Treatment of Acanthamoeba keratitis Standard, problems, and new approaches

Walochnik, J.; Duchene, M.; Eibl, H.; Aspoeck, H.

Acanthamoeba keratitis is a corneal disease associated predominantly with contact lens wear. The occurrence of Acanthamoeba keratitis has been rising since 1990 in correlation to the growing number of contact lens wearers. To date approximately 2000 cases have been published around the world. Due to the complicated diagnostics, the elaborate treatment and the usually bad compliance of the patients, Acanthamoeba keratitis unfortunately very often takes a serious progression, which may lead to serious visual loss and perforating keratoplasty. Today, local treatment with a combination of polyhexamethylene biguanide (PHMB) and propamidine isethionate (Brolene) is considered the first line therapy for Acanthamoeba keratitis. Alternatively also a combination of propamidine and chlorhexidine or neomycine achieves good therapeutic results. However, the complicated mode of application consistently remains a problem. The intensive local treatment, i.e. hourly application of therapeutics during the first three days day and night makes hospitalization inevitable. Moreover, sufficient efficacy can not always be achieved, and also resistance against propamidine has already been observed. Recently propamidine has sometimes been replaced by hexamidine, which seems to have a greater cysticidal activity. A new path might be struck by the application of alkylphosphocholines. These are phosphocholines esterified to aliphatic alcohols. They exhibit in vitro and in vivo antineoplastic activity and have been shown to be cytotoxic against Leishmania donovani, Trypanosoma cruzi, and Entamoeba histolytica. A recent study has demonstrated that particularly hexadecylphosphocholine is highly effective also against various strains of Acanthamoeba.