Will sitting too close to the TV, reading with bad light, etc., ruin your eyes?
When I was a little kid my mother always warned me not to sit too close to the TV because it would "ruin your eyes." Now I am saying the same thing to my two sons. Is this really true? Exactly what eye damage can occur? Is there an optimal distance from which to view a television screen? I am aware of the mental damage that children can incur from watching television but have never been clear about the adverse physical effects of this pastime.
First the good news: according to most eye specialists, claims that you'll ruin your eyes by sitting too close to the TV, reading in bed, using inadequate light, etc., are old wives' tales. The bad news is that the old wives may have been right.
First let's dispose of the TV threat. Virtually no one believes that under ordinary circumstances television watching poses any special danger. (Well, physically, anyway.) Prior to 1968 or so some sets emitted excessive X-rays, but that problem has now been eliminated. More recently concern has arisen about computer video display terminals (VDTs), which typically are viewed at much closer range than televisions; research is inconclusive so far but continuing. To be on the safe side some eye doctors say you shouldn't let your kids get closer than five feet to the TV screen, the room shouldn't be pitch black, etc. But the intention is to prevent eye fatigue, not eye damage.
The more general (and more interesting) question you raise is this: is it possible to ruin your eyesight through overuse, close work, inadequate light, and so on? The usual answer from the MDs is no. But don't be too sure. A fair number of people believe that some eye problems, notably myopia (nearsightedness), are a "product of civilization," as one researcher puts it.
The most striking demonstration of this was a study in the late 60s of eyesight among Eskimoes in Barrow, Alaska. These people had been introduced to the joys of civilization around World War II. The incidence of myopia in those age 56 and up was zero percent; in parents age 30 and up, 8 percent; in their children, 59 percent.
The same phenomenon has turned up in studies of other newly-civilized peoples, suggesting that modern life somehow causes nearsightedness. But how? Nobody knows. The shift among the Eskimoes appeared to be too sudden to be explained by genetics alone (although there is little question that a predisposition to nearsightedness is inherited). On the theory that too much close focusing while young permanently distorts the eyeball, some experts gave kids regular doses of atropine, which relaxes the eye muscles. (Eye doctors use it to dilate your pupils prior to an exam.) A few claimed this halted myopia but failed to convince many of their peers, and there was the obvious practical problem that with your eyes dilated you couldn't see for beans.
Other researchers blame dietary deficiences, e.g., not enough copper or chromium; excessive exposure to pesticides; and so on. But nothing has been proven.
Animal studies tend to support the idea that myopia is caused by eyestrain. Normal monkeys are not myopic; neither are monkeys whose eyes are kept completely sealed off from light. But monkeys whose eyes were sutured so they could see only dimly (I realize this is the kind of thing that outrages animal rights activists) did become myopic, presumably because they could see something and strained their eyes trying to see more.
The idea that the civilization means bad eyes is by no means universally accepted. The Alaska Eskimo study, for example, was criticized for not testing a random sample--presumably the main reason kids were brought to the Barrow clinic was that their parents thought they had vision problems, which of course skewed the results. Other studies have failed to find a correlation between environment and vision.
So what's a father to do? Search me, pard. If you buy the eyestrain argument you could feed the kids whale blubber and chuck the books, TV, and needlepoint lessons, but the tradeoff might not be worth it. Having to wear eyeglasses is hardly a major handicap these days whereas being an uneducated mope is. Till such time as the myopia-inducing component of civilization (if any) is isolated, you're probably best off chalking up a little nearsightedness as a small price to pay for indoor plumbing.