Myopia Is Associated With Lower Vitamin D Status in Young Adults

PURPOSE. To investigate the association between serum vitamin D levels and myopia in young adults. METHODS. A total of 946 individuals participating in the 20-year follow-up of the Western Australian Pregnancy Cohort (Raine) Study were included in this study. Ethnicity, parental myopia, and education status were ascertained by self-reported questionnaire. A comprehensive ophthalmic examination was performed, including postcycloplegic autorefraction and conjunctival UVautofluorescence photography. Serum 25-hydroxyvitamin D-3 (25(OH)D-3) concentrations were determined using mass spectrometry. The association between serum 25(OH)D-3 concentrations and prevalent myopia was determined using multivariable logistic regression. Myopia was defined as mean spherical equivalent <= -0.5 diopters. RESULTS. Of the 946 participants, 221 (23.4%) had myopia (n = 725 nonmyopic). Myopic subjects had lower serum 25(OH)D-3 concentrations compared to nonmyopic participants (median 67.6 vs. 72.5 nmol, P = 0.003). In univariable analysis, lower serum 25(OH)D-3 concentration was associated with higher risk of having myopia (odds ratio [OR] for <50 vs. >= 50 nmol/L: 2.63; confidence interval [95% CI] 1.71-4.05; P < 0.001). This association persisted after adjustment for potential confounders, including age, sex, ethnicity, parental myopia, education status, and ocular sun-exposure biomarker score (adjusted OR 2.07; 95% CI 1.29-3.32; P = 0.002). CONCLUSIONS. Myopic participants had significantly lower 25(OH)D-3 concentrations. The prevalence of myopia was significantly higher in individuals with vitamin D deficiency compared to the individuals with sufficient levels. Longitudinal studies are warranted to investigate whether higher serum 25(OH)D-3 concentration is protective against myopia or whether it is acting as a proxy for some other biologically effective consequence of sun exposure.