A corneal ulcer refers to an infection or an open sore located on the cornea. The cornea is the thin, transparent membrane in front of the iris and pupil. A corneal ulcer is an emergency that needs immediate attention.
Various types of eye infections can cause a corneal ulcer. There are other non-infectious causes as well. It is possible to confuse a corneal ulcer with conjunctivitis or pink eye.

Also Known As



  • Bacterial Keratitis
  • Fungal Keratitis or Mycotic Keratitis
  • Viral/Herpes Simplex Virus Corneal Ulcer
  • Acanthamoeba Keratitis

Causes and Risk Factors

The most common causes for a corneal ulcer are bacteria, virus or a parasite. 

Bacterial keratitis and acanthamoeba (parasitic) keratitis are frequent among contact lens wearers. Failure to correctly handle the lenses increases the risk of infections. For example, wearing contact lenses overnight. Sometimes the infections begin as injuries to the eye, scratches, severe dry eyes or foreign objects in the eye. Or it could be that the cornea is irritated by contact lenses that have not been disinfected.

Fungal keratitis is caused by injuries arising from plant matter or organic matter. Plant matter includes twigs and branches. Those at a higher risk are people who have not disinfected their contact lenses. They also include individuals using steroid eye drops. Further, persons with a suppressed immune system are more likely to suffer from this.

Viral keratitis is caused by the cold sore virus (herpes simplex). It is a rare type that can also occur due to the varicella virus. The varicella virus causes chickenpox and shingles. Still, viral ulcers may arise from physical stress, exposure to sunlight or a deficiency of Vitamin A and protein. 

There are many more causes of corneal ulcers such as:

  • Inflammatory disorders
  • Eyelids that refuse to close like Bell’s Palsy
  • Severe allergic diseases
  • Chemical burns on the cornea

The ones who are at most risk of corneal ulcers are contact lenses’ wearers. It gets worse with extended-wear lenses where they are worn for many days without being removed at night.

Signs & Symptoms

The symptoms of a corneal ulcer may include:

  • Red bloodshot eye
  • Foreign body sensation
  • Sensitivity to light
  • Pus or discharge from the eye
  • Blurry or decreased vision
  • Pain
  • Increased tear production
  • Dull or grey spot on the cornea
  • Itching
  • White layer at the bottom of the cornea
  • Swelling of the eyelid


The eye professional will use fluorescein (yellow, green dye) to light up the cornea. He/she will then use a slit lamp (a microscope/instrument with high magnification) to establish if there is any damage on the cornea. 

A sample of the tissue may be taken for further tests. The sample is cultured in a laboratory to establish whether the infection is bacterial, fungal, viral or parasitic. A corneal biopsy may be required if the culture does not reveal the cause. 

The professional may perform keratometry (measure the cornea’s curve). He/she may test for visual acuity, pupillary reflex response and also do a test for dry eyes.


Treatment of a corneal ulcer is aimed at eliminating the ulcer.

Medical Treatment

Treating a corneal ulcer depends on the cause. If the cause is unknown, the patient will receive antibiotic eye drops. Antibiotics work against many types of bacteria. If it is an established cause, appropriate drops will be administered. 

For example, anti-fungal, anti-viral, anti-acanthamoeba drops and so on. These drops should be administered urgently and frequently. Frequently means sometimes every hour throughout the day for several days. In some instances, glaucoma medication may be required. Drops that dilate the eye may help with pain relief and other complications. In case of swellings and scarring, corticosteroids may be used.

Surgical Treatment

In severe cases where the cornea is not responding to treatment, a corneal transplant will be done. The transplant may also be necessary if the ulcer threatens to puncture the cornea. The transplant involves replacing the diseased cornea with a healthy one from a donor.

Prognosis/Long-term outlook

Failure to treat a corneal ulcer can result to loss of vision; in extreme cases, scars on the cornea or loss of the eye. Other consequences include glaucoma and cataracts. Also, the patient should not go swimming until the ulcer has healed. This is because the acanthamoeba in the chlorinated water can harm the eye.

It is possible to make a complete recovery in 2-3 weeks. Patients may experience a minor change in vision. If the patient notices no difference or worsening symptoms, he/she must immediately contact the doctor.

The prescribed eye drops should be taken as directed. The patient still needs to see the ophthalmologist daily until the ophthalmologist instructs otherwise. If the patient is not responding to a corneal ulcer treatment, he/she may need to be hospitalized.

Prevention/Follow Up

Wear eye protection to avoid eye injury.

Patient education for contact lens wearers is necessary. Individuals should not sleep with the lenses on. Also, they should remove the lenses if the eye is red or irritated. The washing of hands when handling the lenses is critical.  The patient should refrain from using saliva to clean the lenses because saliva contains bacteria. 

Whenever an individual notices an eye infection, he/she should get it promptly treated. This action prevents the infection from developing into an ulcer. 

Artificial tear drops can also be used in case of dry eyes.