Objective To analyze visual impairment before and after refraction in a population of Dachang county,Baoshan,Shanghai aged 60 years and older.Methods Epidemiologieal survey.Cluster sampling was used to select samples.The participants underwent a detailed ophthalmic and medical examination,including slit lamp,the presenting visual acuity testing,subjective refraction and standardized questionnaire.The definitions of blindness and visual impairment which were based on the presenting VA in the better eye were defined by criteria of WHO.The population characteristics of correctable visual impairment were also determined.Results Among the 5199 people entered in the project,4545 were examined (response rate,87.42％).The prevalence of blindness and visual impairment was 0.86％ and 8.84％,respectively.After refraction,The prevalence was 0.66％ and 3.01％,respectively.The prevalence of correctable visual impairment was 5.81％(264/4545),older age and female gender were important risk factors of correctable visual impairment.The leading cause of correctable visual impairment was cataract (45.83％),followed by refractive error (43.18％),macular degeneration (7.95％),diabetic retinoPathy (1.52％),glaucoma (1.14％) and corneal opacity (0.38％).Spectacle coverage was 44.12％,man was higher than woman.The prevalence of spectacle coverage was declining with the increasing of age.Conclusion Uncorrected refractive error was an important cause of visual impairment in older persons.The use of refractive correction is the necessary step to diagnose blindness and visual impairment.