Q. Our indoor house cat, 6 year old female tabby, has suddenly developed what seems to be Anisocoria. How could this have happened?
DR. ANDREA M. BRODIE, DVM
A. Just to make sure we are talking about the same thing here: anisocoria is where one pupil is larger than the other at all times, ie this is not caused by the cat's one eye being in the shade (therefore pupil is bigger) and the other in brighter light (pupil would be smaller.).
Anisocoria is just a sign of a more serious underlying condition such as glaucoma, retinal disease, uveitis, injury to the brain or the nerves running to the affected eye, cancer in the affected eye or a sign of an infection with feline leukemia virus.
Suddenly occurring anisocoria is an emergency and you need to seek veterinary care right away, so that your cat's vision can hopefully can be preserved.