Effect of Time Spent Outdoors at School on the Development of Myopia Among Children in China: A Randomized Clinical Trial
The objective of this study is to assess the efficacy of increasing time spent outdoors at school in preventing incident myopia.
The study selected a cluster randomized trial of children in grade 1 (6 year old) from 12 primary schools in Guangzhou, China.
The study measured the 3-year cumulative incidence rate of myopia among the students without established myopia at baseline and the changes in spherical equivalent refraction and axial length among all students.
There were 952 children in the intervention group and 951 in the control group with a mean (SD) age of 6.6 (0.34) years. The cumulative incidence rate of myopia was 30.4% in the intervention group and 39.5% in the control group.
There was also a significant difference in the 3-year change in spherical equivalent refraction for the intervention group compared with the control group.
Elongation of axial length was not significantly different between the intervention group (0.95 mm) and the control group (0.98 mm).
The addition of 40 minutes of outdoor activity at school compared with usual activity resulted in a reduced incidence rate of myopia over the next 3 years.
Further studies are needed to assess long-term follow-up of these children and the generalizability of these findings.