Purpose To describe the cumulative 5 year incidence of visual impairment and blindness in adult Chinese in Greater Beijing.

Methods The Beijing Eye Study was a population-based cohort study. All participants underwent a comprehensive eye examination, including standard automatic and subjective refraction. Presenting visual acuity (PRVA) and best corrected visual acuity (BCVA) of each eye were recorded. Using the World Health Organization (WHO) definition, low vision and blindness were defined as 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.
Results Visual acuity measurements were available on 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/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/blindness were cataract (39%), glaucoma (17%) and degenerative myopia (11%).  Using the WHO and the United States definitions, incidences of PRVA-low vision and BCVA-blindness were 1.7±0.2% and 0.1±0.06%, and 3.8±0.3% and 0.2±0.08%, respectively.  Incidence of PRVA-visual impairment/blindness (WHO definition) increased significantly with greater age (P<0.001) and less education (P=0.018), and was greater in women (P=0.015).  Major Cause of PRVA-visual impairment/blindness was undercorrected refractive error (76%).
Conclusions In adult Chinese in Greater Beijing, the 5-year cumulative incidence of visual impairment/blindness was 0.6±0.1% (BCVA in better-seeing eye <20/60) or 1.7±0.2% (PRVA in better-seeing eye <20/60), which increased significantly with age.  Measured as presenting visual acuity, this was associated also with female gender and rural region.  The major cause (76%) of decreased presenting visual acuity 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.