title: Prevalence of refractive error in the United States, 1999-2004.
abstract: OBJECTIVE
  To describe the prevalence of refractive error in the United States.
  
  
  METHODS
  The 1999-2004 National Health and Nutrition Examination Survey (NHANES) used an autorefractor to obtain refractive error data on a nationally representative sample of the US noninstitutionalized, civilian population 12 years and older. Using data from the eye with a greater absolute spherical equivalent (SphEq) value, we defined clinically important refractive error as follows: hyperopia, SphEq value of 3.0 diopters (D) or greater; myopia, SphEq value of -1.0 D or less; and astigmatism, cylinder of 1.0 D or greater in either eye.
  
  
  RESULTS
  Of 14,213 participants 20 years or older who completed the NHANES, refractive error data were obtained for 12,010 (84.5%). The age-standardized prevalences of hyperopia, myopia, and astigmatism were 3.6% (95% confidence interval [CI], 3.2%-4.0%), 33.1% (95% CI, 31.5%-34.7%), and 36.2% (95% CI, 34.9%-37.5%), respectively. Myopia was more prevalent in women (39.9%) than in men (32.6%) (P < .001) among 20- to 39-year-old participants. Persons 60 years or older were less likely to have myopia and more likely to have hyperopia and/or astigmatism than younger persons. Myopia was more common in non-Hispanic whites (35.2%) than in non-Hispanic blacks (28.6%) or Mexican Americans (25.1%) (P < .001 for both).
  
  
  CONCLUSIONS
  Estimates based on the 1999-2004 NHANES vision examination data indicate that clinically important refractive error affects half of the US population 20 years or older.
authors.affiliation: Division of Epidemiology and Clinical Research, National EyeInstitute, National Institutes of Health, Bethesda, MD 20892-9301, USA. sev@nei.nih.gov
authors.forename: Susan
authors.initials: S
authors.lastname: Vitale
authors.forename: Leon
authors.initials: L
authors.lastname: Ellwein
authors.forename: Mary Frances
authors.initials: MF
authors.lastname: Cotch
authors.forename: Frederick L
authors.initials: FL
authors.lastname: Ferris
authors.forename: Robert
authors.initials: R
authors.lastname: Sperduto
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D005006:Ethnicity; D006801:Humans; D008297:Male; D008875:Middle Aged; D009749:Nutrition Surveys; D015995:Prevalence; D012030:Refractive Errors / Q000453:epidemiology*; D017678:Sex Distribution; D014481:United States / Q000453:epidemiology