What is ulcerative keratitis?
Ulcerative keratitis is a type of inflammation that occurs in the cornea of the eye. The cornea is the transparent outer layer of the eye and it is composed of three distinct layers of cells. The top surface is called the corneal epithelium. The middle layer is the thickest of the three and is called the corneal stroma. The inner layer is quite thin and is called the corneal endothelium. Ulcerative keratitis is inflammation most commonly associated with the surface layer - the corneal epithelium - causing an erosion (destruction) of the surface tissue. If it progresses into the deeper tissue - the corneal stoma - it is then called a corneal ulcer.
When a cat has been consistently rubbing its eyes, the eyes should be carefully examined by your veterinarian and a special dye called “fluorescein” dye may be used. If there is damage to the surface of the cornea, the fluorescein dye will “stick” to the underlying cells and show up as a temporary green glow in the areas of cell trauma.
My cat is a Persian. Is that why he developed this condition?
While no specific genetic predispositions to ulcerative keratitis have been identified, some cat breeds seem to develop them more commonly, particularly breeds with short muzzles and prominent eyes, such as Persian, Himalayan, and Burmese cats.
In cats, the most common causes of ulcerative keratitis are trauma and infectious disease - particularly an infection with Feline Herpes Virus (FHV-1). If the condition occurs spontaneously in a middle-aged to older cat without an injury to the eye, it can signal a long-term degenerative condition of the cornea. Ulcerative keratitis also may be the result of a chronically low level of tear production called keratoconjunctivitis sicca or dry eye.
What are the signs of ulcerative keratitis?
The signs of ulcerative keratitis depend somewhat on the cause and how long the condition has been present. There may be increased tearing, squinting, or rubbing of the eye. There may be discharge from the eye that can vary from whitish to green. Your cat may avoid light or experience spasmodic blinking in bright light. The tissue around the eye may become swollen and red, and you may be able to see a divot in the surface of the eye. If the keratitis has been present for a while, there may be blood vessels or pigment that develop in the area around the site of the corneal injury. Fluid can also accumulate in the deeper tissues of the cornea, causing the cornea to become hazy or cloudy-looking.
What are the causes of ulcerative keratitis?
There are many potential causes of ulcerative keratitis. They include:
- Trauma to the eye.
- Infectious diseases such as feline herpes virus.
- Inability to close the eyelids completely, exposing the eye surface to air, dust, and other irritants.
- Diseases of the eyelids or tear-producing glands.
- Abnormal tear production or tear quality.
- Primary diseases of the corneas.
How is ulcerative keratitis treated?
Treatment depends on the cause of the keratitis, the length of time it has been present, and the extent of damage to the cornea.
Most cats with superficial corneal injury do not require surgery once the underlying problem is removed or resolved. Antibiotic ointment or drops will be prescribed, and it is important to prevent additional trauma to the cornea by removing excess hair around the eyes or using an Elizabethan collar (an E-collar or cone) for a short time. Ointments have a longer contact time with the tissues of the cornea, so they are typically applied less frequently than eye drops. Topical pain medication may be used, as corneal ulcers are often quite painful. Additional treatments may include oral antibiotics, serum drops (from blood collected from your cat), and drugs designed to kill herpesvirus (such as oral Famciclovir or topical Cidofovir).
Cats with very deep ulcers may need to be hospitalized for frequent treatments or even surgery. Surgery may be as simple as removing loose surface cells once the surface of the eye is anaesthetized. Some corneal ulcers need to be repaired by a board-certified ophthalmologist. This specialist may use a variety of techniques to promote healing, such as graft from the conjunctiva (the pink part of the eye) to help promote healing.
What can I expect in the long term for my cat's eyes?
For a superficial corneal ulcer, the fluorescein dye staining will be repeated to confirm healing. If the ulcer is still present, it may signal the need for additional diagnostics and more aggressive treatment. If surgery is required, assessments will be more frequent and the healing progress will be followed very carefully.
Preventing recurrence of ulcerative keratitis may include applying lubricating ointment (artificial tears ointment) or surgery to provide better closure of the eyelids. If your cat is diagnosed with dry eye, there are prescription ointments to help control the symptoms.
Superficial corneal ulcers typically heal within 5 to 7 days. Chronic ulcerative keratitis may require multiple treatments and may take weeks to heal. Deep corneal ulcers that require surgery generally require additional follow-up to prevent a recurrence.