Board Thread:Theories and Speculation/@comment-32617252-20180317055942/@comment-28323245-20180317204536

I have thought the same as you. The problem in Canon is that in both EMS brother's one was already dying.


 * Izuna was dying from the battle with the Senju (Tobirama Hiraishin Cut) and even though he supposedly also used his own MS, it wasn't as used as Madara's.


 * As for Itachi, he knew about the EMS, that was one of the reason's he wanted Sasuke to kill him and take his eyes. And taking into account that he was nearly dead when they fought, not much could be done either.

But if you get a random pair of Uchiha and have them swap eyes theoretically there should be no problem what-so-ever.