Compliance and Acanthamoeba
BY JOSEPH T. BARR, OD, MS, FAAO, EDITOR
Acanthamoeba is ubiquitous, especially in stagnant water such as ponds, lakes and hot tubs. Acanthamoeba keratitis is rare. It may be as rare as two cases per million contact lens wearers in the United States, but some believe that the incidence may have increased during the past two decades. It could be that we're just better at identifying it and the incidence hasn't changed.
As with any corneal infection, early diagnosis and treatment are vital. The disease is extremely painful in 50 percent of cases and is challenging to treat, and up to nearly 40 percent of cases may result in penetrating keratoplasty. Dendrite-like lesions may appear in the epithelium and radial keratoneuritis may occur. Ring infiltrates are common along with an anterior chamber reaction. When you suspect AK, a board-certified corneal specialist is the best referral.
The American Optometric Association Contact Lens and Cornea Section recently published the following information:
Every day mechanically scrub, using a clean washcloth or clean toothbrush, the inside and outside of your lens case with sterile contact lens solution. Air dry contact lens cases with the caps off when not in use; cover the case and caps with a clean towel. Avoid using tap water on cases or lenses. However, boiling a case in tap water will disinfect it. Microwave dry contact lens cases for three minutes to sterilize them. Replace your case every one to three months. Remove lenses before swimming and before entering a hot tub. If you wear your lenses while swimming, apply a rewetting drop to rehydrate the lenses and remove them as soon as possible after swimming. Wear water-tight goggles while swimming with your lenses. Don't sleep wearing lenses after swimming.
Wash and dry your hands before handling lenses, and rub and rinse the lens surfaces prior to storage in a clean case. Use only sterile products that your practitioner recommends. Don't use salines or rewetting drops for storage — use only fresh solution. Don't top off. Replace lenses according to your practitioner's instructions and don't sleep wearing lenses unless instructed to do so, especially after swimming. Never swap lenses with someone else. See your practitioner for regular check ups; if redness, blur and pain occur, take out your lenses and call your practitioner.
Our patients aren't likely to comply with all of this, but I do hope they start to clean their cases better (using solutions) and air dry them. Remember, Acanthamoeba eat other micro-organisms, so keeping everything clean and being careful with water and swimming can prevent this worst of corneal infections.
Additionally, the Centers for Disease Control and Prevention is attempting to proactively measure the incidence of ulcerative keratitis. If you suspect ulcerative keratitis in any case since Jan. 2005, report it to the CDC through the AOA CLCS Web page at http://www/aoa.org/acanthamoeba.xml.