An almost 7 month old puppy doesn't have the normal whites around the iris of his eyes? It's completely dark brown. It looks like it's always been like that. Nothing is wrong with him, he acts fine and his eyes are fine? He also has one brown and one blue eye if that matters? Does anyone know what this is? Is it a big deal? He's already been to a vet but they didn't say anything and they forgot to say something to them? Any thoughts? Thanks!

ETA: He has such big beautiful iris' that it's hard to even notice it, lol.