by Scholten A


A corneal ulcer 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.

If left untreated, corneal ulcers can lead to vision loss.

Normal Anatomy of the Eye
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A corneal ulcer happens when the surface of the cornea breaks down. The breakdown may be caused by:

  • Infection with a virus, bacteria, parasite, or fungus
  • Injuries to the cornea
  • Inflammation from immune system problems

Risk Factors

Corneal ulcers are more common in farm workers in tropical climates. Other things that raise the risk are:

  • Contact lenses
  • Conditions that weaken the cornea such as:
    • Dry eye
    • Eyelid defects
    • Low levels of vitamin A (rare)
  • A weak immune system
  • Recent eye or eyelid surgery


Corneal ulcer causes symptoms in the eye, such as:

  • Pain
  • Sensitivity to light
  • Discharge and/or tearing
  • Redness
  • Burning and itching sensation
  • Feeling that something is in the eye
  • Swelling
  • Changes in vision

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


The doctor will ask about symptoms and health history. An eye exam will be done. The doctor may look at the eye with a slit lamp. This may be enough to make the diagnosis.

Other tests may be done to find the cause. They may include

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


Early treatment can help prevent more problems and loss of vision. Infections from bacteria need care right away and sometimes a hospital stay.

Medicines may be given as eyedrops, pills or injections. They may be:

  • Antibiotics—to treat or prevent a bacterial infection
  • Antiviral medicine—for infections caused by virus
  • Antifungal medicine—for infections caused by a fungus

Steroid medicine is sometimes used to lower the risk of scarring. It depends on the cause of the ulcer.

Underlying problems, such as dry eye or immune problems, may also be treated.

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


The risk of a corneal ulcer may be lowered by:

  • Using artificial tears
  • Proper use and care of contact lenses
  • Wearing 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: Accessed July 29, 2021.

Corneal ulcer. EBSCO DynaMed website. Available at: Accessed July 29, 2021.

Corneal Ulcer. Merck Manual Professional version. Available at: . Accessed July 29, 2021.

Cunningham ET Jr, Acharya NR, et al. Ocul Immunol Inflamm. 2016;24(5):479-81.

What is a corneal ulcer (keratitis)? American Academy of Ophthalmology website. Available at: . Accessed July 29, 2021.

Revision Information

  • Reviewer: EBSCO Medical Review Board Dan Ostrovsky
  • Review Date: 07/2021
  • Update Date: 07/29/2021