Corneal Ulcers, Canine and Feline - contd.
A tentative diagnosis of corneal ulcer is made based on physical examination findings correlated with the affected animal's history. The diagnosis is confirmed with a fluorescein test. Fluorescein eye drops are placed in the patient's affected eye and then washed away gently with sterile saline. In the normal eye, the stain will wash away completely. If there is an ulcer, the stain will bind to the damaged tissue and appear as an apple-green area on the cornea. Deeper ulcers involving Descemet's membrane often have a dark center and do not bind fluorescein. When stained, this area of the cornea will appear as a dark spot with an apple-green border around it. Illumination with a Wood's lamp, or black light, can enhance detection of fluorescein stain retention.
Once the diagnosis of a corneal ulcer has been confirmed, the veterinarian will search for its underlying cause. The eye and eyelids will be thoroughly examined. Tear production may be measured to determine if tear insufficiency has contributed to the ulceration. Bacterial cultures may be taken to determine if infecting organisms are present in the ulcer. In cats, viral cultures also may be collected to see if herpesvirus, typically FHV-1, is present.
