Up to 90% of school leavers in major Asian cities are suffering from myopia - short-sightedness - a study suggests.
Researchers say the "extraordinary rise" in the problem is being caused by students working very hard in school and missing out on outdoor light.
The scientists told the Lancet that up to one in five of these students could experience severe visual impairment and even blindness.
In the UK, the average level of myopia is between 20% and 30%.
According to Professor Ian Morgan, who led this study and is from the Australian National University, 20-30% was once the average among people in South East Asia as well.
"What we've done is written a review of all the evidence which suggests that something extraordinary has happened in east Asia in the last two generations," he told BBC News. Read More