Why didn't madara and izuna just exchange their eyes to acquire the ems sharingan? Izuna didn't have to stay blind then go out and die in battle while blind. So why? is it possible to do that?
Interesting thought. Perhaps when you lose the eyes you die. That would be the only explanation for it. But you would think that medical ninjutsu would keep you alive.
Maybe med ninjutsu was to primitive? But that wouldn't explain why other Uchiha didn't do it.