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Acanthamoeba keratitis

What is Acanthamoeba keratitis?

Acanthamoeba keratitis is a serious, painful infection of the cornea. It's caused by a microscopic, single-cell organism called Acanthamoeba found in water and soil worldwide. Acanthamoeba keratitis can cause permanent vision loss and even blindness.

Acanthamoeba keratitis symptoms

Symptoms of Acanthamoeba keratitis include:

If you have some or all of these symptoms, see an eye doctor right away. If you wear contact lenses, remove your lenses immediately.

Delayed treatment of Acanthamoeba keratitis increases the likelihood of serious and permanent vision loss from the infection.

Causes and risk factors


Acanthamoeba is a single-cell organism that exists in nature in two forms: an active, growing form (left) and a dormant, stress resistant cyst (right). (Images: Morales, Khan and Walochnik [CC BY 2.0], via Wikimedia Commons) 

Acanthamoeba microorganisms are common and widespread. They are found in soil and in water sources worldwide, including:

  • Lakes

  • Oceans

  • Tap water

  • Swimming pools

  • Hot tubs and spas

Thankfully, though virtually everyone is at risk of exposure to Acanthamoeba, very few people get Acanthamoeba keratitis. The amoeba (or ameba) must come in direct contact with your eyes for Acanthamoeba keratitis to occur. You cannot get the eye infection drinking contaminated water or inhaling or ingesting Acanthamoeba. Also, Acanthamoeba keratitis is not contagious and doesn't spread from person to person.

Wearing contact lenses increases your risk of getting Acanthamoeba keratitis. In the United States, research suggests 85% to 93% of Acanthamoeba eye infections occur among contact lens wearers.

Acathamoeba keratitis treatment

Acanthamoeba keratitis requires early diagnosis and treatment by an eye doctor to avoid vision loss.

Early-stage Acanthamoeba infections can be difficult to separate from other forms of keratitis. A sign of a more advanced Acanthamoeba infection is a ring-like corneal ulcer. Your eye doctor may send a scraping of the affected corneal tissue to a medical lab to determine the best course of treatment.

Acanthamoeba keratitis can be difficult to treat. Antibiotics used to treat other types of corneal infections are ineffective on Acanthamoeba. Effective treatment and management of Acanthamoeba keratitis usually requires aggressive medical treatment for a significant period of time. Also, early treatment is essential for a good outcome.

In some cases, a cornea transplant surgery may be needed to restore vision after an Acanthamoeba keratitis infection.

How to avoid acanthamoeba keratitis

You can significantly reduce your risk of Acanthamoeba keratitis. Take the same steps recommended to prevent all types of corneal and contact lens-related eye infections.

These include:

  • If you sustain a corneal abrasion or other injury to the surface of your eye, see an eye doctor for treatment. Avoid wearing contact lenses until your cornea has fully healed. Also, avoid getting water in your eyes until healing is complete.


Clean and sterilize your contact lens case to avoid Acanthamoeba contamination.

  • Never rinse your contact lenses with tap water.

  • Always wash your hands thoroughly before handling your lenses.

  • Clean your contacts immediately upon removing them from your eyes. Rub the lenses under a stream of multipurpose solution recommended by your eye doctor for at least 20 seconds.

  • Store your lenses in a clean lens storage case filled with 100% fresh multipurpose or disinfecting solution. Do not "top off" solution that's still in the case from the previous day.

  • Clean, rinse and air-dry your contact lens case immediately after removing your lenses from the case. Discard and replace the case at least every three months to help prevent contamination.

Don't take chances

Acanthamoeba keratitis is a very serious eye infection that can have devastating effects on your vision.

Prevention is your best defense against Acanthamoeba eye infections. Always use good hygiene during contact lens use and care.

And if you have any of the symptoms of Acanthamoeba keratitis listed above, see an eye doctor immediately.

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