There is a Naruto character named Tobi who maintains his eyesight though his special ability should have caused a great amount of macular degeneration. The following includes extensive spoilers.
By my math, Tobi possesses his Mangekyo for quite some years. It is his Mangekyo, he stated it himself. So in that case, how come he hadn't gone blind yet? Itachi went almost completely blind in under 10 years. Sasuke got half blind in less than 1 year (because he abused it freely).
So how come Tobi hasn't gone blind? As far as I can figure:
He obviously replaced his other eye, but it was kept behind his one-eyed mask for a long period of time, he didn't use it for vision.