Time Spent Outdoors and Myopia – Corrected Proof

With great interest we read the article by Wu et al on time spent outdoors and myopia. After just 1 year, the results of that prospective, interventional study, in which intervention consisted in encouraging schoolchildren to go outside the classroom for outdoor activities during classes recess, showed that new cases of myopia were significantly less frequent (8.41% vs 17.65%). Additionally, there was also significantly lower myopic progression (−0.25 diopters [D]/year vs −0.38 D/year) comparing the entire 2 groups. However, this difference in mean myopic shift was mainly determined by the difference between nonmyopic subjects (−0.26 vs −0.44 D). Among myopic subjects with or without atropine treatment, the mean myopia progression was not significantly different comparing the intervention group and control group (with atropine, intervention group −0.28 D vs control group −0.31 D; without atropine, intervention group −0.20 D vs control group −0.37 D). Thus, increased outdoor activity showed a protective effect with regard to the onset of myopia, but not against myopia progression. Additionally, in contrast with many previous reports, we found that differences between atropine-treated myopic children and myopic children not receiving atropine were not significant in either the control or the intervention group. Progression in myopic children in the intervention group with atropine (n = 46) was −0.28±0.57 versus −0.20±0.69 D without atropine (n = 113; P = 0.453). Progression in myopic children in the control group with atropine (n = 23) was −0.31±0.44 versus −0.37±0.67 D without atropine (n = 94; P = 0.604). In fact, myopic children with lesser progression were in the intervention group without atropine, although the differences with the other 3 groups were not significant (1-way analysis of variance; P = 0.311).