Dominant eye issue: When your cue stick is misaligned for the shot due to a slightly off perspective view of the shot as seen from the dominant eye.
Well researched: Of course eye dominance is well researched, scientifically proven. But exactly how it affects lining up a shot or shooting a rifle is not so thoroughly understood. It's a simple change in perspective. I mean, I can shoot with my left eye, my right eye, or both eyes, and do a fine job, playing pool or shooting a gun. But this involves subconsciously knowing (proprioception via propreoceptors in muscles) and consciously knowing (kinethesia via receptors in muscles, joints, and skin) that I have my cue, or my sights, lined up appropriately even though I cannot see my grip hand or shooting arm. If I shoot a particular shot with one eye or the other closed, or with both open, my cue stick will always be dead on the correct alignment. The only thing that changes is my body position (stance) and my head position (in order to get the correct perspective for the alignment). No adjustments are needed with the cue itself.
So this makes me think that pool players with an overly dominate eye probably align to shots just fine, according to what they see, but are slightly off in stroke delivery or some fundamental element with their stance or shooting arm or wrist, not a vision center problem.
I'm not saying eye dominance has no influence on lining up a shot correctly. But I do believe many times it is incorrectly diagnosed as the problem, which causes more issues for the struggling player.