Why are you nearsighted?

July 10, 2015

Hereditary myopia

The severity of the condition also runs in families, so if you have a very nearsighted parent, you're at greater risk of developing severe myopia.
The same applies to your children if you or your partner is nearsighted, and to your grandchildren if their parents are affected.
What's more, whereas until recently genetic influences were believed to be the main factor in the development of near sight, recently a new risk has emerged — so even if you are not affected, nearsightedness could still affect your children or grandchildren.

Non-hereditary myopia

Recent surveys suggest that, on average, up to one in four people is nearsighted.
But in the last few decades there have been rapid increases in rates of myopia in most countries around the world — and in Asia, the worst-affected region, the problem has been described as an epidemic.
Rates of nearsightedness vary between countries, but age trends are similar across the world.
Is there something in our environment or our behaviour that might be influencing this trend?

Possible causes

Scientists now think that myopia results from an interplay between genetic and environmental factors. It could be that, during crucial periods of their development, children and adolescents with an inherited likelihood of nearsightedness are even more vulnerable to other influences that promote its development.
Although reading and close work have been implicated, a peculiarly modern factor would seem to be young people spending long hours using computers and playing computer games.
But numerous population studies also show that myopia is especially common among certain groups — such as university students — which could mean environmental factors are partly responsible; close work, such as reading and writing, is the prime suspect.
Another potential culprit is artificial light, while some scientists suspect inadequate physical activity and poor diet play a role.

Myopia and work

Nearsightedness is rare before school age and becomes progressively more common in the school years.
Research has shown that nearsightedness in children progresses faster in the school year than during the summer holidays.
And the incidence of nearsightedness peaks among university students — at the time of the most intensive close work.
For example, it has been reported that virtually all medical students in Taiwan are myopic.
In Singapore, the situation is particularly worrying. According to the Singapore National Eye Center, myopia appears early, high-degree myopia is common, and the number affected has vastly increased in three generations.
Classic studies of Alaskan Inuit children showed a dramatic increase in myopia following the introduction of a "westernized" lifestyle and, especially, of compulsory education.
In an investigation into Alaskan Inuit families, first reported in the American Journal of Optometry and Archives of American Academy of Optometry in 1969, only two out of 130 parents (who had all lived a traditional life of hunting and fishing) were myopic but more than 60 per cent of their children had measurable myopia.
Dr. Francis Young, who led the research team, concluded that long periods of reading at school were to blame.
Not everyone agrees on what's causing the myopia epidemic, but it's wise to reduce eyestrain when doing close work.
And many experts believe that prolonged computer use exacerbates the trend, so protect your sight by taking frequent breaks.

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