Bingo. Seeing front sight clearly matters most, but also being able to see target matters too. Seeing the rear sight doesn't matter much. Don't worry about it if you can't see rear sight.
Also, I don't think wearing reading glasses is practical for shooting. Wear your regular daily life glasses (same as you would for driving). Regular glasses work best for me because I only try to see front sight and target. I ignore rear sight (because my eye is only able to see 2 things at a time). In spite of my bad eyesight, I was an above average pistol shooter with better than average accuracy.
I used to own pistols and rifles. Some came from factory with a white dot on front sight, or a gold plated front side, but some had a black front sight. Sometimes a small black front sight. It's difficult for bad eyes to see a black front sight, especially if it's a small sight.
If the front sight is black, degrease it with 99% alcohol on a paper towel. Wipe front sight with a part of the paper towel that has alcohol on it. Then wipe sight dry with a dry part of paper towel.
Give it a few minutes to dry (in case you didn't wipe it completely dry).
Shake the nail polish vigorously for 15 seconds. Thorough shaking is a key part of successful painting.
Paint front sight with a thin coat of a bright color of finger nail polish (white, yellow, orange, or hot pink). I had best results with vivid safety orange nail polish. If one thin coat isn't enough, then wait an 30-60 min, then add a 2nd thin coat.
Revlon and Lorreal nail polish brands work very well and are tough enough to last many years, but are expensive brands. Amazon nail polish brand is tough enough, works well enough to last years, and is low cost. If you know women who paint their nails, they can tell you of other good brands.
A bright orange front sight is easy for bad eyes to see against a light or dark background. Nail polish is tough laquer paint similar to what used to be used for autobody paint. However, Hoppes #9 gun cleaning solvent will dissolve nail polish. When cleaning gun... Keep solvent away from the painted front sight. If you accidentally get Hoppes #9 or other solvent on the painted front sight, quickly dab (don't wipe) it dry using cotton or paper towel.
I also use black nail polish to touch up scratches or chips in car parts and mobility scooter parts. I use metallic shiny silver nail polish to touch up scratched aluminum rims.
Finger nail polish is an excellent, cheap, easy to apply (without fear of overspray) touchup paint. It's a versatile tool. I have a collection of 6 colors of nail polish that I use for touchup paint on various projects.