Acanthamoeba keratitis is a rare, serious eye infection caused by an amoeba (tiny microorganism). It’s most common in people who wear contact lenses, but anyone can get the infection. It can lead to vision loss or total blindness without prompt treatment.
Acanthamoeba keratitis is a serious infection that affects the cornea (clear outer covering of the eye). It’s caused by an amoeba, which is a tiny, single-celled organism. The amoeba enters your eye and eats through the layers of your cornea. It destroys tissue as it moves through your eye. The acanthamoeba is common in the air, soil, lakes and oceans. Most infections come from fresh water, such as tap water, swimming pools, hot tubs, showers and sewage systems.
Acanthamoeba keratitis is rare, but it can lead to eye pain, permanent vision loss or even total blindness. The infection can affect one or both eyes. It’s not contagious.
Anyone can get acanthamoeba keratitis, but it’s most common in people who wear soft contact lenses. You have a greater risk of this condition if you:
Acanthamoeba keratitis is rare. In the US, only one to two people per million contact lens wearers develop the condition each year. It’s even more rare in people who don’t wear contact lenses.
The acanthamoeba causes this eye infection. The amoeba attaches to the cells on the outer surface of your cornea. It can also invade the eye by entering through small corneal abrasions (scratches). The infection destroys the cells and moves further into the cornea.
Symptoms of early-stage acanthamoeba keratitis may include:
It can take several days to several weeks for symptoms to show up after the acanthamoeba enters your eye.
Left untreated, the infection can cause permanent vision loss or total blindness. Other complications of late-stage acanthamoeba keratitis may include:
A healthcare provider specializing in eye care, such as an optometrist or ophthalmologist, can diagnose acanthamoeba keratitis. They perform an eye exam, review your symptoms and assess your contact lens hygiene (if you wear contacts).
It’s easy to misdiagnose this infection because the symptoms are similar to those of other corneal diseases. So, it’s very important to tell your healthcare provider if you’ve been in contact with any potentially contaminated water or other substances.
Tests for acanthamoeba keratitis may include:
A topical antiseptic is the most common treatment for acanthamoeba. The antiseptic fights microorganisms. It’s applied directly to the surface of your eye. You may need these treatments for six months to a year. Sometimes your healthcare provider scrapes off some of your cornea before applying medication. This helps the medicine get deeper into your eye.
Your healthcare provider may also recommend antibiotics or antifungal medications. Steroids or pain relief medications can help reduce pain and inflammation.
You may need surgery for advanced acanthamoeba keratitis that doesn’t improve with topical therapy. This may include penetrating keratoplasty (PK). A PK is a full-thickness corneal transplant. A cornea from a donor replaces your damaged cornea.
You can reduce your risk of acanthamoeba keratitis by:
The earlier you receive a diagnosis and treatment for acanthamoeba, the better your outlook. Research suggests that people who seek treatment at the first signs of infection are 10 times more likely to recover with vision of 20/25 (mild vision loss) or better. The outlook is poor if the infection is already in the deep parts of the eye.
If you do experience vision loss from this infection, there are a variety of ways you can find support. You may be able to better cope with vision loss by:
Contact your healthcare provider at the first signs of eye pain, redness or sensitivity. Don’t wait until you experience vision loss.
You may want to ask your healthcare provider:
A note from Cleveland Clinic
Acanthamoeba keratitis is a rare, serious eye infection caused by a tiny organism that lives in fresh water. Anyone can get the infection, but it’s more common in people who wear contact lenses. Symptoms can range from eye pain and redness to blindness. Early detection and treatment greatly improve the outlook for people with this infection.
Last reviewed by a Cleveland Clinic medical professional on 05/25/2021.
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