Time Use and Prevalence of Myopia among Chinese Adolescents

Objective: Myopia has been a long-standing epidemic in China. Although previous research has reported an association between time spent outdoors and myopia, no study has examined how the general pattern of time use among different activities (e.g., sleep, study etc.) may be related to risk of myopia. This study intends to identify time use patterns among Chinese adolescents between ages 10 and 18, and explore whether different patterns are related to different prevalence of myopia. Methods: Data were from the nationally representative China Family Panel Studies (CFPS). Both vision status and time use data were self–reported. Results: Latent class analysis identified three major patterns of time use among 4,881 Chinese adolescents in 2010: the “balanced class” (61.3%) had reasonable amount of study hours per day (mean=8.83), sufficient sleep (mean=8.83) and average leisure time (mean=3.09); the “study concentrated class” (19.6%) was characterized by prolonged study hours (mean=11.76), less sleep time (mean=7.62) and leisure time (mean=1.89); the “working and playing class” (18.8%) spent little time studying (mean=.69) but more time working (mean=4.97) and engaging in leisure activities (mean=4.11). Risk of myopia was the same in “balanced class” and “working and playing class”, but the “study concentrated class” had a two-fold risk (OR=2.17, 95% CI=1.64, 2.88). Conclusion: Different time use patterns are associated with different risks of myopia. Adolescents with long hours of study time have higher risk of myopia, while those with balanced hours of time use have the same level of risk with those who spend little time study.