Indoor pursuits increase myopia
THROUGHOUT the world, more and more people are becoming shortsighted or myopic. Instead of having round eyeballs these victims’ eyeballs grow egg-shaped.
A century ago, only a handful of the world’s people were shortsighted.
These days more than 1 billion people are myopic and the numbers are soaring nearly everywhere.
Since 1970 the incidence of myopia has doubled to 42 per cent in the United States. In Alaska, fewer than 1 per cent of Inuit grandparents are shortsighted compared with 50 per cent of their children and grandchildren. Economists calculate that myopia costs Americans US$4-7 billion a year.
The situation is much worse and worsening in Asia. Sixty years ago between 10 and 20 per cent of Chinese were shortsighted. Today 90 per cent of young Chinese and Japanese high school students are shortsighted. Ninety-three per cent of Taiwanese high school girls are myopic as are 95 per cent of Korean 19-year-olds.
With 20 per cent shortsighted, New Zealanders are further down in the league but the percentage is rising, especially in younger people and becoming more aggressive. Australia has even fewer cases.
Since the German astronomer Kepler blamed book-reading for his shortsightedness 400 years ago most people have believed books cause myopia. Just look at all those Jewish scholars who wear glasses as they spend so much time studying the Talmud in darkened rooms.
Later, the condition was thought to be hereditary and there is some truth in that theory as identical twins studies show that to be the case. But the sudden rise in myopia all around the world within a generation can have little to do with heredity.
Recently, investigators in Europe and America surveyed the number of books children read and the time spent reading them. The investigators found little connection between myopia and reading books.
On the other hand, when they measured how much time kids spent indoors and outside the house they got very good statistical connections.
Young people the world over are spending less time outdoors. Throughout the Western world, kids and teenagers are spending most of their days inside, glued to TV, laptops, cellphones and computer games. It is worse in China, Japan and Korea where a high value is placed on educational performance.
Those southeast Asians spend longer hours in the classroom than New Zealand children and are expected to do 15 hours’ homework a week, compared with an average six hours a week in Britain and the US.
This indoor, screen-staring lifestyle explains the dramatic rise in myopia among young people everywhere, but notably in Asia.
American and Singaporean studies show kids who spent more time out of doors were far less likely to become shortsighted. In Singapore, posters have gone up encouraging children to spend more time outside. Australian experiments reveal that a child should spend at least three hours a day out of doors to prevent shortsightedness.
Epidemiologists are alarmed. If today’s youth are so attached to their smartphones, laptops and iPods, what hope is there for tomorrow’s children who have played on laptops and smartphones since the cradle?