Dissecting the complex sex-based associations of myopia with height and weight.

objectivesTo assess height and weight as possible sex-specific risk factors for bilateral myopia among young adults.

methodsWe conducted a cross-sectional study including 101,438 pre-enlisted young adult males and females, aged 17.4 ± 0.6 and 17.3 ± 0.5 years, respectively, and born during 1971-1994. Categories of BMI (body mass index) were defined according to sex-related percentiles for 17-year-olds following U.S. Centers for Disease Control and Prevention growth charts, and subjects were divided into five height and weight categories according to sex-adjusted percentiles. Data included best-corrected visual acuity, diverse socio-demographic variables, anthropometric indices, and refractive errors, namely bilateral myopes and emmetropes.

resultsThe prevalence of bilateral myopia in males and females was 19.1% and 26.0%, respectively. Bilateral myopia displayed a J-shaped associated with BMI, achieving statistical significance only among males (p < 0.0001). Weight displayed a U-shaped association with bilateral myopia among both young males (p < 0.0001) and females (p < 0.005). A higher prevalence of bilateral myopia was observed only among males of the lower height category (p < 0.0001), even when controlling for BMI (from normal to obesity). In a multivariable regression model, obesity was associated with higher prevalence of bilateral myopia (OR: 1.21; 95% CI: 1.07-1.38, p = 0.002), only among males. There were no interactions of BMI with height or weight. Bilateral myopia was also associated with prehypertension among males (OR: 1.10, 95% CI: 1.04-1.15, p < 0.001).

conclusionsA higher risk for bilateral myopia was associated with either BMI solely or height and weight, as well as pre-hypertension, in males. The possible association with low height requires further research.