Keratitis: Symptoms, Causes, and Treatment

Medically Reviewed By Leela Raju, MD
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Keratitis is when your cornea — the clear front covering of the eye — becomes inflamed and the rest of the eye reddens. It is due to infection, injury, or an underlying health issue. Infectious keratitis is caused by bacteria, viruses, and other microorganisms. Systemic conditions like rheumatoid arthritis and direct trauma to the cornea are causes of noninfectious keratitis. Treatment options can include eye drops, oral medications, and eye procedures.

Keep reading to understand keratitis, including how it develops, common symptoms, and how clinicians approach diagnosis and treatment. This article also discusses the outlook, prevention, and potential complications of keratitis.

How does keratitis affect the cornea?

young man outside rubbing his eyes
Javier Díez/Stocksy United

Keratitis is a treatable eye condition where your cornea becomes irritated. Your cornea helps create the outer portion of your eye. It is like the clear glass that covers a watch face. The pupil is the center opening of the iris. This transparent layer helps protect your eye while assisting in vision.

The cornea has five layers. The middle layer is the stroma, which makes up 90% of the cornea. Keratitis can involve this layer alone, or it may start on the surface layer and spread into the stroma.

An infection can cause keratitis, but noninfectious conditions can too. Your treatment will depend on the cause of the inflammation.

Note: Keratitis is different from keratosis and keratoses. These terms are easily confused on internet search engines. Keratosis is a noncancerous type of skin growth, and keratoses is the plural form of the word. Seborrheic keratosis is a type of keratosis.

What are the symptoms of keratitis?

Symptoms of keratitis generally include:

  • redness and pain in your eye
  • excessive tearing
  • blurred vision
  • decline in vision
  • light sensitivity
  • discharge from the eye
  • white spot on the eye from an ulcer

Learn about corneal ulcers here.

When to contact a doctor

If you experience any of the previously mentioned symptoms for longer than a day, contact your primary care doctor.

Your primary physician may diagnose and treat mild keratitis or may refer you to an ophthalmologist. An ophthalmologist is a physician who specializes in eye disease diagnosis and treatment. Depending on your specific circumstances, you may choose to contact a specialist directly.

Prompt diagnosis and treatment can minimize potential complications of keratitis, which can include vision loss.

What are the different types and causes of keratitis?

Infectious and noninfectious keratitis are the two main forms of cornea inflammation.

Infectious keratitis

Infectious keratitis is the most common type of keratitis, according to the National Eye Institute (NEI). Bacteria, parasites, viruses, fungi, and other microorganisms can infect the cornea.

Acanthamoeba keratitis is a serious type of keratitis caused by an amoeba. It lives in contaminated soil or bodies of water. When the amoeba comes into contact with the eye, it can lodge itself in the cornea. Wearing contact lenses and exposing them to any water increases the likelihood of contracting Acanthamoeba keratitis.

Contact lenses are the leading cause of infectious keratitis in general, according to the NEI. Sleeping in contact lenses or overwearing them especially increases the risk.

The herpes simplex virus causes herpes keratitis. Herpes simplex virus accounts for 1.5 million viral keratitis cases globally. It is the most common cause of blindness in one eye. When someone touches an open herpes sore and then their eye, it can spread the virus to the cornea.

Alternatively, the virus can primarily infect the face and eyes, independent of the herpes sores. The virus remains in the nerves. It can cause inflammation in the cornea and the rest of the eye at any time after the initial infection.

Noninfectious keratitis

Noninfectious keratitis causes include eye injuries and medical conditions. These can involve the eye itself or come from a systemic problem that involves the eye.

Injuries may be severe, such as getting something stuck in your eye. Wearing contact lenses for longer than recommended or an unusually positioned eyelash can also cause keratitis.

Rheumatoid arthritis and systemic lupus are two possible causes of noninfectious keratitis. Noninfectious causes of keratitis can be risk factors for infectious keratitis.

