Case Report: “The non-healing corneal ulcer”
Signalment: “Scout” – 20 yr old Arabian with no history of ocular problems prior to presentation.
History: About 7–10 days prior to presentation, the owner noticed Scout’s left eye was squinting, tearing and the lids appeared swollen. The owner initially started applying triple antibiotic, but as the eye did not seem to get better, an appointment was made with the vet.
Clinical Examination, Diagnosis and Treatment: During an ophthalmic examination, it was determined that Scout had a superficial corneal ulcer. He was started on the following treatments: triple antibiotic ophthalmic ointment, atropine ophthalmic ointment and sodium chloride ophthalmic ointment applied multiple times per day. Banamine was also administered for pain control.
Scout’s eye was monitored closely over the next two weeks. During the subsequent rechecks with the veterinarian it was noted that though the cornea continued to attempt to heal, the new epithelial cells were not adhering to the lower layer of the cornea and the ulcer remained open. After two rechecks, Scout was diagnosed with a non-healing superficial corneal ulcer that required more aggressive treatment.
Non-healing corneal ulcer:
Corneal ulcers or abrasions are common in horses and generally heal fairly quickly with appropriate treatment. However in geriatric horses, corneal ulcers tend to heal much more slowly. In some cases the epithelial cells that grow over the ulcer are unable to bind to the lower layer of the cornea. This forms a blister-like covering over the ulcer that usually ends up sloughing off several days later and reopening the ulcer. This type of ulcer is called a “non-healing corneal ulcer” and more aggressive treatment is required.
First the eye must be tested for any evidence of a fungus or bacteria that might be infecting the eye and preventing healing. If an infection is found, appropriate treatment must be administered. The next step is to perform a grid keratectomy. This procedure involves first removing all the loose corneal layers from the eye with a sterile swab. Then the cornea is lightly scratched with a small gauge needle in a grid pattern over the area of the ulcer. This procedure attempts to create grooves in the cornea in which the epithelial cells can follow and better adhere to the underlying layer. Frequently only one procedure is needed to induce healing, but there are some cases that require more then one grid keratecomy before the ulcer will heal.
Summary on Scout’s case:
Scout was treated with a grid keratectomy after it was determined that no bacteria or fungi were present. His non-healing ulcer subsequently healed over the next week and has continued to do well ever since.
Epithelial cells: These are the cells that make up the top layer of the cornea. These cells are the ones lost when an ulcer is formed and need to re-grow and adhere to the lower layers of the cornea to heal the ulcer.
Grid Keratectomy: Surgical incisions made over the area of the cornea that is ulcerated. See Figure 3.
Figure #1- Ulcerated Eye
Figure #1– There is a superficial ulcer (light green area) . There is some corneal edema and vessel grown to the right of the ulcer.
Figure #2- Normal Eye
Figure # 3- Grid Keratectomy
This photo is from Essentials of Veterinary Ophthalmology by Kirk N. Gelatt, page 135