Acanthamoeba keratitis: is water exposure a true risk factor?

Water exposure has been commonly cited in the literature as a significant risk factor for the development of Acanthamoeba keratitis. The purpose of this study was to test the hypothesis that the incidence of tap and contaminated water exposure in Acanthamoeba keratitis patients is no higher than in the normal contact lens population.

We retrospectively reviewed all patients all patients diagnosed with Acanthamoeba keratitis at Massachusetts Eye & Ear Infirmary from 1990-1994, and compared this group to a control population of healthy contact lens wearers assessed by a self-report questionnaire.

A history of water exposure was reported by 64% (seven patients) diagnosed with Acanthamoeba keratitis. In comparison, 100% of the control population of healthy contact lens wearers (100 patients) reported comparable water exposure, and 87% of controls reported multiple sources of water exposure.

The finding that the incidence of water exposure is actually lower in patients with Acanthamoeba keratitis than in the general contact lens population suggests that water exposure may be less important, and other factors more important in the development of this disease than previously assumed.