Myopia - Causes and Prevention

It is generally accepted now that there are two basic causes of myopia: Genetic, and environmental

Environmental factors include:

  • Excessive close work
  • Lack of outdoor activity
  • Poor illumination
  • Uncorrected refractive errors
  • Size of print in books
  • Poor eye-care
  • Unhealthy diet

Other rare causes include Prematurity, Down’s Syndrome and Albinism.

In the majority of cases, the cause of the myopia is a combination of the genetic and environmental factors. This is why Singapore has one of the highest prevalences of myopia in the world. Chinese people have the “myopic gene” – an inherited propensity for myopia. So when a chinese child is subjected to excessive close work, he will most likely develop myopia. Caucasians, generally speaking, do not seem to have the propensity for myopia. In fact, the majority of caucasians are the opposite, i.e. hyperopic (long-sighted).

A study done a few years ago by the Singapore National Eye Centre found that we have the highest prevalence of myopia in the world:

  Age Wearing Glasses
Singapore 7 to 9 34%
Taiwan 7 to 9 19%
Hong Kong 7 to 8 12%
USA 6 to 14 7.5%
Nepal 5 to 15 Less than 3%

There is not much we can do about our genes, except hope that in the future gene therapy will be possible. However we should try to do something about the excessive close work!

Two important studies have shown the relationship of close work to myopia. One is the study done by the late Prof. S.J. Chew on the pattern of myopia in 320,409 Singaporean men aged 15 to 21 (SMJ 1988 Vol29:p201-211). The findings were that “9% of no primary education needed glasses. 85% of A-levels and above needed glasses. Not only was there a greater incidence but the degrees of myopia were higher in the A-levels and above.”

The second study was done recently by Dr.Katherine Rose. It was a 4-year study at Sydney University, which showed that there was less myopia in children who spend more time outdoors.

It is therefore advisable that we encourage more outdoor activities, and more breaks from close work, to prevent the increasing incidence of myopia.

Related Myopia Topics:

Myopia - Types of Myopia and Monitoring
Myopia Treatment: Optical Correction
Myopia - Reducing Myopia Progression
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