It also didn't make sense, u can't say that 1metre left is air is polluted while 1 meter right air is fresh. Similarly we also can't assume, that there is a straight path of mana road, which he just have to follow during travelling. It will make a lot sense if he use eyes to find mana concentrated area.

as u have said, eye is used for the flow of information. But its incorrect to assume that, it can handle brain processing. Yes it can help in things, where we need to perform task which required accurate information gathering through seeing things, but here the task which we want to achieve required our body to react to mana passively. Eye cant help it in any way, bcoz it only able to see mana, not absorb the mana. Example, breathing require nose, lungs etc, and anything but surely except eyes.