Acanthamoeba keratitis and contact lens wear: the patient is at fault

The avoidance of nonsterile solutions is important to curtailing Acanthamoeba keratitis, a serious infection that has been found to occur with all types of contact lens (CL) wear. Increased patient education, revised recommendations regarding the use of tap and distilled water, and improved disinfecting systems are vital to preventing infection. These precautions are particularly important since it appears that Acanthamoeba, unlike Pseudomonas, may not require an epithelial defect to establish corneal infection and, once in the cornea, may not respond to drug therapy or surgical extirpation. Unfortunately, many patients receive poor lens care instructions or cannot be relied on to follow appropriate routines. Finding a foolproof means of lens disinfection for them is critical. Recently, several disinfection systems were tested against Acanthamoeba castellanii and Acanthamoeba polyphaga cysts and trophozoites to see which might prove most effective. Effective systems included heat disinfection at 70 to 80 degrees C for 10 min, 3% hydrogen peroxide for 2-3 h, 0.001% thimerosal with edetate for 4 h, 0.005% benzalkonium chloride with edetate and reagent for 4 h, and either 0.001% chlorhexidine for 4 h or 0.004% chlorhexidine for 1 h. Thus, for patients who are careless or persist in using nonsterile rinsing solutions, it appears that at least some methods of disinfection will help prevent Acanthamoeba infection.