Acanthamoeba is a microscopic organism that has been found in everywhere in the environment. It has been found in hot tubs, swimming pools and tap water; these places are the most common places that the eye would come in contact with the organism. This tiny organism can cause a serious eye infection in contact lens wearers caused by the improper cleaning and handling of the lens. While this type of infection is rare, it can be visually devastating and difficult to treat.
Contact Lenses and Acanthamoeba
The eye infection caused by Acanthamoeba is called a keratitis. In the past, keratitis has been extremely rare in the United States. According to data from the Prevent Blindness America website, 208 cases were reported each year between 1973 and 1988. Since then, there have been several outbreaks reported by the CDC that were associated with homemade saline solutions and a commercially-sold cleaning solution. There has also been an increase in documented cases of keratitis over the past few years that has caused health officials to question whether other causes, such as local water contamination, may exist.
Symptoms
The early stages of a keratisis infection are nonspecific--the patient may present with a red eye, feel like he has something in his eye and have frequent pain. The eye may tear as well. A doctor may suspect Acanthamoeba in a contact lens wearer who presents with those symptoms but the diagnosis is not typically confirmed until the condition does not improve after antibiotic treatment. In the later stages of the infection, a ring-like ulceration may appear on the cornea.
Risk Factors
Any condition that compromises the integrity of the cornea makes it easier for the organism to cause the infection. These conditions include previous corneal disease, other corneal infection and contact lens use. Another risk factor for the development of this type of infection is the use of tap water to clean and care for contact lenses. This includes the rinsing of the contact lenses case with tap water. Swimming in fresh water sources or being in a hot tub with contacts lenses on is another risk factor for the development of Acanthamoeba keratitis. Poor lens care--not following instructions on hand washing, fresh lens solution use and lens handling--also places the patient at risk for this type of keratitis.
Treatment
Unfortunately, Acanthamoeba keratitis is often not diagnosed during the early stages, and it is difficult to treat. Typical antibiotics do not work, but some treatments that have been found to work include the disinfectant agent polyhexamethylene biguanide, Brolene eye drops and chlorhexidine digluconate solution. The eye drops polymixin B, neomycin and clortrimazole 1% have also shown some effectiveness in treating the keratitis. However, for many patients, Acanthamoeba infection results in a long course of treatment that may have varying levels of success. Some patients who develop this condition eventually need a corneal transplant.
Prevention/Solution
Prevention is the best plan for dealing with Acanthamoeba keratitis. Since the majority of people who contract this infection are contact lenses wearers, it is important to follow correct contact lens care. According to the American Optometric Association, contact lens wearers should always employ appropriate hand washing regimens, avoid using tap water on contact lenses, and only use fresh contact lens disinfecting solutions. Contact lens wearers should never put lenses into the mouth or swap lenses with another person. Appropriate cleaning of contact lens cases by using sterile disinfecting solution instead of tap water can lower the risk of infection as well.
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