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Playing Outside May Reduce Nearsightedness

Leigh showing the difference between normal eyes and nearsighted eyes.
Leigh showing the difference between
normal eyes and nearsighted eyes.

Encouraging children to play outside can help fight obesity, but that's not the only benefit. Surprising new research now seems to link exposure to sunlight with reducing nearsightedness.

You read that right. Playing outside 10 to 14 hours a week may help reduce the risk of nearsightedness. Here's how doctors came to that startling conclusion.

Researchers have been looking into the matter because the rates of nearsightedness have risen so dramatically in the last 40 years. In the 1970s, myopia (the clinical term for nearsightedness) was prevalent in about 25 percent of Americans between the ages of 12 to 54. By the year 2000, the incidence of myopia had increased to 42 percent in that same population. That's a startling 68% increase!

In other countries like Singapore, the rate of increase is even higher. In the late 1980s, 43 percent of all young men were diagnosed with myopia, but by 2010 that rate had risen to over 80 percent. That's an increase of 86% in under 30 years.

One of the seemingly obvious culprits was the increase in the amount of "near work" people were engaging in. Reading, television watching, computers, cell phones and gaming units were all suspected because they caused the user to focus on objects up close, for much longer periods of time than previous generations did. The only problem is the clinical studies weren't backing that theory up.

Researchers also noticed the rates weren't increasing in rural areas. Even when rural populations had access to all the modern conveniences like television and computers, the rates of nearsightedness were staying about the same. Something was different in the daily activities of rural and urban populations. Scientists now think one of the important differences is sunlight.

Here's the technical description of what researchers think is happening. Bright light stimulates the release of the neurotransmitter dopamine in the retina. That stimulation limits eye growth. A normal eye can take an image and focus it directly on the retina, keeping near and far objects sharp. When your eye grows too long, it changes your focal point and causes nearsightedness.

  • By staying indoors and avoiding sunlight, our bodies don't release enough dopamine in the retina, the eye grows more than it should and myopia is the result.

  • A variation of that theory is that eyes don't have to work as hard in outdoor light, so they're in a more relaxed position. That relaxation may shut down growth signals that could distort the eye's shape and lead to nearsightedness.

Before you try turning on a bunch of bright lights in the house, you should know there's a huge difference between the intensity of indoor lighting and the sun. When you're indoors, the average house lights give off a little less than 1,000 lux. (Lux is a measure of light intensity.) When you're outdoors on a sunny day, you're exposed to between 28,000 and 130,000 lux. Indoor lighting simply can't compete with the light intensity of the sun.

When you head outside, don't forget to use common sense. Apply sunscreen to exposed areas and don't hesitate to use sunglasses or a hat to shield the eyes. Don't worry, there's no evidence that sunglasses or hats will hinder the protective effect of sunlight. It's believed the level of illumination (the lux) from the sun is too high to be stopped.

This field of research is new, evolving and this information is subject to change. Typically my medical review staff suggest I avoid making recommendations on studies that are still so fresh. The reason I'm sharing this information is because there are so many positive health benefits from children playing outside, the possibility of better eyesight might be the tipping point that encourages you parents to get your kids out of the house more.

Spending an hour and a half to two hours a day outside can help decrease childhood obesity and potentially reduce the risk of nearsightedness. Are you ready to send your kids out to play?

UPDATE: 5/24/2016

Let children play outside to reduce their chances of being nearsighted.

In 2013 we wrote an article about some surprising research on nearsightedness. Over the last 30 years, it's increased an unheard of 68%. Researchers didn't believe it was the modern conveniences (television, computers, cell phones, etc.) that were causing the problem, but rather a lack of exposure to the sun.

When we ran the article, we suggested the solution was to let children play outside for an hour and a half or more daily, as they were growing up. Now a couple of important things have happened.

First, more research has been done that verifies what we initially said. It's not a problem from kids staring at computers or phones all day, it's a lack of sunlight. Kids simply aren't outside getting enough.

Second, the time kids need to spend outside isn't nearly as high as originally thought. Just 40 minutes a day can dramatically lower a child's chances of developing myopia or nearsightedness. What are you waiting for? Get outside and play!

A link to the research paper is here: Prevention of Myopia in Children, JAMA September 15, 2015, Vol 314, No. 11

UPDATE 6/4/2020 - Online Vision Test - Stanford Acuity Test (StAT)

Measure your distance vision, from home, using an AI-based vision test developed at Stanford University.

Link is here: https://myeyes.ai/

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Updated 5/24/2016
Updated 6/4/2020