Up to 90% of school leavers in major Asian cities are suffering from myopia(short-sightedness)and scientists are blaming their academic lifestyles.
Natural light exposure is just one potential factor in a child's eyesight.The time children spend outdoors could be linked to a reduced risk of being short-sighted, research 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.They also found a strong link between short-sightedness and close reading.
The work of Professor Ian Morgan, from the Australian National University in Canberra, and colleagues, suggest the condition - also known as myopia - is due more to environmental than genetic factors.
The scientists told The Lancet medical journal that up to one in five of these students could experience severe visual impairment and even blindness.
According to the research, the problem is being caused by a combination of factors - a commitment to education and lack of outdoor light.
"As a result of massive educational pressures and the construction of a child's day, the amount of time they spend outside in bright light is minimised."
Professor Ian Morgan, from the Australian National University in Canberra, states that many children in South East Asia spend long hours studying at school and doing their homework. This in itself puts pressure on the eyes, but exposure to between two and three hours of daylight acts as a counterbalance and helps maintain healthy eyes.
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| Myopia (short-sightedness) |
The scientists believe that a chemical called dopamine could be playing a significant part. Exposure to light increases the levels of dopamine in the eye and this seems to prevent elongation of the eyeball.
A big concern is the numbers of students suffering from "high" myopia. According to Professor Morgan, this affects between 10% and 20% of students in Asian cities. It can lead to vision loss, visual impairment and even blindness.
"These people are at considerable risk - sometimes people are not told about it and are just given more powerful glasses - they need to be warned about the risk and given some self-testing measures so they can get to an ophthalmologist and get some help."
For decades, researchers believed there was a strong genetic component to the condition. It was believed that people from China, Japan, Korea and other countries were particularly susceptible to developing myopia. But this study strongly suggests an alternative view.
Eye experts say that you are myopic if your vision is blurred beyond 2m (6.6ft). It is often caused by an elongation of the eyeball that happens when people are young.
The study requires further exploration and research but it states that it is good to encourage children to spend more time outside when the sun is shining. It's unlikely to do them any harm.
If not possible it doesn't have to be massively sunny but if kids are getting out for about three hours a day then they're pretty safe.