Home' Trinidad and Tobago Guardian : April 20th 2015 Contents Natural 20/20 vision could soon be
a luxury afforded by few: New research
finds that rates of myopia, or near-
sightedness---a condition in which the
eye grows too long and the images of
distant objects can t be brought into
focus---are rising dramatically.
"It used to be that myopia was a
minor refractory condition," Maria Liu,
OD, PhD, assistant professor of clinical
optometry and head of the Myopia
Control Clinic at the University of Cal-
ifornia, Berkeley, tells Yahoo Health.
Eyesight to some degree, is genetic.
More than 24 genes have been linked
to an increased risk of near-sightedness,
which is a vision problem that s a result
of the eyeball being too long, or the
cornea---the cover at the front of your
eye---being too curved. (When this is
the case, the light that enters your eye
isn t focused the right way, making far-
away sights appear blurry.)
But today, science suggests more
than hereditary factors are to blame for
the condition. The age of onset is earlier:
Myopia used to be thought of as "ado-
lescent myopia," but now it s very com-
mon to see kids becoming near-sighted
in kindergarten. Plus, the numbers of
people who are near-sighted is increas-
ing, as is the overall severity of near-
Take developed East Asian countries
like Japan, South Korea, China, and
Singapore: Instances of myopia have
doubled, and in some places tripled,
there, scientists say. "Eighty to 90 per
cent of children completing secondary
school in East and Southeast Asia are
now myopic," Ian Morgan, PhD, pro-
fessor at the Research School of Biology
at Australian National University, tells
Yahoo Health. But the problem is here
at home, too. In 1986, about 25 per
cent of Americans experienced myopia.
But fast-forward to 2001, that number
jumped to 41 per cent, says Liu.
"Following that trend---almost anoth-
er 15 years later---you can imagine the
myopia prevalence is higher than 41
per cent today," she says.
That s an average overall. But if you
look at data by age, you ll notice some-
thing else, Liu says: a higher prevalence
in children and young adults as com-
pared to older adults. A National Eye
Institute study found that for people
ages 12 to 54, the prevalence of myopia
rose by 66 per cent between 1971 to
1972 and 1999 to 2004.
In Asian countries with incredibly-
high myopia rates, children start study-
ing earlier and harder than children in
Western countries, says Morgan.
"They also tend to stay inside more,
only in part because they are studying.
It is this combination of intense study
and not enough time outside that leads
In China, where Liu was trained, she
can attest: "Kids are imposed with
schoolwork very early on, even at three
or four years old---and reading for hours
on end can have a more intense impact
on the visual system for a four-year-
old than an 18-year-old because the
eyes are still developing."
And while US children may not face
the same heavy academic load from an
early age, the use of electronic devices---
which many elementary schools across
the US (and world) now use---could be
making things harder on the eyes.
"Reading on a handheld is not good
for visual development," says Liu.
"Handheld devices are designed to keep
someone very engaged---and can pro-
duce a very intense shock to visual sys-
tem." Plus, the closer a device is to your
eyes, the higher the intensity, she says.
Duration of use matters, too, says
"It has been suggested that the
impact of the one session of work is
a lot bigger when it comes to myopic
development than breaking work down
into multiple sessions." That s because
your eyes have a system of recovery in
place. But if you don t give them a
break, they can eventually grow longer
at a faster rate than they are supposed
to, she says.
The impact of being outdoors
A break outdoors can do your eyes
wonders, though. "Outdoor activity
has been shown to be protective against
myopia," says Liu. There are multiple
theories as to why Mother Nature can
play a role in eye health---one is directly
correlated with sunlight, says Morgan:
"The typically bright light outside dur-
ing the day releases a neurotransmitter,
dopamine, from the retina, and it
appears to slow the rate of eye elon-
gation, and thus prevents myopia."
In fact, an Australian study of more
than 4,000 kids demonstrated that
children who spent less time outside
were at an increased risk of becoming
near-sighted. Animal studies have also
shown that when exposed to bright
light, the eyeballs do not grow in length
as quickly as when the animals spend
most of their time in normal or dim
lighting, says Liu.
"With more bright, you have a lot
more UV light and exposure to shorter
wavelengths of light, which could be
protective, too," she adds, noting that
animal studies have confirmed such an
idea. But there could be more to the
connection: "My personal understand-
ing is that it s probably a lot more com-
plicated---when we are outdoors, all of
our systems are working totally differ-
ent. The body can sense that you are
in an outdoor environment," says Liu.
It produces more adrenaline, you are
able to see a much farther distance,
and a slew of different activities activate
different systems in your body.
This past January, 23 Florida schools
cut back on recess---some even elim-
inated it---in place of more school time.
But a recent Stanford study demon-
strated that a well-structured recess
not only improves well-being, but also
helps students succeed in the classroom
and ups attendance rates.
Beyond that, Liu urges that outdoor
recess is important for eye health. "In
East Asian countries like Singapore---
which has an alarmingly high prevalence
of myopia---the government is doing
campaigns suggesting that kids have
to spend time outdoors," she says.
body & soul
Guardian www.guardian.co.tt Monday, April 20, 2015
YOUR DAILY HEALTH
News and advice
Why the world is becoming near-sighted
In Asian countries with incredibly-high myopia rates, children start studying
earlier and harder than children in Western countries, says Ian Morgan, PhD,
professor at the Research School of Biology at Australian National
University. "They also tend to stay inside more, only in part because they
are studying. It is this combination of intense study and not enough time
outside that leads to myopia."
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