title: Prevalence and risk factors of lens opacities in urban and rural Chinese in Beijing.
abstract: OBJECTIVE
  To determine the prevalence of lens opacities in the elderly Chinese population in an urban and a rural region of Beijing.
  
  
  METHODS
  Population-based cross-sectional study.
  
  
  METHODS
  The study included 4439 subjects of 5324 subjects invited to participate (response rate, 83.4%). The subjects were divided into a rural part (1973 subjects [44.4%]) and an urban part (2466 subjects [55.6%]). The study was limited to participants age 40 and older, and the mean age was 56.2+/-10.6 years (range, 40-101 years).
  
  
  METHODS
  Nuclear, cortical, and posterior subcapsular lens opacities were assessed based on standardized slit-lamp photographs of the lens using a modification of the grading score of the Age-related Eye Disease Study (AREDS).
  
  
  METHODS
  Grading score of the AREDS.
  
  
  RESULTS
  Lens data were provided for 4378 subjects (98.6%) of 4439 persons examined, which consisted of 8724 eyes. Prevalence of any cataract surgery was 1.3% (95% confidence interval [CI]: 1.0-1.7), which was statistically independent of gender (P = 0.51; odds ratio [OR]: 0.86; 95% CI: 1.00-1.34), rural area versus urban region (P = 0.25), and level of education (P = 0.84). Prevalence of any nuclear lens opacity was 82.0% (95% CI: 80.8-83.2); prevalence of any cortical lens opacity was 10.3% (95% CI: 9.4-11.3); and prevalence of any posterior subcapsular opacity was 4.3% (95% CI: 3.7-4.9). If grade 2 of nuclear lens opacity was considered to be normal, prevalence of nuclear cataract was 50.3% (95% CI: 48.8-51.8), and the overall prevalence of any cataract was 53.1% (95% CI: 51.6-54.6), increasing from 6.5% (95% CI: 5.2-7.8) in those subjects 40 to 49 years of age to 52.3% (95% CI: 47.4-55.3) in those who were 50 to 59 years of age, and to 97.8% (95% CI: 96.4-99.2) in those 70 years and older (P<0.001). Frequencies of any cortical cataract and any subcapsular posterior cataract were 10.3% (95% CI: 9.4-11.3) and 4.3% (95% CI: 3.7-4.9), respectively.
  
  
  CONCLUSIONS
  Cataracts are common among adult Chinese residents in Beijing, with age as the most important associated factor. In view of the relatively low rate of cataract surgery performed so far, one may expect a marked increase in the number of cataract surgeries to meet the visual needs of the growing elderly population in China.
authors.affiliation: Beijing Institute of Ophthalmology, Beijing Tongren Hospital and Capital University of Medical Science, Beijing, China.
authors.forename: Liang
authors.initials: L
authors.lastname: Xu
authors.forename: Tongtong
authors.initials: T
authors.lastname: Cui
authors.forename: Shiyuan
authors.initials: S
authors.lastname: Zhang
authors.forename: Baochen
authors.initials: B
authors.lastname: Sun
authors.forename: Yuanyuan
authors.initials: Y
authors.lastname: Zheng
authors.forename: Ailian
authors.initials: A
authors.lastname: Hu
authors.forename: Jianjun
authors.initials: J
authors.lastname: Li
authors.forename: Ke
authors.initials: K
authors.lastname: Ma
authors.forename: Jost B
authors.initials: JB
authors.lastname: Jonas
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D044466:Asian People / Q000706:statistics & numerical data*; D002386:Cataract / Q000145:classification / Q000208:ethnology*; D002387:Cataract Extraction / Q000706:statistics & numerical data; D002681:China / Q000453:epidemiology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012307:Risk Factors; D012424:Rural Population / Q000706:statistics & numerical data*; D014505:Urban Population / Q000706:statistics & numerical data*