Prevalence and risk factors of myopia in Han and Yugur older adults in Gansu, China：a cross-sectional study

Background Few studies have investigated the prevalence of myopia in Northwest China. This study aimed to investigate the prevalence and risk factors of myopia and high myopia in adults aged 40-80 years in Han and Yugur ethnicities living in Gansu Province, Northwest China. Methods The cross-section study is part of the China National Health Survey (CNHS), which was conducted in 2016, Gansu Province. We compared the age- and sex-standardized prevalence of myopia, high myopia and hyperopia in Han and Yugur participants. Risk factors for myopia and high myopia were identified using multivariable logistic regression models. Results 3845 participants were included. The overall adjusted prevalence of myopia (spherical equivalent (SE)<-0.5 D), high myopia (SE<-6.0D) and hyperopia (SE>+0.5D) were 16.4%, 0.7% and 26.2% in Yugur, and 34.3%, 5.0% and 19.2% in Han. In the multivariable logistic regression model, Han ethnicity (Odds Ratio(OR),0.56; 95% confidence interval (CI): 0.45-0.69), P<0.001), birth in rural areas (OR,0.69; 95%CI: 0.56-0.85, P<0.001), higher education level (OR,1.48; 95%CI:1.18-1.85, P=0.001for middle/high school group and OR, 3.62; 95%CI:2.73-4.82, P<0.001 for Undergraduate/graduate group), indoor work (OR, 0.64; 95%CI: 0.51-0.80, P<0.001), smoking history (OR, 0.69; 95%CI: 0.52-0.90, P=0.007) and a family history of myopia (OR,2.83; 95%CI: 1.22-6.51, P=0.015 for one patient) were found to be associated with myopia. The risk factors of high myopia included Han ethnicity (OR, 0.33; 95%CI: 0.15-0.73, P=0.006), 50-59 age group (OR, 0.65; 95%CI:0.43-1.0, P=0.049), 60-69 age group (OR,0.49; 95%CI: 0.25-0.97, P=0.039), birth in rural area (OR, 0.61; 95%CI: 0.40-0.94, P=0.025) and a family history of myopia (OR, 4.32; 95%CI: 1.74-10.7, P=0.002 for one patient; OR, 22.3; 95%CI: 2.41-206.1, P=0.006 for both patients). Conclusion The prevalence of myopia and high myopia in Han adults aged 40-80 was significantly higher than that in Yugur. The risk factors of myopia included Han ethnicity, birth in rural area, higher education level, indoor work and a family history of myopia. This study provided valuable information on risk factors of myopia and revealed an ethnic disparity on the susceptibility of myopia, which would be useful in identifying high-risk population and initiating more targeted strategies preventing myopia in China.