Eosinophilic Keratitis - Proliferative Keratoconjunctivitis

What is eosinophilic keratitis?  

This condition is commonly seen in cats and is characterized by an area of corneal opacity (white to pink) in one or both eyes. The white lesions contain white blood cells, some of which are called eosinophils. A corneal cytology helps establishing the diagnosis. The "film" on the cornea may start on the edge, but with chronicity, the entire cornea may become affected leading to visual impairment.

What causes eosinophilic keratitis?

The exact cause of eosinophilic keratitis is unknown. However, the development of eosinophilic keratitis is commonly associated with Feline Herpes Virus infection.

What are the signs of eosinophilic keratitis?

White to pink lesions on one or both eyes of your cats can be noticed. Signs of ocular discomfort are inconsistent. Early lesions tend to be painless, but squinting of the affected eye(s) and ocular discharge become more pronounced as lesions progress. Many cats also have concurrent corneal ulcerations possibly caused by Feline Herpes Virus contributing to the discomfort. The signs of ocular pain may be subtle and include squinting, tearing, and elevation of the third eyelid.

How is eosinophilic keratitis treated?

The condition usually responds well to treatment with topical steroids. However, in cases with concurrent ulcerations other medications may be chosen such as cyclosporine eye drops or megestrol acetate tablets. Megestrol acetate is highly effective. However, it is not the first line treatment and should be reserved for difficult cases. The systemic use of megestrol acetate carries potentially serious side effects including diabetes mellitus, increased appetite, and mammary hyperplasia and neoplasia.

What is the prognosis?

With appropriate treatment, the condition improves greatly in most cases. However, flare ups are possible and some cats need long term medications to control the condition. In cats with concurrent flare ups of herpetic corneal ulcers, the treatment regimen may need to be adjusted repeatedly.