Quantcast
Health

Surprising Reason Why Nearsightedness Has More Than Doubled in 50 years

In certain parts of the world, children are developing myopia—or near-sightedness—at much higher rates than they have in the past, according to an article published in the esteemed scientific journal Nature.

In China, rates of myopia have increased from 10–20 percent 60 years ago to as many as 90 percent of young adults today. Photo credit: ImagineChina/Corbis

Myopia, which causes blurred vision and requires prescription lenses, is reaching epidemic proportions in some populations; in China, rates have increased from 10–20 percent 60 years ago to as many as 90 percent of young adults today. The rates of myopia in the U.S. and Europe have doubled during the same time period.

According to the Nature article, researchers have explored the many possible reasons for these increases, and have proposed genetics and watching more television as possible explanations.

Several reports published in the last 10 years suggest a related—but very different—reason for the cause. Research at Ohio State University and from Australia found that children who spent less time outside were more likely to develop myopia. Australian researchers then identified the reason why spending more time inside effected eyesight: children’s eyes got less exposure to direct sunlight.

Specifically, looking at sunlight less actually changes the shape of the eyeball to become elongated. As a result of an elongated eyeball, light gets focused front of the retina instead of on the retina. This change in where the eye focuses light causes people to see less clearly and have difficultly seeing objects far away.

“We're really trying to give this message now that children need to spend more time outside,” Kathryn Rose, head of orthoptics at the University of Technology, Sydney, said in the Nature article.

Ian Morgan, a myopia researcher at the Australian National University in Canberra, stated in the Nature article that children should spend three hours per day under light levels of at least 10,000 lux. This amount of sunlight will protect them from developing myopia. Ten thousand lux would be about the amount of light someone would get from sitting under a shady tree on a bright summer day while wearing sunglasses. A well-lit schoolroom or office provides a much lower amount of lux light—generally less than 500 lux.

In Australia, where three hours of outdoor time is normal, only 30 percent of 17-year olds are nearsighted. In other parts of the world where myopia rates are higher—like the U.S. and Europe—many children don’t see more than an hour or two of outdoor time.

“We've got proof of principle that increasing the amount of time children spend outside actually works,” Dr. Morgan said in Nature. “The question then is how do we make this work in practice at a level that would have a significant impact?”

Programs and research are in the works to measure the benefits of adding outdoor class time to school schedules. So far, notable improvements in myopia rates are being seen when compared to control groups.

Dr. Morgan is now working on programs to have classrooms made of glass so that children can be exposed to high levels of lux light during school hours.

YOU MAY ALSO LIKE

Obama Initiative Seeks to Get 4 Million Fourth Graders Exploring America’s Public Lands

Top 10 Park Systems in the U.S.

Are You Flushing Your Baby Wipes Down the Toilet? Here’s Why You Shouldn’t

Show Comments ()

EcoWatch Daily Newsletter

Sponsored
Health
Bob Berg / Getty Images

How Summer and Diet Damage Your DNA, and What You Can Do

By Adam Barsouk

Today, your body will accumulate quadrillions of new injuries in your DNA. The constant onslaught of many forms of damage, some of which permanently mutates your genes, could initiate cancer and prove fatal. Yet all is not doomed: The lives we lead determine how well our cells can handle this daily molecular erosion.

Keep reading... Show less
Animals
Emilie Chen / Flickr / CC BY-ND 2.0

Against All Odds, Mountain Gorilla Numbers Are on the Rise

By Jason Bittel

The news coming out of East Africa's Virunga Mountains these days would have made the late (and legendary) conservationist Dian Fossey very happy. According to the most recent census, the mountain gorillas introduced to the world in Gorillas in the Mist, Fossey's book and the film about her work, have grown their ranks from 480 animals in 2010 to 604 as of June 2016. Add another couple hundred apes living in scattered habitats to the south, and their population as a whole totals more than 1,000. Believe it or not, this makes the mountain gorilla subspecies the only great apes known to be increasing in number.

Keep reading... Show less
Animals
Sumatran Orangutan Conservation Programme / Maxime Aliaga

300+ Mammal Species Could Still Be Discovered, Scientists Say

By Sara Novak

You can't protect an animal that you don't know exists. Tapanuli orangutans, for example, are found only in the Tapanuli region of Sumatra; they were only identified as a species last year, when scientists found them to be genetically different from other Bornean and Sumatran orangutans. With just 800 left, this newly discovered species is the most critically endangered ape.

It's hard to believe that with only seven great ape species on the planet—Tapanuli, Sumatran and Bornean orangutans, eastern and western gorillas, chimpanzees and bonobos—a species could have gone undiscovered until 2017. But, in fact, new research shows that many mammals still fly under the radar.

Keep reading... Show less
Climate
An iceberg is threatening to break and flood the village of Innarsuit. Karl Petersen / Getty Images

Giant Iceberg Threatens Tiny Greenland Village

Add another potential disaster to the climate change hazard list: iceberg caused tsunamis.

Keep reading... Show less
Sponsored
Animals
A Kemp's ridley sea turtle like this one was found strangled by a beach chair Saturday. EPA

World’s Most Endangered Sea Turtle Found Strangled by Beach Chair

An extremely endangered sea turtle was found dead on a Fort Morgan, Alabama beach Saturday, strangled by an abandoned beach chair, the Miami Herald reported Sunday.

The turtle's death was documented by a series of Facebook posts by the Fort Morgan branch of Alabama sea turtle conservation group Share the Beach.

Keep reading... Show less
Animals
White-tailed deer flee in a nighttime photograph. George Shiras

People Are So Annoying That Animals Are Becoming More Nocturnal

By Jason Bittel

It's official: Animals around the world are sick of our sh . . . enanigans.

Keep reading... Show less
Sponsored
Food
Garlic mustard flower. Gary J. Wood / Flickr / CC BY-SA 2.0

10 Edible Weeds Likely Growing in Your Yard

By Brian Barth

You work so hard on your vegetable garden, primping and pruning to the point of exhaustion each spring. One of the biggest chores, of course, is weeding. But in doing so, you might be throwing away valuable produce.

Keep reading... Show less
Health
Pixabay

If Meditation Is Not Your Thing, Try a Walk in the Woods

By Karin Klein

There are times when I don't know what to do with myself. I feel at odds with the world, irritated by the people in it, in a funk about myself and what I'm achieving or, rather, not achieving, overwhelmed by the obstacles and complications of life. Happiness seems like an entirely elusive state of being.

Keep reading... Show less
Sponsored

mail-copy

The best of EcoWatch, right in your inbox. Sign up for our email newsletter!