Guys,
The eyesight issue is a very valid problem as we get older. I did about three years worth of reserch for a magazine article about eyesight and shooting. What I found was that far sighted people are able to shoot well for a much longer period of time as compared to those of us who are near sighted. It is ok to have the target a blurr, not so ok if you can not see the target at all.
There are several "tricks" that you can use to extend your ability to shoot iron sights, such as an artificial pupil on glasses or the stick-on, adjustable pupil devise, made by Meritt. I pretty much used them all, trying to maintain top class competitive scores, until I finally had to switch to optics. But......
I did another magazine article you might have read in a national magazine about Lasik surgury. It is the ultimate sight adjustment and it can produce truly fantastic results. Both of my eyes were done, at the same time, in 1998. My eyesight was 20/15 after surgery. However, eyes being eyes, 12 years later my eyesight is today 20/40. Eye sight, with very few exceptions, does degrade with age, regardless of assistance by man.
By the by there is also a trick to Lasik eyes, go find some .5 magnifier glasses and wear them while shooting. You can see the target out to 200 yards and the sights very clearly. Magic for iron sight, shooting.
Best,
Ed