Researchers at the University of Western Australia are trying to find a possible link between the growing rates of myopia and how sun exposure, time in the classroom and genetics combine to cause it.
Professor David Mackey from the Centre for Ophthalmology and Visual Science told 720 ABC Perth there was still so much to learn about myopia, or nearsightedness.
“The simplest explanation of myopia is that the focusing power of the eye isn’t matched to the length of the eye,” Professor Mackey said.
“Most people who are short-sighted, their eyeballs are a little bit too long.
“It’s above a natural amount of growth.”
Myopia epidemic sweeping Asia
A study of 20-year-olds in Western Australia found 23 per cent were short-sighted. But in East Asia, rates have been recorded as high as 90 per cent.
“This started in Singapore, Hong Kong and Taiwan and now is spreading to the big cities in China, where up to 90 per cent of the students [entering university] are short-sighted and needing glasses,” Professor Mackey said.
There are genetic factors that predispose a person to myopia.
But previous research has uncovered two environmental factors that appear to be linked to myopia — time spent in education and time spent outdoors.
“If you just do primary school you are less likely to be short-sighted than if you finish high school, than if you finish university, and than if you go to do a post-graduate degree,” he said.
“The other major piece of data that is coming out, and a lot of it came from research in Australia, is the lack of time spent outdoors is a major risk factor.”
Skin cancer vs spectacles
A university study of adults in Busselton, south of Perth, compared the eyesight of people who had had skin cancer with people who had not.
“Clearly people who have had skin cancer spend a lot more time outdoors than those who don’t — and they were half as likely to be myopic,” Professor Mackey said.
“Only 10 per cent of them were short-sighted compared with just over 20 per cent [in those that hadn’t had skin cancer].
“Something about being outdoors is involved in preventing you being myopic. We still haven’t nailed this down and this is part of ongoing research.
“The clear problem that was raised with that Busselton study is that if we tell people to spend more time outdoors, we don’t want to create a new epidemic of skin cancer.”
Myopia can lead to blindness
While myopia itself can be easily corrected by glasses or contact lenses, it can also be a precursor to more serious eye problems.
“The main worry, particularly with the myopia epidemic in East Asia, is that with the eye lengthening it actually stretches important structures — the retina and the optic nerve,” he said.
“That predisposes people to retinal detachment, tears in their macula and they can get tears around the optic nerve, causing glaucoma.
“That can cause permanent blindness.”
Countries affected by the myopia epidemic can expect to see increases in blindness as the population ages, Professor Mackey said.
“That is not reversible, and therefore we need to be preventing myopia to prevent blindness.”
Screens not to blame
And while parents have traditionally warned children not to read in the dark or sit too close to the television, there was no clear evidence to link this behaviour with eye damage, according to Professor Mackey.
“When I started doing my research, everyone blamed the computers and televisions,” he said.
“People now will tell me it’s clearly due to tablet devices, although they have only been around for seven years.