Outdoor activity during class recess prevents myopia onset and shift in premyopic children: Subgroup analysis in the recess outside classroom study

Purpose

To investigate whether premyopia is a risk factor for myopia onset and whether outdoor activities can protect against myopia development in premyopic children in the Recess Outside Classroom (ROC) study.

Methods

Nonmyopic schoolchildren aged 7–11 years were recruited from two schools in Taiwan. One school implemented the ROC program, which encouraged children to go outdoors during recess. The control school maintained its usual schedule. A cycloplegic autorefraction was performed. Premyopia was defined as spherical equivalent refraction ≤ +0.75 diopters (D) and > –0.50 D.

Results

After one year of follow-up, multivariate logistic analysis revealed that the ROC program reduced the risk of myopia onset by 61 % (odds ratio [OR] = 0.39, 95 % confidence interval [CI]: 0.21–0.70, P = 0.002). However, premyopia status increased the risk of myopia onset by 14 times compared to hyperopic status (OR = 14.0, 95 % CI: 1.86–105.3, P = 0.010). In the subgroup analysis of premyopic children, the myopic shift was also significantly lower in the ROC group than in the control group (–0.20 ± 0.60 D/year vs. –0.40 ± 0.66 D/year, P = 0.017). Myopia incidence in premyopic children was significantly lower in the ROC group than in the control group (19.6 % vs. 37.8 %, P = 0.001). Multivariate regression analysis showed that participation in the ROC program was significantly associated with a lower myopic shift in premyopic children (–0.22 D/year, 95 % CI: –0.39 to –0.06, P = 0.008)

Conclusions

Premyopia is a risk factor for myopia onset. A school policy that includes more outdoor time can effectively prevent myopia onset and shift in premyopic children.