Experts have blamed intense levels of education for an epidemic of shortsightedness sweeping across eastern Asia.
Myopia,or short-sightedness,now affects between 80 percent and 90 percent of school leavers in the major cities of countries such as China,Japan and South Korea,say researchers.
Between 10 percent and 20 percent of sufferers are said to have high myopia,which can lead to loss of vision and even blindness.
Writing in The Lancet medical journal,Professor Ian Morgan,from the Australian National University in Canberra,and colleagues suggest that the powerful Asian education ethic may be largely responsible for myopia.
Recent evidence suggests that short-sightedness is to a great extent because of environmental rather than genetic factors.
Numerous studies have shown a link between close reading and intensive study and myopia.
The rise in myopia prevalence in urban east Asia might therefore be plausibly associated with the increasing intensity of education, the Daily mail quoted the experts as writing in the journal.
Moreover,east Asian countries with high myopia now dominate international rankings of educational performance, they said.
One Australian investigation,the Sydney Myopia Study,showed that children who read continuously or at a close distance were more likely to be short-sighted.
More recent work had indicated that increased amounts of time spent outdoors might protect against myopia.
The protective effect seems to be associated with total time outdoors,rather than with specific engagement in sport, experts said.
Greater exposure to sunlight may protect eyesight by stimulating the release of retinal dopamine,a neurotransmitter involved in nerve signalling.
According to the experts,the ability of bright light to reduce myopia risk had been demonstrated in animals,including primates.
They added that genetic factors also played a role in myopia risk. The contribution made by many small-impact genes,and gene-environment interactions,was yet to be established.
Even if successful prevention is possible,east Asia will still be faced,for close to the next 100 years,with an adult population at high risk of developing pathological (high) myopia, experts said.
Further progress in our understanding of the natural history of pathological myopia is thus essential,and while there have been some promising developments in treatment,more effective treatments are still required, they added.