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. 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. 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 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 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 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 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
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 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 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 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 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 Heart Radio, visit the iHeart Radio app, Apple Podcasts, or wherever you listen to your favorite shows.