Independent Influence of Parental Myopia on Childhood Myopia in a Dose-Related Manner in 2,055 Trios: The Hong Kong Children Eye Study

To determine the effects on childhood myopia of parental myopia, parental education, children's outdoor time, and children's near work. Population-based cross-sectional study. A total of 6,155 subjects in 2,055 family trios (1 child and both parents). Cycloplegic autorefraction was measured for children and noncycloplegic autorefraction for parents. Parental education, children's outdoor time, and near work were collected by questionnaires. Children were categorized into 10 groups based on parental myopia levels. Associations of the above factors with myopia were evaluated by regression analyses. The areas under the receiver operating characteristic curve (AUROCs) for myopia were evaluated. Mild parental myopia did not increase childhood myopia's risk, but the risk was 11.22-folds when both parents were highly myopic. Higher parental education (Father: OR 1.08, P  =.046; Mother: OR 1.11, P  =.001) and more reading time of children were risk factors (OR 1.21, P  =.044). Reduced odds of myopia were associated with more time spent on outdoor activities (OR 0.78, P  =.017). Notably, all these factors became insignificant after adjustment, except for parental myopia. Children with more severe parental myopia spent more time on reading, but less on electronic devices. Parental myopic status alone accounted for 11.82% of myopia variation in children. With age and parental myopia, the AUROC for myopia was 0.731. Among parental and environmental factors, parental myopia confers, in a dose-related manner, the strongest independent effect on childhood myopia. Therefore children with high risk of myopia can be identified for early prevention, based on parental myopia data.