my theory is ;
They don't actually have large eyes, but possibly could be some sort of.. "Interface" with a glossy black back-ground, and what they see inside is the stats of where they are or some sort of display, but it could also have some sort of biological use too, it could allow them to better see in dark a(n) dark enviroment(s). (you know how barn owls have black eyes?, this could be an adaptation to their body like owls have that allows them to scan and enviroment easier)