Glaucoma In Cats (Hard Eye) Symptoms and Treatments

Glaucoma is due to an increase in fluid pressure within the eyeball. There is a continuous exchange of fluid between the eyeball and the venous circulation. Anything that upsets this delicate balance can cause a buildup of pressure and produce a hard, enlarging eye. When eye pressure becomes greater than the arterial blood pressure, arterial blood cannot enter the eye to nourish the retina.

Glaucoma is classified as either primary or secondary in cats.

Primary Glaucoma usually begins in one eye, but almost always eventually involves both eyes, leading to complete blindness.

Secondary Glaucoma occurs when other eye diseases cause decreased fluid drainage. Common causes of secondary glaucoma are inflammation inside the eye (uveitis), advanced cataracts, cancer in the eye, lens subluxation or luxation, and chronic retinal detachment. Glaucoma in cats is usually secondary to chronic uveitis.

Inflammations and infections within the eye are the most common causes of acquired or secondary glaucoma in cats (Uveitis). Other causes are cataracts, eye injuries and cancers within the eye. Primary (congenital) glaucoma is rare but has been observed in the Persian, Siamese and domestic shorthair breeds.

Determining if your pet has primary or secondary glaucoma is important because the treatment needed and the prognosis for vision is different for each type. Veterinary ophthalmologists use slit lamp biomicroscopy, indirect ophthalmoscopy, and gonioscopy to determine the type and cause of glaucoma in your pet. Gonioscopy helps determine how predisposed the remaining visual eye is to develop glaucoma when primary glaucoma is suspected. This test involves placing a special contact lens on the eye which allows examination of the drainage angle. Gonioscopy is usually performed under sedation or anesthesia.

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