1684 (83.5%). In children aged 30-47 months, the prevalence of decreased presenting VA was 2.1%, and in children 48-72 months, it was 2.05%, with no significant difference between boys and girls in both age groups (p=0.15 and p=0.85). Causes for decreased presenting VA in those 30-47 months were refractive error (7/11, 63.6%), amblyopia (1/11, 9.1%) and "no explanation" (3/11, 27.3%), and 17/24 (70.8%), 5/24 (20.8%) and 2/24 (8.3%), respectively, for those aged 48-72 months. The types of refractive error were astigmatism (15/24, 62.5%), myopia (6/24, 25.0%), hyperopia (2/24, 8.3%) and hyperopia with astigmatism (1/24, 4.2%).
  
  
  CONCLUSIONS
  The prevalence of decreased VA among Singaporean Chinese preschoolers is low, with uncorrected refractive error being the main cause in both children 30-47 and 48-72 months.
authors.affiliation: Singapore Eye Research Institute, Singapore, Singapore. dirani@unimelb.edu.au
authors.forename: M
authors.initials: M
authors.lastname: Dirani
authors.forename: B
authors.initials: B
authors.lastname: Zhou
authors.forename: D
authors.initials: D
authors.lastname: Hornbeak
authors.forename: B C
authors.initials: BC
authors.lastname: Chang
authors.forename: G
authors.initials: G
authors.lastname: Gazzard
authors.forename: A
authors.initials: A
authors.lastname: Chia
authors.forename: Y
authors.initials: Y
authors.lastname: Ling
authors.forename: P
authors.initials: P
authors.lastname: Selvaraj
authors.forename: T L
authors.initials: TL
authors.lastname: Young
authors.forename: R
authors.initials: R
authors.lastname: Varma
authors.forename: T Y
authors.initials: TY
authors.lastname: Wong
authors.forename: S M
authors.initials: SM
authors.lastname: Saw
mesh_terms: D000550:Amblyopia / Q000453:epidemiology* / Q000209:etiology; D002657:Child Development; D002675:Child, Preschool; D002681:China / Q000208:ethnology; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D015995:Prevalence; D011788:Quality of Life; D017678:Sex Distribution; D012846:Singapore / Q000453:epidemiology; D013285:Strabismus / Q000453:epidemiology*; D015354:Vision, Low / Q000453:epidemiology* / Q000209:etiology; D014792:Visual Acuity