tried playing with only my right eye, and it's a lot harder. Yeah, I don't think I can withstand that change if it actually happened to me, it feels like a doom to have your sight skewed/removed for the rest of your life... it's scary.
As for my own, I have asymmetrical eyelids, and my eyes lack movement capability which makes me see a fast-moving object (that is, high-speed Taiko notes) as two (or even more) notes {I don't know if it's my eyes or the CPU though, I'm hard to focus anyways}. I can only rotate my eyes together in the same way, and I cannot do anything else. Lack of muscular abilities, if you prefer that. Fortunately my sight itself hasn't got even the slightest blur... yet.
Anyway, have my salute, OP and you guys.