Yes, their eyes can grow back. Let's go back to the scene where Kaneki is just discovering his abilities and he is fighting Tsukiyama in the church along with Nishio. Touka drops in a surprise attack on Tsukiyama and blinds him in the process, however, he recovers almost immediately, regaining back his eyesight.
My theory is that Yomo is going to appear and fight(remember we haven't seen his abilities against the doves) Arima, with Touka as his backup.
I don't agree with that though. From the looks of it, BOTH of Kaneki's eyes became ghoul eyes, and I think his abilities will go maybe a step further. He'll probably become even more badass.
Oh I mistook the eyes. I thought they grew back. Then I'll change my previous statement. I still don't think Yomo or Touka's going to help him. I remember that they might have gone into hiding. I don't know if they owl's dead. Maybe he might help him.
I think they can, but since his brain was affected, then it may take longer.
Can ghoul's eyes grow back? Man... in chap 140, did Kaneki lose both of his eyes? And that Arima guy always scares the crap outta me, every single time he appears, I was like "shit".