Board Thread:Questions and Answers/@comment-88.134.19.85-20170720095618/@comment-186.223.149.87-20170725081710

I'm afraid not. While it's unusual, the masks that doesn't have any visiable eyeholes are probably made of see-through materials, like some faceless masks people sell on the internet.

Besides that, if the mask does impair their vision, ghouls are known to have extremely enhanced senses, and some of them can pretty much rely on their hearing and smell to make up for their disturbed vision.

While it's not mentioned, it seems the only use of the kakugan is to serve as the ghoul's intimidation factor, while hunting or fighting.