I had a foster cat who had patches of color like that in his eyes. His were from having eye infections from when he was at the shelter, and the vet said it was scarring on his retina or whatever it is that they have (is it the same??). It didn't harm Bear's sight, but when he had horrendous eye infections at the shelter and his eyes were always pasted shut, you'd see more of them later on. While he was with me, his eyes never got like that because I always made sure I cleaned them, put ointment in them. I never saw any additional ones either.

I'd take him to the vet, ferocity or not, and have the vet check it out. Peace of mind is better for you and you should make sure kitty is not sick.