What you need to know about corneal ulceration

What is it?

The cornea is the transparent part of the outer layer of the eye. Corneal ulcers occurs when a pet injures or irritates his cornea. When the cornea becomes irritated or scratched, it can result in damage to the layers of the cornea, which is called ulceration. Damage can occur if the eye is irritated by chemicals, dust, lack of tears, or by scratches. 

Another way the cornea can be damaged is with a condition that is called an entropion, when the pet’s eyelid turns inward and the eyelashes damage the cornea. This is commonly reported in Chow Chows and Shar Peis. The cornea can also become damaged when the animal has a condition called keratoconjunctivitis sicca, also known as dry eye. In addition, some viral infections such as feline herpesvirus can cause corneal irritation and ulceration.

There are two types of ulcerations, superficial, affecting only a small amount of the top layer of the cornea, and deep, which extends through the layers of the cornea and can result in severe scarring and even eye rupture.

Most cases of corneal ulcer heal without complication when treated promptly. If treatment is delayed, that minor injury gives bacteria and other pathogens, such as viruses and fungi, an opportunity to cause infection, which can further complicate the situation. Without proper treatment, or with severe injury, corneal scarring will impair the pet’s vision. He could even face the loss of the eye.

What are signs of corneal ulceration?

Corneal ulcers are extremely painful. Animals with this condition usually squint their eyes and tear excessively. With deep ulcerations or with scarring, loss of vision is possible. Symptoms include:

·        Closed eyelids

·        Tearing, swelling, redness of the eyes

·        Conjunctivitis (inflammation of the membrane lining the eye)

·        Corneal lesion

·        Rubbing at the eye

·        Sensitivity to light

·        Presence of third eyelid 

How is it diagnosed?

Veterinarians diagnose corneal ulcers after staining the eye with a sterile yellow dye and examining it.  Although it sounds painful, staining the eye is painless and quick. The veterinarian uses Fluorescein eye drops or gently touches the eye surface with a sterile strip containing Fluorescein stain. Once the eye has been stained the vet examines the cornea in a darkened room using a black light (ultraviolet light.)

If the cornea is damaged, the dye will stick onto the damaged area. Under the black light, the lesion will appear as a bright yellow area. If the corneal ulceration is suspected to be caused by keratoconjunctivitis (dry eye) then a test called Schirmer tear test is performed. This test determines if the eyes are producing adequate tears, which are necessary to keep the cornea lubricated and healthy.                                                                  

Treatment

How your veterinarian treats the corneal ulcer depends on what caused it.  If the cause is due to an entropion, the vet will surgically alter the eyelid so the eyelashes return to a normal placement and avoid contact with the cornea.

Topical antibiotic therapy, pain medication, and eye lubricants are often used while the pet recovers from the surgery. Corticosteroids not used with corneal ulcerations because they hinder the healing process.

With large lacerations resulting from an injury, a special surgical procedure is performed in which a piece of conjunctiva (the pink part around the eyes) is removed and placed over the ulceration like a patch.  The conjunctiva helps protect the lesion and help keep it moist while it heals.