A corneal ulcer is an open sore on your cornea. It's often caused by an eye infection. It may also be caused by other eye disorders.

The cornea is the clear layer that covers the front of the eye. It helps protect the rest of the eye from germs and debris. It also plays an important role in focusing your vision. Infections or injury to your cornea can cause an ulcer to form. A corneal ulcer needs treatment right away.

Corneal ulcers are common and may occur in people of any age. Corneal ulcers may differ in severity based on their cause. In the U.S., contact lens use often plays a role. Vitamin A deficiency is a factor in some countries. Corneal ulcers are a leading cause of vision impairment and blindness in these countries. In the U.S., such problems are much less common.

Many health conditions can cause a corneal ulcer. These include:

• Bacterial infections (such as Staphylococcus).
• Viral infections (such as herpes).
• Fungal infections.
• Parasitic infections.
• Scrapes (abrasions) or burns to the cornea.
• Conditions that dry out the cornea, such as dry eye syndrome or Bell palsy.
• Autoimmune disease, such as rheumatoid arthritis.
• Injury to the cornea.
• Reduced blood flow (for example, from diabetes).
• Allergies causing allergic keratoconjunctivitis.
• Vitamin A deficiency (rare in the U.S.).

Using contact lenses increases your chance of an infection of your cornea. This can lead to a corneal ulcer.

If you use contact lenses, some things put you more at risk. These include:

• Wearing soft contact lenses.
• Wearing extended-wear contact lenses.
• Wearing your lenses longer than advised.
• Not cleaning your lenses and lens case as your eye doctor advises.
• Exposing your contact lenses to water.
• Sleeping in contact lenses that are not meant for overnight wear.

Having a weak immune system due to another health condition may also raise your risk of getting a corneal ulcer.

If you have a corneal ulcer, you may have one or more of these symptoms:

• Severe eye pain
• The feeling that something is in your eye
• Tearing
• Eye discharge
• Sensitivity to light
• Blurred vision
• Eye redness
• Swollen eyelids
• A white spot on your cornea

It's important to seek treatment right away if you have any of these symptoms. Most of them should go away once you have the corneal ulcer treated and it has healed. If untreated, a corneal ulcer can lead to vision loss and even blindness.

Your eye doctor will start with a health history and a full eye exam. This will include checking your vision in both eyes. Your doctor will likely place a dye on your eye. This lets your doctor more closely check your cornea. Your doctor will likely need to use a device called an ophthalmoscope. This uses a light to look into the back of your eye. You also might need to look into a large microscope called a slit lamp. This lets your doctor see your eye in more detail.

Often your eye doctor will send a scraping from your cornea for culture to find out if there is an infection. If you wear contact lenses, your doctor may also send your contacts for culture. In some cases, your doctor might also want to take blood tests to help find the cause of your corneal ulcer. Finding the cause of the ulcer is important because certain causes have different treatments.

Treatment will vary depending on the cause. Possible treatments include:

• Antibiotics to treat a bacterial infection of the cornea.
• Antiviral medicines to treat a viral infection.
• Antifungal medicines to treat a fungal infection.
• Pain medicine.
• Steroids.

You may need to take some of these medicines in the form of eye drops. Your eye doctor may also give you specific instructions about protecting your eye as it heals. For example, you may need special eye drops or a special contact lens while your eye heals. (Don't wear your normal contacts unless your doctor says it's okay.)

Your eye doctor may also want to treat any other hidden diseases that could be causing your ulcer. This can help prevent new ulcers from developing. Examples of other conditions that might need treatment include dry eye, vitamin deficiency, and autoimmune disease.

Problems caused by a corneal ulcer might need more treatment.

If your cornea has lasting (permanent) scarring and damage, your vision can be impaired in the long term. If not treated right away, corneal ulcers can lead to lasting scarring. If your problems are serious, you may need more treatment. Possible treatments include:

• A special type of contact lens.
• Eye surgery with a laser (phototherapeutic keratectomy).
• Transplant of a new cornea.

Treating the corneal ulcer right away reduces the chances that you will need these sorts of treatments.

Not all types of corneal ulcer can be prevented. Wear protective eyewear when doing any activity that might lead to eye injury. If you use contacts, be sure they fit well and that you care for them correctly. If you have problems with your eyes, get medical care as soon as possible. Treating your other health conditions quickly may also help prevent ulcers. Contacting your eye doctor at the first sign of infection may also help.

If you wear contact lenses, caring for them correctly can help reduce your chances of corneal infection and corneal ulcer.

• Don't wear your contacts longer than recommended.
• Clean your contact lenses exactly as your eye doctor advises.
• Never re-use lens solution or use homemade lens solution.
• Clean, rinse, and air-dry your lens case every time you remove your lenses.
• Don't expose your contact lenses to any water.

Contact your eye doctor right away if you have any symptoms of a corneal ulcer. These include severe eye pain, blurred vision, or eye discharge. A corneal ulcer will need treatment by an eye doctor as soon as possible.

• A corneal ulcer is an open sore on your cornea. This is the clear outermost layer that covers the front of the eye.
• Infection, injury, and other health conditions can lead to corneal ulcers.
• You might need antibiotics, antiviral medicine, or other treatments.
• To help prevent corneal ulcers, follow your eye doctor's instructions about contact lens care and wear.
• Get medical attention right away if you have severe eye pain or other symptoms.
• If you have serious damage to your cornea, you may need follow-up treatments such as a corneal transplant.

Tips to help you get the most from a visit to your doctor:

• Know the reason for your visit and what you want to happen.
• Before your visit, write down questions you want answered.
• Bring someone with you to help you ask questions and remember what your doctor tells you.
• At the visit, write down the name of a new diagnosis, and any new medicines, treatments, or tests. Also write down any new instructions your doctor gives you.
• Know why a new medicine or treatment is prescribed, and how it will help you. Also know what the side effects are.
• Ask if your condition can be treated in other ways.
• Know why a test or procedure is recommended and what the results could mean.
• Know what to expect if you do not take the medicine or have the test or procedure.
• If you have a follow-up appointment, write down the date, time, and purpose for that visit.
• Know how you can contact your doctor if you have questions.