Cresent moon shaped shadows on GSD's eye

I have just taken my new boy (GSD that i rescued today) out for his last toilet break and went to settle him down for sleep. As i bent down to give him a kiss i noticed he has a cresent moon shaped shadow on his pupil in his left eye. He has an appointment at the vets tomorrow morning for a general health check and i will obviously be pointing it out. But now i cant sleep because im worried about what it could be. Any ideas?

If it is in his pupil I expect it is just a pigment leak. My dog has one in his eye, he gets eye tested annually and the specialist vet says this is quite common.

Remember Madeline the missing girl? If you remember, or google, she has a similar distinctive pupil.

Yes, just colouring. And well done for getting him out of there.
BTW I would be very careful about putting your face up to a new dog - he might misunderstand as dogs don`t show affection like that.

I did relise after that i was a bit stupid to do it, i just had to give him a kiss been to the vets and he has said its nothing to worry about that its just a pigment leak.