title: A population-based study of lens opactities.
abstract: OBJECTIVE
  Age-related lens opacity is the main cause of vision disability in elderly population all over the world. This study was designed to investigate the prevalence and incidence of lens opacity.
  
  
  METHODS
  1817 eyes of 932 adults over 45 years-old were sampled randomly from 4 villeges within Doumen, a county located in the south of Guangdong provience, China. The procedure of the examination was performed by ophthalmologists. The lens opacities were graded according to a standarized photo of the Lens Opacities Classification System II (LOCS-II).
  
  
  RESULTS
  The prevalence of lens opacities in nuclear color, nuclear opacity, cortical opacity and subcapsular opacity was 16.1%, 28.6%, 30.3% and 8.7%, respectively. The frequency of all four types of opacities increased with age. The prevalence of lens opacities in four types was higher in female than that in male.
  
  
  CONCLUSIONS
  The data we got are important for prevalence of lens opacities of population-based study as well as basic information for cohort study in the future.
authors.affiliation: Zhongshan Opthalmic Center, Sun Yat-sen University of Medical Sciences, Guangzhou, China.
authors.forename: J
authors.initials: J
authors.lastname: Xu
authors.forename: Q
authors.initials: Q
authors.lastname: Yu
authors.forename: S
authors.initials: S
authors.lastname: Zhu
authors.forename: Q
authors.initials: Q
authors.lastname: Liu
mesh_terms: D000368:Aged; D002386:Cataract / Q000453:epidemiology*; D002681:China / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D011897:Random Allocation; D012737:Sex Factors