Concur with above advice recommending a peep sight. You can get one with dovetail to replace existing rear sight. Take a look at Skinner sights. I've got a couple on "unmentionables" and am happy with them.
Before cataract surgery last year I used a piece of electrical tape with a 1/8" hole punched in it taped to my shooting glasses. It worked great. Now, I don't need anything to see the sights or target.