Why is Obito not blind?

[TheAwesomeOne]

I believe it's because Kamui doesn't have as much strain on the user's eyes as Amaterasu, Tsukuyomi, and Susano'o.

 

[natssuu]

Answer for all questions: Hashirama's cells.

 

[Phantom Guardian]

pass some of that senju dna over here bro.

 

[lion fang master]

Very simply hashirama DNA too much life energy

 

[Tartarus]

zetsu cells

 

[Silverblade]

Two things.

1. Obito mastered the use of his Sharingan where he can use Kamui without it transforming to MS.

or 2. Since he has one Sharingan instead of both. It would take a lot longer for him to go blind since both eyes are not in sync.

The True Power of The Mangekyou Sharingan comes with a hefty price. You have to remember that Obito has never awaken his eyes true power. I won't say Senju DNA like a moron because Kakashi has Mangekyou Sharingan as well. He experienced slight eye deterioration since he questioned Itachi about his eyes.

EDIT:

Manga never mentioned Kakashi eye sight deteriorate. I don't know if he read the Uchiha tablet or not.