Monday, September 10, 2012

Nearsightedness: Nature or Nurture?

Does it seem like there are more nearsighted kids running around than there used to be? If it does it's because there ARE more nearsighted kids! Why is that? Is the some sort of genetic change, an evolution thing? Are nearsighted parents having more children than farsighted parents? Or is it something in the environment? Some new exposure that older people didn't have that is now promoting nearsightedness in our kids?

It turns out that the answer to all of these questions is YES! Nearsightedness, or MYOPIA, is genetically programmed into some people. Children DO inherit the tendency to become nearsighted from their parents. Dr. White likes to say that the acorn never falls far from the tree! Being able to see things up close is probably an evolutionary thing, a part of the changes in the human brain that provide an advantage for survival.

What is probably different nowadays is the fact that even some kids who have a mild tendancy to become nearsighted almost always do just that. In generations previous someone might end up with little or no nearsightedness even though they had the genentic tendency to do so. Here is where the nurture or environmental part of the equation comes into play, but not in the way you might think. There is no THING that our kids are exposed to. No chemical or substance in their surroundings. It is rather the ACTIVITIES that they are now exposed to in a greater amount that probably explains the increase in nearsighted kids.

It turns out that the more up-close visual work a child does while growing, the greater the likelihood that he or she will become nearsighted. Think about how much more reading kids are doing now, and much younger at that. Now add in all of the gadgets and "screens" they use, again at a much younger age. Computers, video games of all sorts, cell phones and tablets. All of these increase that amount of stimulation for that genetic tendency to become nearsighted to kick in!

Tha opposite appears to be true as well. We have seen at least a dozen studies that show that kids who play outside, especially in the sunshine, end up less nearsighted than kids who are inside all day. Is this because of exposure to sunlight, or because they are not in front of a screen while they are playing? Nobody knows the answer to that particular question.

In the end moderation in all things is probably still the best policy. Go ahead and encourage your kids to read and read a lot. But also send them outside to play!

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