Mila Kunis

The Black Swan star successfully managed to hide a major medical secret from Hollywood directors for a vast portion of her early career.

Kunis suffered from chronic iritis—an inflammation of the iris—which completely blinded her in her left eye and caused severe cataracts.

Speaking about her secret struggle and subsequent corrective surgery, she stated: "I was blind in one eye for many years and nobody knew. I'm not blind anymore... They cut it open and dropped a new lens in there."