A corneal ulcer is a defect or abrasion of the clear outer part of the eye. Ulcers may be shallow or deep. As this is a painful condition, the clinical signs are those associated with pain in the eyes, such as tearing, rubbing or pawing at the eye, redness in the eye, and excessive squinting.
Ulcers in dogs are usually caused by trauma to the cornea such as in a fight with another animal, a foreign body in the eye such as a grass seed, or an abnormality of the eyelids. In cats however, ulcers are commonly caused by a flare-up of feline herpesvirus. Over 90% of all cats worldwide are infected with feline herpesvirus infection, and in times of stress or immune-compromise, the virus can replicate and damage the corneas to form ulcers.
Treatment for Corneal Ulcers
Treatment for corneal ulcers involves recognising the primary problem where possible, and then controlling associated infection and pain. Most of the time we can do this with medication, including drops or ointments into the eye after correcting the underlying problem. A special type of ulcers, also known as “indolent ulcers”/”boxer ulcers”/”SCCEDS (superficial chronic corneal epithelial defects” can occur when there is an inherent issue with the corneal surface cells adhering to the layer beneath. This creates a chrnic ulcer that can not heal, despite the body’s best efforts.
In some cases however, the ulcer may be so severe that surgery is needed to not only save vision but to save the eye. In the worst cases the eye may rupture, resulting in the need for major corneal surgery. As with most eye diseases, the earlier an eye specialist can start treatment the better the chances of success in saving the eye and vision.
Corneal dystrophy is a disease characterised by cloudy deposits within the cornea. The deposits are a combination of calcium and fats (cholesterol) within the superficial and deep layers of the cornea. These may occur in one or both eyes, and often have no obvious cause, although may be associated with some diseases such as hypothyroidism. They are usually not painful, and do not interfere with vision. Certain breeds may be predisposed such as Beagles, Collies, Cavalier King Charles Spaniels, and Huskies.
In older animals, corneal degeneration may result in similar deposits. Occasionally an ulcer may develop on the surface of the deposits which is then painful. In these cases it may be necessary to remove the deposits by surgery. These older animals can also have slow corneal healing after surgery, and so often a special technique is employed to enhance corneal healing post-operatively.