Association between age at menarche and risk of myopia in the United States: NHANES 1999-2008.

We evaluate the effect of menarche on myopia in women in the United States (US). A cross-sectional survey and examination were conducted using data from the 1999-2008 US National Health and Nutrition Examination Survey (NHANES), and 8,706 women aged ≥20 years (95% confidence interval [CI], 44.23 to 45.37) were enrolled. Characteristics were compared between nonmyopic and myopic participants. Univariable and multivariable logistic regression analysis was performed to evaluate the risk factors for myopia. A minimum p-value approach was used to estimate the cut-off point for age at menarche. The prevalence of myopia was 32.96%. Mean spherical equivalent (SE) were -0.81 diopters (95% CI, -0.89 to -0.73) and the mean age of menarche was 12.67 years (95% CI, 12.62 to 12.72). In the crude logistic regression model, age (odd ratio [OR] 0.98), height (OR, 1.02), astigmatism (OR, 1.57) (all p < 0.0001), age at menarche (OR, 0.95; p = 0.0005), white ethnicity, being born in the US, higher level of education, and higher annual household income (all p trend <0.0001) were significantly associated with myopia. 1-year increments in age at menarche was associated with a 4% decrease in the risk of myopia after adjusting for age, height, body mass index (BMI), ethnicity, and astigmatism (OR, 0.96; 95% CI, 0.93 to 0.99, p = 0.0288). The cut-off value for age at menarche was 15 years by the maximum chi-square test (p < 0.0001). Age at menarche may attribute to myopia progression, along with other environmental and individual risk factors.