What is Acanthamoeba Keratitis? Eye infection in contact lens wearers

06 January 2022

Author: Kate Green

Acanthamoeba Keratitis

What is Acanthamoeba Keratitis?


Acanthamoeba Keratitis (AK) is a parasitic eye infection which was first identified in 1973. Acanthamoeba is the name of an organism with only one cell, while Keratitis is the medical term for corneal inflammation. Acanthamoeba are usually found in water such as tap water, swimming pools, lakes, and contact lens solution, as well as in soil and vegetation. If left untreated, AK can cause loss of vision or total blindness due to corneal damage from the parasite. As soon as the Acanthamoeba makes contact with the eye’s surface, it invades through the epithelium, grouping around the corneal nerves. AK is particularly associated with contact lens wearers as the parasite can become trapped between the eye’s surface and the contact lens itself, worsening its effect.


What are risk factors for Acanthamoeba Keratitis?


There are a number of lifestyle factors and health issues that put you at greater risk of developing AK. Primarily, contact lens wearers suffer the most with AK. In fact, studies have shown that 89% of patients diagnosed with AK wore contact lenses. In the UK, 1 in 30,000 contact lens wearers develop AK each year, not to mention those who develop it following a corneal injury. Two important things to note are that AK is not contagious from person to person, nor can it be contracted by drinking infected water.


Previous corneal trauma is also a huge risk factor for developing AK after exposure to Acanthamoeba. Anywhere that the cornea hasn’t completed healed, or where there is still a corneal abrasion, means that the parasite can enter the eye more easily and begin the process of infection.


The most important steps you can take to prevent AK from developing all involve practising good contact lens hygiene. You must avoid:

  • Cleaning your contact lenses with tap water
  • Storing your contact lenses in tap water
  • Reusing contact lens solution
  • Showering or swimming with contact lenses
  • Putting in contact lenses with wet hands
  • Adding fresh contact lens solution to old solution


These actions all allow the Acanthamoeba to come into contact with your eyes and potentially remain trapped there between the contact lens and the eye’s surface. Studies on contact lens hygiene have shown that up to 800 in 10,000 contact lens users had their lens storage contaminated with Acanthamoeba. Contact lens hygiene is absolutely crucial in preserving your vision and eye health.


What are the symptoms of Acanthamoeba Keratitis?


The main symptom of AK is that your eye becomes painful and inflamed. In a study of patients affected by AK, 95% of them complained of severe pain. It’s important to note that the symptoms of AK might be intermittent, coming and going before the condition becomes more serious.


Knowing if you have AK, rather than another microbial corneal infection, can be difficult as the symptoms are often quite similar. Your eye doctor may have to run some tests before confirming exactly which type of infection you have. Determining your type of eye infection is crucial as it allows the best treatment to be delivered to you, as soon as possible. With AK, the longer the infection is left untreated, the more devastating the impact of the visual loss is.


Symptoms of Acanthamoeba Keratitis are:

  • Red eyes
  • Watery eyes
  • Light sensitivity
  • Eye pain
  • Blurry vision
  • Foreign body sensation


If you are experiencing any combination of these symptoms, especially if you’re a contact lens wearer, it’s crucial that you seek treatment quickly.


How can you treat Acanthamoeba Keratitis?


Experts say that prevention is much more effective than treatment when it comes to AK as the effects can be so devastating, and not always 100% treatable. As we’ve discussed in our ‘risk factors’ section, the best way to prevent the AK is to practice good contact lens hygiene. Even for non-contact lens wearers, it’s a good rule of thumb to touch your eyes as little as possible, to prevent transmission of infections. This means that if you have the Acanthamoeba organism on your hands from either water or soil and vegetation, you can avoid it making contact with your eyes. It is also suggested that contact lens wearers try daily disposable lenses, rather than reusable lenses, to reduce the likelihood of Acanthamoeba living in contact lens solution.


Once you have developed AK, antiseptic drops may be prescribed to help with the infection. Some doctors will also prescribe their patients any one of or a combination of antibiotic, antiviral, antifungal and antiparasitic drugs. However, treatment has been described as lengthy and not always effective, with different patients having varying reactions to combinations of treating drugs.


For severe cases in which none of the antibiotics etc. work, a corneal transplant may be recommended. This is particularly necessary in cases where the infection has left corneal scarring or ulceration which impacts your vision to the extent that you cannot see. 19% of AK cases require a corneal transplant which just goes to show that treatment is only effective 80% of the time.


Acanthamoeba Keratitis is a terrifying infection with devastating impacts, often resulting in partial or total visual loss. Practicing good contact lens hygiene and washing and drying your hands thoroughly before touching your eyes should go a long way to helping prevent development of the infection. Alternatively, you could consider laser eye surgery as a way to cut the risks and hassle of contact lens infections from your life. Learn more about laser eye surgery, or book in for your free consultation online. Feel free to contact us if you have any questions – we’re more than happy to help!


If you are seeking support and guidance following an AK diagnosis, Acanthamoeba Keratitis Patient Advocates have set up a Facebook support group.

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