Supplementary Material for: Recalled age of myopia onset may predict risk of high adult myopia in Chinese adults

Introduction: This study aimed to investigate the relationship between age of myopia onset and high myopia and to explore if age of onset mediated the associations of high myopia with parental myopia and time spent on electronics.
Methods: This cross-sectional study enrolled 1118 myopic patients aged 18 to 40. Information was obtained via a detailed questionnaire. Multivariable logistic regression and linear regression models were utilized to assess age of onset in relation to high myopia and spherical equivalent refractive error, respectively. Structural equation models examined the mediated effect of onset age on the association between parental myopia, time spent on electronics and high myopia.
Results: An early age at myopia onset was negatively correlated with spherical equivalent refractive power. Subjects who developed myopia before the age of 12 were more likely to suffer from high myopia than those who developed myopia after the age of 15. Age of myopia onset was the strongest predictor of high myopia, with an area under the curve (AUC) in Receiver Operator Characteristic (ROC) analysis of 0.80. Additionally, age of myopia onset served as a mediator in the relationships between parental myopia, electronic device usage duration, and the onset of high myopia in adulthood.
Conclusions: Age of myopia onset might be the single best predictor for high myopia, and age at onset appeared to mediate the associations of high myopia with parental myopia and time spent on electronics.