Indolent Corneal Ulcer (Boxer Ulcer)

The cornea is the clear tissue on the outermost surface of the eye. An indolent or non-healing ulcer results when the cornea becomes nicked or scratched, creating the initial ulcer, and cells of the outer surface of the cornea fail to adhere to the underlying tissue as they are trying to heal. This causes edema (cloudiness) of the cornea, pain, and blood vessel growth into the cornea. Once the cornea is ulcerated, bacteria can multiply in the affected area and cause the ulcer to become worse. These ulcers may persist for long periods of time if left untreated.

Indolent ulcers are most commonly seen in older-aged dogs and Boxer dogs of any age; hence the term “Boxer Ulcer.”

What are the signs of an indolent ulcer?

Some of the signs of an indolent ulcer include pain and squinting, redness of the conjunctiva or white part of the eye, tearing and discharge from the eye, and an abnormal appearance to the cornea. This abnormal appearance may include a bluish or white discoloration, red blood vessels growing into the cornea, and a dark brown discoloration from pigment on the cornea.

A veterinarian can detect an indolent ulcer by applying a fluorescent green, non-toxic dye to the surface of the cornea. A careful examination of the eye is also necessary to identify any underlying cause for the ulcer, such as dry eye, eyelid defects, or abnormal hairs.

A “bandage” contact lens on a Himalayan cat. Note the four black dots, which allow the owner to visualize if the contact is still in place.

Indolent ulcers are treated differently depending on the cause, severity, and whether infection is present. Treatment can include repeated debridement, grid keratotomy, or superficial keratectomy.

Debridement of the ulcer promotes healing by removing the outer non-adhering layer of the cornea with a cotton swab. This procedure may have to be repeated several times. A “bandage” contact lens may be placed over the surface of the cornea to cover exposed nerve endings and make the patient more comfortable.

A grid keratotomy is a procedure performed in dogs in which the tissue under the diseased outer surface of the cornea is altered by making tiny scratches on the surface with a fine gauge hypodermic needle. This procedure helps to promote healing and may require repeating. It is generally performed with only topical anesthesia, and again, a “bandage” contact lens may be placed.

For chronic cases or those not responding to grid keratotomy procedures, a superficial keratectomy is necessary. With this procedure, the outer or superficial layer of the affected cornea is surgically removed by careful dissection, using an operating microscope. This procedure is associated with a 100% success rate in a single surgery, but requires general anesthesia. However, surgery is generally reserved as a last resort, since 50% of indolent ulcers will heal with a debridement alone, and 76% will heal with a grid keratotomy.