11 Causes of Keratitis, a Serious Eye Inflammation

Keratitis is a serious eye condition marked by inflammation, pain, tearing, and other symptoms. Learn more about treating this potentially vision-robbing condition.

What is keratitis?

Keratitis, an inflammation of the cornea, is a serious and potentially vision-robbing eye condition that requires immediate medical attention.

Your cornea helps your eye focus light so you can see clearly.

“It is like a watch glass on a watch,” explains cornea specialist Stephanie Marioneaux, MD, a clinical spokesperson for the American Academy of Ophthalmology and an assistant professor at the Eastern Virginia Medical School in Norfolk, Virginia.

“Your cornea is normally crystal clear, but it can be clouded by disease and injuries.”

Also known as a corneal ulcer, keratitis symptoms may include:

Keratitis symptoms can range from mild to severe, and this condition can strike one or both eyes. When keratitis only affects the surface layer of your cornea, it’s superficial keratitis, but when it strikes the deeper layers of your cornea, it’s stromal keratitis or interstitial keratitis.

(Pink eye or conjunctivitis, an inflammation of the conjunctiva, may be confused with keratitis.)

man getting eyes examined by an ophthalmologistseb_ra/Getty Images

What causes keratitis?

There are many potential causes of keratitis, including the following.


A scratch or chemical burn from fumes or liquids splashed in the eye can result in keratitis. Microorganisms can enter the eye after such an injury, causing infection and inflammation, Dr. Marioneaux explains.

When there is a chemical injury to the eye, your eye doctor may see a bunch of injured cells on your cornea (superficial punctate keratitis).

If you scratch your cornea and rub your eye with dirty fingers or hands to see if there is something there, you can unwittingly introduce an infection.

“If you get a scratch in your eye, see an eye doctor to make sure you don’t have what could turn into a devastating infection,” Dr. Marioneaux warns.

Don’t splash water or even use wet compresses on the affected eye, she says. “Keep your eye closed, wash your hands, and get right over to the ophthalmologist or emergency room for an evaluation.”

If the pain is severe, an over-the-counter non-steroidal anti-inflammatory medication like Motrin can help.

Sleeping in your contact lenses

You know you shouldn’t sleep with your contacts, but sometimes you forget, and other times you are just plain lazy.

Bacteria can grow on your lenses or contact lens case if you don’t clean and store them properly. The risk for keratitis is greatest if you wear extended-wear contact lenses.

“Daily disposable soft lenses are the way to go to decrease chance of severe eye infection,” says Christopher J. Rapuano, MD, the chief of the Cornea Service of Wills Eye Hospital and a professor of ophthalmology at Sidney Kimmel Medical College of Thomas Jefferson University in Philadelphia.

“Put a new pair on every morning and throw them out before bed.”

Swimming in your contacts

Swimming or even going in a hot tub or taking a shower with your contacts on is a setup for disaster, Dr. Marioneaux warns. It’s one of the worst contact lens mistakes because it can lead to Acanthamoeba keratitis, which she calls “the most heinous keratitis cause of all.”

Acanthamoeba is a microscopic, free-living amoeba found in water and soil around the world. It can cause a rare but serious infection by burrowing into the eye, multiplying quickly, and eating through the layers of the cornea. This is most common in people who wear contact lenses, but anyone could get it.

“This crafty little worm causes significant pain because it travels around the nerves, and it can morph into cystic form and grow resistant to antibiotics,” she says. “We do not have a medicine geared to Acanthamoeba keratitis.”

Doctors may compound special eye drops using pool cleaner to kill this microorganism. “This is one of the worst infections, and the prognosis is poor,” Dr. Marioneaux says. Many people will need a cornea transplant.

Just because it hasn’t happened to you yet doesn’t mean it won’t, she notes.

“These amoebae are everywhere, and your risk really depends on how clean the water is.” It’s better to be safe than sorry.

“Swim with prescription goggles and shower with glasses instead of contacts,” she says. This is another reason not to rinse out your eye or use wet compresses after scratching your cornea.

Bacterial infections

Many types of bacteria can cause corneal ulcers. This is why you must see a cornea specialist, Dr. Marioneaux says.

“You can’t look at infection and say, ‘This is staph,’ or, ‘This is strep,'” she says.

A cornea specialist can take a sample and send it to a lab to find out what’s causing your infection and better pair it with the correct antibiotic, she says.

“We may start antibiotic eye drops based on our best guess to prevent a worsening infection, and when we get the culture back, we can try and adjust treatment.” (Learn about antibiotic-resistant superbugs.)

