Risk Factors for High Myopia in Koreans: The Korea National Health and Nutrition Examination Survey

To investigate risk factors for high myopia in the general Korean population.In this nationwide population study, the dataset of the Korea National Health and Nutrition Examination Survey 2008-2012 was analyzed. The study cohort included 11 703 participants, aged 25-49 years, who underwent neither refractive nor cataract surgery. The association between demographic, socioeconomic, behavioral, and systemic variables and high myopia was investigated.The mean participant age was 37.9 ± 6.8 years, and the prevalence of high myopia ≤-6.0D was 7.0 ± 0.3% in the study population. The right eyes (-1.76 ± 0.03 D) were more myopic than the left eyes (-1.70 ± 0.03 D; P < 0.001). In multivariate logistic regression analysis, high myopia was associated with age (odds ratio [OR], 0.97 per 1 year-increase) and female sex (OR, 1.24). Other identified risk factors included education level ≥ university graduation (OR, 1.91), the presence of hypertension (OR, 1.69), and serum glucose level (OR, 1.01 per 1 mg/dL). Sunlight exposure of ≥5 h/day (OR, 0.67) and serum 25-hydroxyvitamin D level (OR, 0.97 per 1 ng/mL) showed protective effect against high myopia.High myopia is associated with younger age, female sex, high education level, longer sunlight exposure, and some other systemic conditions.