More time spent outdoors reduces the onset of nearsightedness (or myopia) in children and adolescents, according to a systematic review and meta-analysis of research on the association between time spent outdoors and myopia.
Xiong, Shuyu et al. “Time spent in outdoor activities in relation to myopia prevention and control: a meta-analysis and systematic review.” Acta ophthalmologica vol. 95,6 (2017): 551-566. https://doi.org/10.1111/aos.13403.