title: Prevalence of cataract and pseudophakia/aphakia among adults in the United States.
abstract: OBJECTIVE
  To determine the prevalence of cataract and pseudophakia/aphakia in the United States and to project the expected change in these prevalence figures by 2020.
  
  
  METHODS
  Summary prevalence estimates of cataract and of pseudophakia/aphakia were prepared separately for black, white, and Hispanic persons (for whom only cataract surgery data were available) in 5-year age intervals starting at 40 years for women and men. The estimates were based on a standardized definition of various types of cataract: cortical, greater than 25% of the lens involved; posterior subcapsular, present according to the grading system used in each study; and nuclear, greater than or equal to the penultimate grade in the system used. Data were collected from major population-based studies in the United States, and, where appropriate, Australia, Barbados, and Western Europe. The age-, gender-, and race/ethnicity-specific rates were applied to 2000 US Census data, and projected population figures for 2020, to obtain overall estimates.
  
  
  RESULTS
  An estimated 20.5 million (17.2%) Americans older than 40 years have cataract in either eye, and 6.1 million (5.1%) have pseudophakia/aphakia. Women have a significantly (odds ratio = 1.37; 95% confidence interval, 1.26-1.50) higher age-adjusted prevalence of cataract than men in the United States. The total number of persons who have cataract is estimated to rise to 30.1 million by 2020; and for those who are expected to have pseudophakia/aphakia, to 9.5 million.
  
  
  CONCLUSIONS
  The number of Americans affected by cataract and undergoing cataract surgery will dramatically increase over the next 20 years as the US population ages.
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: Johannes R
authors.initials: JR
authors.lastname: Vingerling
authors.forename: Barbara E K
authors.initials: BE
authors.lastname: Klein
authors.forename: Sheila
authors.initials: S
authors.lastname: West
authors.forename: David S
authors.initials: DS
authors.lastname: Friedman
authors.forename: John
authors.initials: J
authors.lastname: Kempen
authors.forename: Benita
authors.initials: B
authors.lastname: O'Colmain
authors.forename: Suh-Yuh
authors.initials: SY
authors.lastname: Wu
authors.forename: Hugh R
authors.initials: HR
authors.lastname: Taylor
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D001036:Aphakia, Postcataract / Q000208:ethnology*; D044383:Black People / Q000706:statistics & numerical data*; D002386:Cataract / Q000208:ethnology*; D005260:Female; D006630:Hispanic or Latino / Q000706:statistics & numerical data*; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D019591:Pseudophakia / Q000208:ethnology*; D017678:Sex Distribution; D014481:United States / Q000453:epidemiology; D044465:White People / Q000706:statistics & numerical data*; D001741:Black or African American