But Batman's mask fits to his face, whereas to me it looks like Bane's mask protrudes farther out, a few inches from his face, especially the part over his nose. That would probably obstruct the center of his field of vision making it hard to see things that were close to him.
Open your hand with your fingers together and touch your palm to your nose, then try to look at something about a meter or half a meter away from you. That's pretty much what Bane would be looking at.
It's the same reason why in American Football wide receivers and other ball-handling positions usually wear different face-masks with no center bar.