[PKK]

It's not uncommon. It's genetic and runs in the family however can't be bred for reliably. So far it has happened with banded and/or dom spot and the hamster has cinamon or carries cinamon. It shows up best with camera flash and direct light. And there's nothing to worry about. However the general rule in rodents at least is the lighter the eye color the more sensitive to light it is. A red eyed hamster is bothered more by light then a black eyed one.