title: The etiology of vision impairment in target population.
abstract: OBJECTIVE
  research the etiology of vision impairment in target persons over 45 years old in Doumen county, Guangdong province.
  
  
  METHODS
  Depending on the prevalences of the blindness among the person aged over 50 years, the theoretic sample rate is 1,000/4,8733 x 100% = 2.05%. The 8 districts were divided into 3 parts according to the local economic situation and the proportion of the population in the areas. In fact, the sampling rate is 932/10055 = 88.34%.
  
  
  RESULTS
  We found that impairment < 0.3 accounted for 10.94%. The prevalence of bilateral blindness and low vision was 1.61% and 3.22%, respectively. Both prevalences of blindness and low vision were increased with age. The leading cuase of blindness was cataract (45.2%). The second was corneal opacity (16.7%). Prevalences of the low vision and the blindness were higher in females than in males (P < 0.005).
  
  
  CONCLUSIONS
  Curable and preventable diseases were the leading cause for the blindness (70%). Prevalences of blindness and the low vision increase with age. We will continually follow up the population over 50 years of age in Doumen county.
authors.affiliation: Zhongshan Ophthalmic Center, Sun Yat-sen University of Medical Sciensces, Guangzhou, China.
authors.forename: S
authors.initials: S
authors.lastname: Zhu
authors.forename: J
authors.initials: J
authors.lastname: Xu
authors.forename: Q
authors.initials: Q
authors.lastname: Yu
authors.forename: Q
authors.initials: Q
authors.lastname: Liu
mesh_terms: D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D001766:Blindness / Q000453:epidemiology / Q000209:etiology*; D002386:Cataract / Q000150:complications; D002681:China / Q000453:epidemiology; D003318:Corneal Opacity / Q000150:complications; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012737:Sex Factors; D015354:Vision, Low / Q000453:epidemiology / Q000209:etiology*