Prevalence and risk factors for refractive error in older adults in eight ethnicities in China: The China national health survey

PurposeThis study aimed to investigate the prevalence of refractive error (RE) and risk factors for myopia among older adults in the Han and various minority ethnic groups across seven provinces in China.MethodsThis cross-sectional study forms a part of the ophthalmic dataset of the China National Health Survey (CNHS). Face-to-face interviews and ophthalmic examinations were conducted in seven provinces located in western and northern China. The age- and sex-adjusted prevalence of RE among Han and seven other ethnic groups aged 50–80 years were compared. A mixed-effects model was used to identify the risk factors associated with RE.ResultsA total of 12,902 participants, including 8800 Han and 4102 from ethnic minorities, were included in the study. The age- and sex-adjusted prevalence of myopia, high myopia, hyperopia, and astigmatism ranged from 15.3 % (Manchu) to 22.9 % (Han), 0.2 % (Yugur) to 2.8 % (Han), 21.6 % (Tibetan) to 48.9 % (Uyghur), and 38.7 % (Yi) to 57.5 % (Manchu) across different ethnicities, respectively. Compared to the Han population, the Mongolian (odds ratios (OR) 0.62, 95 % confidence interval (CI) 0.46–0.84, p = 0.002), Tibetan (OR 0.66, 95 % CI 0.52–0.85, p = 0.001), Uyghur (OR 0.63, 95 % CI 0.49–0.80, p < 0.001), Yi (OR 0.65, 95 % CI 0.46–0.92, p = 0.014), and Yugur (OR 0.65, 95 % CI 0.50–0.85, p = 0.001) ethnicities were less likely to have myopia. There was no significant difference in the prevalence of myopia between the Manchu, Korean, and Han ethnic groups. Factors associated with a lower prevalence of myopia included rural residence (p < 0.001), a body mass index (BMI) > 18.5 kg/m2 (all p < 0.001), residence in higher latitude areas (p = 0.020), and a history of smoking (p = 0.002 in the past smoking group, p = 0.031 in the current smoking group). The Mongolian (p = 0.006) and Yugur (p = 0.007) populations, participants living in rural areas (p = 0.012), and those with a BMI >24 kg/m2 (p = 0.038 in the >24.0 ≤ 27.0 kg/m2 group or p = 0.041 in the >27.0 kg/m2 group) were less likely to have high myopia. Factors associated with a higher prevalence of hyperopia included older age (all p < 0.001), rural residence (p = 0.039), higher latitude areas (p = 0.031), smoking history (p = 0.040), and Mongolian (p = 0.001), Uyghur (p < 0.001), Yi (p < 0.001), and Yugur (p = 0.002) ethnicities. Conversely, the Manchu population (p = 0.004) and individuals with higher education levels than illiteracy (p = 0.024 or p < 0.001) were less likely to have hyperopia.ConclusionsMyopia affected more than one-fifth of the older adults in the Han population in this survey. Significant differences in the prevalence of RE were observed between minority ethnicities and Han individuals, except for the Manchu and Korean groups.