title: [Prevalence of blindness among adults aged 40 years or above in Linzhou county of Lasa].
abstract: OBJECTIVE
  To estimate the prevalence of blindness among older adults aged >/= 40 years in Linzhou county, Lasa, China.
  
  
  METHODS
  Cluster sampling was used in randomly selecting individuals aged >/= 40 years in 44 villages in Linzhou county in May, 2000. A total of 3 153 individuals were examined for visual acuity and eye condition. The prevalence of blindness was calculated according to the pinhole vision with WHO blindness criterion (criterion A) and presenting vision with blindness criterion (criterion B).
  
  
  RESULTS
  The individuals examined were enumerated. The response rate was 97.4% (3 071/3 153). When the bilateral pinhole vision < 3/60 was defined as the blindness criterion, the prevalence of blindness was 2.3% [95% confidence interval (CI), 1.8 - 2.8]. The blindness prevalence was increased with age (P < 0.001). Men had a higher prevalence of blindness than women (P > 0.05). After adjusting for age, the difference had statistical significance (P < 0.05). Prevalence of blindness was higher among the illiterate persons than among those with 1 or more years of schooling (P < 0.001). But after adjusting for age, the difference had no statistical significance (P > 0.05). When the bilateral presenting vision < 6/60 was defined as the blindness criterion, the prevalence of blindness was 3.2% (95% CI, 2.6 - 3.8). The blindness prevalence was increased with age (P < 0.001). Men had a higher prevalence of blindness than women. The crude male-to-female odds ratio for moderate and severe blindness was 1.17 (P > 0.05). After adjusting for age, the difference had no significance too (P > 0.05). Prevalence of blindness was higher among the illiterate persons than among those with 1 or more years of schooling (P < 0.001). But after adjusting for age, the difference had no statistical significance (P > 0.05).
  
  
  CONCLUSIONS
  The prevalence of blindness is higher in the area of plateau. The principal cause of blindness is cataract.
authors.affiliation: Department of Ophthalmology, General Hospital, Chinese People's Armed Police, Beijing 100039, China. houbaojie@sina.com
authors.forename: Baojie
authors.initials: B
authors.lastname: Hou
authors.forename: Ji
authors.initials: J
authors.lastname: De
authors.forename: Haiyang
authors.initials: H
authors.lastname: Wu
authors.forename: Danzeng
authors.initials: D
authors.lastname: Gesang
authors.forename: Pengda
authors.initials: P
authors.lastname: Bu
authors.forename: Suolang
authors.initials: S
authors.lastname: Qiangba
authors.forename: Hai
authors.initials: H
authors.lastname: Tao
authors.forename: Wa
authors.initials: W
authors.lastname: Da
authors.forename: Anchun
authors.initials: A
authors.lastname: Du
authors.forename: Bu
authors.initials: B
authors.lastname: Luo
authors.forename: Xiaoping
authors.initials: X
authors.lastname: Qin
authors.forename: Mingfang
authors.initials: M
authors.lastname: Gao
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D001766:Blindness / Q000453:epidemiology* / Q000209:etiology; D002681:China / Q000453:epidemiology; D005128:Eye Diseases / Q000150:complications; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012737:Sex Factors