I am in my mid-40's. I was born with bilateral crossed eyes which causes blurred and double vision. The medical standard of care back in the early 60's was to wait on the corrective surgery until six years old or so. I had the surgery when I was six at the Ochsner Eye Institute in New Orleans. However, medicine now realizes that waiting that long causes amblyopia (lazy eye): in order to have any vision at all, the infantile brain learns to suppress the vision from one eye and that eye will usually never recover after prolonged visual suppression of more than a few months. The eye is perfectly functional, but the neurological connections and visual processing in the young brain never developed and never will. Nowadays, newborns with crossed eyes receive surgery within the first few days of life to avoid amblyopia.
So I am right handed, but my left eye is the good one. I cannot see well enough out of the right to read, drive or do much anything else. I am for all intents and purposes, half-blind. What this means is that I shoot long guns left handed, and shoot hand guns right handed using a weaver or isoceles stance. It is a pain in the rear end when my AR-15 and what not ejects the hot brass into my face, even with the deflector.