There's a tidal wave of myopia sweeping across Hong Kong and other East Asian countries, and the lack of time spent outdoors is thought to be a major cause.
According to a new paper published in The Lancet, myopia, or short-sightedness, now affects between 80 and 90 per cent of school-leavers in major cities in East Asian countries such as China, Japan, Singapore and South Korea. Of these people, 10 to 20 per cent have 'high' myopia, which can eventually lead to vision loss, visual impairment and even blindness.
The paper's main author, Professor Ian Morgan of the Australian Research Council Centre of Excellence in Vision Science at the Australian National University in Canberra, notes that while myopia had been thought to have a mainly genetic basis, more recent evidence implicates environmental factors.
For example, in Singapore, the three major ethnic groups (Chinese, Indian, Malay) have all seen sharp rises in myopia since 1996, suggesting similar sensitivity to the risk factors.
Migrant studies have also been vital. Students of Chinese origin in Australia, for instance, show lower levels of myopia than those in urban centres in East and Southeast Asia.
Epidemiological surveys have shown that increased amounts of time outdoors protect against the development of myopia. Trials are ongoing in Singapore and on the Chinese mainland to test the effect of increased outdoor exposure as a preventive measure.
The authors say: 'Even if successful prevention is possible, East Asia will still be faced, for the next 100 years, with adults at high risk of developing [high] myopia. More progress in our understanding of ... pathological myopia is thus essential, and while there have been some promising developments in treatment, more effective treatments are still required.'
How much do you know about myopia? Test yourself here.
1. A myopic person
a. Can see distant objects clearly, but nearby objects appear blurred
b. Can see nearby objects clearly, but distance objects appear blurred
c. Cannot see either distant and nearby objects clearly
2. Which one of the following is not a complication of myopia?
a. Retinal detachment
3. Which of these is not a good habit when working on the computer?
a. Keeping a working distance of about 50cm from the monitor
b. Ensuring that all room lights are switched off
c. Taking vision breaks of about three to five minutes after every 30 to 40 minutes of continuous close-up work
4. When should you go for an eye check-up?
a. At least once a year if you are myopic
b. When you want to buy a new pair of spectacles
c. When images become blurred
Answers: 1. b; 2. None - all are complications of myopia; 3. b; 4. a & c