Hello! I recognize you from my friends list! I was thinking more of the ones who just happen to be blind, and you don't know it until they make some mistake or lose their monocle. The secret flaw! I love it.

I wondered if there was some cultural deeper significance or symbolism to partial blindness that I'm unaware of. However, given the number of missing limbs in general that turn up, I reckon you're right; it's all about cool prosthetics. (I'm pretty new to manga.)