Corneal ulcers and infections

Alternative names:

acanthamoeba keratitis; bacterial keratitis; fungal keratitis; herpes simplex keratitis; herpes zoster ophthalmicus

Definition:

A non-penetrating erosion, or open sore in the outer layer of the cornea, the transparent area at the front of the eyeball. See also corneal injury.

Causes, incidence, and risk factors:

Corneal ulcers are most commonly caused by an infection of bacteria, viruses, fungi, or amebas. Other causes are abrasions or foreign bodies, inadequate eyelid closure, severe dry eyes, severe allergic eye disease, and various inflammatory disorders.

Bacterial keratitis may be caused by numerous organisms. Contact lens wear, especially soft contact lenses worn overnight, may be a precipitating factor. Herpes simplex keratitis is a serious viral infection. It may have recurrences that are triggered by stress, exposure to sunlight, or any condition, disease or treatment which impairs the immune system. Corticosteroid therapy, given in the presence of herpetic keratitis, has been associated with more extensive ulcers.

Fungal keratitis can occur after corneal injury involving plant material, in an agriculture setting, or in immunocompromised (immunosuppressed) people. Acanthamoeba keratitis occurs in contact lens users, especially those who use homemade cleaning solutions.

Risk factors are dry eyes, severe allergies, history of inflammatory disorders, contact lens wear, immunosuppression, prolonged exposure to sunlight, and infection.