Prevalence and risk factors of myopia in adult Korean population: Korea national health and nutrition examination survey 2013-2014 (KNHANES VI)

Purpose To evaluate the prevalence and risk factors of myopia in adult Korean population. Methods Population-based cross-sectional data of 3,398 subjects aged 19 to 49 years was obtained using the Korea National Health and Nutrition Examination Survey 2013-2014 (KNHANES VI). Data, including refractive errors and potential risk factors were analyzed. The prevalence and risk factors of myopia, low myopia, and high myopia-defined as a spherical equivalent (SEQ) <= -0.5 diopters (D), -6.0 D < SEQ <-0.5 D, and SEQ <= -6.0 D, respectively-were evaluated. Results The prevalence of myopia and high myopia were 70.6 (standard error (SE), +/- 1.1)% and 8.0 (SE, +/- 0.6)%, respectively. In multivariable analysis, younger age, higher education (>= 12 years), parental myopia, lower serum 25-hydroxyvitamin D (25(OH)D) concentration (< 9 ng/mL), longer time spent on near work (>= 3 hours/day), and higher white blood cell (WBC) count (5-8.9 x 10(3)) were associated with increased prevalence of both myopia and high myopia. Serum 25(OH)D concentration of >= 9 ng/ml was significantly associated with decreased prevalence of high myopia in participants with near work of >= 3 hours/day, although the effect was not significant in myopia and low myopia. Conclusions The prevalence of myopia and high myopia in Korean adults was substantially high, which increased with decreasing age. In addition to parental myopia, the serum 25(OH)D concentration, near work and inflammation reflected by WBC counts may be associated with myopia.