In recent decades, parents and doctors worldwide have seen a disturbing increase in the number of children who have to squint in order to see properly.
The number of children and young people with nearsightedness is exploding – so much so that the World Health Organization (WHO) estimates that half of the world’s population will be nearsighted in 30 years.
Not being able to see clearly is difficult in itself, but it also puts you at extra risk of developing other serious long-term eye problems.
These include glaucoma, cataracts and retinal detachment, which can eventually lead to low vision and blindness.
That’s why researchers have been working on the problem for a long time, wondering if there’s anything we can do to prevent our children from becoming nearsighted.
The answer is yes. That is certainly possible.
Eye can become too long
There is a well-documented resource that we can all easily get hold of: daylight.
So says the Danish ophthalmologist Kristian Lundberg, who researched the causes of myopia in children.
“We know for sure that a lack of sunlight exacerbates myopia in children,” he says, referring to several international studies.
‘Conversely, we see that exposure to light and spending time outside can prevent or make myopia less severe. So being outside is a determining factor. There are several theories about the cause of this,’ he explains.
According to Lundberg, the most common theory is that light stimulates the production of dopamine, which inhibits eye growth – in a good way.
At birth, the eye is short and farsighted, but during childhood the eye grows in length until it has the correct shape for normal vision.
Nearsightedness occurs when the eye becomes too long.
This problem arises only in childhood, when the length growth of the eye is in full swing. In adults, growth in height is stabilized.
‘That is why the research mainly focuses on prevention in children,’ says Lundberg.
Direct relationship between light and sight
Population surveys in countries such as Australia, China, Taiwan and Singapore have looked into the issue.
And the results clearly point to the importance of sunlight, says Kristian Lundberg.
“A direct link has been shown between the amount of time children spend outside and the limitation of their nearsightedness,” he says. He specifically points to a study from China, where almost 60 percent of schoolchildren between the ages of 6 and 18 are already nearsighted.
In that study, researchers followed two groups of children over a three-year period.
One group spent 40 minutes more outside each day than the other – and it turned out that after three years, the group that spent the most time outside had about 25 percent less myopia than the group that spent less time outside.
This suggests that just 40 minutes outdoors can make a significant difference to the risk of nearsightedness.
According to Kristian Lundberg, genes also play a role, because if one of the parents – or both – is nearsighted, the child is also more likely to have bad eyesight.
But even taking that factor into account, daylight plays a surprisingly important role in counteracting or slowing myopia, says ophthalmologist Lundberg.
“Spending as much time outside as possible is the best protection against developing nearsightedness,” he says.