Myopia and BMI: a nationwide study of 1.3 million adolescents

Abstract Objective This study analyzed the association between adolescent BMI and myopia severity. Methods This cross‐sectional study comprised 1,359,153 adolescents who were medically examined before mandatory military service. Mild‐to‐moderate and high myopia were defined based on right‐eye refractive data. BMI was categorized based on the US age‐ and sex‐matched percentiles. Logistic regression models were applied separately for women and men to estimate odds ratios (ORs) for myopia per BMI category. Results A total of 318,712 adolescents had mild‐to‐moderate myopia and 23,569 had high myopia. Compared with low‐normal BMI (reference group), adjusted ORs for mild‐to‐moderate and high myopia increased with increasing BMI status, reaching 1.39 (95% CI: 1.23‐1.57) and 1.73 (95% CI: 1.19‐2.51) for men with severe obesity, respectively, and 1.19 (95% CI: 1.12‐1.27) and 1.38 (95% CI: 1.14‐1.65) for women with mild obesity, respectively. ORs for mild‐to‐moderate and high myopia were also higher in men with underweight (OR = 1.20; 95% CI: 1.18‐1.23 and OR = 1.39; 95% CI: 1.30‐1.47) and women with underweight (OR = 1.06; 95% CI: 1.03‐1.09 and OR = 1.12; 95% CI: 1.04‐1.22). The overall size effect was greater for men than women ( p interaction < 0.001), in whom the group with severe obesity did not reach statistical significance. Conclusions BMI was associated with myopia in a J‐shaped pattern, with the size effect being greater for adolescent men than women. This study indicates that both low BMI and high BMI are associated with mild‐to‐moderate and severe myopia.