title: Five-year incidence of visual impairment and blindness in adult Chinese the Beijing Eye Study.
abstract: OBJECTIVE
  To describe the cumulative 5-year incidence of visual impairment and blindness in adult Chinese in greater Beijing.
  
  
  METHODS
  Population-based study.
  
  
  METHODS
  The Beijing Eye Study 2006 included 3251 subjects who had participated in the Beijing Eye Study 2001 and returned for re-examination.
  
  
  METHODS
  Using the World Health Organization (WHO) definition, low vision and blindness were defined as best corrected visual acutiy (BCVA) <20/60 to 20/400 and as BCVA <20/400 in the better-seeing eye, respectively. Using the United States standard, low vision and blindness were defined as BCVA <20/40 to 20/200 and as BCVA <20/200 in the better-seeing eye, respectively.
  
  
  METHODS
  Incidence of low vision and blindness.
  
  
  RESULTS
  Visual acuity measurements were available for 3249 (99.9%) participants. Using WHO and United States definitions, the incidences of low vision and blindness were 0.5 ± 0.1% (mean ± standard error) and 0.1 ± 0.04%, and 1.1 ± 0.2% and 0.1 ± 0.04%, respectively. In multivariate analysis, incidence of BCVA visual impairment or blindness increased significantly with greater age (P = 0.01), but was not associated with gender, region, or level of education. Causes of BCVA visual impairment or blindness were cataract (39%), glaucoma (17%), and degenerative myopia (11%). Using the WHO and the United States criteria, incidences of low vision and blindness based on presenting visual acuity, were 1.7 ± 0.2% and 0.1 ± 0.06%, and 3.8 ± 0.3% and 0.2 ± 0.08%, respectively. Incidence of visual impairment or blindness (presenting visual acuity, WHO definition) increased significantly with higher age (P < 0.001) and less education (P = 0.018) and was greater in women (P = 0.015). The major cause of presenting VA visual impairment or blindness was undercorrected refractive error (76%).
  
  
  CONCLUSIONS
  In adult Chinese in greater Beijing, the 5-year cumulative incidence of BCVA visual impairment or blindness was 0.6 ± 0.1% (BCVA in better-seeing eye, <20/60) or 1.7 ± 0.2% (presenting VA in better-seeing eye, <20/60), which increased significantly with age. Measured as presenting VA, this also was associated with female gender and rural region. The major cause (76%) of decreased presenting VA was undercorrected refractive error, followed by cataract. Treating undercorrection of refractive error may be the easiest and most efficient method to improve vision in this community.
  
  
  BACKGROUND
  Proprietary or commercial disclosure may be found after the references.
authors.affiliation: Beijing Institute of Ophthalmology, Beijing Tongren Hospital, Capital Medical University, Beijing, China.
authors.forename: Qi Sheng
authors.initials: QS
authors.lastname: You
authors.forename: Liang
authors.initials: L
authors.lastname: Xu
authors.forename: Hua
authors.initials: H
authors.lastname: Yang
authors.forename: Ya Xing
authors.initials: YX
authors.lastname: Wang
authors.forename: Jost B
authors.initials: JB
authors.lastname: Jonas
mesh_terms: D000328:Adult; D017677:Age Distribution; D000368:Aged; D000369:Aged, 80 and over; D001766:Blindness / Q000453:epidemiology*; D002681:China / Q000453:epidemiology; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D015994:Incidence; D008875:Middle Aged; D012189:Retrospective Studies; D013997:Time Factors; D014505:Urban Population; D015354:Vision, Low / Q000453:epidemiology*; D014792:Visual Acuity