Keratitis refers to inflammation of the cornea (the clear windshield of the eye). Conjunctivitis refers to inflammation of the white part of the eye (the conjunctiva). Eosinophilic keratitis is an inflammatory condition of the cornea and/or conjunctiva which occurs almost exclusively in cats. Classically, white or pink raised plaques are noted on the corneal surface often accompanied by blood vessels. These plaques are composed of eosinophils (a type of white blood cell).


Other than the white plaques which can be visualized on the cornea, cats will also exhibit squinting, redness, and discharge in the affected eye.

The condition is progressive and without treatment the plaques can grow across the entire cornea leading to functional blindness.

Eosinophilic keratitis typically affects one eye initially; however it can progress to affect both eyes.


The exact cause of eosinophilic keratitis is unknown. It is thought to be an auto-immune attack on the cornea. Feline Herpesvirus has also been implicated as an underlying cause of Eosinophilic keratitis.


A full ophthalmic examination is performed under a slit lamp microscope. If eosinophilic keratitis is suspected, a corneal scraping will be obtained from the surface of the eye. The presence of eosinophils in the scraping confirms the diagnosis.


Topical anti-inflammatories are necessary to clear the corneal inflammation. Topical immunosuppressant medications such as Tacrolimus and Cyclosporine may also be recommended. Topical anti-viral medications may also be prescribed if underlying Herpesvirus is suspected.

As long term medication will be necessary, your pet’s ophthalmologist will taper or decrease medications slowly over time to find the lowest maintenance level necessary to control the condition.


Eosinophilic keratitis is a condition which we can control but not cure. With long-term medical management, the prognosis for vision and comfort is good.