Genetic and environmental factors were blamed, with follow up studies including investigations into whether Singapore children have too much homework and spend too much time in front of television and computer screens.

The study showed the number of seven-year-olds suffering from myopia had doubled in three years, with children of Chinese descent the worst affected.

Professor Donald Tan of the Eye Research Institute, which assisted with the survey, said studies were under way to try to reverse the syndrome.

"We were quite taken aback by these figures. We have always known Chinese have a higher degree of myopia than other ethnic groups, but there is something in our environment in Singapore which triggers it more than Hong Kong and Taiwan," Tan told AFP.

The new data, taken from a 1999 study of 1005 children aged between seven and nine, found 34 percent had myopia, compared to a rate of 19 percent in Taiwan, 12 percent in Hong Kong and 7.5 percent in the United States.

Of seven-year-olds, one in four was myopic compared to one in eight in 1996. By the time the children reached nine, 43 percent will suffer from myopia or short-sightedness, the report found.

By ethnic background, 34 percent of the Chinese children in Singapore have myopia, compared to 24 percent of Indians and 19 percent of Malays.

Tan said the gene pool in Singapore had not changed much in the past five decades while cases of myopia had escalated in recent years.

"It's the million dollar question as to what is the cause. Is it because suddenly in Singapore our children are spending many hours reading, writing and doing homework. Maybe using computers. Maybe it's the lighting in homes," Tan said.

"We're predicting a rising prevalence of very severe myopia, much worse than we've seen in the older cohorts," he said.

A 1997 study of young men enrolling for national service found 83 percent were myopic.