title: [Prevalence of age-related cataract among adults aged 50 and above in four rural areas in western China].
abstract: OBJECTIVE
  To assess and compare the prevalence of age-related cataract (ARC) among adults aged 50 years or older in Western China.
  
  
  METHODS
  Questionnaire survey and ophthalmologic examination were conducted among 5562 permanent rural residents aged 50 years and above in Ping' an County, Qinghai Province, Chuxiong City, Yunnan Province, Liupanshui City, Guizhou Province, and Chongzuo City, Guangxi Zhuang Autonomous region, selected by cluster sampling. All lenses were graded and classified for lens opacities by slit lamp, using the Lens Opacification Classification System (LOCS) II and standard photographs. Definite ARC was defined as either LOGS II nuclear opalescence of grade 1.0 or more and/or cortical cataract of grade 1.0 or more and/or posterior subcapsular cataract of grade 1.0 or more in persons with the visual acuity worse than 10/16.
  
  
  RESULTS
  The overall response rate was 88.4%. The prevalence rates of ARC in one or both eyes was 41.8% in Qinghai, 48.2% in Yunnan, 18.8% in Guizhou and 39.4% in Guangxi. After age correction under the data of China Census 2000, the age-adjusted prevalence of ARC correspondingly changed to 44.1% in Qinghai, 45.9% in Yunnan, 18.8% in Guizhou, and 32.8% in Guangxi. The prevalence of ARC increased significantly with increasing age. In those eyes with ARC, cortical cataract was more common in Qinghai and Guizhou, while nuclear cataract was more common in Yunnan and Guangxi. The proportion of grades 4 lens opacities in Qinghai was 17.49%, higher than those in Yunnan, Guizhou, and Guangri (15.58%, 11.03%, and 10.00%. respectively).
  
  
  CONCLUSIONS
  Generally the ARC prevalence among the permanent rural residents aged 50 and above in Western China is higher than that in Eastern China. And there is difference in the prevalence rate among different areas. Special attention should be paid toward this situation.
authors.affiliation: People Eye Center, Peking University People's Hospital, Beijing 100044, China. drbaoyz@sina.com
authors.forename: Yong-zhen
authors.initials: YZ
authors.lastname: Bao
authors.forename: Xiao-guang
authors.initials: XG
authors.lastname: Cao
authors.forename: Xiao-xin
authors.initials: XX
authors.lastname: Li
authors.forename: Jie
authors.initials: J
authors.lastname: Chen
authors.forename: Jian-xin
authors.initials: JX
authors.lastname: Hu
authors.forename: Tong
authors.initials: T
authors.lastname: Zhu
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D002386:Cataract / Q000453:epidemiology*; D002681:China / Q000453:epidemiology; D006801:Humans; D008875:Middle Aged; D015995:Prevalence; D012424:Rural Population / Q000706:statistics & numerical data*; D011795:Surveys and Questionnaires