title: Prevalence and associations of cataract in a rural Chinese adult population: the Handan Eye Study.
abstract: BACKGROUND
  Cataract remains the leading cause of blindness and visual impairment in the world and in China. However, data on the prevalence of cataract based on standardized lens grading protocols from mainland China are limited. This paper estimated the age- and gender-specific prevalence and risk factor for cataract
  
  
  METHODS
  In a population-based Chinese sample, participants underwent a comprehensive ophthalmic examination, including assessment of cortical, nuclear, posterior subcapsular (PSC) and mixed lens opacities from slit-lamp grading using the Lens Opacities Classification System III.
  
  
  RESULTS
  Of the 7,557 eligible subjects, 6,830 took part in the study (90.4% response rate), and 6,544 participants (95.8%, mean age 52.0 ± 11.8 years) had lens data for analyses. The prevalence of any cataract surgery in at least one eye was 0.8% (95% confidence interval [CI], 0.62, 1.06), with similar rates between men and women. The overall prevalence of any cataract or cataract surgery was 20.8% (95% CI, 19.8, 21.8), higher in women than in men after adjusting for age (23.6% vs 17.6%; OR: 1.78; 95% CI: 1.54-2.07). When distinct lens opacity was categorized in each eye as cortical, nuclear, PSC or mixed, based on one randomly selected eye, cortical cataract was the most common distinct subtype (12.3%), followed by mixed (3.2%), nuclear (1.7%), and PSC (0.2%) cataract. The prevalence of all lens opacities increased with age (P < 0.001). After excluding other causes for visual impairment, the proportion of people with best corrected visual acuity <20/60 was 21% among those with PSC, and 12% among those with mixed opacities in the better-seeing eye. In multivariable logistic regression models, myopia was associated with all cataract types, while higher fasting plasma glucose and diabetes were only associated with PSC cataract.
  
  
  CONCLUSIONS
  Cataract affects 20% of the population aged 30 years and older living in rural China, with cortical cataract the most common subtype. Risk factors for cataract include myopia and diabetes.
authors.affiliation: Beijing Tongren Eye Center, Beijing Tongren Hospital, Beijing Ophthalmology & Visual Sciences Key Lab, Capital Medical University, No. 1 Dongjiao Min Xiang, Dongcheng District, Beijing 100730, China.
authors.forename: Xin Rong
authors.initials: XR
authors.lastname: Duan
authors.forename: Yuan Bo
authors.initials: YB
authors.lastname: Liang
authors.forename: Ning Li
authors.initials: NL
authors.lastname: Wang
authors.forename: Tien Yin
authors.initials: TY
authors.lastname: Wong
authors.forename: Lan Ping
authors.initials: LP
authors.lastname: Sun
authors.forename: Xiao Hui
authors.initials: XH
authors.lastname: Yang
authors.forename: Qiu Shan
authors.initials: QS
authors.lastname: Tao
authors.forename: Rui Zhi
authors.initials: RZ
authors.lastname: Yuan
authors.forename: David S
authors.initials: DS
authors.lastname: Friedman
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D044466:Asian People / Q000208:ethnology*; D002386:Cataract / Q000145:classification / Q000208:ethnology*; D002387:Cataract Extraction / Q000706:statistics & numerical data*; D002681:China / Q000453:epidemiology; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D015995:Prevalence; D012307:Risk Factors; D012424:Rural Population / Q000706:statistics & numerical data*; D017678:Sex Distribution