At some point, corrective lenses and paint will not fix the problem that you cannot focus on the iron sights on a pistol. After that, it depends on how much inaccuracy are you willing to live with, due to the fact that you cannot clearly see what you are doing.
Even with corrective lenses, or taking them off, my sight picture all around is fuzzy. I can still do this with irons:
But this is not good enough for competition. I can't shoot an iron sighted pistol and be competitive anymore, so I had to make changes to a number of pistols, and that meant Ultradot's. I had to send this off to Ruger so they could install a sight base, as this was not something they were doing when this pistol was new. I have, and do, occasionally shoot this in Bullseye competition instead of my
M46
Which I also had drilled and tapped for an optical sight base. I can shoot these at 50 yards and I can see what I am aiming at, even though the Ultradot has zero magnification.
Of course, at 50 yards, I have to use a scope to see the bullet holes.
With a rifle, I can still use irons and a front aperture sight.