I need to tell you about the eyes of army ants, and it's Alex Wild's fault. @alexwild He posted a gallery of army ants and I've been reading about their eyes all day.
Here's the deal, their ancestors lived underground. Like many subterranean insects the ommatidia in their compound eyes decreased in number until in some cases they had only one ommatidia left. This isn't an eye, more like a light sensor.
