This is a relatively recent trope, with all shows using it having shown up within the past decade. In even more recent media, this trope has seen a much wider range of uses, ranging from the function of making a character look funny, to simply depicting eyes on a character too far away to be drawn in detail. See also Prophet Eyes for characters whose eyes are always completely white, and Color Failure for when they lose color all over. In some cases, it can also overlap with Dies Wide Open. You can sort of do this if you roll your eyes into the back of your head.