Cat eye issues

So I have a 2.5 year old Ragdoll called Haku. I saw something in his eye in the bathroom yellow lighting. It looked almost like a small hole in his eye and a yellow-y oil around it that kinda looks as if you were to drop some oil in water. In any other lighting i cant see it. He still plays eats and doesnt seem like hes in any pain. What could this be?