title: Prevalence and causes of visual impairment in Asian and non-Hispanic white preschool children: Multi-ethnic Pediatric Eye Disease Study.
abstract: OBJECTIVE
  To determine the prevalence and causes of decreased visual acuity (VA).
  
  
  METHODS
  Population-based cross-sectional study.
  
  
  METHODS
  Multi-ethnic sample of children 30 to 72 months of age identified in Los Angeles.
  
  
  METHODS
  All eligible children underwent a comprehensive ophthalmic evaluation including monocular VA testing, cover testing, cycloplegic autorefraction, fundus evaluation, and VA retesting with refractive correction. Decreased VA was defined as presenting or best-measured VA worse than 20/50 in children 30 to 47 months of age and worse than 20/40 for children 48 months of age and older. The prevalence and causes of decreased VA were determined, for both presenting and best-measured VA, in the better-seeing and the worse-seeing eyes.
  
  
  METHODS
  Prevalence and causes of decreased vision.
  
  
  RESULTS
  Presenting VA was assessed in 1840 children and best-measured VA was assessed in 1886 children. Presenting VA was decreased in the worse eye of 4.2% of Asian children and of 3.6% of non-Hispanic white (NHW) children. Close to one-fourth of these cases had no identifiable cause, and 81% of these resolved on retesting. Decreased presenting VA in the worse eye with an identifiable ophthalmic cause was present in 3.4% of Asian children and in 2.6% of NHW children. Decreased presenting VA attributable to simple refractive error (myopia ≥ 0.5 diopters [D]; hyperopia ≥ 3.0 D; astigmatism ≥ 2.0 D or ≥ 1.5 D for children older than 36 months) was present in the worse eye of 2.3% of Asian children and of 1.4% of NHW children and in the better eye of 0.5% of Asian children and of 0.3% of NHW children. Decreased best-measured VA attributable to a cause was present in the worse eye of 1.2% of both Asian children and NHW children and in the better eye of 0.2% of Asian and of 0.3% of NHW children. Amblyopia related to refractive error was the most common cause, and was 10 times as common as ocular disease. Severe visual impairment was rare.
  
  
  CONCLUSIONS
  Seventy percent of all decreased VA in Asian and NHW preschool children and more than 90% of decreased VA with an identifiable cause is related to refractive error--either uncorrected refractive error or amblyopia resulting from refractive error.
  
  
  BACKGROUND
  The author(s) have no proprietary or commercial interest in any materials discussed in this article.
authors.affiliation: Department of Ophthalmology, Keck School of Medicine, University of Southern California, Los Angeles, California 90033, USA.
authors.forename: Kristina
authors.initials: K
authors.lastname: Tarczy-Hornoch
authors.forename: Susan A
authors.initials: SA
authors.lastname: Cotter
authors.forename: Mark
authors.initials: M
authors.lastname: Borchert
authors.forename: Roberta
authors.initials: R
authors.lastname: McKean-Cowdin
authors.forename: Jesse
authors.initials: J
authors.lastname: Lin
authors.forename: Ge
authors.initials: G
authors.lastname: Wen
authors.forename: Jeniffer
authors.initials: J
authors.lastname: Kim
authors.forename: Rohit
authors.initials: R
authors.lastname: Varma
mesh_terms: D001213:Asian / Q000208:ethnology*; D002648:Child; D002675:Child, Preschool; D003430:Cross-Sectional Studies; D005128:Eye Diseases / Q000150:complications; D005260:Female; D006801:Humans; D015141:Los Angeles / Q000453:epidemiology; D008297:Male; D015995:Prevalence; D012029:Refraction, Ocular / Q000502:physiology; D014786:Vision Disorders / Q000208:ethnology* / Q000209:etiology*; D014787:Vision Tests; D014792:Visual Acuity / Q000502:physiology; D019987:Persons with Visual Disabilities / Q000706:statistics & numerical data*; D044465:White People / Q000208:ethnology*
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