Board Thread:Theories and Speculation/@comment-25132842-20180312025951/@comment-33156027-20180313100050

Madara and Izuna made an experiment, both of them didn't know whether it work or not and they didn't expect eternal version of the MS. EMS is just MS but without consequence of using it which is blindness. Some people said that MSes are fusing and new user of the eyes regained his MS and can also use abilities of the original MS of those eyes, but Sasuke never use Tsukuyomi after he got Itachi's eyes so it's unconfirmed (Kakashi's case is different, because he isn't Uchiha and he never had his own Sharingan, and his eye was somehow still linked to his owner who was still alive at that time). Maybe there are more options to make your MS eternal, like six paths chakra or Hashirama's cells like in Obito's case (Asura's yang energy combine with Uchiha's chakra). If it works, we can call it EMS, can we?