Parents who come and see you saying that they are worried that their children risk nearsightedness because they spend too much time on ‘near work’ can breathe a sigh of relief.
New research suggests that the increased incidence of myopia is due to the amount of time children spend indoors rather than the hours spent playing on a computer or reading books.
Among children who spend the same amount of time outside, the amount of near work has no correlation with nearsightedness. Hours spent indoors looking at a screen or book simply means less time spent outside.
Researchers say it’s to do with the way the eye develops. They suspect that bright outdoor light helps children’s developing eyes maintain the correct distance between the lens and the retina – which keeps vision in focus. Dim indoor lighting doesn’t seem to provide the same kind of feedback. As a result, when children spend too many hours inside, their eyes fail to grow correctly and the distance between the lens and retina becomes too long, causing far-away objects to look blurry.
Among children who spend the same amount of time outside, the amount of near work has no correlation with nearsightedness. Hours spent indoors looking at a screen or book simply means less time spent outside.
One study published in 2008 in the Archives of Ophthalmology compared six and seven-year-old children of Chinese ethnicity living in Sydney, Australia, with those living in Singapore. The rate of nearsightedness in Singapore (29 per cent) was nearly nine times higher than in Sydney. The rates of nearsightedness among the parents of the two groups of children were similar, but the children in Sydney spent on average nearly 14 hours per week outside, compared with just three hours per week in Singapore.
Similarly, a 2007 study by scholars at Ohio State University found that, among American children with two myopic parents, those who spent at least two hours per day outdoors were four times less likely to be nearsighted than those who spent less than one hour per day outside.
To put it succinctly, the biological mechanism that once kept vision naturally sharp cannot support visual development under modern environmental conditions.
