There is a name for our pained eyes: Computer Vision Syndrome. CVS, similar to carpal tunnel syndrome, occurs when your eyes are continuously staring into a screen (more often than not: a computer). Much like other repetitively straining actions, CVS can deteriorate your temporary vision the more stressed your eyes are. CVS is very common in this day-and-age; research shows that between 50 percent to 90 percent of computer-using employees incur symptoms. However, the real question is whether or not this degeneration is permanent, advancing with age and time, or merely transient. Research exposes all sides...
Several studies show that the screens themselves are not doing the actual damage. However, the atmosphere in which the screens inhabit are creating the extra stress on our eyes - like lighting, placement, glare, etc. So, it appears to be the case that while we were always told not to sit too close to the television screen, it is actually an old wives tale. According to the American Academy of Ophthalmology (AAO), they have not [yet] discovered evidence that such an act can damage our eyes.
With that being said, we are always advised to still sit at least twenty to twenty-four inches away from our computer screens. There must be a reason for a recommendation like this. Other sources say that prolonged exposure to the computer, while already experiencing symptoms of CVS can actually permanently impair your distance vision.
The truth is we don't know all of the after-effects of what will harmful to us, or not as technology continuously grows. We do know that while reading in general is more straining for our eyes than something that doesn't demand a lot of focused attention, computer use is still harder on our eyes than simply reading from a piece of paper. This is mainly because of reflections of light bouncing off of the screen, and the fact that there tends to be more going on for our eyes to focus on whilst staring at screen, than just words in a book.
So, there it is: generally speaking, our eyes won't necessarily be worse-off as we age than our parents or grandparents. Of course, age may very well increase our chances of needing prescription eyeglasses, we may just be in the same situation as they currently are. However, just in case, always try to wear glasses while you work on the computer or watch television - even if they are cheap eyeglasses with only anti-reflective coating on them. If nothing else, doing this will help your fleeting optical annoyances, and very well could save your vision in the long run.