Purpose  To estimate the prevalence of pterygium and investigate its risk factors in a population aging 50 years and older of Shanghai, China.
Methods  A sample of 4186 subjects were randomly selected with a stratifying and clustering method, from a downtown community called Sanle and a suburb village named Dangtian in Shanghai. A detailed interview and a comprehensive ophthalmic examination were conducted by experienced ophthalmologists at local clinical sites. Outcome measures were total and stratified prevalence rates, risk factors analysis, and correlation evaluation between rates and latitudes.
Results  Total participation rate was 78.52% (3287 of 4186 attended), being 87.30% (1781 of 2040) in urban population and 70.17% (1506 of 2146) in rural area respectively. 404 (12.30%; 95% confidence interval [CI], 11.20% to 13.47%) subjects were diagnosed as unilateral pterygium, while 155 (38.37%; 95%CI, 33.60% to 43.30%) were bilaterally involved. Within northern hemisphere, the rates were negatively correlated with the latitude degrees by bivariate correlation analysis (Correlation Coefficient, -0.943; p=0.005). The stepwise logistic regression model showed that, rural residence (p=0.004; odds ratio [OR], 2.661; 95%CI, 1.365 to 5.189), increasing age (p=0.017), and lower education (p<0.05) remained independent risk factors for pterygium formation.
Conclusion  In Shanghai, pterygium was a common disease in suburbs and less common in downtown area. More emphases should be placed upon preventive strategies and ocular health education for rural residents.