Your mom lied, sitting close to a TV = not bad

Despite the repeated warnings of your mother, sitting too close to the TV will not damage your eyes. Prior to 1968 or so some sets emitted excessive X-rays, but that problem has now been eliminated. So no damaging rays are actually given off from the set that can hurt you. However, sitting too close to the TV could strain your eyes. Some eye doctors recommend that you sit no closer than five feet from the TV screen, but this precaution is merely to prevent eye fatigue. There are some people who believe that eyestrain can lead to myopia, or nearsightedness, and a few animal studies seem to support this theory, but there is little conclusive evidence.
Several other sources confirmed that sitting smack dab in front of the TV does not damage your eyes. According to the American Academy of Ophthalmology, kids, the usual culprits, can focus up close better than adults, so they often develop the habit of sitting right in front of the television. However, sitting too close to the TV may indicate that your child needs glasses.

While TV may not ruin your eyes, the jury is still out as to its effects on your brain. via