So, at 56 and being blessed with ageing eyes and astigmatism I go a couple of routes. One is Peep hole sights. On a pistol you ask? Nope, on my shooting glasses. There is a product out there you have to place on your glasses, dominant eye, and acts just like a peep hole sight, which makes everything clear
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Option two is I had my Optometrist provide me with lenses at the exact focal length of my Glock 34 I shoot with Iron sights. For me it is exactly 26 inches.
You take your shooting stance, with an unloaded, and twice verified gun or your preference, extend the gun to your shooting position and move to a wall. Best way, have someone measure form your nose bridge to the wall or front post and now you have your focal length.
Readers had worked at 1.5 and the Optometrist said it would help but it did not account for my astigmatism.
I tried the two eye bit but was too blessed with headaches and vertigo.