Myopia, or nearsightedness, is on the rise among both adults and children. We know that too much time in front of the computer can be to blame, but newer studies suggest time spent out in the sun may be an even more important factor. So how can we prevent or eventually correct myopia?
What Causes Myopia?
Well, doctors aren’t entirely sure because it is likely a mix of a few factors. There is clearly an observed genetic link: two parents with myopia are more likely to have a myopic child. Dozens of genes have also been associated with an increased chance of having myopia.
However, myopia is on the rise at a rate that is too fast to be explained purely through genetics. There are also many children (like me) who have two parents with perfect vision but still develop myopia in grade school. Clearly lifestyle must be a contributing factor.
Doctors have known for a long time that myopia can also be caused by overuse or stress on your eye - such as when you force the eyes to do a lot of focusing on nearby objects, like books or computer screens. As long as 400 years ago, the astronomer Johannes Kepler, blamed his own nearsightedness on his extended hours of study. In the 19th century, students were encouraged to use headrests, much like the ones we prop our chins in when we get an eye test, to stop their eyes from getting too close to their books.
Even if you don’t have myopia yourself, you may have even experienced a temporary, or so-called “pseudo,” myopia after a long period of intense work (perhaps after a marathon study session or work on a project). After bingeing on screen time, sometimes your eyes need some time to be able to focus on more distant things again.
Go Play Outside!
However, recent research into the causes of myopia is starting to turn up an even more important factor than book or computer work: time spent outside. Two separate studies have confirmed this theory. A 2007 study of 500 children in California led by Dr. Donald Mutti and his collaborators came to the same conclusion as Dr. Kathyrn Rose and her team did in their study of 4,000 children in Australia conducted around the same time.
The result: Children who spent less time outdoors had a higher chance of getting myopia!
The benefit of being outdoors seems to be anchored in the increased light exposure, but the specifics of why this works are still being explored. Some doctors believe that the additional bright light causes a release of the neurotransmitter dopamine in the retina which stops any elongation from happening.
As we learned in the earlier Everyday Einstein episode on anxiety, neurotransmitters are chemicals that aid in passing information across the gaps between our neurons so that our brain can communicate with the rest of our body.
Not all doctors agree that the link between light exposure and nearsightedness is so clear, in part because most of the studies connecting the two rely on sometimes inaccurate self-reporting of daily activities. More studies are needed in this active area of research that is becoming an issue for more and more of the population.
In the meantime, getting more time outside – or at least time away from technology - either for yourself or for your children can’t hurt. I know I’ll be headed to the park this weekend (well, as soon as it stops raining).
Until next time, this is Dr. Sabrina Stierwalt with Everyday Einstein’s Quick and Dirty Tips for helping you make sense of science.
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