Causes of corneal ulcers include:
- Bacterial infections. Bacterial infections are the most common cause of corneal ulcers. These infections are common in contact lens wearers who don’t properly clean their contacts or wear them while sleeping. Pseudomonas aeruginosa, coagulase-negative staphylococcus and staphylococcus aureus are common bacterial causes.
- Viral infections. Viruses that can flare up and cause corneal ulcers include cold sores (herpes simplex) and shingles (herpes zoster).
- Fungal infections. These infections can happen if you have an injury to your cornea followed by an infection with plant or vegetable material. Aspergillus, Fusarium, Scedosporium apiospermum, phaeohyphpmycetes and candida species are common fungal causes.
- Parasitic infections. Acanthamoeba is an amoeba found in air, fresh water and soil. An infection, Acanthamoeba keratitis, occurs when the organism gets into your eye. This can happen if you wear contact lenses and clean your lenses with tap water instead of disinfectant solution.
- Corneal abrasions. Bacteria can infect cuts, scrapes or scratches to your eye. Abrasions can happen from a fingernail scratch to your eye, a particle of dirt or other material that gets trapped or rubbed in your eye and other causes.
- Corneal burns. Certain chemicals found at home or work can get into your eye and erode your cornea.
- Severe dry eyes. This is a condition in which your tears (your eye’s “windshield washers”) can’t properly clean and lubricate your eyes. Without tears, particles remain on your eye and may scratch it and infection can set in.
- Eyelid closure problems. Disorders that don’t allow your eyelids to close all the way can lead to dry eye conditions, which can lead to a corneal ulcer. Disorders include Bell’s palsy, Grave’s disease and other thyroid disorders. Other eyelid or eyelash problems that can lead to corneal ulcers include ingrown eyelashes (trichiasis), eyelid inflammation (blepharitis) and an in-turned eyelid (entropion).
- Autoimmune diseases. Several autoimmune diseases can cause peripheral ulcerative keratitis (PUK), which leads to a corneal ulcer. Types of autoimmune diseases tied to PUK include rheumatoid arthritis, Wegener granulomatosis, relapsing polychondritis, polyarteritis nodosa, Churg-Strauss syndrome and microscopic polyangiitis.
- Vitamin A deficiency. Lack of vitamin A causes the cornea to become dry. It also helps build new eye tissue. Most people in developed countries get plenty of vitamin A, but people with digestive problems or unusual diets can have low vitamin A. In the developing world, vitamin A deficiency is a major cause of childhood blindness.