Prevalence survey of cataract among adults aged 40 or above in a multiethnic rural district in the high altitude area of Yunnan province

Abstract

Objective To estimate the prevalence of cataract and cataract blindness among adults aged 40 or above in Gongshan county of Yunnan Province. Methods Cluster sampling was used in randomly selected individuals in 4 sub-districts of Gongshan County.The protocol consisted of questionnaire,visual acuity testing and ocular clinical examination.Cataract was graded clinically using the Lens Opacity Classification System (LOCS) Ⅲ system. Results Among 1236 eligible residents,1116(90.29％) were finally enrolled in the present study.The prevalence of cataract was 23.84％ among adults aged 40 or above.The prevalence of cataract in individuals aged 70 or above and illiteracy was significantly higher statistically.When the bilateral best refractive vision ＜3/60 was defined as the blindness criterion,the prevalence of cataract blindness was 1.25％.When the bilateral presenting vision ＜6/60 was defined as the blindness criterion,the prevalence of cataract blindness was 3.58％.The prevalence of blindness were much higher in woman,illiterates,higher altitude and persons aged 70 or above. Conclusions The prevalence of cataract and cataract blindness is higher,and cataract blindness is a serious public health problem in aged individuals and illiteracy in Gongshan County. Key words: Cataract; Prevalence; Blindness