monochromatic eyes [mon-uh-krah-mat-ik-ahys]
1. In real-life, some people can have different colored irises, but there entire eyeball cannot be the same color. However, in fiction, this obstacle is ignored for several reasons. Often it used to highlight the alien and/or unusual, either through supernatural characters, stylized anime characters, or may show that the character is going through an unnatural experience, like a psychic episode. In comic books, it is very common, especially among characters who wear masks to disguise their faces. The eye holes in their masks are usually turned pure white and this does help give their disguises added, but fantastic credibility. One problem with this design choice is that, for some readers/viewers, such design choices are disconcerting or make it difficult to discern a character's emotional motives.
EX. Batman be creeping with those monochromatic eyes, but add a pair of pupils and it just gets worse.