One eye or two
I hate to shock some folks, but it don't matter. I shot rifles and shotguns for years with one eye closed. In '92 I had an accident and am now blind in my left eye. Literally, my first thought when I found out was "Thank God it wasn't my shootin eye". I can shoot just as well either way, since I only see light and fuzzy images in my left eye. I have also noticed that I see my sights clearer with my left eye closed, however, I do keep both eyes open when shooting hundreds of pistol rounds just because it fatigues my eye to keep it closed that long. Being blind in one eye is like closing it, so I don't see the difference. Do what works for you.