The cornea, the transparent part of the eye, forms a cover over the iris and pupil. It also admits light to the inside of the eye. A corneal ulcer occurs when deeper layers of the cornea are lost and can be classified as superficial or deep.
The most common causes is a wound or scrape to the surface of the eye. Common causes of corneal ulcers include:
- Rough contact with plants, thorns, or bushes
- Scratches from another animal
- Self trauma
- Chemical irritation (such as getting shampoo in the eye during a bath.)
- Foreign body injury (plant material can get stuck under an eyelid and can scrape the cornea.)
- Infections with certain viruses, bacterial or fungal infections
- Dry eye or Keratoconjunctivitis sicca, a disease resulting in decreased production of tears. A lack of protective tears to keep the cornea moistened can lead to an ulcer.
Symptoms include squinting, tearing, redness apparent within tissues lining the inner surface of the eyelid, rubbing the eye, discharge. A film over the eye or cloudiness may also be apparent.
A special fluorescent stain is used to confirm the presence of the ulcer or erosion. If the cornea is damaged, the stain will stick to the damaged area and show bright green under a fluorescent lamp. Schirmir Tear Test measures the eyes tear production. Corneal ulcers can be caused by lack of tear flow to the eye. This test helps to determine if the cause of the ulcer is due to dry eye.
Treatment: A routine corneal ulcer should heal easily. Topical antibiotics are used to treat current infection and prevent the damaged cornea from secondary infection. Atropine 1% drops or ointment can be used in cases where there is significant pain. Because the tear duct system is connected to the nose and mouth, the patient will also taste the above medications and atropine is famous for its bitter taste. Dogs do not seem to mind this, but cats will drool shortly after the medication. This is a normal reaction to the Atropine as is the dilated pupil.
An Elizabethan collar is necessary to prevent self-trauma of the eye. It is important to have the pet wear this collar the entire course of treatment until the ulcer is healed.
Re-Check in One Week
It is important that the eye be stained again after one week of therapy. Most ulcers will have healed in this time but some will require an additional week. If the ulcer has not healed after two weeks, special procedures may be needed and/or a veterinary ophthalmologist may be required. If the inflammation goes deeper into the eye, the situation becomes more serious; it is very important that the one week re-check not be skipped. If there is any question about the eye’s healing progress, the eye should be re-checked sooner.