My kitten has a problem with his left eye.?

My kitten is about 8 weeks old. The problem with his left eye has occurred within this week. I have a picture and would like any suggestions if anybody knows what is wrong with his eye. My vet did not know but felt he has a congenital problem with his eye.He has no discharge coming from the eye. It seems to be his pupil and or iris that has the problem. Thank you.