What is a corneal ulcer?
Your cornea is the clear layer at the front of your eye. A corneal ulcer is an open sore on your cornea.
An Inside Look at the Eye
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Corneal ulcers are usually caused by infection
The infection may start with an eye injury or scratch, irritation from a contact lens, or certain eye diseases
You may have eye pain, tears, sensitivity to light, and red, bloodshot eyes
Doctors usually treat corneal ulcers with antibiotic eye drops
Sometimes after a corneal ulcer heals, your cornea has a cloudy scar that affects your vision
See a doctor right away if you think you have a corneal ulcer because it can lead to blindness.
What causes corneal ulcers?
Most corneal ulcers are caused by:
Infection
Many different bacteria, viruses, and parasites Overview of Infectious Disease An infection is when microorganisms (germs) invade part of your body and make you sick. Microoganisms are tiny living creatures that are so small they can't be seen without a microscope. There... read more can be involved.
Usually, you also have an eye problem that makes infection more likely, for example:
A scratch on your eye
Irritation from your contact lenses, for example, from wearing them while you sleep or not cleaning them properly
Irritation from in-growing eyelashes Trichiasis Trichiasis is misalignment of eyelashes, which rub against the eyeball, in a person who does not have entropion. Trichiasis develops most commonly some time after chronic blepharitis (inflammation... read more or an in-turned eyelid Entropion and Ectropion Entropion and ectropion are eyelid problems. Normally, your upper and lower eyelids close tightly to protect your eye. Entropion is when the eyelid turns inward. It most commonly affects older... read more
What are the symptoms of a corneal ulcer?
Usually, a corneal ulcer develops in only one eye.
Symptoms of a corneal ulcer include:
Red, watery, bloodshot eye
Eye pain
Feeling like you have something in your eye
Light hurts your eye
A white or grayish spot on your eye
If a corneal ulcer isn't treated, it can go deeper, and the infection can damage other parts of your eye.

Sometimes you have a scar after a corneal ulcer heals. The scar can affect your vision.
How can doctors tell if I have a corneal ulcer?
Doctors diagnose a corneal ulcer by looking at your eye. They'll do a full eye exam, including checking your vision, and may also:
Scrape off a sample of the corneal ulcer for testing
How do doctors treat corneal ulcers?
A corneal ulcer can lead to blindness, so it is important to see a doctor right away if you think you may have a corneal ulcer.
Doctors will treat you right away with:
Antibiotic eye drops to fight infection
Eye drops to dilate your eye, which helps with the pain
You may need to use the antibiotic eye drops every hour or two at first.
Rarely, if a scar affects your vision, doctors may do a corneal transplant Corneal Transplantation Corneal transplantation (keratoplasty) is a common and highly successful type of transplantation. A scarred, severely painful, perforated, misshapen, or cloudy cornea (the clear layer in front... read more (an operation to take out your cloudy cornea and replace it with a healthy, clear one).