Understanding the vampire's eye :
Here we see a depiction of different states of the vampire eye. Strangely enough, one of the changes that happens when the creaturees become a vampire is their Iris and pupil seem to conjoin in one single round shape. In it swirl, indefinitely, a sort of liquid that changes color depending on the creature's state of mind and health. Almost all vampires will be able to somewhat control that swirling motion to hypnotize their prey, aklthough some are more adept than others. It is interesting to note however that no matter the state of the creature, the liquid will contain particles of an undertemined nature, that refracts light, similar to what humans call "glitter". I suspect this might be both to help them catch their prey's attention, and to better their abilities to see in the dark, since they seem to be able to see as long as there is a slight light source.
-art from Mai chi