Anisocoria in Cats

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(Picture courtesy of Freepik.com)

Anisocoria is a condition in which a cat’s pupils are different sizes. In some instances, the abnormal pupil may be the smaller one and in other instances, the abnormal pupil may be the larger one.

 

 

 

 

 

 

 

 

 

(Picture courtesy of Freepik.com)

This condition is typically caused by one of the following:
Congenital defect of the iris, when the tissue fails to develop properly.
Corneal injury such as an ulcer.
Brain injury or injury to the nerves running to the affected eye, such as Horner’s syndrome.
Glaucoma, a disease marked by increased pressure within the eye, resulting in a dilated pupil.
Uveitis, an inflammation of the eye’s interior, causing that eye’s pupil to be constricted.
Scar tissue formation between the iris and lens that may develop following uveitis.
Retinal disease.
Iris atrophy, a decrease in the tissue within the iris, usually associated with aging.
Cancer within the affected eye.
Spastic pupil syndrome that may be associated with FeLV (feline leukemia virus).
Other infectious diseases such as FIV (feline immunodeficiency virus) or toxoplasmosis.

Besides a discrepancy in pupil size, and depending on the reason for it, the white part (sclera) of the affected eye may be red, the cornea (the outer surface of the eye) may be cloudy or bluish, there may be a discharge from the eye, the eyelid on the affected eye may droop, the cat may be squinting or rubbing her eye, the third eyelid may be raised, or she may be less active than usual.

(Picture courtesy of Freepik.com)

Should you notice any of the above in YOUR kitty, seek veterinary care immediately to reduce the risk of her vision being permanently affected. Your vet will perform a thorough physical examination of your cat, including a detailed examination of the structures of the eye in question. Depending on these findings, your vet may then measure the tear production and intraocular pressure for both eyes; stain the cornea of the affected eye with fluorescein dye to look for underlying corneal injuries or ulcers and obtain conjunctival scrapings or biopsies to be sent to a diagnostic lab for specialized testing. Blood tests may also be performed to determine if your kitty has a systemic condition such as FeLV or FIV. In some cases, your vet may refer you to a veterinary ophthalmologist for even further diagnostic testing.

Because treating anisocoria depends entirely on the condition causing it, your vet will discuss the options most appropriate for your cat, with the prognosis for a full recovery also dependent upon the condition causing it. In some cases, your cat may require long-term medication to control that condition. Sadly, however, if your cat should go blind as a result of her condition, it’s unlikely that her blindness can be reversed.