Most eye doctors will assure you that watching too much television won't permanently damage your eyes. However, it's worth noting a few interesting studies on the subject. Several of these reports have illustrated a link between myopia (nearsightedness) and environment.
First, a little bit about your eyes and myopia. The cornea and the lens are the parts of the eye that focus images. In a normal eye, these parts have a perfect shape and curve. The curve refracts light so it makes a sharply focused image right on the retina. In a myopic eye, the cornea or lens usually curves too much, causing a refractive error. This causes the light to focus in front of the retina, making faraway objects appear blurry.
If you suffer from myopia, you can see nearby objects clearly, but objects far away are out of focus. You might have to squint to see more clearly. Myopia can be slight or severe and is easily treated with corrective glasses or contact lenses.
Some people believe that environmental factors may also cause myopia -- like sitting too close to the television or computer monitor, or too much close reading. Back in the late 1960s, a controversial study of Eskimo families ignited this debate. Researchers studied a group of Eskimos who hadn't been introduced to formal schooling or modern civilization until around World War II. The researchers made an interesting discovery -- in this group, people aged 56 or older had zero incidence of myopia. Parents aged 30 and up had about an 8 percent incidence, but their children -- who were the first of their group to start reading -- had a 59 percent incidence of myopia. The obvious conclusion was that close focusing, like reading, caused myopia. Some question this study, however, since the children who were tested were brought to the eye clinic because their parents already thought they had vision problems [source: Adams].
More recently, an Australian study found that children who spend more time outside don't develop myopia as often as children who spend more time indoors. The study compared two groups of children. Both groups spent an equal amount of time watching television, reading and playing computer games. However, one group spent only 30 minutes a day outside, while the other group spent about two hours outside. The second group had much fewer instances of myopia, leading researchers to believe that the sun may help regulate growth of the eyeball during childhood. Time spent watching TV didn't make much of a difference.
While watching TV may not cause blindness or any other permanent damage to the eyes, it can cause eyestrain. More about that on the next page.