Corneal ulcer, also called keratitis, is a sore on the cornea. The cornea is the dome that covers the front of the eye. A healthy cornea protects the inside of the eye and guides light into the eye.

Normal Anatomy of the Eye

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A corneal ulcer is caused by a breakdown of the surface of the cornea. The breakdown may be caused by:

  • Inflammation from an infection with a virus, bacteria, parasite, or fungus
  • Injuries to the cornea
  • Inflammation from autoimmune diseases

Risk Factors

Factors that may increase the risk of corneal ulcer include:

  • Wearing contact lenses, especially if the lenses are worn longer than directed or not cleaned properly
  • Conditions that weaken the cornea such as dry eye, eyelid abnormalities, or Vitamin A deficiency (rare)
  • Dry eye or having reduced blinking and tears
  • A weakened immune system
  • Recent ocular or eyelid surgery
  • Working in a setting with eye hazards, such as metal working or gardening
  • Severe eye allergies


Symptoms in the eye may include:

  • Pain
  • Redness
  • Discharge and/or tearing
  • Burning and itching sensation
  • Foreign body sensation
  • Swelling
  • Sensitivity to light
  • Changes in vision

If an infection is present, there may also be a fever.


You will be asked about your symptoms and medical history. An eye exam will be done. The doctor will probably be able to make the diagnosis after a visual exam using a slit lamp.

Your bodily fluids and tissues may need to be tested to determine the cause. This can be done with:

  • Corneal culture—A swab of fluid from the eye is tested for infections.
  • Biopsy —A sample of tissue is removed for testing.


Talk with your doctor about the best treatment plan for you. Early treatment can help prevent complications that can lead to vision loss.

Medications may be recommended to treat an infection or prevent one from happening while the eye heals. Medication may be changed based on results from the culture. Options may include:

  • Antibiotics to treat a bacterial infection or prevent an infection from developing
  • Antiviral medication for infections caused by virus
  • Antifungal medication to infections caused by a fungus

Steroid medication is sometimes used to reduce the risk of scarring. This medication is not always used because it may also increase the risk of or worsen infection.


Severe damage or injury to the cornea will decrease vision. Surgery may be needed to repair or replace the cornea.


To help reduce your chance of getting keratitis, take these steps:

  • If you have dry eye, use artificial tears to protect your cornea.
  • Follow you doctor’s instructions for the use and care of your contact lenses.
  • Wear protective eyewear at work and when playing sports if eye injury is possible.

American Academy of Ophthalmology

Centers for Disease Control and Prevention


Canadian Ophthalmological Society

Health Canada


Basics of bacterial keratitis. Centers for Disease Control and Prevention website. Available at: Updated January 27, 2015. Accessed December 14, 2017.

Corneal ulcer. EBSCO DynaMed website. Available at: Updated April 21, 2015. Accessed December 14, 2017.

Keratitis (corneal ulcers). Kellogg Eye Center website. Available at: Accessed December 14, 2017.

What is keratitis? American Academy of Ophthalmology website. Available at: Published April 3, 2012. Accessed December 14, 2017.

Corneal Ulcer. Merck Manual Professional version. Available at: Updated December 2016. Accessed December 14, 2017.

Last reviewed November 2018 by EBSCO Medical Review Board Michael Woods, MD, FAAP  Last Updated: 5/24/2016