Objective: To describe the prevalence of visual impairment/blindness among older adults aged > or = 50 years in rural populations in Shandong Province, China.
Methods: Population-based, cross-sectional study was designed in this survey. Three counties and one suburbs representative of the different levels of socioeconomic development were selected as the study areas within the province from April to July 2008. Geographically defined cluster sampling was used in randomly selecting a cross-section of residents aged > or = 50 years from each county. Eligible persons were invited to local examination sites for visual acuity (VA) testing and eye examination. Those presenting with VA < or = 0.5 in either eye were refracted to achieve best-corrected VA. Chi2-test was used to compare the prevalence of blindness and visual impairment in the different groups. Multiple logistic regressions were used to investigate the association of age, gender, education, and county with presenting and best-corrected visual impairment and blindness. Adjusted odds ratio was used to compare the prevalence of blindness and visual impairment in the different counties.
Results: Of 19 583 enumerated eligible persons, 17 816 (90.98%) were examined and tested for VA. The prevalence of presenting visual impairment (0.05- < 0.3) in the better-seeing eye was 7.01% (the age-standardized rate was 6.56%) and presenting blindness (< 0.05) was 1.58% (the age-standardized rate was 1.48%). Across the 4 counties, presenting visual impairment ranged from 4.51% to 8.65%, and presenting blindness from 1.35% to 1.77%. With best-corrected VA, the prevalence of visual impairment was 3.66% (the age-standardized rate was 3.38%), and 1.33% for blindness (the age-standardized rate was 1.24%). The ranges across the 4 counties were 2.63% to 4.38% for visual impairment and 1.06%-1.54% for blindness. The prevalence of visual impairment with presenting VA was higher than that with best-corrected VA (2 = 201.262, P = 0.000). There was no significant difference between the prevalence of blindness with presenting VA and that with best-corrected VA (Chi2 = 0.117, P = 0.732). Based on both presenting and best-corrected VA, visual impairment and blindness were associated with older age, female gender, lack of education, and county (P < or = 0.05).
Conclusions: Visual impairment and blindness are important public health problems in rural older adults aged > or = 50 years in Shandong Province. Un-corrected refractive error is one of the main causes of visual impairment.