How is keratitis diagnosed?

An ophthalmologist may make a preliminary diagnosis by looking at your eye closely using a microscope. They will evaluate the cornea and other structures in your eye for signs of injury.

If your doctor suspects infectious keratitis, they may take a sample of the area to identify the cause. This will help them pinpoint an accurate treatment plan.

What is the treatment for keratitis?

For infectious keratitis, treatment depends on the cause and the severity of the condition. The following is a summary of treatment by cause:

  • Bacterial keratitis: Doctors prescribe antibiotic eye drops and perhaps medications you take by mouth.
  • Fungal keratitis: Treatment depends on the specific type of fungus. Your doctor may recommend a topical antifungal, such as natamycin (Natacyn).
  • Viral keratitis: A common treatment is antiviral medication and corticosteroid medication to reduce swelling in the cornea. Long-term use of oral antivirals, such as acyclovir, may also be recommended to prevent it from returning.
  • Acanthamoeba keratitis: These infections are difficult to treat. Doctors tailor treatment to the individual and the severity of the infection. It may require surgery to remove the diseased cornea and replace it with a donor cornea.

For noninfectious keratitis, doctors manage the underlying cause. For example, the doctor may recommend eyelid alterations or hair follicle treatment for misaligned lashes.

If there is a systemic health issue, such as rheumatoid arthritis, treatment involves medication to reduce inflammation. Your doctor may prescribe artificial tears or a corneal bandage to give your eye the protection it needs to heal.

What are the potential complications of keratitis?

Complications of keratitis include:

  • corneal ulcer, which can scar the cornea
  • corneal perforation, or hole
  • corneal swelling, leading to double vision, blurry vision, and halos around lights

What are ways to prevent keratitis?

You can reduce your chance of keratitis by keeping your eyes clean and protecting them from injury. Specific tips include the following:

  • Wear eye protection, such as goggles, during activities that can potentially injure the eye.
  • Wear goggles when underwater.
  • Rinse your eyes immediately if dirt, water, or a foreign object comes into contact with the eye.
  • Avoid touching your eyes, and always wash your hands with soap and water first.

For contact lens wearers:

  • Wash and rinse your contact lenses with the appropriate contact solution. Replace the solution when it expires or if it looks cloudy.
  • Wear your contact lenses only for the duration of time recommended by your optometrist.
  • Always wash your hands before handling the lenses. Never wear them while in any body of water, including in hot tubs.

What is the outlook?

The outlook depends on the cause and the promptness of diagnosis and treatment. Early intervention is vital to reducing the chance of complications.

Viral keratitis can be a long-term health issue. Fungal keratitis may cause worse complications than bacterial keratitis. Acanthamoeba keratitis may take months to fully heal.

If corneal scarring occurs, you may be able to wear corrective lenses to increase your vision. A corneal transplant may be an option and necessary in some cases.

Frequently asked questions

Here are some other questions people have asked about keratitis.

What is the most common cause of keratitis?

In resource-rich areas like the United States, contact lenses are the most common cause of keratitis. In developing countries, the most common cause is trauma to the eye.

What happens if keratitis is left untreated?

Keratitis may heal on its own sometimes. Treatment is necessary to address the infection and reduce inflammation. Left untreated, it can lead to corneal scarring and blindness. This can require a corneal transplant to regain eyesight.

Summary

Keratitis is inflammation of the cornea. Infections, injuries, and other medical conditions can cause it. Symptoms include blurred vision, excessive tearing, and eye redness, pain, or discharge. Wearing contact lenses — especially overwearing them — increases the likelihood of keratitis.

Prompt treatment can help reduce the chance of complications, such as corneal ulcers and blindness. Treatment options include medicated eye drops, oral medications, and procedures to repair or replace the cornea.

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Medical Reviewer: Leela Raju, MD
Last Review Date: 2022 Jun 11
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.