A corneal ulcer is an eye infection that causes an open sore on the cornea (the clear layer in front of the iris and pupil).
Contact lenses, injuries, disorders, drugs, and nutritional deficiencies can cause open sores (ulcers) to form on the cornea.
Pain, foreign body sensation, redness, tearing, and light sensitivity are common symptoms.
Antibiotic, antiviral, or antifungal eye drops are usually given as soon as possible.
Corneal ulcers may begin with a corneal injury, which then becomes infected with bacteria, fungi, or the protozoan Acanthamoeba (which lives in contaminated water). Viral ulcers (often due to a herpes virus) can be triggered to recur by physical stress or may recur spontaneously. Ulcers can also occur if a foreign object scratches, penetrates, or lodges in the eye or, more often, if the eye is irritated by a contact lens, especially when contact lenses are worn during sleep or are not adequately disinfected (see Care and complications). A deficiency of vitamin A and protein may lead to the formation of a corneal ulcer. However, such ulcers are rare in the United States.
When the eyelids do not close properly, the cornea may become dry and irritated. This kind of irritation can lead to injury and the development of a corneal ulcer. Corneal ulcers may also result from in-growing eyelashes (trichiasis), an in-turned eyelid (entropion), or eyelid inflammation (blepharitis).
Corneal ulcers cause redness, pain, usually a feeling like a foreign object is in the eye (foreign body sensation), aching, sensitivity to bright light, and increased tear production. The ulcer often appears as a white or dull and grayish spot on the cornea. Sometimes, ulcers develop over the entire cornea and may penetrate deeply. Pus may accumulate behind the cornea, sometimes forming a white layer at the bottom of the cornea (called a hypopyon). The conjunctiva usually is bloodshot. The deeper the ulcer, the more severe the symptoms and complications.
Doctors evaluate the ulcer by using a slit lamp (an instrument that enables doctors to examine the eye under high magnification). To see an ulcer clearly, a doctor may apply eye drops that contain a yellow-green dye called fluorescein. The fluorescein temporarily stains damaged areas of the cornea, making it possible for the doctor to see damaged areas of the cornea that are not otherwise visible.
In some situations, doctors scrape the surface of large ulcers for a sample. The sample is then grown in a laboratory (cultured) to identify the bacterium, fungus, virus, or protozoa causing the infection. Once the organism is identified, doctors choose the best drug to fight the infection.
A corneal ulcer is an emergency that should be treated immediately.
Antibiotic, antiviral, or antifungal eye drops are usually needed immediately and must be given frequently, sometimes every hour around the clock.
Drops that dilate the eye, such as atropine or scopolamine, can help with pain and reduce the chance of complications.
Corneal transplantation (keratoplasty) is sometimes needed.