Board Thread:Theories and Speculation/@comment-35023081-20190916124836/@comment-9782468-20190916191318

Stoyan P. wrote: The Susano'o is a Visual Jutsu of the Mangekyo Sharingan. So by that defintion, no it is not just an ability that comes with the Visual Prowess. But still I thought you would at least need active Visual Prowess for a Visual Jutsu, be it the Susano'o or Amaterasu or whatever.

Sasuke also went blind from using the Mangekyo Sharingan after his fight with Danzo but once he did, his Susano'o fell apart, seemingly for good. And whilst Madara would have had more Chakra when he used it without his eyes, that would not have been the case for Itachi who had just fought to the death with Sasuke and drugged himself. So like...? Based on what we're given in the series, you do not need an active Mangekyo Sharingan to use Susanoo, but you need both Mangekyo to unlock the jutsu. Once it's unlocked, you can use it with no eyes like Madara or when the Sharingan fades from your eyes, like in Itachi's case against Sasuke.

Sasuke didn't go blind from using his MS. His vision got blurry from overuse though.

Sasuke's Susanoo didn't fall apart for good, Sasuke was just overextending himself in terms of chakra and stamina.

Itachi was beyond ill, probably not feeling much of the pain associated with Susanoo, and ready to die either from chakra loss or sickness or Sasuke. He was ready for Susanoo to be his last technique. That's why he activated it and kept it active, even while low on chakra.