It's a problem with tri-clopses in comics and cartoons. If you've got a character with three eyes, people just draw a normal bi-clops and then draw an eye on the forehead. I want to see tri-clopses with a skull shaped as if there's an extra eye-socket in there - you know, put some real thought into the anatomy that triple-vision would involve!
It's a small thing, but it irritates me. Someone needs to put some serious thought into the subject and do something about it. I recommend Abelard Snazz.
(He used to wear glasses, but the kids at school called him eight-eyes, so he stopped.)