I frequently have a real problem with eye fatigue. Last time I was out shooting, about 50% of the time my target was blurry. The target would go in and out of being in focus. I’ve tried closing my eyes between shots and taking frequent breaks. Would I have better luck trying to shoot with both eyes open? I’ve tried it before but after 2 shots I quit. I’ve also heard of people doing things to strengthen their eye muscles. I’m only 43 years old, which is old old, but not that old!