[Maximo]

Good question. I have noticed in photos of some very senior Yorkies that their eye shine seems rather opaque, and I wondered if this was just a natural part of aging.

To see my boys' pupils, I have to put them on the counter in good light to distinguish the black pupil from the dark brown iris. Underneath the direct light, I can see the pupil dilate and grow smaller depending on which direction their eyes are in relationship to the overhead can light.

At your girls' next vet visit, you can ask your vet to take a look. I don't know the proper name for the exam, but they turn out the lights and use a magnifying tool that shines a bright light into the eye so that the doctor can see the retina and interior structures.