Core Viewpoint - The article emphasizes the importance of outdoor activities in preventing myopia among children and adolescents, highlighting that daily outdoor exposure of at least two hours is essential for effective prevention [1][3][7]. Summary by Sections Outdoor Activity and Myopia Prevention - Outdoor activities stimulate the retina to release more dopamine, which inhibits excessive growth of the eyeball and thus prevents myopia [1][2]. - Adequate light intensity during outdoor activities is crucial, with effective levels being 1000 lux (overcast conditions) to 3000-10000 lux (sunny conditions), while indoor lighting is typically only 300-500 lux [1][3]. Effective Duration of Outdoor Activities - Daily outdoor activity of two hours is identified as the "effective dose" for myopia prevention, with children engaging in less than one hour of outdoor activity having a myopia incidence 2-3 times higher than those exceeding two hours [3][4]. - The timing of outdoor activities is also important, with recommended periods being before 10 AM and after 4 PM when light intensity is moderate [3]. Accumulation of Outdoor Activity Time - Both cumulative and continuous outdoor activity of two hours yield similar myopia prevention effects, as the key factor is the total daily light exposure rather than the duration of a single session [4]. - Children can flexibly arrange outdoor activities throughout the day, utilizing breaks and after-school time to meet the two-hour requirement [4]. Importance of Natural Light - Natural sunlight is essential for effective myopia prevention, as glass barriers significantly reduce the beneficial light spectrum needed for dopamine secretion [5][6]. - Even for children already diagnosed with myopia, outdoor activities remain beneficial, primarily in slowing the progression of myopia rather than reversing it [7]. Dynamic vs. Static Outdoor Activities - Effective outdoor activities should involve dynamic movements rather than static tasks like reading or writing, as the latter can lead to eye strain and diminish the preventive effects of outdoor exposure [8]. - A collaborative effort among families, schools, and children is necessary for sustained myopia prevention [8].