Diagnosis: Corneal Ulcer
The eyes are delicate organs of the body. Any abnormality with one or both eyes should be treated as an urgent matter to preserve sight.
The surface of the eye is called the cornea. It is a thin, multi-layer membrane that is transparent. The three layers of the cornea are the outer layer (epithelium), middle layer (stroma), and inner layer (endothelium). Continuous tear production along with the action of the eyelids closing regularly helps keep the outer surface of the cornea healthy and transparent. Corneal ulcers usually begin by affecting the epithelium.
Many things can cause an ulcer to develop. Keratoconjunctivitis sicca or dry eye is an abnormally low level of tear production that causes the cornea to become dry and worn away. Cat scratches, scratches from a branch, foreign material in the eye, or even abnormal eyelash contact with the cornea can result in corneal ulcers.
Symptoms of an ulcer are squinting, excessive tearing, and pawing or rubbing at the eye. Veterinary attention is critical to prevent the ulcer from eroding through all the layers and resulting in rupture of the eye.
A corneal ulcer is diagnosed by staining the surface of the eye with fluorescein dye. Fluorescein cannot adhere to a normal cornea. However, if there is a defect in the surface, the dye will stick to the defect. Shining a Wood’s lamp into the eye will cause the dye to glow fluorescent green. Sometimes a topical numbing agent may need to be applied so that the pet will open the eye wide enough to perform the staining. If the dye sticks to the edges of the defect, but not the center, this is a true emergency. This occurs when the epithelium and stroma are completely gone and only the final layer or endothelium remains. This is called a descemetocele because the bottom layer is called Descemet’s membrane. Surgical treatment is required to prevent rupture.
An ulcer that has been caused by a scratch or some foreign matter in the eye is usually very easily treated. Dilating the pupil and applying topical antibiotics every 4 to 6 hours will usually result in complete recovery. The pupil is dilated to prevent iris muscle spasms from causing more pain in the eye. Following the instructions on all prescribed medications is very important. Improper treatment (especially not applying the medications often enough) can result in failure to heal. If there are complicating factors, such as a resistant infection, dry eye, or a continued irritation to the surface of the eye, recovery is more complicated. Different antibiotics may need to be chosen, medications to combat dry eye should be used in these cases, and abnormal eyelashes or eyelid structure may need to be addressed surgically.
Follow-up care is extremely important. Your veterinarian will probably want to examine and stain the eye every other day initially. Sometimes it is difficult for you to tell if the treatment is effective. If things are progressing well, your veterinarian will schedule a recheck in several days to make sure that the ulcer is completely resolved.
Prognosis for complete recovery is very good for an uncomplicated case. For complicated cases, complete recovery may require much more intensive therapy. Dedication to the treatment will improve the chances of a full recovery. Some ulcers will progress despite aggressive and appropriate therapy. It is possible in some cases that the eye will have to be removed.
Please note that this information does not replace onsite, professional, veterinary care. It is solely for educational purposes. Your pet's medical condition should be evaluated by a veterinarian before any medical decisions are implemented. If there is a potentially life-threatening emergency involving your pet, take your pet to a veterinarian or veterinary facility immediately.
Veterinary Technical Services Department