How can my vampire explain his red eyes to the humans?

He is one of few vampires that have red eyes. Most have a pale green, ice blue, or pure black. I was thinking maybe it could be because of a gene he had as a human. But, I need a way he can explain them while pretending to be a human in front of Veronica and Jamie( girl. ). I was thinking of an excuse like contacts, but that sounds like it would be used a lot.