just remember to keep your glasses on when you're shooting so you can see your target, and you should be ok
Wrong, you don't need to see the target sharply, the sights is what you need to see sharply. Basic shooting class at police academy.
The instructor will first have you shoot at a target installed in reverse direction (bull's-eye away from shooter; in other words, you are looking at a white square piece of carton). When your technique is getting good (body position, hand grip, trigger pull, breath, anticipation) and you are grouping say 3 inches at 20m, he then asks you to install the targets normally so you can see the bull's-eye. Invariably your group will open to 5 inches or more: That's because you are now looking at the target. Try it, it's a very convincing exercise.
In theory, if your sights are
perfectly aligned and you are pointing an inch off center because target is fuzzy, the bullet will hit one inch off center, regardless of distance. In practice too. But if your sights are the least bit misaligned (because you are distracted by the target), the point of impact offset can be much more.
Human depth of field in good light condition is about 4 ft to infinity. That means all objects are in focus over that range, assuming your eyes are not re-focusing away from infinity (target). If you hold your pistol at arms length, front sight is closer than 4 feet (unless you're built like a monkey...). With a riffle, still not there yet. Bottom line is you need to chose: front sight is the best choice. That is why peep sight (aka "diopter") with smallest aperture is best solution for rear sight: because it takes away some of the imprecision in your acquisition (alignment) of the rear sight.
This dilemma improves in bright light conditions because the depth of field of your eyes improves (smaller aperture of your iris). It worsen in low light.
I once shot with a Swiss guy who was rumored to have tweaked his eyeglass prescription. He was punching repeated "mouche" (2") at 300m open sights (diopter at rear, actually). I suspect he had a positive fraction of a diopter (+0,25 or +0,5) over the normal perfect prescription.
My self, I now have better than 20/20 vision with my right eye (only 20/20 with left...), since Lazik got me rid of my former (and not at all regretted) "bottom of Coke bottles". I need to use reading glasses of course, because I am passed the age when the ability to refocus closer is lost (for most people). On my upcoming visit to the optometrist, I want to discuss with him this issue and decide on the best correction to improve focus at front sight distance. Since the receiver is the actual registered part of a firearm, I was intending to bring only the slide (incl. sights) of one of my target pistols, so we can find the best compromise with his ting-a-ma-gig machine with all the different lenses. Will keep you posted on the value in diopter that we determine optimum. This value will be independent of shooter, as long as his (her) eye vision is 20/20 or corrected to 20/20 and our arm's length are similar.
Cheers.