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Eye-Eating Parasite newspaper headline

The Truth Behind The Eye-Eating Parasite

Recent newspaper headlines describe Acanthamoeba as a “Parasite” or “Eye-Eating Bug that can cause death”. In this article, we’ll take a look at the truth behind Acanthamoeba and provide tips to avoid infection.

Acanthamoeba is not a parasite, as it does not need a host to survive. It’s true that it can cause severe and long lasting damage to the front surface of the eye. However, it is unlikely that it will result in death. 

Acanthamoeba can cause three main types of illness: 

•    Involving the eye (Acanthamoeba keratitis).
•    Involving the brain and spinal cord (Granulomatous Encephalitis).
•    Infections that can spread throughout the entire body (disseminated infection).

Infections involving the brain and spinal cord are extremely rare, and can be deadly. However, deaths through cases of Acanthamoeba Keratitis are almost unheard of.


The amoeba can be found in:

•    Tap water, swimming pools, hot tubs, lakes, oceans and contaminated water.
•    Soil.
•    Dust and Air.

We regularly come into contact with Acanthamoeba when we wash, swim, or drink water. It doesn’t generally cause harm, but can cause a serious eye disease if it manages to infect the cornea. Any disturbance to the corneal surface (injury, scratch) can leave the cornea vulnerable to infection.

Risk Factors Of Acanthamoeba Keratitis

There are a number of different factors which are known to increase the risk of contracting Acanthamoeba Keratitis. The biggest risk factor is exposure to water, but the following poor contact lens hygiene practices can also cause infection:

•    Swimming or showering in contact lenses.
•    Rinsing or storing lenses in water.
•    Handling lenses with unwashed or wet hands.
•    Failure to disinfect lenses properly.
•    Failure to clean and dispose of contact lens cases appropriately.
•    Use of non-sterile solutions.
•    Topping up solution in a contact lens case rather than using fresh solution.

Woman inserting contact lens

Symptoms Of Acanthamoeba

The symptoms can be very similar to those of other common eye infections. If Acanthamoeba is suspected, you will be referred to a hospital eye department. There, further tests can be carried out to identify the specific cause.

Testing may involve a corneal scrape. This is where some cells from the surface of the cornea are removed (with anaesthetic), or a swab of the cornea is taken to check for Acanthamoeba DNA.

Symptoms are not the same for everyone, and can include:

•    Pain, sometimes disproportionate to the signs noted on the eye.
•    Redness.
•    Blurred vision.
•    Light sensitivity.
•    Gritty sensation.
•    Excessively watery eye.

Treatment Of Acanthamoeba

Acanthamoeba is typically treated with antiseptic drops, which have an anti-amoebic effect. Usually, you’ll need to take these drops every hour for the first few days (including overnight). As the treatment progresses, this will usually reduce to 2-hourly by day and then less frequently. 

In addition to the anti-amoebic eye drops, you may be given anti-inflammatories or painkillers to help with the pain. You may also be given a dilating drop early in the infection to stop painful spasms of the iris. 

It is possible that you’ll be prescribed with antibiotics, as well as the other drops. This will help to protect against potential bacterial infection while the surface of the eye is vulnerable.

The disease can take four to six months to resolve. However, all patients react differently to the infection and your doctor will provide the most appropriate treatment plan for you.

Man having his eyes checked

Tips To Prevent Acanthamoeba Infection

Follow these guidelines to help reduce the risk of eye infections:

•    Visit your Optician for regular eye examinations and contact lens checkups.
•    Keep your contact lenses away from water. Remove your lenses before showering, using a hot tub or swimming.
•    Wash your hands with soap and water, and then dry before handling contact lenses.
•    Do not over wear your lenses - stick to the schedule prescribed by your optician.
•    Replace your contact lenses according to your optician’s advice.
•    Disinfect your contact lenses based on manufacturer’s guidelines and your optician’s instructions. 
•    Never reuse or top off old solution. Use fresh cleaning or disinfecting solution each time lenses are cleaned and stored to prevent diluting the efficiency of the solution.
•    Never use saline solution to disinfect your lenses, as it does not have disinfecting properties.
•    Rub and rinse your lenses each time you remove your contact lenses to help remove debris.
•    Contact lens cases should be rubbed and rinsed with sterile contact lens solution (never use tap water), emptied, and left open to dry after each use to limit contamination.
•    Replace your contact lens case once a month.

Moist contact lenses

Should I Worry About Acanthamoeba?

Acanthamoeba is a very harmful protozoa that can cause an immense amount of damage to your eye. However, if you avoid habits that make you susceptible to an infection, then it is extremely unlikely that you’ll ever be affected by it. 

By keeping your contact lenses clean and away from water, while following your Optician’s wear and care instructions, you should stay infection-free.