Board Thread:Theories and Speculation/@comment-25132842-20180312025951/@comment-33156027-20180313090212

Erich Zann III wrote:

Indra Otsutsuki had the Mangekyo Sharingan. It was not unknown. Madara and Izuna were just the first Uchiha to unlock it. Hagoromo also had the Mangekyo. So Hagoromo was the first to activate the Mangekyo. But he mostly used his Rinnegan, so his eyes never took that much damage.

And Madara did take Izuna's eyes. Awekening of the Rinnegan can restore eyesight, so even if Hagoromo's eyes took damage because of using Mangenkyou to much his eyes should be fully recovered, like in Madara's case when he regained sight in the right eye after use of izanagi. Anyway, the fact that Sage of the six paths had sharingan isn't canon, it is just anime only. Maybe he has the sharingan but he was born with Rinnegan, and he bypassed stage of an evolution from sharingan to Rinnegan because he was Kaguya's son and had six paths chakra from the very beginning. In case of Indra, he was Hagoromo's son and probably because of that also had six paths chakra so maybe his mangenkyou never caused blindness and he could use perfect susanno like in Obito's case