Association of outdoor activity time with myopia among schoolchildren at vulnerable age of myopia onset

  Objective  To examine the time spent on outdoor activities and its association with myopia among urban Beijing schoolchildren at vulnerable age of myopia onset.

  Methods  Using cluster sampling, we conducted a questionnaire survey and visual examination among 2 196 schoolchildren aged 10 – 11 years in 11 primary schools in an urban district of Beijing during November – December 2018.

  Results  For the 2 031 valid participants, the average outdoor activity time was 2.24 ± 0.67 hours per day (h/d) and the outdoor time for leisure and physical activities were 1.12 ± 0.46 h/d and 1.12 ± 0.40 h/d, respectively. The detection rate of myopia among the participants was 62.3%. The overall outdoor activity time was not significantly different between the 1 266 myopic participants and the 765 participants with normal vision (P > 0.05). The subgroup analysis demonstrated that the myopic participants had significantly less outdoor leisure time than the normal vision participants did (1.11 ± 0.44 h/d vs. 1.15 ± 0.49 h/d, P < 0.05); while, the disparity was significantly different only for the outdoor leisure time on weekends (1.21 ± 0.87 h/d vs. 1.33 ± 1.01 h/d, P < 0.05) but not for that on weekdays (1.06 ± 0.45 h/d vs. 1.09 ± 0.49 h/d, P > 0.05).

  Conclusion  Among the schoolchildren aged 10 – 11 years in urban Beijing, the outdoor activity time is insufficient and the detection rate of myopia is high; the schoolchildren with myopia spend less outdoor leisure time on weekends than those with normal vision.