BrainStuff Classics: Why Are So Many People Nearsighted?

By 2050, half the world will be nearsighted. Researchers tracking this eye condition (also called myopia) have a few hypotheses about why it's happening. Learn more in this classic episode of BrainStuff, based on this article: https://health.howstuffworks.com/human-body/systems/eye/half-the-world-will-be-nearsighted-2050.htm

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Episode Transcript

Speaker 1 (00:01):
Welcome to brain Stuff production of I Heart Radio. Hi
brain Stuff, Lauren bogel Bam here with another classic episode
from our podcast archives. The world is increasingly near sighted,
and I'm not talking metaphorically. Researchers say that by the
year twenty fifty half of the world will be near sighted.

(00:22):
Today's question is why, Hey, brain Stuff, Lauren bogel Bam here,
there's a myopia epidemic going on. In n seventy two,
about of Americans aged twelve to fifty four were diagnosed
with this condition, which is also called near sightedness. But
today some forty of young Americans are receiving the same diagnosis.

(00:46):
And that's nothing compared to Asian countries, where of high
school kids are now near sighted. In seal, ninety six
point five percent of nineteen year old males are myopic,
and researchers say that by the year twenty fifty five
billion people will be wearing glasses to combat near sightedness.
That's more than half the people in the world. How
did this happen so fast and so many people. While

(01:09):
intuitively you might think it has something to do with
all the time we spend staring at computer or smartphone screens,
it's not so cut and dried. The rise and near
sightedness started happening before the prevalence of those screens, and
has been studied at least since the nineteen sixties. The
latest research reveals that the world's rising myopia rates stem
from spending too much time indoors. In general, several studies

(01:30):
show the less time children spend outdoors, the more likely
they are to develop myopia. This could explain the much
higher myopia rates in Asian countries, where a stronger focus
on education keeps kids indoors for more hours than children
living in most other parts of the world. We spoke
with Dr Adam Claren, a Florida optometrist. He said the

(01:50):
progression of the number of myoptic patients has risen too
fast to be explained by genetics alone. Unfortunately, the data
is not conclusive enough to determine what parts of being
outside is protective against myopia. Is that the sunlight, is
it looking at distant objects, or is it something we're
not even thinking about. Near sightedness is caused by an
elongated eyeball. Normally, the light that flows into your eyes

(02:13):
focused directly on the surface of the retina, but if
your eyeball is a bit too stretched out, the lens
will focus the lights slightly in front of the retina instead,
resulting in blurry vision. The hypothesis about myopia that's gaining
the most traction says that when the neurotransmitter dopamine is
released into the retina, it prevents your eyeball from elongating
and blurring your vision, and light is what stimulates this

(02:36):
release of dopamine. Normally, a pair of glasses or contact
lenses is all that's needed too sharpen your vision. However,
of those with the condition have a heightened form called
high myopia. People with high myopia are at a risk
for developing cataracts, glaucoma, torn or detached retinas, and even blindness.
Although no one knows how much time spent outdoors is

(02:57):
enough to forestall myopia, one researcher at the Australian National
University in Canberra estimated the amount at three or more
hours per day. It's also possible that strong indoor lights
could help, but Dr roheat Varma, director of the University
of Southern California I Institute, told us via email that
even if the myopia boom is not directly related, to

(03:17):
children spending more time indoors looking at a screen quote,
These are two sides of the same coin. Spending more
time indoors equates to spending less time outdoors, especially during
the day. Researchers are still trying to determine the real
fix for the myopia epidemic. Dr Claarin said other studies
have shown that a low dose of atropine eye drops

(03:38):
can also slow the progression of myopia. These studies are
completely unrelated to the studies on being outdoors, so there's
obviously more than one mechanism at play. Hopefully, continuing research
will shed some light on this growing problem. Today's episode
is based on the article half the World will be

(03:59):
near sited by fifty on how stuff works dot Com,
written by Melanie Radzekei McManus. Brain Stuff is production by
Heart Radio in partnership with how stuff Works dot Com
and is produced by Tyler Clay. Four more podcasts my
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