Combined Treatment of Acanthamoeba Keratitis With Propamidine, Neomycin, and Polyhexamethylene Biguanide

We developed an intensive treatment regimen of topical neomycin, propamidine, and polyhexamethylene biguanide that was tapered to a maintenance level over a 14- to 28-day period as toxicity developed. Since July 1991, we used this treatment on six eyes of five patients in whom Acanthamoeba keratitis was diagnosed clinically. All patients had positive cultures for microorganisms from their corneas or contact lens cases or had pathognomonic findings of pseudodendritic subepithelial infiltrates and radial keratoneuritis. After therapy, all patients improved within two to four weeks, with regression or resolution of neuritis and infiltrates, healing of epithelial defects, and lessening of pain. By three to four months, visual acuity had returned to 20/20 in all eyes. We believe the addition of polyhexamethylene biguanide to our treatment regimen in Acanthamoeba keratitis dramatically aided and hastened the clinical improvement in five consecutive patients and may, with early diagnosis, increase the number of medical cures.