Corneal Ulcer - Causes, Symptoms & Treatment
A corneal ulcer, commonly known as an eyesore, is an ulcer on the surface of the cornea (the clear structure on the surface of the eye that covers the iris). Although the condition is relatively common worldwide, it is more frequently seen in the tropics and developing countries.
What Causes Corneal Ulcers?
The most common cause of corneal ulcers is infection of the cornea. Ulcers caused by bacterial infection occur when bacteria invade the corneal surface, causing inflammation and producing toxins that lead to ulceration. Viruses may also cause corneal ulcers, with the most common pathogens being the herpes simplex virus and the varicella virus (chickenpox/shingles). In rare cases, a fungal infection can cause a corneal ulcer, usually resulting from improper maintenance of contact lenses or use of steroidal eyedrops.
Infection of the cornea typically happens after a tiny cut or scratch compromises the corneal surface. Such cuts can be caused by minimal trauma, such as dust particles, chemical irritation, or simply rubbing your eyes the wrong way. In addition, people with dry eyes are more susceptible to corneal ulcers because they don't have enough tears to effectively clean and fight infection within the eye. Thus, facial muscle disorders that make it difficult to close the eye completely can lead to an increased susceptibility to corneal ulceration due to dry eyes.
People that wear contact lenses are at increased risk for corneal ulcers for multiple reasons. Contact lenses can scrape and irritate the corneal surface, leaving it open to infection. Small particles of dust and dirt can be trapped underneath contact lenses, scratching the cornea and introducing bacteria.
Studies have shown that the risk for corneal ulceration increases by 10 for people that use extended wear contact lenses. This is probably because wearing contact lenses for several days at a time blocks oxygen from reaching the cornea, creating an environment in which anaerobic bacteria can thrive. Individuals with suppressed immune systems (patients with AIDS, lupus, rheumatoid arthritis) are also more susceptible to corneal ulcers, as are people with conditions that cause loss of sensation on the corneal surface.
Corneal Ulcer Symptoms and Diagnosis
The symptoms of a corneal ulcer are bothersome and usually prompt patients to seek treatment within the first 24 to 72 hours. Corneal ulcers cause redness, pain, a sensation that a foreign object is stuck in the eye, excessive tearing, and a thick pus discharge that drains from the corner of the eye. Vision may also be blurred, and many people experience an increased sensitivity to light.
Corneal ulcers are relatively easy to diagnose because they appear as a grayish-white area on the cornea, which is usually completely transparent. However, it may be difficult to see some smaller corneal ulcers without an illuminated microscope. Thus, when a patient complains to an ophthalmologist about any type of pain on the surface of their eyes, and other causes have been ruled out, a special optical microscope called a slit lamp is used in combination with fluorescein dye (which contrasts the ulcer making it more visible) to examine the patient's eye.
If the ophthalmologist suspects that the corneal ulcer is being caused by an infection, a sample of the ulcer may be sent to the laboratory for testing so that an appropriate treatment regimen can begin if necessary.
Corneal Ulcer Treatment, Prognosis, and Complications
Treatment for a corneal ulcer depends on the exact cause. Since most corneal ulcers are caused by bacterial infection, antimicrobial eyedrops are the most common treatment. However, if the infection is being caused by a virus, or a particularly virulent bacterial infection has taken root, oral antibiotics or antiviral medications may be prescribed. Doctors also usually prescribe a tear substitute to help keep the eye moisturized during the healing process.
If the corneal ulcer was caused by chemical or physical irritation, the irritated agent must be washed from the eye, usually by flushing with large amounts of water. After the eye is flushed, antibiotics and anti-inflammatories may be prescribed to reduce the risk of a secondary infection and/or corneal scarring. In rare cases, if the ulcer becomes so severe that it begins to perforate the cornea and threatens to damage vision, emergency surgery may be needed to transplant the cornea.
Most corneal ulcers will completely heal within 2 to 3 weeks with proper treatment. However, if left untreated the ulcer can spread into the eye, causing permanent vision loss or even complete blindness in the affected eye. If your corneal ulcer does not begin to completely heal after treatment, it is imperative to return to a physician as soon as possible to prevent such serious complications.