There isn't a single person in my extended family who wears glasses, but you can develop a need for glasses through straining your eyes, as I did through lots of hours spent reading in very poor light. I even used to do the old flashlight under the covers thing so my mother wouldn't come in and yell at 4 am in the morning because I was still up reading
Those kind of eye problems don't usually get very bad, though, thank-goodness. My prescription has changed very little over the years, and I only wear them for real distance. If your eyesight isn't that bad, as you age the shape of the eyeball changes, making you more far-sighted, and the near-sightedness gets better.
The problem with contacts for some people, including me, is that they pop out constantly if you have rather dry eyes. Then you're told to put liquid tears in your eyes all the time. It was too much of a hassle so I just wear glasses for when I really need them, i.e. driving and watching tv from across a room or watching a film at the cinema.
Maybe I'm strange, but I like the way people look in the right glasses, including me.
I'm rather intrigued by the whole color blindness thing, particularly the fact that people often don't know they have it. For years my father would make what seemed like strange comments about the color of things, or when asked to go get something of a certain color, wouldn't be able to choose. When he was in his sixties he went in for an eye test because he was getting so far-sighted and they told him. From what I remember it's mostly a male thing, isn't it?