The last 2 times I went to our local range I experienced the same problem. Each time it was near the end of shooting. I too am right eye dominant with 20/15 vision and lefthanded. Shoot with right eye shut. I do everything lefty. Shoot, throw, write. Each time it was after going out to range a resetting targets - come back and look through scopes and see a heavy black ring an outside and fuzzy. I move head backwards and forward to try and adjust, but it doesn't clear up until I rest my eyes. I'm thinking fatigue and maybe in combo with overclinching my right eye causes it. I've never experienced it when I'm hunting - hope you don't either!
My stash -
.300 Winchester Magnum
Remington 1100 Slug gun
30/30 Winchester
Remington Nylon 66 .22
CVA Hunterbolt
Traditions Hawken
Ruger Mark II .22 pistol