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About this tool
Plan daily daylight minutes against the 2 hours a day and 11 hours a week outdoor targets used in myopia research, with a lux-hour estimate.
The Outdoor Time For Eyes Planner measures the daylight a child or adult actually gets each week against the targets used in myopia research: about 2 hours a day, the 11 hours a week figure from school-based programmes, or the 40 extra minutes per school day tested in the Guangzhou Outdoor Activity Longitudinal Trial. That trial, published in JAMA in 2015, cut 3-year myopia incidence from 39.5% to 30.4%. The planner totals weekday, weekend and school outdoor minutes, reports the shortfall, and estimates the light dose in lux-hours from the conditions you are usually outdoors in.
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Measures against the 2-hour, 11-hour and 40-minute figures actually used in the research, not a made-up goal.
Outdoor minutes provided at school or work are added in, so the plan only asks for the genuine gap.
Converts time and conditions into lux-hours and shows how long the same dose would take indoors.
About 2 hours a day, or roughly 11 hours a week, is the figure used in most school-based programmes. The Guangzhou trial tested a smaller change — one extra 40-minute outdoor session on each school day — and still reduced 3-year myopia incidence from 39.5% to 30.4%.
No. The relevant threshold is generally taken as exposure above about 1,000 lux, and even a heavy overcast day outdoors runs several thousand lux, against 300 to 500 lux in a normally lit room. Shade outdoors is fine and avoids the sun-safety trade-off.
The strong evidence is for delaying onset in children who are not yet myopic. Evidence that outdoor time slows progression in children who are already short-sighted is much weaker, so it should sit alongside — not instead of — myopia management options discussed with an eye care professional.
The light exposure still counts, since the illuminance reaching the eye is what the hypothesis rests on, but the near-focus demand of a phone does not go away outside. The clearest benefit comes from being outdoors and looking at distance, which is also why outdoor time and the 20-20-20 rule address different halves of the same problem.