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Study sheds light on child myopia

21 May 2012

Short-sightedness affects 28 per cent of seven-year-olds in Singapore
Photo: The Straits Times © Singapore Press Holdings Ltd
A recent paper published in leading medical journal The Lancet has attributed the high occurrence of child myopia in East Asian cities to rising educational pressures and lifestyle changes, which lead to children spending less time outdoors.

Co-author Prof Saw Seang Mei from the Saw Swee Hock School of Public Health at NUS highlighted that the Singapore myopia rates are one of the highest in the world. Short-sightedness affects 28 per cent of children as young as seven years, with the number rising as they grow older. The rate hits 83 per cent when they reach 18, noted Prof Saw who is also Vice Dean (Research) at the Yong Loo Lin School of Medicine.

The joint research with Prof Ian G Morgan of the Australian National University and Prof Kyoko Ohno-Matsui of the Tokyo Medical and Dental University pointed out that the alarming rise in myopia in the region may be due to the interaction between genes and environment.

"The top environmental risk factors are excessive reading, writing, computer use and lack of time spent outdoors. Time spent outdoors exposed to high light levels may cause the release of dopamine in the retina and prevent excessive eye growth and myopia development," said Prof Saw.

A study of six-year-old Chinese children shows that the myopia rates are 29 per cent in Singapore but only 3 per cent in Sydney. Comparing the behavioural risk factors, a key difference is observed - children in Sydney spent 14 hours per week outdoors while children in Singapore spent only three hours per week outdoors. In view of this, she advises children to spend at least 10 hours weekly doing outdoors activities.

A randomised controlled trial named "Family Incentive Trial" has kicked off to prevent myopia and obesity. Some 285 children were enrolled, with those in the intervention arm spending 2.5 hours more time outdoors than the control arm. Prof Saw's team is currently planning a larger and longer school trial with a modified outdoor programme to further increase outdoor time.

Future research will focus on the prevention of myopia and associated ocular pathology, especially in identifying the genetic variants of myopia in high-risk children, interventions such as novel contact lenses to slow myopia progression, and screening for visually disabling ocular pathologies related to high myopia.