Corneal Ulcer

Causes

Bacterial infections cause corneal ulcers and are common in contact lens wearers. Bacteria can directly invade the cornea if the corneal surface has been disrupted. Some bacteria produce toxins that can cause ulceration of the cornea.

Viruses that may cause corneal ulcers include the herpes simplex virus (the virus that causes cold sores) and the Varicella virus (the virus that causes both chickenpox and shingles) if it involves the upper eyelid and tip of nose (herpes zoster ophthalmicus). Although these viral illnesses usually cause only herpes simplex or herpes zoster keratitis or keratoconjunctivitis, corneal ulcers can develop. Fungal infections can cause corneal ulcers and may occur with improper care of contact lenses or overuse of eye drops that contain steroids. Parasites like Acanthamoeba may also cause corneal ulcers.

Tiny cuts or scratches in the corneal surface may become infected and lead to corneal ulcers. Injuries damage the corneal surface and make it easier for bacteria to invade and cause a corneal ulcer. A corneal abrasion is a larger loss of the corneal surface and may ulcerate if left untreated.

Disorders that cause dry eyes (keratitis sicca) can leave the eye without the germ-fighting protection of the tear film and cause or aggravate corneal ulcers.