Board Thread:Theories and Speculation/@comment-1512913-20161119171442/@comment-1512913-20161204162912

Hm. I'm 99% sure that Susanoo uses Sharingan chakra, the same 'special uchiha brain chakra' as Sharingan does, but you don't really need eyes for it once you already can use it, the chakra is in the brain, doesn't need to go to the eyes to use Susanoo.