WEBVTT - BrainStuff Classics: Why Are So Many People Nearsighted?

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<v Speaker 1>Welcome to brain Stuff production of I Heart Radio. Hi

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<v Speaker 1>brain Stuff, Lauren bogel Bam here with another classic episode

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<v Speaker 1>from our podcast archives. The world is increasingly near sighted,

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<v Speaker 1>and I'm not talking metaphorically. Researchers say that by the

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<v Speaker 1>year twenty fifty half of the world will be near sighted.

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<v Speaker 1>Today's question is why, Hey, brain Stuff, Lauren bogel Bam here,

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<v Speaker 1>there's a myopia epidemic going on. In n seventy two,

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<v Speaker 1>about of Americans aged twelve to fifty four were diagnosed

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<v Speaker 1>with this condition, which is also called near sightedness. But

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<v Speaker 1>today some forty of young Americans are receiving the same diagnosis.

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<v Speaker 1>And that's nothing compared to Asian countries, where of high

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<v Speaker 1>school kids are now near sighted. In seal, ninety six

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<v Speaker 1>point five percent of nineteen year old males are myopic,

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<v Speaker 1>and researchers say that by the year twenty fifty five

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<v Speaker 1>billion people will be wearing glasses to combat near sightedness.

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<v Speaker 1>That's more than half the people in the world. How

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<v Speaker 1>did this happen so fast and so many people. While

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<v Speaker 1>intuitively you might think it has something to do with

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<v Speaker 1>all the time we spend staring at computer or smartphone screens,

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<v Speaker 1>it's not so cut and dried. The rise and near

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<v Speaker 1>sightedness started happening before the prevalence of those screens, and

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<v Speaker 1>has been studied at least since the nineteen sixties. The

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<v Speaker 1>latest research reveals that the world's rising myopia rates stem

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<v Speaker 1>from spending too much time indoors. In general, several studies

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<v Speaker 1>show the less time children spend outdoors, the more likely

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<v Speaker 1>they are to develop myopia. This could explain the much

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<v Speaker 1>higher myopia rates in Asian countries, where a stronger focus

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<v Speaker 1>on education keeps kids indoors for more hours than children

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<v Speaker 1>living in most other parts of the world. We spoke

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<v Speaker 1>with Dr Adam Claren, a Florida optometrist. He said the

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<v Speaker 1>progression of the number of myoptic patients has risen too

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<v Speaker 1>fast to be explained by genetics alone. Unfortunately, the data

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<v Speaker 1>is not conclusive enough to determine what parts of being

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<v Speaker 1>outside is protective against myopia. Is that the sunlight, is

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<v Speaker 1>it looking at distant objects, or is it something we're

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<v Speaker 1>not even thinking about. Near sightedness is caused by an

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<v Speaker 1>elongated eyeball. Normally, the light that flows into your eyes

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<v Speaker 1>focused directly on the surface of the retina, but if

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<v Speaker 1>your eyeball is a bit too stretched out, the lens

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<v Speaker 1>will focus the lights slightly in front of the retina instead,

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<v Speaker 1>resulting in blurry vision. The hypothesis about myopia that's gaining

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<v Speaker 1>the most traction says that when the neurotransmitter dopamine is

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<v Speaker 1>released into the retina, it prevents your eyeball from elongating

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<v Speaker 1>and blurring your vision, and light is what stimulates this

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<v Speaker 1>release of dopamine. Normally, a pair of glasses or contact

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<v Speaker 1>lenses is all that's needed too sharpen your vision. However,

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<v Speaker 1>of those with the condition have a heightened form called

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<v Speaker 1>high myopia. People with high myopia are at a risk

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<v Speaker 1>for developing cataracts, glaucoma, torn or detached retinas, and even blindness.

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<v Speaker 1>Although no one knows how much time spent outdoors is

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<v Speaker 1>enough to forestall myopia, one researcher at the Australian National

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<v Speaker 1>University in Canberra estimated the amount at three or more

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<v Speaker 1>hours per day. It's also possible that strong indoor lights

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<v Speaker 1>could help, but Dr roheat Varma, director of the University

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<v Speaker 1>of Southern California I Institute, told us via email that

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<v Speaker 1>even if the myopia boom is not directly related, to

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<v Speaker 1>children spending more time indoors looking at a screen quote,

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<v Speaker 1>These are two sides of the same coin. Spending more

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<v Speaker 1>time indoors equates to spending less time outdoors, especially during

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<v Speaker 1>the day. Researchers are still trying to determine the real

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<v Speaker 1>fix for the myopia epidemic. Dr Claarin said other studies

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<v Speaker 1>have shown that a low dose of atropine eye drops

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<v Speaker 1>can also slow the progression of myopia. These studies are

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<v Speaker 1>completely unrelated to the studies on being outdoors, so there's

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<v Speaker 1>obviously more than one mechanism at play. Hopefully, continuing research

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<v Speaker 1>will shed some light on this growing problem. Today's episode

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<v Speaker 1>is based on the article half the World will be

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<v Speaker 1>near sited by fifty on how stuff works dot Com,

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<v Speaker 1>written by Melanie Radzekei McManus. Brain Stuff is production by

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<v Speaker 1>Heart Radio in partnership with how stuff Works dot Com

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<v Speaker 1>and is produced by Tyler Clay. Four more podcasts my

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