title: Causes and prevalence of visual impairment among adults in the United States.
abstract: OBJECTIVE
  To estimate the cause-specific prevalence and distribution of blindness and low vision in the United States by age, race/ethnicity, and gender, and to estimate the change in these prevalence figures over the next 20 years.
  
  
  METHODS
  Summary prevalence estimates of blindness (both according to the US definition of < or =6/60 [< or =20/200] best-corrected visual acuity in the better-seeing eye and the World Health Organization standard of < 6/120 [< 20/400]) and low vision (< 6/12 [< 20/40] best-corrected vision in the better-seeing eye) were prepared separately for black, Hispanic, and white persons in 5-year age intervals starting at 40 years. The estimated prevalences were based on recent population-based studies in the United States, Australia, and Europe. These estimates were applied to 2000 US Census data, and to projected US population figures for 2020, to estimate the number of Americans with visual impairment. Cause-specific prevalences of blindness and low vision were also estimated for the different racial/ethnic groups.
  
  
  RESULTS
  Based on demographics from the 2000 US Census, an estimated 937 000 (0.78%) Americans older than 40 years were blind (US definition). An additional 2.4 million Americans (1.98%) had low vision. The leading cause of blindness among white persons was age-related macular degeneration (54.4% of the cases), while among black persons, cataract and glaucoma accounted for more than 60% of blindness. Cataract was the leading cause of low vision, responsible for approximately 50% of bilateral vision worse than 6/12 (20/40) among white, black, and Hispanic persons. The number of blind persons in the US is projected to increase by 70% to 1.6 million by 2020, with a similar rise projected for low vision.
  
  
  CONCLUSIONS
  Blindness or low vision affects approximately 1 in 28 Americans older than 40 years. The specific causes of visual impairment, and especially blindness, vary greatly by race/ethnicity. The prevalence of visual disabilities will increase markedly during the next 20 years, owing largely to the aging of the US population.
authors.affiliation: Wilmer Eye Institute, Wilmer 120, 600 N. Wolfe Street, Baltimore, MD 21287, USA. ncongdon@jhmi.edu
authors.forename: Nathan
authors.initials: N
authors.lastname: Congdon
authors.forename: Benita
authors.initials: B
authors.lastname: O'Colmain
authors.forename: Caroline C W
authors.initials: CC
authors.lastname: Klaver
authors.forename: Ronald
authors.initials: R
authors.lastname: Klein
authors.forename: Beatriz
authors.initials: B
authors.lastname: Muñoz
authors.forename: David S
authors.initials: DS
authors.lastname: Friedman
authors.forename: John
authors.initials: J
authors.lastname: Kempen
authors.forename: Hugh R
authors.initials: HR
authors.lastname: Taylor
authors.forename: Paul
authors.initials: P
authors.lastname: Mitchell
mesh_terms: D000328:Adult; D001741:Black or African American / Q000706:statistics & numerical data*; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D001315:Australia / Q000453:epidemiology; D001766:Blindness / Q000208:ethnology* / Q000209:etiology; D002386:Cataract / Q000150:complications / Q000453:epidemiology; D015984:Causality; D005060:Europe / Q000453:epidemiology; D005260:Female; D005901:Glaucoma / Q000150:complications / Q000453:epidemiology; D006630:Hispanic or Latino / Q000706:statistics & numerical data*; D006801:Humans; D008268:Macular Degeneration / Q000150:complications / Q000453:epidemiology; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D014481:United States / Q000453:epidemiology; D015354:Vision, Low / Q000208:ethnology* / Q000209:etiology; D014792:Visual Acuity; D019987:Persons with Visual Disabilities / Q000706:statistics & numerical data*; D044465:White People / Q000706:statistics & numerical data*