title: Causes and five-year incidence of blindness and visual impairment in urban Southern China: the Liwan Eye Study.
abstract: OBJECTIVE
  We determined the causes and five-year incidence of blindness and visual impairment (VI) in an adult, urban Chinese population.
  
  
  METHODS
  Participants underwent a comprehensive eye examination at baseline in 2003 and then five years later. The World Health Organization (WHO) and United States (US) definitions were used to define incident blindness (WHO visual acuity [VA] < 20/400 in the better-seeing eye, US VA ≤ 20/200) and incident VI (WHO VA < 20/60-20/400, US VA < 20/40->20/200).
  
  
  RESULTS
  Among 1405 baseline participants, 924 (75%) of 1232 survivors (87.7%) participated in the 5-year follow-up. The incidences of VI and blindness were 5.38% (95% confidence interval [CI] 3.99% ∼ 7.07%) and 0.33% (95% CI 0.07% ∼ 0.95%), respectively, based on the WHO definition, and 9.85% (95% CI 7.96% ∼ 12.0%) and 1.42% (95% CI 0.76% ∼ 2.41%), respectively, based on the US definition. Incidence of blindness and VI (WHO definition) increased significantly with older age (P < 0.001) and poorer baseline presenting VA in the worse-seeing eye (P < 0.001). The leading cause of best-corrected VI (WHO definition) was cataract (64.6%), whereas the main causes of presenting VI were refractive error (40.4%) and cataract (38.4%).
  
  
  CONCLUSIONS
  The incidence of VI in urban Southern China is high. The major causes are unoperated cataract and undercorrected refractive error, reflecting the need for better surgical and refractive care, even in this urban setting.
authors.affiliation: State Key Laboratory of Ophthalmology, Zhongshan Ophthalmic Center, Sun Yat-sen University, Guangzhou, China.
authors.forename: Lanhua
authors.initials: L
authors.lastname: Wang
authors.forename: Wenyong
authors.initials: W
authors.lastname: Huang
authors.forename: Miao
authors.initials: M
authors.lastname: He
authors.forename: Yingfeng
authors.initials: Y
authors.lastname: Zheng
authors.forename: Shengsong
authors.initials: S
authors.lastname: Huang
authors.forename: Bin
authors.initials: B
authors.lastname: Liu
authors.forename: Ling
authors.initials: L
authors.lastname: Jin
authors.forename: Nathan G
authors.initials: NG
authors.lastname: Congdon
authors.forename: Mingguang
authors.initials: M
authors.lastname: He
mesh_terms: D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D001766:Blindness / Q000453:epidemiology / Q000209:etiology; D002386:Cataract / Q000150:complications; D002681:China / Q000453:epidemiology; D016001:Confidence Intervals; D005260:Female; D006801:Humans; D015994:Incidence; D016015:Logistic Models; D008297:Male; D008875:Middle Aged; D012030:Refractive Errors / Q000150:complications; D014505:Urban Population / Q000706:statistics & numerical data; D014786:Vision Disorders / Q000453:epidemiology* / Q000209:etiology
keywords: China; causes; incidence; urban; visual impairment and blindness