I spent ~3 minutes poking around and found something that says he has stargardt disease. He might still have some peripheral vision but if he's legally blind then he's definitely not staring at anyone or anything.

why would he have a "blindness registration card" with him there as well?

Probably to get annoying people like these two to leave him alone while he's staring off into nothingness, though apparently that doesn't even work if they're low enough on the bell curve.