The problem of believing that glassware on your gun can cure vision defects is epidemic. Optics on the gun are not a cure all but often the first choice for those with failing vision.
We will all face the problem of aging and the natural process of our eyes lenses stiffening causing problems with short range focus. It can be particularly frustrating with handgun when you can't focus well on the front sight.
The many problems associated with scopes can be most extremely annoying. Few people understand the critical issues of mounting, parallax, correct zeroing, windage and elevation, and eye relief.
They fall into the trap of throwing a cheap hunk of glassware on a gun and never figuring out why they still can't hit the broad side of a barn although they can see it clearly now through the glass.
Scopes are not a solution! Fix your eyes and not your gun!
Finding a good ophthalmologist, who is a shooter and understands guns and sights, is difficult. They can't associate or comprehend the need for that short to mid range focus necessary to clearly see the sights. If you can't convey the concepts involved, take a yard stick and measure the distance from your eye to the front sight. Take it with you for your eye exam and insist that you have clear vision at the measured distance. Glasses or contacts can be made to achieve that although you may have to purchase an extra pair or specific contacts just for shooting.
Mono-vision, or having one eye focus differently from the other, can be both blessing and annoyance. It takes some time to get used to but the brain eventually figures it out and learns to switch dominance from one eye to the other depending on what you are looking at and how far away it is. It will drive you nuts for several months until you adapt but you will adapt.
Cataracts offered me little choice. It was either implants or a cane and guide dog!
Despite the most modern and sophisticated equipment to take the measurements, my specialist in the field screwed up, claiming that they were too thick for the machine to get an accurate measurement. He rather undershot the magnification on the lens in both eyes. Still, I walked out with better vision than I had my entire life! I was not happy and made a lot of noise about it, including mention of a lawyer. He quickly decided "I can fix that with Lasik!" Ok, WTF? Nothing to lose at that point.
Left eye was -2. He performed the Lasik (which I found more uncomfortable than the surgery to replace the lens with the implant) but, it's fast settles in to final vision in a week or so.
Well, now he overshot the correction and left eye is farsighted at +1. Cool beans! I can count individual pine needles on a tree at 150yds! Not worth a damn for close vision though.
Right eye, my dominant shooting eye remains at -1. Not great for counting those pine needles but perfect for focusing on sights! Also perfect for close up and I can read the newspaper without glasses or contacts although reading glasses prevent eye strain from prolonged reading and small type.
The mono-vision, or difference between the two drove me nuts at first. We talked about further correction as I was not happy. After a few months, I adapted to it and now can unconsciously switch eyes depending on what I am looking at and find it no bother at all.
Shooting is the best of both worlds. I can see the target (and the holes) at distance with the left eye and the right puts the front sight of pistol and rifle in perfect focus to pull the trigger.
I'm not complaining anymore. It worked out for the best vision I have had my entire life!