A corneal ulcer forms when the surface of the cornea is damaged or compromised. Ulcers may be sterile (no infecting organisms) or infectious. The term infiltrate is also commonly used along with ulcer. Infiltrate refers to an immune response causing an accumulation of cells or fluid in an area of the body where they don't normally belong.
A major cause of blindness worldwide, corneal ulcers produce corneal scarring or perforation. They occur in the central or marginal areas of the cornea, vary in shape and size, and may be singular or multiple. Marginal ulcers, caused by a sensitivity to Staphylococcus aureus, are the most common form. Prompt treatment (within hours of onset) can prevent visual impairment.
Corneal ulcers generally result from bacterial, protozoan, viral, or fungal infections. Common bacterial sources include Staphylococcus aureus, Pseudomonas aeruginosa, Streptococcus viridans, Streptococcus (Diplococcus) pneumoniae, and Moraxella liquefaciens; viral sources, herpes simplex type 1, and varicella-zoster viruses; and common fungi, such as Candida, Fusarium, and Cephalosporium.
Other causes include trauma, exposure, reactions to bacterial infections, toxins, and allergens. Tuberculoprotein causes a classic phlyctenular keratoconjunctivitis; vitamin A deficiency results in xerophthalmia; and fifth cranial nerve lesions, in neurotropic ulcers.
Signs and symptoms
Typically, corneal ulceration begins with pain (aggravated by blinking) and photophobia, followed by increased tearing. Eventually, central corneal ulceration produces pronounced visual blurring. The eye may appear injected (red). If a bacterial ulcer is present, purulent discharge is possible.
A history of trauma or use of contact lenses and a flashlight examination that reveals an irregular corneal surface suggest corneal ulcer. Exudate may be present on the cornea, and a hypopion (accumulation of white cells in the anterior chamber) may appear as a half-moon.
Fluorescein dye, instilled in the conjunctival sac, delineates the outline of the ulcer. Culture and sensitivity testing of corneal scrapings, which may identify the causative bacteria or fungus, indicate appropriate antibiotic or anti fungal therapy.
A corneal ulcer needs to be treated aggressively, as it can result in loss of vision. The first step is to eliminate infection. Broad spectrum antibiotics will be used before the lab results come back. Medications may then be changed to more specifically target the cause of the infection. A combination of medications may be necessary. Patients should return for their follow-up visits so that the doctor can monitor the healing process. The cornea can heal from many insults, but if it remains scarred, corneal transplantation may be necessary to restore vision. If the corneal ulcer is large, hospitalization may be necessary.
Prompt, early attention by an ophthalmologist for an eye infection may prevent the condition from worsening to the point of ulceration. Wash hands and pay rigorous attention to cleanliness while handling contact lenses, and avoid wearing contact lenses overnight.
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