Prevalence and risk factors of refractive error: a cross-sectional Study in Han and Yi adults in Yunnan, China

Few studies have investigated the prevalence of refractive error (RE) in older adults in China, and most have focused on East China. Our study determined the prevalence and risk factors of RE in Han and Yi adults aged 40-80 years in rural and urban areas in Yunnan Province, Southwest China.

Our cross-sectional study is part of the China National Health Survey (CNHS). The age-adjusted prevalence rates of RE in Han and Yi adults aged 40-80 years in Yunnan were compared. We used a multivariate logistic regression model to identify risk factors for myopia and hyperopia.

Among 1626 participants, the age-adjusted prevalence rates of myopia, hyperopia, high myopia and astigmatism were 26.35% (95%CI 24.01-28.70%), 19.89% (95%CI 18.16-21.61%), 2.64% (95%CI 1.75-3.53%), and 56.82% (95%CI 54.31-59.34%). Compared to the Yi population, the Han population had higher prevalence of myopia (31.50% vs 16.80%, p < 0.0001), high myopia (3.34% vs 1.31%, p = 0.049) and astigmatism (60.07% vs 50.67%, p = 0.026) but lower prevalence of hyperopia (16.58% vs 27.37%, p < 0.0001). In the multivariate logistic regression, individuals aged 45-49 (p < 0.001), 50-54 (p < 0.001), 55-59 (p = 0.014), and 60-64 years (p = 0.005) had a lower myopia risk than those aged 40-44 years, and individuals aged 50-54 (p = 0.002), 55-59, 60-64 and 65 years and older (all p < 0.001) had a higher hyperopia risk than those aged 40-44 years. Myopia was also associated with height (p = 0.035), time spent in rural areas (p = 0.014), undergraduate/graduate education level (p = 0.001, compared with primary school or lower education level) and diabetes (p = 0.008). The Yi population had a higher risk of hyperopia than the Han population (p = 0.025). Moreover, hyperopia was related to time spent in rural areas (p < 0.001) and pterygium (p = 0.019).

Our study investigated the overall prevalence of RE in older adults in rural and urban areas of Southwest China. Compared to the Yi population, the Han population had a higher prevalence of myopia, high myopia and astigmatism but a lower risk of hyperopia. The prevalence of myopia in the Han population in underdeveloped Southwest China was similar to that of residents in East China or of Chinese Singaporeans under urban or rural settings.