70s Americans Had Strong Eyesight. Four Decisions Changed That

追加: 2026-05-25

[00:00:00]Pull out your old-school class photo.

[00:00:04]A fifth-grade class from 1972.

[00:00:07]A high school yearbook from 1975.

[00:00:10]A group of friends sitting on the lawn at the end of the year.

[00:00:14]Look at the eyes.

[00:00:16]Look at the faces.

[00:00:18]Almost nobody's wearing glasses.

[00:00:20]30 kids in the picture, maybe one has frames, maybe.

[00:00:26]Now, look at your grandkids' class photo.

[00:00:29]Count again.

[00:00:31]In your old picture, almost every kid could see across a room. In theirs, almost half of them cannot.

[00:00:40]In 1971, one in four young Americans was nearsighted. By 2004, it was nearly half.

[00:00:47]In parts of East Asia today, more than four out of five high schoolers cannot see clearly across a classroom.

[00:00:54]By 2050, researchers project that 740 million children on Earth will be myopic.

[00:01:01]In this video, we're going to uncover four hidden things built quietly across schools, homes, and entire industries during your lifetime that reshaped how the developing eye grows.

[00:01:11]And by the time we reach the end, you will get something that most people don't quite understand.

[00:01:16]It was not bad genes from your side of the family. It was something much bigger than that.

[00:01:22]The world around the eye changed in ways that made it harder to see.

[00:01:27]Stay with us. The fourth thing is one almost nobody has heard of, and there is a country that has already proven the whole thing can be stopped.

[00:01:36]You remember how the days worked.

[00:01:38]Mornings began outside. You walked to school. Recess was outdoors. After school, you dropped the books at the door and went back out until dinner. On weekends, you disappeared into the neighborhood, into backyards and sidewalks and the empty lot behind the school. That was childhood. Outside.

[00:01:59]Researchers estimate the average kid in 1975 spent several hours every day outdoors. Not running a marathon, just outside under real sky. Eyes open to the horizon.

[00:02:13]That sounds like a small thing. It is not.

[00:02:17]Bright outdoor light, the kind your eye gets from real sky, releases a chemical in the retina called dopamine.

[00:02:24]And dopamine does something very specific. It tells the developing eye, very quietly, to stop growing. To hold its perfect shape. To stay round.

[00:02:36]Without enough of that sunlight, the eye keeps elongating. A few millimeters too long. And once that happens, distant objects blur for the rest of that child's life.

[00:02:47]By the 2000s, the default flipped.

[00:02:49]Outside was no longer where kids went.

[00:02:52]Inside was where the entertainment was.

[00:02:54]Inside was where the friends were, on the other end of a screen. Inside was where the schedule lived.

[00:03:01]A typical kid in 1975 averaged about 40 hours of unstructured outdoor play a week. A typical kid today averages four.

[00:03:10]Some get fewer than two.

[00:03:13]Most people didn't notice it was happening, and even fewer understood what the consequences would be.

[00:03:19]The shape of childhood just changed. And the eye, which had been built across millions of years to look up at the sky, slowly stopped looking up.

[00:03:29]But the disappearance of outdoors was just the start.

[00:03:32]Here is the second thing.

[00:03:34]Through the 1970s and 1980s, schools across the country were renovated.

[00:03:39]Big classroom windows were sealed shut.

[00:03:41]Some were bricked over entirely. New buildings went up with smaller windows, deeper interiors, and rows of fluorescent tubes humming overhead. It was cheaper. And it changed the lighting that millions of children grew up reading and writing under.

[00:03:58]Fluorescent light is not sunlight, not even close.

[00:04:01]Outdoor light on an ordinary day measures around 10,000 units of brightness. A classroom under fluorescent tubes measured 300.

[00:04:10]Sometimes less.

[00:04:12]Six hours a day, five days a week for 12 years, your kids and grandkids sat under a light their eyes did not recognize as daylight.

[00:04:21]The schools were just being modernized.

[00:04:24]Parents were told the buildings were safer and more efficient. They were.

[00:04:28]They were also dimmer than the sky.

[00:04:30]But the third thing was the one happening at home.

[00:04:34]In 1975, the average American home had one television. It sat against the far wall. The family sat 8, 10, sometimes 12 feet away. Reading was done at a desk.

[00:04:45]Homework was done at the kitchen table.

[00:04:47]Eyes had distance.

[00:04:50]Then something started shrinking.

[00:04:52]The screens got closer.

[00:04:54]In 1985, the home computer arrived, 18 inches from your face.

[00:05:00]By 1995, it sat on every desk in every house. In 2010, the phone sat 6 inches from your nose. By 2020, that screen become the place your grandkids reads, watches, works, and falls asleep at night.

