Here's the reason why sasuke closed 1 eye

[limitedpowers]

Could be possible, I wonder how he knows all of these jutsu already though.

Its gotta be how like Goku transformed to Super Sayain. It kinda just happens/unlocks... you know, after training and unlocking sharingans and stuff

 

[assface3]

Sasuke's about to go HAM...again!

 

[TrollKing]

Sasuke's about to go HAM...again!

Seems like sasuke will have to tank 2 eyes madara while sasuke having his eye closed

 

[Roronoa Solos]

Sasuke saw what happened to Kakashi and doesn't want his eye stolen as well lol. In all seriousness it's probably to conserve chakra or it could be that closing his eyes helps to regenerate the tomoe, seeing as we saw in the previous chapter that his eye was losing a ring of tomoe with each use of his eye.

 

[Tantalus Thief]

Sasuke's about to go HAM...again!

Can't wait