Acanthamoeba and contact lens use
Acanthamoeba is a form of microscopic amoeba (single-celled organism) that lives in the environment. Acanthamoeba can be found in dust, soil, seawater, freshwater (including rivers, lakes, unchlorinated pools and farm dams), tap water, bottled water, and chlorinated spas and swimming pools.
Acanthamoeba can exist in two different life forms:
- an infective (feeding or trophozoite) phase
- a dormant cyst phase.
Acanthamoeba is resistant to disinfection with chlorine, so it can survive in chlorinated tap water, spas and swimming pools.
Is Acanthamoeba a health risk?
Although Acanthamoeba is very common in the environment, it rarely causes infection. However, contact lenses can increase the risk of infection as they may cause microscopic abrasions of the eye surface.
If Acanthamoeba contacts the eye from a contaminated contact lens or from water, the abrasions may allow it to enter the eye, causing a severe infection called Acanthamoebic keratitis.
This can happen, for example, if the contact lens wearer swims or immerses their head in water (even where goggles are also worn), or the contact lenses have been washed with or stored in tap water or bottled water.
While contact lenses are the most common risk factor, people with a recent history of sand in the eye, or other abrasion or physical injury to the eye, are also at risk if water containing Acanthamoeba gets in the eye.
What is Acanthamoebic keratitis?
Acanthamoebic keratitis (sometimes called Acanthamoeba keratitis) is a painful infection of the cornea (the transparent front part of the eye). It can lead to:
- permanent visual impairment (even blindness in the affected eye)
- unsightly opacity of the eye
- in some cases, loss of the eye.
Early detection is difficult, but essential for effective treatment.
The symptoms are:
- eye pain
- eye redness
- light sensitivity
- blurred vision
- watery eyes
- sensation that something is in the eye.
You should see your family doctor or eye care provider immediately if you or your child experience any of these symptoms. Parents of children who wear contact lenses should also be particularly alert if your child experiences any of these symptoms.
As these symptoms are similar to those of other eye infections, be sure to mention that you wear contact lenses or have recently had an eye injury.
How is Acanthamoebic keratitis diagnosed?
Early diagnosis is essential for effective treatment. However, this can be difficult because the signs and symptoms of Acanthamoebic keratitis are similar to those of other eye infections.
Eye doctors can make a likely diagnosis of Acanthamoebic keratitis from the patient’s history and clinical presentation.
Acanthamoeba may be seen by looking through a special confocal microscope, if one is available. The diagnosis is usually confirmed by the identification of Acanthamoeba from a scraping of the eye.
How is Acanthamoebic keratitis treated?
The infection can be difficult to treat. Treatment can last from 6-12 months using one or more prescription antibiotics and other medications. Reinfection can occur.
If you suspect you or your child has an Acanthamoebic eye infection, it is essential to seek referral to an eye doctor from your usual doctor or eye care provider.
How can I prevent getting Acanthamoebic keratitis?
Careful contact lens hygiene is essential. All users should follow set guidelines.
- Wear and replace contact lenses according to your eye care provider’s instructions.
- If you use contact lenses only sometimes, choose single-use disposable lenses. This avoids the need for storage of reused lenses.
- Visit your eye care provider regularly for eye examinations.
- Always remove contact lenses before coming in contact with water, for example before showering, swimming or using a spa. If desired, wear prescription goggles instead.
- Never swap lenses with another person.
- Never put contact lenses in your mouth.
- Always wash hands with soap and water, and dry them thoroughly before handling contact lenses.
- Parents of children who wear contact lenses should consult their child’s eye care provider for further advice and assistance on contact lens hygiene.
Cleaning and storing contact lenses
- Clean contact lenses according to your eye care provider’s instructions and contact lens manufacturer’s recommendations.
- Always use fresh contact lens solution recommended by your eye care provider each time the lenses are cleaned and stored. Never reuse or top up old solution.
- Always rub and rinse your lenses (after removing them) with contact lens solution prescribed by your eye care provider. This will help remove harmful microorganisms and residues.
- Never use tap water to wash or store contact lenses, unless immediately after it has been boiled and cooled under hygienic, sterile conditions. The same applies to bottled water.
- Never use saline solution or rewetting drops to wash or store contact lenses.
- Reusable lenses should be stored in the proper storage case.
- Storage cases should be rubbed and rinsed with contact lens solution prescribed by your eye care provider (not tap water), emptied, and left to air dry after each use.
- Storage cases should be replaced every three months.
Where to get help
- See your doctor
- Visit a GP after hours
- Ring healthdirect on 1800 022 222
- Contact lenses are the most common risk factor for Acanthamoebic eye infection, so careful hygiene in their use and storage is essential.
- Early detection is difficult, but essential for effective treatment.
- If you suspect you or your child has an Acanthamoebic eye infection, it is essential to seek referral to an eye doctor immediately from your usual doctor or eye care provider.
Environmental Health Directorate
Department of Health
PO Box 8172
Perth Business Centre WA 6849
Telephone: 9388 4999
Facsimile: 9388 4910
This publication is provided for education and information purposes only. It is not a substitute for professional medical care. Information about a therapy, service, product or treatment does not imply endorsement and is not intended to replace advice from your healthcare professional. Readers should note that over time currency and completeness of the information may change. All users should seek advice from a qualified healthcare professional for a diagnosis and answers to their medical questions.