00:00You've been told your whole life, don't watch too much TV, it'll ruin your eyes.
00:04But here's the twist, it's not the screen that makes you nearsighted.
00:07It's being locked inside. Sounds like a stretch.
00:11There's an experiment that all but proves it. In China, about 80% of high school students wear
00:16glasses. In the countryside, around 15%. A five-fold gap. You might think East Asians are
00:23just genetically prone to bad eyes. This experiment demolishes that. Researchers took
00:28two groups of Chinese children, ages 6 to 7. One group lived in Sydney. The other in Singapore.
00:35Same bloodline, similar income, almost identical conditions. Result? Sydney, 3.3% nearsighted.
00:43Singapore, 29.1%. Nearly a nine-fold difference. But here's the unsettling part. The Sydney kids
00:51actually spent more time studying at desks than the Singapore kids. The group that read more had
00:56one-ninth the nearsightedness. So what different? Outdoor time. Sydney kids, 13.75 hours outside a
01:04week. Singapore kids, just 3. It's only about 10 hours a week. And they're not doing anything special,
01:11just running, jumping, zoning out. How does that create a nine-fold gap? The answer lies somewhere
01:17almost nobody thinks to look, light. First, be clear, myopia isn't your eyes getting weaker.
01:22It's your eyeball getting longer. When the eyeball stretches, focus falls in front of the retina,
01:28so distance blurts. That's why myopia is irreversible, a stretched eyeball doesn't shrink
01:32back. Glasses, contacts, laser, they correct the focus, they don't cure it. So what makes the eyeball
01:39grow long? The leading theory, the dopamine hypothesis. Strong light hitting the eye triggers
01:44the retina to release dopamine. And dopamine slows eye growth. The key word is strong light.
01:51Light intensity is measured in lux. A well-lit classroom. Maybe 400 to 500 lux. Step outside,
01:58even cloudy, even under a tree, even with sunglasses, and you're at about 10,000. Outdoor light is roughly
02:0420 times brighter than indoor. So it's not the screen hurting your children's eyes. It's that.
02:10The house doesn't have enough light. You might say, my living room feels bright. That's exactly
02:16the cruel part. Your eyes adapt fast, your pupils dilate, and your sense of brightness gets flattened.
02:22You can't feel that 20-fold difference. But your retina can. And it doesn't tell you through feelings.
02:28It tells you through your kid's prescription a decade later. All that was observational.
02:33And observation carries a suspicion, what if kids who love the outdoors just don't strain their eyes
02:38reading? To rule that out, someone had to run an experiment. In 2009, researchers in Guangzhou did
02:44exactly that. They randomly picked six primary schools. For some six to seven-year-olds, they added
02:50a 40-minute outdoor class before the end of the day. Everything else stayed the same. Three years later,
02:56the outdoor group had a 30% myopia range. The control? 40%. 40 minutes a day, three years,
03:0310 points. And the truly protective dose is about three hours. Even a third of that crushed 10 points.
03:10Then 2020. Handed everyone a reverse experiment. Kids were locked at home doing online classes.
03:17A Chinese study published in the Journal of the American Medical Association recorded it.
03:21Among third-graders of the same schools, myopia jumped from 13.3% in 2019 to 20.8% in
03:282020.
03:29Compared to the previous class, their eyeballs grew 0.08 millimeters longer. Less than the thickness
03:34of a hair. But that eyeball is never going back. Now a bit of fairness. Close-up use isn't completely
03:41innocent. International consensus is clear, myopia does rise with education level. Long hours of
03:47reading may be a factor. But the same documents say this, myopia was already spreading before screens
03:53existed. The phone isn't a brand new culprit. It's just a new form of close-up work.
03:58Push to the front to take the blame. You might say 10 points isn't much. But about 20% of
04:03nearsighted people develop high myopia. That means the eyeballs stretch too long, the retina thing too
04:09much. Retinal detachment, macular degeneration, glaucoma. Risks all climb. And the earlier you
04:16become nearsighted, the more likely you end up highly nearsighted. So those 10 points aren't just
04:21about glasses. For some, it's their retina decades down the road. The prescription is simple.
04:27Two to three hours of outdoor time every day. No strenuous exercise needed. Walking, spacing out,
04:33sitting still all count. The key is being outside, where your eyes catch natural light.
04:38Even overcast days work. The light won't hit sunny day levels, but it's still far above any indoor
04:44space. Through glass. Basically useless. Sitting by a window can't replace going outside. Already
04:54show the outdoors protects against worsening myopia at least to age 30. And one more thing,
04:59pass this on to the kids you know. Because the best time to save their eyesight is right now,
05:04on the other side of your front door.
05:34Visit school. We Brandsburgec countries. And find us facing up your dad
05:35highest maintenance. So those at least görev this is my situation. So there is sort of a
05:38closeout. all has the best of your attitude to you know. Has a good voy at this
05:41part of your watch. Byclock,ピ kaylee. Do not get like this one better.
05:41And remember what you mocked your job is for those of you.
05:42To the kids you know. The honey frigu kısy and try it up around and think about yourself.
05:43So this one has done a sudden the practice. With this reason by trying to
05:43you, we will finally do very short. The巴ill so clever on the show isn't
05:43of tonight. But you're off. We will always switch some steps in policy.
05:43Anyway you touched your life in the car. We want to go with that.
05:43Got around.
