I had fantastic eyesight when I was young. I could read street names from about 500 yards when my folks couldn't even see the signs.
But a couple of years ago I went to the doc about constant headaches and an eye test showed I needed reading glasses. Didn't stop the headaches, but that's another story. Now to be honest, these glasses are barely shaped at all. Their magnification is practically nothing, but the difference when I put them on is amazing. I can read things without them, but small text at about 60 or 70 yards basically turns into an illegible blur.
I think the problem is that these days things have been set up so that everything you need is close to you, especially office jobs. So your eyes get no exercise switching focus from near to middle distance to far and the muscles get lazy.
I don't wear my glasses at work for this reason. It means that during the day the muscles have to work more as I'm walking round the office or looking around at people, or just staring into space (which I do a lot)
Of course it's still getting worse, even with the glasses, I can tell. Hopefully I won't ever get to the stage where I need them all the time, but you never know.
Creepy as it may sound, they're doing amazing things with bionic eyes for completely blind people these days. The current cells are too small for decent resolution (I think the first one was 8x8 resolution, the newer ones are far higher), but the previously 100% blind test subjects can tell shape and colour. Which is better than nothing. And with chips getting smaller all the time it won't be long until you'll be able to get 1080p eyeballs with 2ms response or something
So I wouldn't worry too much about going blind. All that's happening is your muscles failing, same as happens to any muscle that doesn't get used as much.
Try spending a few minutes each day just switching your focus between distances. Look at your hands for a few seconds, then maybe across the other side of the street for a bit, then the other end of the street, then something just below the horizon. You might not reverse the process, but you can certainly slow down it's progress.