Date Posted: 22.02.2013

Scientists believe they may be able to discover why children who spend much of their time indoors rather than playing outside are more likely to develop short-sightedness following a breakthrough study into the genetics of myopia.

More than two dozen genes have been linked to an increased risk of developing myopia, a finding that may finally allow researchers to understand why children today are more likely to become short-sighted than children in the past.

Myopia now affects about one in three people in the West and up to 80 per cent of people in Asia. In some countries in the Far East as many as 90 per cent of children are short-sighted, compared to less than 20 per cent a couple of decades ago.

Although short-sightedness tends to run in families and has a strong inherited component, the explosive increase in the condition over recent years has been linked with an increase in the time that children spend indoors either studying or playing computer games and watching TV, scientists believe.

A study of more than 45,000 people from Europe and Asia has identified 24 new genes that appear to be involved in triggering the onset of myopia. It has also confirmed the role of two further genes that were already suspected of being involved with short-sightedness, the scientists said.

“We already knew that myopia, or short-sightedness, tends to run in families, but until now we knew little about the genetic cause. This study reveals for the first time a group of new genes that are associated with myopia,” said Professor Chris Hammond of King’s College London, who led the study published in Nature Genetics.

“Carriers of some of these genes have a tenfold increased risk of developing the condition…It is an extremely exciting step forward which could potentially lead to better treatments or prevention in the future for millions around the world,” he said.

Myopia is caused when the eyeball grows too long, causing light to be focussed just short of the light-sensitive retina at the back of the eye. Ambient light levels in childhood are thought to control the growth of the eyeball, with low light leading to myopia, Professor Hammond said.

Children who develop myopia when they are very young are more likely to suffer vision problems in later life compared to children who were not short-sighted. In extreme case, myopia can lead to serious vision problems after mid-life, such as glaucoma, detached retina and blindness caused by macular degeneration.
 

Source : Irish Independent