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Acanthamoeba Keratitis

Close up of an adult inserting contact into eye.

Acanthamoeba keratitis is a rare but serious eye infection that can lead to permanent eye damage or blindness. It is caused by an organism that is too small to be seen with the naked eye. This organism is a free-living ameba (single-celled living organism) called Acanthamoeba.

Acanthamoeba causes Acanthamoeba keratitis when it infects the clear outer layer of the eye called the cornea.

Acanthamoeba amebas are very common in nature and can be found in bodies of water (for example, lakes and oceans), soil, and air. Infections are most common in people who wear contact lenses or have an injury to their eye.

Acanthamoeba Keratitis 101

The symptoms of Acanthamoeba keratitis can be very similar to the symptoms of other eye infections. These symptoms, which can last for several weeks or months, may include:

  • Eye pain
  • Eye redness
  • Blurred vision
  • Sensitivity to light
  • Sensation of something in the eye
  • Excessive tearing

Patients should contact their eye doctor if they have any of the above symptoms. Acanthamoeba keratitis will eventually cause severe pain and possible vision loss or blindness if untreated.

It is important to see your doctor as soon as possible if you think you may have Acanthamoeba keratitis. There are several prescription eye medications that can be used for treatment. However, Acanthamoeba keratitis can be difficult to treat. Work with your doctor to decide on the best treatment for you.

Acanthamoeba keratitis is most common in people who wear contact lenses, but anyone can get it. For people who wear contact lenses, certain practices can increase the risk of getting Acanthamoeba keratitis, such as:

  • Storing and handling lenses improperly.
  • Disinfecting lenses improperly (such as using tap water or homemade solutions to clean the lenses).
  • Swimming, using a hot tub, or showering while wearing lenses.
  • Coming into contact with contaminated water.
  • Having a history of trauma to the cornea.

Provider Information

Free-living ameba infection, Acanthamoeba keratitis, is a Wisconsin disease surveillance category II disease:

Wisconsin case reporting and public health follow-up guidelines:

Last revised January 9, 2024