Fungal infections

Sometimes keratitis comes from a fungal infection, Dr. Rapuano says. This typically occurs when trauma is caused by a stick, thorn, or plant, according to the U.S. Centers for Disease Control and Prevention (CDC). Common culprits include the following fungi:

  • Fusarium species
  • Aspergillus species
  • Candida species

An eye doctor will scrape the eye for a small sample to see if it’s fungal keratitis. Treatment includes anti-fungal eye drops and oral medications. “We treat this aggressively as the damage can be permanent,” Dr. Rapuano says.

Prevention is key. People who work with plants or garden as a hobby should wear protective eyewear, the CDC states.

Herpes keratitis

Oral herpes can cause cold sores around your mouth, lips, and cheek, but also in your eyes, Dr. Rapuano says. Treatment options include antiviral drops as well as ointments or pills and/or steroids to cool inflammation.

Surgery is sometimes necessary if scarring on the eye occurs. It can come back, too, he warns. This is a form of neurotrophic keratitis because the nerves in your cornea can’t function properly.


Painful shingles can also affect the cornea, causing keratitis. This too is a form of neurotrophic keratitis.

This is more common when shingles affects your face, Dr. Rapuano says. Shingles occurs when the virus that causes chickenpox reactivates.

“This can come back again and again,” he says. “I advise the shingles shot for everyone who is eligible.” The CDC recommends that adults age 50 and over get the shingles shot.

Autoimmune diseases

If you have rheumatoid arthritis, lupus, or another type of autoimmune disease characterized by body-wide inflammation, you’re at risk for developing keratitis, too, Dr. Rapuano says.

In these cases, your eye doctor may need to work with your rheumatologist to make sure all of the inflammation is under control, he says. This is filamentary keratitis, a form of the disease with the presence of filaments on the surface of your cornea.

Sunburnt eyes

Also called snow blindness or photokeratitis, this type of eye inflammation is akin to having a sunburn in your eyes, the American Academy of Ophthalmology notes.

It is caused by exposure to natural or artificial UV light. Snow blindness is from UV rays reflected off ice and snow, which often happens during skiing, snowmobiling, and mountain climbing. The longer your eyes are exposed to UV rays, the more severe your symptoms will be.

The good news? Photokeratitis and snow blindness usually go away on their own. Prevent them from happening in the first place by wearing sunglasses or goggles that block UV rays when spending time in the sun.

Using sunscreen will reduce the risk of skin cancer and premature aging.

(Here are the other worst places on your body to get sunburnt.)

Dry eye

Dry eye syndrome is also called keratitis sicca. It occurs when the tear layer covering your cornea isn’t producing enough high-quality tears. This can cause your cornea to dry out, leading to inflammation or keratitis. These dry eye treatments will help you feel better fast. This is also a form of filamentary keratitis.

Eyelid disorders

Disorders of your eyelid, such as blepharitis, can cause swelling and irritation. As a result, your cornea can dry out or become inflamed, and keratitis can develop, according to the National Eye Institute. Treatment may entail keeping your eyelids clean, antibiotics, and/or steroid eye drops.

When to see your doctor

If you scratch your cornea or notice any symptoms suggestive of keratitis, see an eye doctor, preferably a cornea specialist, as soon as you can.

“It’s very, very important that patients understand the severity of ulcers and not try to manage them at home,” Dr. Marioneaux says.


Denise Mann, MS
Denise Mann is a freelance health writer whose articles regularly appear in WebMD, HealthDay, and other consumer health portals. She has received numerous awards, including the Arthritis Foundation's Northeast Region Prize for Online Journalism; the Excellence in Women's Health Research Journalism Award; the Journalistic Achievement Award from the American Society for Aesthetic Plastic Surgery; National Newsmaker of the Year by the Community Anti-Drug Coalitions of America; the Gold Award for Best Service Journalism from the Magazine Association of the Southeast; a Bronze Award from The American Society of Healthcare Publication Editors (for a cover story she wrote in Plastic Surgery Practice magazine); and an honorable mention in the International Osteoporosis Foundation Journalism Awards. She was part of the writing team awarded a 2008 Sigma Delta Chi award for her part in a WebMD series on autism. Her first foray into health reporting was with the Medical Tribune News Service, where her articles appeared regularly in such newspapers as the Detroit Free Press, Chicago Sun-Times, Dallas Morning News, and Los Angeles Daily News. Mann received a graduate degree from the Medill School of Journalism at Northwestern University in Evanston, Ill., and her undergraduate degree from Lehigh University in Bethlehem, Pa. She lives in New York with her husband David; sons Teddy and Evan; and their miniature schnauzer, Perri Winkle Blu.