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The truth behind acanthamoeba

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You may have recently seen shocking headlines describing an ‘eye-eating parasite’ that can be fatal. But the reality, though serious, isn’t quite as dramatic. In fact, we come into regular contact with acanthamoeba – the micro-organism in question.

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Acanthamoeba is an organism commonly found in tap water, fresh water (such as lakes), swimming pools, soil, dust and air. We regularly encounter it when we shower, swim, or drink. It generally doesn’t cause harm but can result in a serious eye disease if it infects the cornea. Particularly, any disturbance to the corneal surface such as an injury or scratch can leave it vulnerable to infection.

Water running from tap

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In this article, we’ll tell you all about acanthamoeba and the risks, answering some of the most common questions.

How much damage can acanthamoeba do to my eye?

Acanthamoeba can cause three main types of illness:

  • Acanthamoeba keratitis (involving the eye)
  • Granulomatous encephalitis (involving the brain and spinal cord)
  • Disseminated infection throughout the body

It’s important to note that infections involving the brain and spinal cord are extremely rare and can be deadly, but fatal cases of acanthamoeba keratitis are pretty much unheard of.


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What causes acanthamoeba keratitis?

There are various factors known to increase the risk of getting acanthamoeba keratitis. The biggest risk factor is exposure to water, but poor contact lens hygiene can also cause infection. The key contributors are:

  • Swimming or showering in contact lenses
  • Rinsing or storing your lenses in water
  • Handling your lenses with unwashed or wet hands
  • Failing to disinfect your lenses properly
  • Failing to clean and dispose of your contact lenses appropriately
  • Using non-sterile solutions
  • Topping up your solution rather than using fresh solution

What are the symptoms of acanthamoeba keratitis?

Blue eye close up

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The symptoms of acanthamoeba keratitis are very similar to that of other common eye infections, including:

  • Pain and redness
  • Blurred vision
  • Light sensitivity
  • A gritty sensation
  • Excessively watery eye

If it’s suspected that you have acanthamoeba keratitis, you will be referred to a hospital for further tests and treatment. One of the tests may involve a corneal scrape to collect cells from the surface of the cornea (you will be given anaesthetic). Alternatively, a swab is taken to check for acanthamoeba DNA.

How is acanthamoeba keratitis treated?

Anti-amoebic antiseptic drops are typically used to treat the infection. They should be administered every hour for the first few days (including overnight). As the treatment progresses, you’ll only need to use the drops every 2 hours and then less frequently until the treatment is finished.

As well as anti-amoebic eye drops, you may be given anti-inflammatories or painkillers. You might also be given a dilating eyedrop early in the infection to stop any painful spasms of the iris. It is possible you may be prescribed antibiotics to help protect against potential bacterial infection while the surface of your eye is still vulnerable.

Acanthamoeba keratitis can take four to six months to heal. But all patients react differently to the infection and your doctor will provide the most suitable treatment plan for you.

Optical equipment

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How can I prevent acanthamoeba keratitis?

There are several things you can do to help reduce the risk of eye infections such as acanthamoeba keratitis. Let’s face it, no one wants to have to deal with this!

  • Keep your contact lenses away from water. Remove your lenses before showering, using a hot tub, or swimming.
  • Wash your hands thoroughly with soap and water and dry them before handling your lenses.
  • Do not over-wear your lenses – stick to the prescribed length of time.
  • Disinfect your contact lenses according to the manufacturer’s guidelines and your optician’s advice.
  • Never reuse or top up old lens solution. Use a fresh cleaning or disinfecting solution every time.
  • Never use saline solution to disinfect your contacts, as it will not work.
  • Be sure to rub and rinse your lenses every time you remove them to help get rid of debris.
  • Replace your contact lens case once a month.
  • Rinse your contact lens case with sterile solution, empty it and leave it open to dry after each use to limit contamination.
  • Visit your optician regularly for examinations and check-ups

Close up of eye

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Acanthamoeba can cause an immense amount of damage to your eye. However, if you avoid the bad habits we mentioned above, then it is extremely unlikely that you’ll ever be affected by it. Follow our top tips and keep in touch with your optician and you should be just fine!