What animal has eyes on the side of its head?

I would think it would be something like mono-opticular, if that's what you mean. I can't think of any animals that naturally have one eye, as almost every animal is symmetrical. They could get an infection in their eye or attacked by a predator, which would result in the loss of an eye. The tuatara, a lizard-like living fossil from the time of the dinosaurs that lives in New Zealand has a third pineal eye on the top of its head, but it can only detect light an darkness.

In Greek mythology there are giant humans with one eye they are called cyclopses (plural) cyclops (singular)