title: [The survey of prevalence of blindness in Nan'an District of Chongqing].
abstract: OBJECTIVE
  To investigate the prevalence of blindness and low vision, their changes and the main causes of blindness in persons aged 50 years and above in Nan'an District in Chongqing.
  
  
  METHODS
  This survey was conducted from April to July, 2005. By cluster random sampling, 29 clusters were selected and 5079 persons received the eye examination. The response rate was 89.4%. A quality assurance evaluation had performed in two examination teams before the survey.
  
  
  RESULTS
  In this population, the prevalence of blindness was 1.8% based on the pinhole visual acuity. The prevalence of blindness was higher in older persons, especially in persons aged eighty or above. Cataract was the leading cause of blindness, but the proportion of cataract-caused blindness decreased from 40.0% to 31.6%. Retinal diseases was the second important cause of blindness, followed by refraction error, cornea disease and glaucoma.
  
  
  CONCLUSIONS
  Cataract is the leading cause of blindness in Nan'an District of Chongqing, followed by retinal diseases. The decrease of cataract-caused blindness indicates that the prevention of blindness, mainly through the performance of cataract surgery, has gained successful. It is important on the prevention of the age-related eye diseases, retinal diseases and glaucoma.
authors.affiliation: Department of Ophthalmology, the Second Affiliated Hospital of Chongqing Medical University, Chongqing 400010, China. liusu2836@sina.com
authors.forename: Su
authors.initials: S
authors.lastname: Liu
authors.forename: Lin
authors.initials: L
authors.lastname: Chen
authors.forename: Lin
authors.initials: L
authors.lastname: Ouyang
authors.forename: Qing
authors.initials: Q
authors.lastname: Peng
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001766:Blindness / Q000453:epidemiology*; D002681:China / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence