This subject has been on my mind too. When I took up shooting regularly at 45 (7 years ago) I already lost one eyeball due to disease which is not a shooting problem but the other eye is going downhill. I look over my glasses to get the front blade in focus which makes the target fuzzy. It doesn't stop me from enjoying going but it would be nice to shoot better before I have to give it up. Last week I noticed Bob Munden still shoots like there's no tomorrow so there's still hope I guess. He must be well into his 60s and he hit a balloon at 200 yards offhand with a snubbie 38.