The Prevalence and Causes of Visual Impairment in an Elderly Chinese Bai Ethnic Rural Population: The Yunnan Minority Eye Study

PURPOSE. To assess the prevalence and causes of visual impairment in the elderly Bai ethnic group in rural China. METHODS. Random cluster sampling was used to identify the Bai ethnic group 50 years and older living in the Dali county of Yunnan, China. Presenting visual acuity (PVA) and best-corrected visual acuity (BCVA) were measured using the Early Treatment Diabetic Retinopathy Study visual chart. Blindness and low vision were defined according to World Health Organization criteria. The major cause of visual impairment was identified for all participants who were visually impaired. RESULTS. Of the 2742 eligible individuals, 2133 (77.8%) participated in the study, and 2115 (77.1%) had visual acuity data available. With the PVA, the prevalence of blindness and low vision was 3.59% and 15.22%, respectively. When the BCVA was used, these rates were reduced to 2.88% and 7.75%. Blindness and low vision were associated with older age and lack of education, but no sex difference was seen. Based on the BCVA, the predominant causes of blindness were cataract (70.5%), corneal opacity (8.2%), and glaucoma (6.6%). The majority of PVA-defined low vision cases were attributable to cataract (53.0%) and uncorrected refractive error (22.0%). CONCLUSIONS. A higher rate of visual impairment was seen in this Bai nationality sample than has been reported from the Han nationality population in rural China. Since potentially treatable eye disease, cataract, and uncorrected refractive error were the most important causes of visual impairment in this population, affordable provision of surgery and low-vision rehabilitation programs would help to address this problem. (Invest Ophthalmol Vis Sci. 2012;53:4498-4504) DOI:10.1167/iovs.12-9429