Will going outside prevent myopia progression?
The number of people with myopia is increasing and there are estimates that this will reach 50% of the global population in the next few years.
When I was an undergraduate the knowledge at that time was that people with myopia above 6 dioptres had a greater risk of retinal detachment and myopic maculopathy than those with lower refractive error. This has proven not to be true in that even low levels of myopia increase these risks compared to no myopia.
With this in mind researchers have been looking for ways to prevent axial elongation. This is the cause of myopic progression. There have been studies on using dual focus contact lenses, multifocal contact lenses and glasses, orthokeratology and atropine instillation.
Other studies have suggested that spending time outdoors is protective against myopia onset with 11 or more hours of outdoor activity per week linked to a 50% reduction in myopia incidence over a one-year period. The biological mechanism for this is unknown. It has been proposed that the smaller pupil when outdoors leads to less peripheral retinal hyperopic blur which is thought to be a driver for axial elongation.
The effect may be related to vitamin D production when outside, or more distance focus or physical activity or less close work or a combination of these and other factors yet to be considered. An association between myopia progression and close work (≤20cm) for prolonged periods of time (>45 minutes) has also been proposed.
There is no harm in advising people at risk of myopia to get off the couch, go outside (assuming protective measures are taken to avoid excessive UV exposure) and spend less time looking at devices.