Somewhere between ages 40-50 everyone's eyes lose their ability to refocus. Instead of having a limited range of focus, you will have a single fixed point and your prescription will be changed to suit that need, or maybe you will have multiple pairs of glasses for different situations (computer glasses, car glasses, etc). Look forward to it!
Telling people about this is one of those xkcd 'my hobby:' things for me. It seems like it is widely not in our public health curriculum even though it is something almost all humans will get to enjoy at that age.
I'm mid 50s now and, over the past couple of years have noticed a deterioration in how close I can focus. My minimum focussing distance is probably about 30-40cm now. Which means, as long as the font size isn't minuscule, I can still read most things by holding them slightly further away. I 'joke' that as long as my my focal length is shorter than my arm, I can avoid the embarrassment of having to adopt reading glasses.
In this respect, the fact that a lot of the reading we do these days is on-screen, is a godsend, as you can generally increase the font size. However, I do carry a wee magnifying lens in my pocket for those times when I'm out and about and can't make out the small print on the label of something I'm thinking of buying.
Someone said, in effect, "So what. I've worn glasses since I was 11". I think that misses the point. It's not wearing glasses per se that's the problem. For those of us who have always had sharp eyesight [Of which I'm one. My long vision is still pin sharp] it's just another depressing sign of the descent into old age and decrepitude --like losing your hair, becoming harder of hearing, etc. and, irrational though it is, I think most of us feel that, if we can mask the symptoms for a while longer then somehow we've not actually reached that stage yet.
On the subject of this thread; I read a week or so ago [on HN?] about experiments showing that exposure to long wavelength red light in the mornings could 'rejuvenate' ageing eyes. I can't find that link at the mo'.
There's two different things - the stuff you get at birth and the stuff you get as you get older.
Short sightedness (myopia), long sightedness (hyperopia) and astigmatism are effectively genetic conditions that you are born with. They are variations of your eye being slightly the wrong shape to focus correctly. The precise impact of this varies as you grow with your prescription changing, but if you need correction then you'll need it from a young age onwards (unless you have it permanently treated - e.g. Lasik, or cataract surgery).
Presbyopia is an effect that happens over time. The lens hardens and so the muscles that manipulate it to refocus can't quite do the job any more. This impacts on your ability to close distances, and so you can off the shelf reading glasses to aid in that.
Telling people about this is one of those xkcd 'my hobby:' things for me. It seems like it is widely not in our public health curriculum even though it is something almost all humans will get to enjoy at that age.