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Go out and play

Parents used to tell their kids to eat their carrots for good eyesight. While good nutrition is always important, scientists now offer equally simple and beneficial advice: Go outside.

As the rates of myopia, or nearsightedness, in children rise around the world, Dr. Donald Mutti, an optometry researcher at The Ohio State University, is among a group of researchers globally who have studied sunlight’s effect on nearsightedness.

They recommend two hours of sunlight a day to help children avoid developing myopia.

We talked with Dr. Mutti about his findings and how parents can help.

Your research is telling us that time spent outdoors can actually help prevent nearsightedness. Is this true no matter where you live?

Time outdoors reducing the likelihood a child will become nearsighted is something that almost all research groups agree on, no matter where they are in the world — which is really unusual because what causes nearsightedness has been a subject of controversy for a few hundred years.

What about the outdoors prevents myopia? Is it brighter light, exercise, vitamin D?

Our preliminary data supports the hypothesis that it's because the light is brighter. That creates a release of dopamine from the retina, and that dopamine slows down the growth of the eye, keeps the eye smaller and prevents or lowers the risk of becoming myopic. Vitamin D may still have a small part to play.

Is it possible to recreate that bright light indoors?

The idea of a glass-cube classroom is being tried in Asia. That may be one of the strategies that becomes something schools are willing to adopt, making the indoor light environment brighter.

From what we can tell, though, the amount of light that you need to get the goodness of time outdoors has to come from outdoors right now.

Tell kids: Go outside. Get the extra benefits of a little physical activity, the extra benefits as far as general health goes, the physical activity. Don’t forget sunscreen. Don’t forget sunglasses. Have fun.

You bring up a good point. How do you balance greater exposure to outdoor light with protection from UV rays?

Ultraviolet rays are harmful to the skin and the eye. People need to remember that spending time outdoors means applying the usual protections as far as skin and eyes go: sunscreen, sunglasses, a hat.

What are the health concerns associated with myopia?

Beyond the inconvenience of wearing glasses or contacts or having refractive surgery such as LASIK, which has its limitations because corrections change, there are health consequences to being nearsighted: retinal detachment, glaucoma and cataracts are all related to being nearsighted.

The increased risk is low at low levels of myopia, but it's still there.

In Asia, where about 80 percent of children are nearsighted, myopic macular disease is becoming a significant factor in visual impairment and new cases of blindness.

Can parents prevent their children from becoming myopic?

Well, children should select their parents wisely, because it does start with genetics. Kidding aside, there is a certain genetic risk that's inescapable.

In general, the chances that two myopic parents will have a myopic child, at least for European heritage, is about 40 percent.

But if the child of two myopic parents doesn’t spend much time outdoors, their chance of becoming nearsighted increases to about 60 percent.

If the same child spends about two hours outdoors every day, the chances of becoming myopic drop to 20 percent.

What if your child already wears glasses? Does the exposure to outdoor light have an effect?

This is one of the mysteries about the positive effect of outdoor light. Children who are nearsighted do not get the same beneficial effects. That's in our data, and that's in data from Asia as well. It does not slow down the rate of progression in children who are already nearsighted. It will take a lot more work to figure it out.

Does a myopic kid need to spend two times more time outside? Do we need to start at age 3 for every child to benefit from time outdoors? These are great questions for the future.

Is there anything parents can do to help slow the progression of myopia if it already exists?

We’re testing peripheral optical treatments that use multifocal contact lenses to slow the progression of myopia, through a National Eye Institute study at Ohio State called BLINK.

We’re also studying overnight orthokeratology, which uses gas permeable contact lenses to reshape the cornea.

The other myopia treatment is low-dose atropine. Atropine is something that's been used as an anti-myopia therapy for more than 100 years, but usually in a high dose that kids can't tolerate.

Researchers have found that very low doses are way more tolerable to kids and also seem to have some benefit. Many eye-care providers offer peripheral optical treatments or low-dose atropine.

These are all in the category of they won't do harm, and they might do some good.

What about reading on phones and tablets — doesn’t that strain eyesight?

While there is some controversy over the role of reading and other close work on computers, smartphones, tablets — all the trappings of school in modern society — we can't find any evidence that any aspect of what we call “near work” affects a child's risk of becoming nearsighted or the rate of progression of their nearsightedness.

I'm not sure that everybody across the globe would agree with that statement, but that's what our research shows. We started our longitudinal study in 1989, finished in 2012 and enrolled just under 5,000 children. I'm not sure that anybody's going to do it any bigger or any longer.

Do you wear glasses?

I have one eye that's nearsighted and one eye that's farsighted. Part of my reason for getting into eye care was I had a lot of eye problems as a child. I’ve got a lot of sympathy for anybody's prescription. I wore contact lenses for a lot of years. Then, when I hit the magic age of needing something for near, I just bailed out and got glasses. And they’re working very well, too. Regular eye care is good for every age.