The time children spend outdoors
could be linked to a reduced risk of
being short-sighted, research
suggests.
An analysis of eight previous
studies by University of Cambridge
researchers found that for each
additional hour spent outside per
week, the risk of myopia reduced
by 2%.
Exposure to natural light and time
spent looking at distant objects
could be key factors, they said.
The studies involved more than
10,000 children and adolescents.
Researchers are presenting their
findings at the American Academy
of Ophthalmology annual meeting
in Florida.
Dr Justin Sherwin and his research
team concluded that short-sighted
children spent on average 3.7
fewer hours per week outdoors
than those who either had normal
vision or were long-sighted.
But they said the reasons why were
not yet clear.
They expected to find that children
who spent more time outdoors
also spent less time doing activities
like reading, studying or playing
computer games, but no such link
was found in two of the eight
studies which looked at this
relationship.
Any increase in time spent
outdoors must be weighed against
exposure to UV radiation.”
End Quote Dr Justin Sherwin
University of Cambridge
However, Dr Sherwin said they
would now need more precise data
to try to understand which factors,
such as increased use of distance
vision, reduced use of near vision,
natural ultra violet light exposure
or physical activity, are most
important.
There are also other factors to
consider, he said.
Risk and benefit
"Any increase in time spent
outdoors must be weighed against
exposure to UV radiation - and the
increased risk of skin cancer,
cataracts and other cancers.
"On the other hand, increasing
outdoor physical activity could
protect against diabetes and
obesity, vitamin D deficiency and
osteoporosis, for example," he said.
Short-sightedness is a common eye
condition that causes distant
objects to appear blurred, while
close objects can be seen clearly.
Myopia is the medical term for
short-sightedness.
It is much more common today in
the UK and the United States than it
was just 30 to 40 years ago.
Approximately 1-2% of five to
seven olds in the UK have myopia.
Around five million British people
are short-sighted and some
200,000 of them will be seriously
short-sighted.
In some parts of Asia, more than
80% of the population suffers from
short-sightedness.
Short-sightedness results from
excessively long growth of the eye-
ball, or a steeply curved cornea.
Dr Susan Blakeney, optometric
adviser at The College of
Optometrists, said that normal
children are born long-sighted.
"As they grow they become less
long-sighted so that by the time
children stop growing their
eyesight should be perfect.
"If a child is not born long-sighted
enough then they will overshoot
and end up short-sighted. This
tends to happen around puberty.
"There are numerous factors which
could influence that journey - the
question is what is the key bit that
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