Eyes: Uneven Pupils

It may be normal, or maybe not. Get a good physical exam.



We have recently acquired a new cat to our household. She is an odd eyed white. The pupil in the blue eye is always larger than the pupil in the yellow eye. Is this normal? She seems to be in good health otherwise.


Dr. Nichol:

Congratulations on your new kitty. You were smart to examine her carefully. Actually there are lots of white cats with eyes of different colors. Many with one or both blue eyes are deaf. That part’s really OK. But differing pupil size (called anisocoria) may or may not be normal. There could be several possible causes including cancer, glaucoma, infections, or nerve damage.


This girl needs a thorough physical exam. It should include an evaluation of the interior of her eyes using an ophthalmascope as well as measurements of the pressures inside her eyes. These procedures plus a few neurologic tests will hopefully show negative for disease. Last, ask for a Feline Leukemia test. This potentially fatal infection can cause “spastic pupil syndrome”. (This sounds strangely like descriptions of me in grade school). The blood test is fast and reliable.


I know it sounds grim but the truth is that most cats with anisocoria are actually fine-what we call a variant of normal. But don’t gamble. Your girl sounds special. Get her checked out for your peace of mind.