For older shooters that can no longer see iron sights quickly or in focus- consider this.
I'm assuming that those shooters wear prescription eyeglasses, and that the focus length is set for the standard 20-foot for distance vision glasses. But, the focus point on eye glasses can be set for any distance by the optical techs. All you have to do it ask.
My 'iron sight' glasses are the same prescription as my regular distance glasses, but the focus distance it set for 25-inches. The sights are sharp and clear, and I can even read a license plate at 13-yards. The targets are slightly, but not overly, blurred. But do you really need the target to be in sharp focus? Put focused sights on a slightly blurred target and you get a hit. Put blurry sights on a focused target and you get a miss.
I made IDPA SSP MA & Bug, and EX in SSR, ESP, CDP and Steel Challenge A Class in RFPI and RFRI with those glasses.