Since aging eyesight has come up frequently on this thread, I'll add a couple more comments.
Presbyopia (far-sightedness) is a fact of life as eyes age. In my own case, I can no longer achieve sharp focus on objects within about 24" under typical indoor lighting. The cause has to do with the gradual lessening of flexibility in the lens of our eyes:
https://www.mayoclinic.org/diseases-conditions/presbyopia/symptoms-causes/syc-20363328
In bright outdoor lighting I can focus much closer -- 'depth of field' increases with decrease in pupil diameter:
https://www.nfi.edu/depth-of-field/
Corrective lenses do just that: correct the focus at a more comfortable distance. The problem for shooters is that both correct focus and broad depth of field are desirable with open firearm sights.
I tried a couple pairs of conventional Rx glasses without much success, mostly because I shoot indoors a lot where the lighting is relatively dim. They'd be fine for the sights, but make the target too blurry to center on. I even tried bifocals with plain glass on top, but no joy -- at least for me.
After I bought my Wehrmann target rifle and found I could not see the Lange Visier sight's rear notch, I decided it was time to invest in
real shooting glasses (see my avatar at left).
You'll see these at the Olympics: an open frame with an almost unlimited variety of positions for mounting a corrective lens, adjustable iris and/or blinder. The blinder just serves as an aid to keeping the non-shooting eye open; the real benefit is the combination of iris and lens. I bought a kit made by Jaggi, but there are several other brands available. They are expensive!
https://freelandssports.com/product/jaggi-nova-shooting-glasses-for-rifle-shooters/
When I took the frame to Kaiser Optometry to have a corrective lens for my prescription fitted, the clerk said it was a first for them. The difference these made to my shooting (with the iris stopped down fully) was night and day. That is to say, I could finally see the sights and the target with enough clarity to make shooting with open sights fun again. I remain a mediocre shot, but at least you can now tell which target I'm aiming at.