Eye Spy Trouble: A Closer Look at Corneal Ulcers

The cornea is the clear portion on the front part of the eye. A corneal ulcer is when the cornea becomes eroded, gets scratched or has damage to several layers.

The outer layer of the cornea, or epithelium, is protected by a tear film and is tolerant of bacteria. If this outer layer is scratched away the bacteria can infect the next layer known as the stroma. Extensive innervation of the epithelium makes a corneal ulcer very painful. Typical clinical signs of a corneal ulcer include squinting, tearing, rubbing the eye and

redness or swelling of the tissues around the eye. If these clinical signs are observed, your veterinarian will likely use a special florescent stain to diagnose a corneal ulcer. Fluorescein stain will stick to the damaged corneal surface, whereas it just washes off the normal corneal epithelium.

Treatment of a corneal ulcer typically includes a topical antibiotic eye drop, oral pain medication and sometimes a cone to prevent further damage to the eye by rubbing or scratching. It is important to recheck in 1 week to make sure the ulcer has resolved as some ulcers will persist- these are known as indolent ulcers. It is important to remember that topical corticosteroids are contraindicated with corneal ulcers because they slow healing.

Indolent ulcers have a flap of unattached epithelium along the edge of the ulcer. This flap of tissue needs to be removed to allow the ulcer to heal. The cornea can be de-sensitized with a topical anesthetic and the flap of tissue is removed. Although most ulcers heal in 7 to 10 days, an indolent ulcer can persist and require treatment for several weeks.

A very serious form of corneal ulceration is called a descemetocele. The deepest or last layer of cornea is called Descemet’s membrane. It is only 3-12 micrometres thick, making corneal rupture a real risk. Therefore, these ulcers are treated more aggressively, often referred to a veterinary ophthalmologist for a conjunctival graft (a peninsula of the conjunctiva or pink tissue around the eye is sewn over the defect to protect and bring healing blood supply to the damaged cornea).

If you are concerned about your pet’s eye(s), it is best to have them examined by a veterinarian as soon as possible to maintain vision and the health of your pet’s eyes.