Corneal Ulcers

Laurie Anne Walden, DVM

Public domain photo from pixy.org

Corneal ulcers are common causes of eye redness in dogs and cats. A corneal ulcer is an area of damage to the surface of the cornea, the clear structure at the front of the eye. These ulcers are painful but usually heal readily with treatment. Sometimes corneal ulcers develop complications that require surgery or other interventions.
 
Causes
Anything that scratches, hits, or irritates the surface of the eye can cause a corneal ulcer. Animals with low tear production are at increased risk for corneal ulcers because they have a low volume of tears to wash away irritants. These are some of the things that cause corneal ulcers:

• Trauma from a cat claw or object poking the eye
• Foreign object in the eye
• Hairs or eyelashes rubbing the cornea (for example, from rolled-in eyelids or skin folds around the eyes)
• Chemical irritation
• Eyelids that don’t adequately cover the cornea (common in brachycephalic, or short-faced, animals with shallow eye sockets and large eyelid openings)
• Immune system disorders that affect the tear film or cornea
• Abnormalities of corneal cells
• Infections
• Neurologic disorders affecting nerves of the eye or eyelids

 
Complications
Some animals have a defect of the corneal epithelium—the surface layer of corneal cells—that increases the risk of ulcers and keeps ulcers from healing. These slow-healing ulcers are called indolent ulcers. Corneal ulcers can become infected, threatening the animal’s vision. Deep corneal ulcers and wounds can penetrate all the way through the cornea and rupture the eye.
 
Eye medications that contain steroids (commonly used to treat conjunctivitis and other inflammatory eye conditions) prevent corneal ulcers from healing properly. Steroid-containing eye medications can also increase the risk of corneal infection.
 
Signs
The signs of eye discomfort are the same whether they are caused by a corneal ulcer or by another eye disorder. Typical signs are squinting, redness of the white part of the eye, and clear or cloudy eye drainage. The animal might rub the eye, and the cornea might look cloudy. Deep ulcers are sometimes visible without an ophthalmoscope and look like a dent or divot in the cornea. Superficial ulcers are usually not visible to the naked eye.
 
An animal with any of these signs should see a veterinarian right away. Although uncomplicated corneal ulcers are relatively minor, they are painful. Some of the conditions that cause the same signs are medical emergencies that require immediate treatment to save the eye.
 
Diagnosis
Corneal ulcers are diagnosed with fluorescein dye applied to the eye. This green dye shows areas where the normal corneal epithelium is disrupted or missing. The eye is also examined under magnification to assess the depth and size of the ulcer, detect complications, and find the cause.
 
Treatment
An uncomplicated ulcer is treated with eye medication to prevent infection and relieve pain. The animal might be fitted with a protective collar (the lampshade type) to prevent eye rubbing. The cause of the ulcer is also treated, if possible. The eye is rechecked with fluorescein dye after a few days to be sure the ulcer has fully healed.
 
Complicated ulcers are treated according to their cause and severity. Indolent ulcers are treated with a procedure to remove loose corneal epithelium. This procedure can often be performed in an awake animal with drops to numb the eye. Some indolent ulcers need a more extensive procedure with the animal under general anesthesia. Deep ulcers and wounds that might rupture the eye need surgical treatment by a veterinary ophthalmologist.
 
Image source: https://pixy.org/6427021/

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