[00:05:14]When a child stares at something close, a book, a screen, a phone, for hours at a time, something happens.

[00:05:21]Doctors have a name for it, accommodative strain.

[00:05:24]When the eye holds its focus close for hours at a time, the muscles around it begin to lock. The shape of the eye itself starts to shift to match what it is being asked to do all day.

[00:05:36]The 1970s eye spent its day looking across a yard, down a hallway, out to the horizon.

[00:05:41]>> [music] >> The modern eye spends its day looking at a rectangle 8 inches from its face. The eye adapted. It always does. But, the fourth thing is the one almost nobody has heard of, and it is the one that turned a problem into an industry.

[00:05:56]If you're finding this as fascinating as we think you are, hit subscribe right now. Every week, Growing Up On Screen uncovers the hidden systems behind the world you grew up in. You won't want to miss what's next.

[00:06:08]Now, let's keep going.

[00:06:10]By the 1990s, optometry as a profession had a new opportunity in front of it.

[00:06:15]Millions of children were growing up nearsighted, and every one of them needed glasses, then stronger glasses, then contact lenses, then progressive lenses by middle age, and surgery.

[00:06:27]A nearsighted child is a 40-year customer.

[00:06:30]There were studies, even back in the 1970s, showing that interventions could slow myopia in children. More outdoor time, specific lens designs, eye drops in very low concentration. These things were known, and they were published.

[00:06:45]But, they were not the standard of care.

[00:06:48]And here is something that genuinely surprised us when we found out. There is a drug, a low-dose eye drop called atropine, that in clinical trials in Asia slows myopia progression in children by anywhere from 20 to 60%.

[00:07:03]It is cheap. It is widely used in Singapore and Taiwan.

[00:07:07]The exact same trial run in the United States showed zero effect on American kids.

[00:07:13]The leading theory is that without enough outdoor light to work with, the drug has nothing to amplify.

[00:07:19]The treatment exists. It is just not the conversation in the American waiting room.

[00:07:25]Four things. Now, you have seen all four. However, the story doesn't end there, because while these four things were quietly unfolding here, somewhere else in the world, someone was running the experiment in reverse. [music] Here is what happened when one country decided to test it.

[00:07:41]In Taiwan, researchers ran an experiment across elementary schools. They did not change the food, they did not change the curriculum. They did one thing. They required kids to be outside during recess.

[00:07:54]That was it.

[00:07:55]After 1 year, the rate of the new myopia cases in the schools that did it dropped by 54% compared to the schools that did not.

[00:08:03]In the kids who were already on their way to needing glasses, the protection was even stronger, 61%.

[00:08:10]Within a single school year, Taiwan had reversed a trend that's still getting worse everywhere else in the world.

[00:08:18]China saw the data. So did Singapore. So did South Korea. Each of them is now restructuring schools around it. Less indoor study, more outdoor time on a national scale.

[00:08:30]The world has quietly already started fixing this.

[00:08:34]Here's what this actually means. The kids in those old photographs were not blessed with better genes. Their eyes were not stronger. Their family histories were not different from your grandkids.

[00:08:45]They were simply growing up in a world that had not yet been redesigned. A world with bigger windows, longer afternoons outside, distance between their eyes and the next thing they had to focus on.

[00:08:56]And then, piece by piece, that world was traded in for one that did the opposite.

[00:09:03]But here is why that is good news. It means nearsightedness was never written into your bloodline.

[00:09:08]The genes you pass down are doing exactly what they did in 1972. They just landed in a different world.

[00:09:15]And that world can be changed back.

[00:09:17]Taiwan has already proved it.

[00:09:19]The sunlight and the horizon are still out there. The simple habits, looking up, looking far, walking outside, putting the screen down, still work exactly the way they did when you were a kid.

[00:09:31]You weren't imagining it. The childhoods you grew up in had something built [music] into it.

[00:09:36]Now you know what it was, and you can give a piece of it back.

[00:09:41]The school photos from the 1970s are real.

[00:09:44]The clear eyes are real. The long afternoons outside, the wide classrooms, the room between the reader and the page, all of it was real.

[00:09:52]And so were the four quiet things that changed about how childhood would look from then on.

[00:09:58]They didn't make headlines, [music] they weren't called out, they were just absorbed into how things now were.

[00:10:04]That is what we do here at Growing Up Unseen. We take the world you grew up in, the one you remember with warmth and maybe a little wonder, and we show you what was running underneath it. Not to take anything away. The memories are the whole point.

[00:10:18]But they deserve the full story. And now you have it.