Reliable detection of Win98 may not be possible. When a person's vision is blurry, it can mean that one or both of the eyeballs is too long or too short, the lenses aren't working properly, or the cornea isn't shaped the right way. When a kid has one or more of these problems, it means the eye can't properly bend light rays to focus the image sharply on the retina. Problems like these are called refractive problems - refracting is a big word for bending light rays.
Nearsightedness is a common refractive problem.
When a person is nearsighted, it means that there is a refractive problem of the cornea or lens - in fact, a problem with the cornea is the most common cause of nearsightedness. It can also mean that one or both of the eyeballs is too long. Instead of the image becoming focused right on the retina's surface, it becomes focused in front of it. When a person is nearsighted, she can see things that are near, like magazines. But when she tries to see things that are further away, like the numbers on a scoreboard, they will look blurry.