Board Thread:Theories and Speculation/@comment-25132842-20180312025951/@comment-734582-20180312071403

Erich Zann III wrote: How the hell that works, I don't know, but whatever. Obito has a regular MS but doesn't go blind despite spamming Kamui. He also has Hashirama's cells. The implication is that the eye goes blind due to damage from the jutsu it casts.

EMS somehow prevent that damage from occurring once more, possibly because everyone has a unique way of damaging their eye (and so, on transplant, the eye isn't vulnerable to that particular caster's weakness)