Anisocoria

It's usually due to a serious condition though. (Brain tumor, meningitis, etc.)

When its that serious there is a problem, anisocoria isn't USUALLY that pronounced. Usually its less than a 1mm difference between the 2 pupil sizes.
But still really cool to see!

My brother just got a concussion at a football game yesterday, and when he came home he had this.... not that badly, though.

My friend has this. She is blind in the eye with the large pupil. She had uvitis and it caused permanent damage