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A corneal ulcer is a break in the outer corneal layers. Uncomplicated ulcers, although initially painful, should heal in 3 to 4 days with limited care. Those ulcers that persist longer than this period of time prove to be complicated ulcers.
Corneal ulcers fail to heal for two broad categories of reasons. The first category is comprised of those that fail to heal due to external causes. These causes include ongoing trauma, unresolved infections, foreign bodies embedded within the eyelid, and abnormally placed eyelashes. These ulcers require the treatment of the external cause to permit normal healing.
The second category of non-healing ulcers is those that are due to failure to heal for internal reasons. These causes include other ocular diseases and primary tissue healing defects. Other ocular diseases that would prevent corneal healing would be dry eye syndrome, glaucoma, and intraocular inflammation. Healing defects refers to conditions in which the tissue itself fails to heal in a normal fashion. This process is recognized in certain breeds of dogs, like the boxer and is sometimes referred to as a "Boxer ulcer".
Evaluation of the patient with the complicated corneal ulcer requires a number of diagnostic instruments and techniques. Probably the most important in the evaluation of a corneal ulcer is the slit lamp - biomicroscope. This instrument permits the veterinary ophthalmologist to carefully evaluate the cornea with a high degree of magnification and resolution.
Frequently, specimens are obtained for bacterial culture, virus isolation, and cytological evaluation.
Treatment of a non-healing corneal ulcer is dependent on the results of the diagnostic procedures. Those that involve external causes require those causes to be treated and, normally, healing rapidly follows. Those that involve other ocular diseases will require those ocular diseases to be treated in an effort to permit healing of the ulcer.
The most frustrating ulcer may be the healing defect ulcer. These ulcers, although generally not sight threatening, have a prolonged course. Medical therapy at this time consists of debridement, followed with hyper-osmotic agents. If medical therapy proves ineffective, a surgical procedure known as a superficial keratectomy is recommended.
EYE THREATENING ULCERS
If the ulcer becomes deep, a perforation of the cornea may be the result. These ulcers require aggressive medical and often surgical intervention. Various surgical techniques have been used to treat deep corneal ulcers. The most common procedures used in this clinic are the application of cyanomethylmethacrylate and a conjunctival pedicle graft.
The first technique, the application of cyanacrylate (medical grade of super glue) to the ulcer, follows a careful debridement of the ulcer. The eyelids many times are sutures partially shut to serve as a soft bandage over the weakened tissue.
The second technique involves the transplantation of a piece of conjunctiva into the corneal defect. The advantage of this procedure is that it provides an immediate seal to the corneal ulcer with a healthy piece of ocular tissue. The tissue is allowed to remain in place for a period of 4 to 6 weeks. Following this therapy, the graft may be trimmed under local anesthetic.
Corneal ulcers are a frequent problem in veterinary medicine. Your regular veterinarian is equipped to evaluate and manage most of these problems. Only those patients with severe or chronic ocular diseases are referred for evaluation to the veterinary ophthalmologist. Your veterinary ophthalmologist is especially trained and equipped to treat unusual ocular diseases in pets and animals.