Loosing his powers toward the end

It seems Cho-in was loosing his powers at the end, even his eyesight.

It never explains why but i think it's because he never used it that much before clashing with the good guy.

While watching this i was thinking about the Sharingan in Naruto, by using the ocular powers too much, the wielder looses his eyesight.

Anyway, it's a nice movie with great soundtracks.