Corneal Ulcers, Canine and Feline - contd.
The type of treatment the veterinarian prescribes for the affected dog or cat will depend on the severity of the corneal ulcer, its duration, and the suspected underlying cause. Generally, veterinary care is focused on treating or preventing infection, controlling pain and inflammation, preventing further corneal damage, and minimizing the disruption of the clear cornea by limiting scar formation.
For superficial ulcers, the use of an antibiotic ointment is very effective in preventing bacterial infection while the eye heals. Viral-associated corneal lesions in cats may benefit from topical antiviral preparations, which are likely to be used for several weeks. Fungal infections are uncommon, but when present must be treated with specific antifungal medications for a successful outcome.
Corneal ulcers often cause painful spasms within the eye. Topical atropine eye drops may be used to reduce these spasms. Atropine also dilates the pupil; in so doing, it reduces the potential for adhesion of the iris to the cornea. Dogs and cats given this treatment should be kept in a low-light area, since the atropine will make the eyes very sensitive to direct sunlight.
Deeper ulcers must be treated aggressively to minimize complications. When the ulcer involves Descemet's membrane, surgery will be needed to place a protective graft over the ulcer. Several surgical techniques are available. The most common type is a conjunctival pedicle graft, in which a flap is created from the conjunctivae, which are the thin membranes attached to the eye, and is stitched to the edges of the ulcer. This graft protects and supports the ulcer as it heals, and provides a blood supply to facilitate healing. The graft is removed when sufficient healing has occurred.
If the Descemet's membrane ruptures through all the layers of the cornea, the fluid within the front part of the eye will leak out, resulting in collapse of the eyeball. This is a surgical emergency and quick action is needed if the eye is to be saved and vision spared.
Corneal ulcers that are not healing properly may require additional treatment measures. Tissue adhesives are used to treat selected superficial punctures, deeper ulcers that do not appear to be healing properly and non-healing superficial corneal ulcers. Surgical debridement, or excision, of necrotic and uneven tissue margins on the surface of a chronic non-healing ulcer is commonly performed to facilitate healing. Chemical debriding agents may also be used. Multiple procedures are usually required over several weeks to months, depending on the ulcer's progress. In many cases systemic antibiotics in addition to topical ones are prescribed. Drugs that promote epithelial growth and anti-proteases that inhibit degradative enzymes may also be given.
Self-trauma can dramatically worsen any eye lesion, and most animals will be tempted to rub or scratch the painful eye. Elizabethan collars are often recommended to limit the possibility of such self-trauma, especially when the dog or cat patient is unsupervised.
A dog or cat undergoing treatment for a corneal ulcer must return to the veterinarian frequently for re-evaluation until the ulcer has healed. Complete healing is evident when fluorescein drops placed on the cornea no longer stain it. Complicated cases may require referral to a veterinary ophthalmologist.
