An international study has found that one in every seven children in Britain is now short-sighted.
Called myopia, signs of the condition include sitting close to the TV, computer or mobile phone, difficulty reading words from a distance, having headaches, tired eyes and regularly rubbing the eye.
Children who spend more time indoors than outdoors are more likely to be affected, especially when spending long periods looking at nearby objects, such as books and computers.
Experts in the UK have long advised children to spend at least two hours a day outside.
Bristol Eye Hospital ophthalmology consultant Richard Haynes said the reason for the rise in myopia in recent years has been unclear, but large population studies suggest that being outside during childhood and playing in the fresh air reduces the risk of myopia developing.
“This is excellent news as it also helps promote good mental health and general happiness!”
Myopia is normally picked up by an optician during eye checks, and glasses can be prescribed to help.
The report, which studied more than five million children and adolescents in fifty countries, said that globally more than one child in three could have myopia.