Corneal ulceration is one of the most common eye diseases in the dog and cat. The cornea is a transparent, very thin covering over the front of the eyeball. It is less than 1mm thick and is multi-layered like an onion. The cornea has numerous nerve endings and is extremely sensitive. It readily reacts to irritants from both outside and inside the eye.
The healthy cornea is normally very resistant to infection. When the cornea becomes injured, it loses its transparency and may become partially or totally cloudy. Corneal cloudiness (edema) may be caused by trauma, allergic reactions, infection (viral and bacterial), birth defects, metabolic/endocrine disease, chemicals and other irritants. If an injury occurs which damages the cornea, it may allow bacteria to penetrate, causing an infection in the deeper layers of the eye.
A corneal ulcer is an erosion through one or more layers of the cornea. Rapid deterioration of the cornea may result in very serious disease, even blindness. The scientific name for this condition is “Ulcerative Keratitis.”
Corneal ulcers result in pain, blepharospasm (eyelid blinking), scleritis (reddening of the white part of the eye), conjunctivitis (inflammation of the pink tissues), and sensitivity to bright light and discharges from the eye. Blindness or potential loss of the eye can result if the ulcer is not properly treated.
Sometimes an ulcer on the cornea cannot be seen with the naked eye. A special stain must be used to assess the size and severity of the erosion. Treatment is based upon the severity of the erosion and may range from topical antibiotics to surgery for deep infections. Corneal ulcers are classified based upon what caused it and how deep the ulcer is. Descemet’s membrane is the innermost layer of the cornea. A desmetocele is a true ophthalmic emergency as it is a corneal ulcer so deep that only one layer remains as the final barrier separating the anterior chamber from the external environment. Desmetocele is a bulging of the membrane after a deep ulcer has eroded all of the above corneal layers. This is a medical emergency and requires immediate ophthalmic care and most likely surgery.
Most deep corneal ulcers may require surgical intervention such as a corneal or conjunctival flap to provide additional support. Topical and oral therapy will also be required. Failure to treat this disease in a timely manner can result in rupture and collapse of the eyeball. Please contact a specialist for a full ophthalmic evaluation to determine the best course of action for your pet.