Bisping lost his eye due to competing in MMA. He did show incredible tenacity to keep fighting even after suffering a handicap. However, he is not the only fighter to have fought at the highest levels with one functioning eye.
Maybe my favorite kick boxer of all time Faldir Chabari from Morocco fought with one functioning eye his entire career. Chabari would fight high level competition such as Petrosyan, Buakaw, Souwer, and Holzken. While he wasn't able to beat the best, he was able to hold his own.
As far as I am aware he never once mentioned his handicap and how it affected his performance.