Parental history of myopia, sports and outdoor activities, and future myopia.

Purpose: To identify whether parental history of myopia and/or parent-reported children's visual activity levels can predict juvenile-onset myopia.

Methods: Survey-based data from Orinda Longitudinal Study of Myopia subjects from 1989 to 2001 were used to predict future myopia. Univariate and multiple logistic regression analyses were performed, and receiver operator characteristic (ROC) curves were generated. Differences among the areas under the ROC curves were compared using the method of multiple comparison with the best.

Results: Of the 514 children eligible for this analysis, 111 (21.6%) became myopic. Differences in the third grade between eventual myopes and nonmyopes were seen for the number of myopic parents (P < 0.001) and for the number of sports and outdoor activity hours per week (11.65 +/- 6.97 hours for nonmyopes vs. 7.98 +/- 6.54 hours for future myopes, P < 0.001). Analysis of the areas under the ROC curves showed three variables with a predictive value better than chance: the number of myopic parents, the number of sports and outdoor activity hours per week, and the number of reading hours per week. After controlling for sports and outdoor hours per week and parental myopia history, reading hours per week was no longer a statistically significant factor. The area under the curve for the parental myopia history and sports and outdoor activities model was 0.73. A significant interaction in the logistic model showed a differential effect of sport and outdoor activity hours per week based on a child's number of myopic parents.

Conclusions: Parental history of myopia was an important predictor in univariate and multivariate models, with a differential effect of sports and outdoor activity hours per week based on the number of myopic parents. Lower amounts of sports and outdoor activity increased the odds of becoming myopic in those children with two myopic parents more than in those children with either zero or one myopic parent. The chance of becoming myopic for children with no myopic parents appears lowest in the children with the highest amount of sports and outdoor activity, compared with those with two myopic parents.