A.M.
My 7 year old has been doing the same. It comes and goes, and at first I was very concerned. It seems that it is just OCD for him and I try not to draw attention to it. If it continues, I will take him to the chiropractor and see if chiropractic therapy works to correct the issue.
I was told that boys at this age tend to do OCD type things and they generally outgrow it. Again, I don't bring a lot of attention to the issue. The reason I know it's not an actual eye issue is because when he got a cut on his face he went from eye rolling to stretching out his lips (reopening the sore over and over) because he said he had to do it. Once the sore healed (after a month) he resorted back to eye rolling.