WHAT IS A CORNEAL ULCER? The cornea is the transparent front layer of the eyeball similar o the glass of a camera. It is less that 1mm thick and consists of several layers. An ulcer is caused by disruption in one or more layers of the cornea, starting from the outside going inwards. An ulcer may be very shallow, similar to a scrape or an abrasion, or it may be very deep, even to the point of causing the eye to rupture. The deeper the ulcer is, the more vision is threatened. The cornea is well supplied with nerves and therefore ulcers are quite painful.
WHAT ARE THE CAUSES OF CORNEAL ULCERS?
- alkalis, acids, detergents
- bacterial (possibly following trauma)
- viral (e.g. herpes)
- fungal (rare)
- Tear film abnormalities
- KCS (“dry eye syndrome”): tear glands do not produce adequate fluid to lubricate the eye and the cornea dries out and can ulcerate.
- Cilia abnormalities
- “distichiasis” and “ectopic cilia”: tiny hairs on the eyelids rub on the surface of the eye, causing irritation and damage.
- Exposure Keratopathy
- breeds that have protruding eyes (e.g. Pug, Shih Tzu, etc.) and/or shallow orbits may have poor closure of the eyelids and the eye subsequently is not moistened adequately and damage is done to the cornea.
HOW ARE CORNEAL ULCERS TREATED? Superficial, uncomplicated ulcers will normally heal within 4 to 7 days and topical antibiotic ointment is all that is required. Indolent ulcers are complicated ulcers which do not heal due to loose tissue surrounding the ulcer and blocking corneal cells from invading the damaged area promoting healing. In select cases that do not heal with traditional treatment we utilize superficial keratectomy with Corneal Cross-Linking. This involves removing some of the diseased tissue and placed enhanced riboflavin drops in the eye for 20 minutes. We then irradiate the cornea with Ultraviolet irradiation for 2 minutes. This activates the riboflavin, allowing cross bonds to form in between the layers of the cornea. This strengthens the cornea and promotes faster healing. Deep ulcers may potentially go through all layers of the cornea, causing the eye to rupture. To prevent this from happening, surgery is required: a “conjunctival flap” placed over the ulcer; corneoconjunctival transposition uses the pet’s own cornea and conjunctiva as a flap to slid down over the damaged area; partial thickness corneal transplant buttresses the deep ulcer. The conjunctival flap is performed by attaching a portion of the pink soft tissue that surrounds the eye directly onto the ulcer. This flap provides protection and supplies blood directly to the ulcer site, which aids in healing. It heals directly on to the cornea and will remain permanently. Part of the flap may be taken away 3-4 weeks after surgery.
WHAT WILL I NEED TO DO AT HOME? When using eye drops, be sure to hold the lids open and point the nose towards the ceiling so the medication is placed directly onto the eyeball. Wait 10 minutes between different drops so as not to flush out the previous medication before it has been absorbed. If you are require to use ointment, always apply it AFTER the drops have been given as it is thick and forms a barrier, preventing following drops from being absorbed. Keep the elizabethan collar on, even at night. A scratching paw can easily break the fine sutures holding the flap in place. Gently wipe away any discharge from the eye with a clean, moist Kleenex or washcloth.