Acanthamoeba keratitis is a rare eye infection caused by bacteria in the cornea. It is commonly associated with contact lens wearers. Here, we take a look at its symptoms, causes and treatment available.

How is acanthamoeba keratitis caused?

Acanthamoeba keratitis is caused by a tiny organism known as an amoeba, which is usually found in bodies of water, such as lakes, rivers and swimming pools.

Why do contact lens infections develop?

Contact lens wear can cause scrapes on the corneal surface (clear front surface of the eye), oxygen deprivation, and contamination due to poor hygiene.2 Not following contact lens care guidelines can increase the risk of acanthamoeba keratitis and other eye infections – the most common causes being:1,3

  • Improper storing and handling of your contacts
  • Wearing contacts at night – if they’re not continuous wear lenses
  • Wearing ill-fitting lenses that can scratch the corneal surface
  • Using tap water to clean your lenses
  • Swimming or showering with contacts
  • History of injury to the eye (scratches make it easier for infectious organisms to enter the eye)1

What are the different types of contact lens eye infections?

Bacterial keratitis

Also known as corneal ulcers, this is the most common eye infection associated with contact lens wear. It is usually caused by bacteria called Pseudomonas aeruginosa4. These infections are often treated with antibiotics.

Viral keratitis

The herpes simplex virus (the kind that causes cold sores) can also cause eye infections. Viral keratitis may be treated with cold compresses and artificial tears or an antiviral ointment may be prescribed.4

Fungal eye infections

These are less common but can happen if you injure your eye, store lenses incorrectly, and handle or clean lenses incorrectly. They are treated with antifungal eye drops.

Parasitic eye infections

An eye parasite, acanthamoeba, that lives in tap water, swimming pools, hot tubs, lakes, soil and oceans, can cause acanthamoeba keratitis.

Eye infections are treatable, but it’s important to recognise the signs and symptoms early to receive care as soon as possible.

What is acanthamoeba keratitis?

Acanthamoeba keratitis is an eye infection affecting the cornea that can lead to pain and visual impairment. It’s caused by a microscopic organism called acanthamoeba which is commonly found in water, air, and soil.3 It’s a rare eye infection, but studies show that it is more common in people who wear contact lenses.5

What are the symptoms of acanthamoeba keratitis?

Symptoms of acanthamoeba keratitis are similar to symptoms of other eye infections and include pain, redness, blurred vision, light sensitivity, a gritty sensation in the eye, and excessive watering. 

If you notice any of these symptoms, you should stop wearing your contact lenses and get in touch with your GP/optometrist right away. This is especially important if you feel any severe pain — as this will be quick to set in. You should save your contact lenses and take them to your appointment if possible, as this could help identify what has caused the infection.

How do you test for acanthamoeba keratitis?

Your eye specialist may be able to diagnose the infection based on your history and symptoms. Confocal microscopy, a type of laser scanning that provides very detailed images of the eye, is also used to diagnose acanthamoeba keratitis.3

How do you treat acanthamoeba keratitis?

Usually, a combination of antiseptics and disinfectants (chlorhexidine and propamidine) is prescribed for 2-4 weeks. Antibiotics and steroids may also be used alongside these.6

How do you prevent acanthamoeba keratitis?

Contact lenses are completely safe, provided you practice good hygiene. Studies show that 60 per cent of contact lens wearers who develop acanthamoeba keratitis have irregular disinfecting practices and 30 per cent have gone swimming in their contact lenses.5

Here are some things you can do to reduce your risk and prevent acanthamoeba keratitis:7

  • Avoid tap water contamination of your contact lenses
  • Do not swim or shower with your contacts
  • Use only sterile contact lens solution to disinfect and store your lenses
  • Change your storage case every month
  • Use daily disposable contact lenses to minimise your risk of acanthamoeba infection

Are there any herbal remedies for acanthamoeba keratitis?

At present, there is no completely effective plant-based treatment for this infection.8

You should always seek medical advice if you suspect contact lens eye infection, as self-treatment or delayed treatment can lead to serious complications, including permanent loss of vision.

Learn more about contact lens care on our contact lens hub or book an appointment with a Specsavers optician to discuss contact lens eye infections or other eye health concerns.


  1. Kellogg Eye Center University of Michigan Health System. (no date). Signs of Infection from Contact Lenses. [Online]. Available at: [Accessed 4 November 2019].
  2. Contact Lens Use Under Adverse Conditions: Applications in Military Aviation. (no date). Adverse Effects of Contact Lenses. [Online]. Available at: [Accessed 4 November 2019].
  3. Centers for Disease Control and Prevention. (no date). Parasites – Acanthamoeba – Granulomatous Amebic Encephalitis (GAE); Keratitis. [Online]. Available at: [Accessed 4 November 2019].
  4. Watson S, Cabrera-Aguas M, Khoo P. Common eye infections. Aust Prescr. 2018;41(3):67–72. [Online]. Available at: [Accessed 4 November 2019].
  5. Seal DV, Beattie TK, Tomlinson A, Fan D, Wong E. Acanthamoeba keratitis. British Journal of Ophthalmology. Volume 87, Issue 4. [Online]. Available at: [Accessed 4 November 2019].
  6. American Academy of Ophthalmology. (no date). Acanthamoeba Keratitis Treatment. [Online]. Available at: [Accessed 4 November 2019].
  7. Radford CF, Minassian DC, Dart JK. Acanthamoeba keratitis in England and Wales: incidence, outcome, and risk factors. Br J Ophthalmol. 2002;86(5):536–542. [Online]. Available at: [Accessed 4 November 2019].
  8. Hadaś E, Derda M, Cholewiński M. Evaluation of the effectiveness of tea tree oil in treatment of Acanthamoeba infection. Parasitol Res. 2017;116(3):997–1001. [Online]. Available at: [Accessed 4 November 2019].