The causes of myopia are a mix of genes and environment. You can’t do much about your genes, but as environment is the trigger behind the increasing myopia epidemic, we can do something about that.
There is lots of evidence and evidence is building that it is probably outdoor light that affects eye growth and that outdoor light is a potentially useful intervention against myopia onset and progression. The catch-cry ‘more green time, less screen time’ is promoted by optometrists to encourage parents to urge their children to spend more time outside in natural light, and less time inside glued to screens. This is why traditionally Australia, with its sporty outdoors lifestyle, has had lower myopia rates than many Asian countries where children might spend more time inside on screens.
Australian optometrists were the first to show that increasing exposure to outdoor light was the key to reducing the myopia epidemic in children. Their ground-breaking research, the Role of Outdoor Activity in Myopia (ROAM) study, followed 101 children aged 10 to 15, of whom 41 were myopic and 60 were non-myopic, from 42 Brisbane schools.
Researchers, Associate Professors Scott Read, and Stephen Vincent and Professor Michael Collins, found that outdoor light appeared to be the main protective factor against myopia development and progression.
They said optometrists could now advise parents that children need to spend more than one hour and preferably at least two hours a day outside to help prevent myopia from developing and progressing.
Their study found no protective association with outdoor physical activity or reducing near work as suggested by some previous studies but suggested ‘near work’ on computer and other screens was not itself causing myopia although screens are responsible for children spending more time indoors.
Professor Read told Optometry Australia: “It would be prudent for optometrists to advise that less than 60 minutes a day exposure to light outdoors is a risk factor for faster eye growth and potentially becoming myopic and myopia progression.”
A review of 25 studies of myopia and outdoor light published in 2017 demonstrated a protective effect of improved outdoor time for onset of myopia, but not progression (once myopia was established). The researchers from China and the Brien Holden Vision Institute in Sydney, Australia found about an extra 1.25 hrs/day compared with control/baseline time spent outdoors reduced the risk of onset of myopia by 50 per cent.
Interestingly, time outdoors had a stronger protective effect in children aged 6 years compared with kids aged 11 to 12 years. The authors said: ‘It is well known that the various ocular components undergo growth and maturation in younger children, and thus, the ocular growth patterns may be more sensitive to environmental influences, including outdoor time, during this period.’
Another recent study found that adding 40 minutes daily of outdoor time led to less myopia in Chinese children.
More green time and less screen time helps prevent myopia. Photo by Bruno Saito from Pexels. Found here.
Other tips on how to slow or prevent myopia, from optometrists who are expert in child myopia, Drs Kate and Paul Gifford and their My Kids Vision website include:
- Catching early signs before it fully develops can slow onset and progression
- Children should not spend more than three hours a day – in addition to school time – on close work such as reading, homework or screen-time
- Ensure computers are properly positioned to avoid eye strain and take breaks every 20 minutes by looking across the room for 20 seconds
- Smart phones are popular for children and teenagers’ texting, social media, reading and games but too much screen time is linked to myopia, can cause dry eyes, and increase risk of eye damage and diseases in adulthood similar to UV damage
- Children should avoid the blue-white bright light from tablets and phones for three hours before bedtime as this can interfere with sleep
- Outdoor sport and play of at least 90 minutes a day can reduce risk of myopia
- Evidence suggests exposure to outdoor light is beneficial in slowing onset and progression of myopia but UV protection is important so wear sunglasses and a hat
In some Asian countries where child myopia rates are very high, they are considering measures such as building glass classrooms in China to expose children to more natural light to try to reduce myopia rates. And in Taiwan they have made outdoor time part of the curriculum and since they increased time outdoors to several hours daily, children’s vision is improving.
