Board Thread:Theories and Speculation/@comment-1872728-20151019025302/@comment-734582-20151023072429

Georgio722 wrote: My point is, how do you know that Obito never manifested his Susanoo? Shisui did manifest his with only one eye, even though it says that you need two eyes to manifest. Sishui had both eyes. He also had MS in both eyes. Obito gave away his eye before MS was achieved and before Susanoo could be manifested.

Because once Susanoo is completely manifested, it can be used without eyes.