What is a corneal ulcer?

At the front of the eye is a clear layer of tissue called the cornea. The cornea is like a window that lets light enter the eye. Tears defend the cornea against bacteria, viruses, and fungi.

A corneal ulcer is an open sore that forms on the cornea. It’s usually caused by an infection. Even small injuries to the eye or erosion caused by wearing contact lenses too long can lead to infections.

The main cause of corneal ulcers is infection.

Acanthamoeba keratitis

This infection most often occurs in contact lens wearers. It is an amoebic infection and, though rare, can lead to blindness.

Herpes simplex keratitis

Herpes simplex keratitis is a viral infection that causes repeated flare-ups of lesions or sores in the eye. A number of things can trigger flare-ups, including stress, prolonged exposure to sunlight, or anything that weakens the immune system.

Fungal keratitis

This fungal infection develops after an injury to the cornea involving a plant or plant material. Fungal keratitis can also develop in people with weakened immune systems.

Other causes

Other causes of corneal ulcers include:

  • dry eye
  • eye injury
  • inflammatory disorders
  • wearing unsterilized contact lenses
  • vitamin A deficiency

People who wear expired soft contact lenses or wear disposable contact lenses for an extended period (including overnight) are at an increased risk for developing corneal ulcers.

You may notice signs of an infection before you’re aware of the corneal ulcer. Symptoms of an infection include:

  • itchy eye
  • watery eye
  • pus-like discharge from the eye
  • burning or stinging sensation in the eye
  • red or pink eye
  • sensitivity to light

Symptoms and signs of the corneal ulcer itself include:

  • eye inflammation
  • sore eye
  • excessive tearing
  • blurred vision
  • white spot on your cornea
  • swollen eyelids
  • pus or eye discharge
  • sensitivity to light
  • feeling like something is in your eye (foreign body sensation)

All symptoms of corneal ulcers are severe and should be treated immediately to prevent blindness. A corneal ulcer itself looks like a gray or white area or spot on the usually transparent cornea. Some corneal ulcers are too small to see without magnification, but you’ll feel the symptoms.

An eye doctor can diagnose corneal ulcers during an eye exam.

One test used to check for a corneal ulcer is a fluorescein eye stain. For this test, an eye doctor places a drop of orange dye onto a thin piece of blotting paper. Then, the doctor transfers the dye to your eye by lightly touching the blotting paper to the surface of your eye. Then the doctor uses a microscope called a slit-lamp to shine a special violet light onto your eye to look for any damaged areas on your cornea. Corneal damage will show green when the violet light shines on it.

If you have an ulcer on your cornea, your eye doctor will investigate to find out its cause. To do that, the doctor may numb your eye with eye drops, then gently scrape the ulcer to get a sample for testing. The test will show if the ulcer contains bacteria, fungi, or a virus.

Once your eye doctor discovers the cause of the corneal ulcer, they can prescribe an antibacterial, antifungal, or antiviral eye medication to treat the underlying problem. If the infection is bad, your doctor may put you on antibacterial eye drops while they test the ulcer scrapings to find out the cause of the infection. In addition, if your eye is inflamed and swollen, you may have to use corticosteroid eye drops.

During treatment, your doctor will likely ask you to avoid the following:

  • wearing contact lenses
  • wearing makeup
  • taking other medications
  • touching your eye unnecessarily

Corneal transplants

In severe cases, the corneal ulcer may warrant a corneal transplant. A corneal transplant involves the surgical removal of the corneal tissue and its replacement with donor tissue. According to the Mayo Clinic, a corneal transplant is a fairly safe procedure. But like any surgical procedure, there are risks. This surgery may cause future health complications such as:

  • rejection of the donor tissue
  • development of glaucoma (pressure within the eye)
  • eye infection
  • cataracts (clouding of the eye’s lens)
  • swelling of the cornea

The best way to prevent corneal ulcers is to seek treatment as soon as you develop any symptom of an eye infection or as soon as your eye is injured.

Other helpful preventive measures include:

  • avoiding sleeping while wearing your contact lenses
  • cleaning and sterilizing your contacts before and after wearing them
  • rinsing your eyes to remove any foreign objects
  • washing your hands before touching your eyes

Some people may also develop a severe loss of vision along with visual obstruction due to scarring over the retina. Corneal ulcers can also cause permanent scarring on the eye. In rare cases, the entire eye may suffer damage.

Although corneal ulcers are treatable, and most people recover quite well after treatment, a reduction in eyesight may occur.