title: Prevalence of anisometropia and its association with refractive error and amblyopia in preschool children.
abstract: OBJECTIVE
  To determine the age and ethnicity-specific prevalence of anisometropia in Australian preschool-aged children and to assess in this population-based study the risk of anisometropia with increasing ametropia levels and risk of amblyopia with increasing anisometropia.
  
  
  METHODS
  A total 2090 children (aged 6-72 months) completed detailed eye examinations in the Sydney Paediatric Eye Disease Study, including cycloplegic refraction, and were included. Refraction was measured using a Canon RK-F1 autorefractor, streak retinoscopy and/or the Retinomax K-Plus 2 autorefractor. Anisometropia was defined by the spherical equivalent (SE) difference, and plus cylinder difference for any cylindrical axis between eyes.
  
  
  RESULTS
  The overall prevalence of SE and cylindrical anisometropia ≥1.0 D were 2.7% and 3.0%, for the overall sample and in children of European-Caucasian ethnicity, 3.2%, 1.9%; East-Asian 1.7%, 5.2%; South-Asian 2.5%, 3.6%; Middle-Eastern ethnicities 2.2%, 3.3%, respectively. Anisometropia prevalence was lower or similar to that in the Baltimore Pediatric Eye Disease Study, Multi-Ethnic Pediatric Eye Disease Study and the Strabismus, Amblyopia and Refractive error in Singapore study. Risk (OR) of anisometropic amblyopia with ≥1.0 D of SE and cylindrical anisometropia was 12.4 (CI 4.0 to 38.4) and 6.5 (CI 2.3 to 18.7), respectively. We found an increasing risk of anisometropia with higher myopia ≥-1.0 D, OR 61.6 (CI 21.3 to 308), hyperopia > +2.0 D, OR 13.6 (CI 2.9 to 63.6) and astigmatism ≥1.5 D, OR 30.0 (CI 14.5 to 58.1).
  
  
  CONCLUSIONS
  In this preschool-age population-based sample, anisometropia was uncommon with inter-ethnic differences in cylindrical anisometropia prevalence. We also quantified the rising risk of amblyopia with increasing SE and cylindrical anisometropia, and present the specific levels of refractive error and associated increasing risk of anisometropia.
authors.affiliation: Department of Ophthalmology, Westmead Millennium Institute, Centre for Vision Research, University of Sydney, New South Wales, Australia.
authors.forename: Sonia
authors.initials: S
authors.lastname: Afsari
authors.forename: Kathryn A
authors.initials: KA
authors.lastname: Rose
authors.forename: Glen A
authors.initials: GA
authors.lastname: Gole
authors.forename: Krupa
authors.initials: K
authors.lastname: Philip
authors.forename: Jody F
authors.initials: JF
authors.lastname: Leone
authors.forename: Amanda
authors.initials: A
authors.lastname: French
authors.forename: Paul
authors.initials: P
authors.lastname: Mitchell
mesh_terms: D000550:Amblyopia / Q000453:epidemiology* / Q000209:etiology; D015858:Anisometropia / Q000150:complications / Q000453:epidemiology* / Q000208:ethnology; D001315:Australia / Q000453:epidemiology; D002675:Child, Preschool; D006801:Humans; D007223:Infant; D015995:Prevalence; D012030:Refractive Errors / Q000453:epidemiology; D012307:Risk Factors
keywords: Child health (paediatrics); Epidemiology; Public health