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Acanthamoeba Keratitis FAQs

Infection of the Eye with Acanthamoeba

What is Acanthamoeba keratitis?

Acanthamoeba keratitis is a rare but serious infection of the eye that can result in permanent visual impairment or blindness. This infection is caused by a microscopic, free-living ameba (single-celled living organism) called Acanthamoeba. Acanthamoeba causes Acanthamoeba keratitis when it infects the transparent outer covering 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.

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What are the symptoms of infection?

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 consult with 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.

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Who is at risk for infection?

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

  • 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

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How is Acanthamoeba keratitis diagnosed and treated?

Early diagnosis is essential for effective treatment of Acanthamoeba keratitis.

The infection is usually diagnosed by an eye care provider based on symptoms, growth of the Acanthamoeba ameba from a scraping of the eye, and/or seeing the ameba by a process called confocal microscopy.

The infection is treated with one or more prescription medications. An eye care provider can determine the best treatment option for each patient.

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What can I do to reduce my risk of developing Acanthamoeba keratitis?

These guidelines should be followed by all contact lens users to help reduce the risk of eye infections, including Acanthamoeba keratitis:

  • Visit your eye care provider for regular eye examinations.
  • Wear and replace contact lenses according to the schedule prescribed by your eye care provider.
  • Remove contact lenses before any activity involving contact with water, including showering, using a hot tub, or swimming.
  • Wash hands with soap and water and dry before handling contact lenses.
  • Clean contact lenses according to instructions from your eye care provider and the manufacturer's guidelines.
    1. Never reuse or top off old solution. Use fresh cleaning or disinfecting solution each time lenses are cleaned and stored.
    2. Never use saline solution or rewetting drops to disinfect lenses. Neither solution is an effective or approved disinfectant.
    3. Be sure to clean, rub, and rinse your lenses each time you remove your lenses. Rubbing and rinsing your contact lenses will aid in removing harmful microbes and residues.
  • Store reusable lenses in the proper storage case.
    1. Storage cases should be rubbed and rinsed with sterile contact lens solution (never use tap water), emptied, and left open to dry after each use.
    2. Replace storage cases at least once every three months.

Contact lens users with questions regarding which solutions are best for them should consult their eye care providers. They should also consult their eye care providers if they have any of the following symptoms: eye pain or redness, blurred vision, sensitivity to light, sensation of something in the eye, or excessive tearing.


This information is not meant to be used for self-diagnosis or as a substitute for consultation with a health care provider. If you have any questions about the parasites described above or think that you may have a parasitic infection, consult a health care provider.

 

A square ad showing an infected eyeball with Acanthamoeba. The caption reads, "Delayed diagnosis means poorer outcomes - think Acanthamoeba keratitis."

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  • Page last reviewed: November 2, 2010
  • Page last updated: August 21, 2012
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