Obito constantly spams Kamui, and Kamui is a MS technique. I have not seen side-effects from Obito using Kamui. Does the senju DNA help prevent blindness?
Haven't seen side effects for Kakashi or Danzo either it seems one eyed characters not only keep their eyes activated but they don't take in any side effects either.
What If it's not a MS tech?
You're most likely correct about that; but no other Uchia has ever shown anything even remotely close to ST/Kamui?It is, there's no denying that Kamui comes from Obito's MS. Without Obito's eye(s), Kamui is impossible to use.
OT: Senju DNA lessens or nullifies the toll of using MS techniques.
danzo had senju dna however with kakashi u can clearly see it effects his body.. maybe not as much now because he is constantly tired
It seems only Tsukuyomi, Susanoo and Amateratsu cause blindness. Kamui has yet to show any side effects. The only thing Kakashi had was his chakra drained quickly, but now his body can handle it.