Dilated pupils in cats can be a sign of iris atrophy or a more serious underlying condition. Here’s how to know when to seek veterinary care.

A cat with two differently sized pupils has captured viral attention online after his picture was shared on Tuesday. Ricardo—who uses the Reddit handle RikTehSpik—lives in Los Angeles with his ...

Non-circular pupil shapes found in vertebrates include not only the vertical slits familiar to us from cats' eyes, but also horizontal slits, crescents, heart shapes, and keyhole shapes.

Cat pupils are long and vertical, narrowing to a slit in broad daylight but expanding up to 300-fold when it’s darker (human pupils grow only 15 times bigger).