THE EPIDEMIC OF ACANTHAMOEBA-KERATITIS - WHERE DO WE STAND

Purpose. To review from a historical perspective the recent epidemic o f Acanthamoeba keratitis and its association with the use of contact l enses and to provide a summary of recent techniques that have allowed earlier diagnosis and treatment. Methods. The authors reviewed availab le literature on Acanthamoeba keratitis from 1973 to the present, with emphasis on the history of the epidemic and its association with cont act lenses, identification of risk factors, preventive measures, and c urrent diagnostic techniques. We also estimated the annual incidence o f Acanthamoeba keratitis during 1985 through 1987 from available data. Results. Before the popularization of sof-contact-lens wear. Acantham oeba keratitis was extremely rare; however, an epidemic began in the e arly 1980s, and the number of cases increased dramatically beginning i n 1984. By 1985, the association of this infection with the use of con tact lenses was firmly established, and in 1987, the infection was sho wn to occur more commonly among men, as well as in contact-lens wearer s who failed to disinfect their lenses as frequently as recommended, s wam while wearing lenses, or used homemade instead of commercially pre pared saline solution. Adoption of ''disposable'' contact lenses in th e late 1980s did not decrease the risk of Acanthamoeba keratitis, and concerns remain regarding the effectiveness of some contact-lens disin fectants; however, recent advances in diagnosis and treatment have imp roved the prognosis. The annual incidence during 1985 through 1987 was conservatively estimated at 1.65 to 2.01 cases per million contact-le ns wearers. It is unclear whether the incidence is declining. Conclusi on. Acanthamoeba keratitis has now been recognized worldwide, and ther e are clear associations of this infection with improper contact-lens hygiene, particularly contact with water. Recent methods allow earlier diagnosis and thus improved outcomes. The epidemic provides a valuabl e lesson on how a new technology can be associated with unforeseen com plications and exemplifies how rapid dissemination of epidemiologic in formation can aid in controlling an emergent epidemic.