OBJECTIVE: To study the influence of near-work and outdoor activities on myopia progression in school children. METHODS: Eighty 7-11-year-old school children with myopia were randomly assigned into an intervention group (n=41) and a control group (n=39). The children in the intervention group did near- and middle-vision activities less than 30 hrs per week and more outdoor activities than 14-15 hrs per week. Myopia progression was observed regularly over 2 years after which ophthalmologists administered questionnaires regarding near-vision work (reading, writing and using computer), middle-vision work (watching TV and extracurricular learning activities), outdoor activities, using nature light, wearing glasses, etc. RESULTS: The annual mean myopia progression (0.38±0.15 D) in the intervention group was significantly lower than that in the control group (0.52±0.19 D; P<0.01). The children in the two groups spent similar amounts of time in near-vision activities, but the children in the intervention group spent less time in middle-vision activities (P<0.01) and more outdoor activities (13.7±2.4 vs 6.2±1.6 hrs/wk; P<0.01). When considering all children in the study, there were 4 factors that significantly correlated with less myopia progression: more outdoor activities, more time spent wearing glasses, more time spent in natural light and less time using a computer. When analyzing the intervention group separately, more outdoor activity was inversely correlated with myopia progression (t=-2.510, P<0.05). Separate analysis of the control group indicated that more time wearing glasses was correlated with less myopia progression (t=-3.115, P<0.05). CONCLUSIONS: Myopia progression in school children may be slowed by more outdoor activities, more time spent in natural light and more time wearing corrective glasses.