The cornea is the transparent front part of the eyeball that admits light to the eye.
A corneal ulcer is a hole in the top layer of the cornea. The most common cause of corneal ulcers is trauma. Grass seeds, a cat scratch, shampoo and sticks cause most of the corneal ulcers we see at Hall Vet Surgery.
Dry eye develops because of abnormal tear formation in older dogs and is also a common cause of corneal ulcers. Some diseases that affect the whole body like diabetes mellitus, Cushings disease, and hypothyroidism sometimes predispose a dog to corneal ulcers, too.
A corneal ulcer is very painful. The affected dog rubs the eye and squeezes it tightly closed. The eye looks red and watery.
Superficial corneal abrasions are difficult to see. A drop of fluorescein stains the area of ulceration and shows it up clearly under a special blue light.
A superficial corneal abrasion generally heals within 5 days. Antibiotic eye drops or ointment prevent bacterial infections. Atropine eye drops or ointments relieve spasm and pain.
If the corneal ulcer is deep or slow healing or a descemetocele has formed we protect the eye and promote healing with a surgical overlay of conjunctiva, the third eyelid or the upper and lower eyelids.
Atropine relieves the pain from the ulcer but dilates the pupil making the dog sensitive to light. Do not be alarmed if the pupil stays dilated for several days after the last dose.
Atropine travels down the tear ducts to the mouth and because it tastes bitter causes drooling and pawing at the mouth in some dogs.
When the fluorescein stain test is negative your vet will tell you to discontinue the treatment. This is usually after at least 5 days of treatment.
The normal cornea has no blood vessels in it. When it is ulcerated blood vessels grow in from the white part of the eye, the sclera, to heal it and may obstruct vision. If they don’t retreat once the ulcer is healed we clear them with cortisone drops or ointment.