Purpose:
The recent increase of contact-lens associated Acanthamoeba keratitis (AK) has drawn renewed attention to the link between the organism and consumer contamination of lenses. This study presents a novel method that resembles real life conditions to ensure accurate assessment of the effectiveness of the rub-and-rinse steps of the lens-care regimen. In this method, lenses are soaked in the test organism milieu overnight, giving the organism time to attach. By contrast, the standard FDA method calls for the lens to be inoculated with the organism, followed by a 5-10 minute drying time.
Methods:
Serratia marcescens and Acanthamoeba polyphaga trophs were used as test organisms. Lenses were either inoculated directly and allowed a 5-10 minute drying time per the FDA method, or they were soaked in the test organisms overnight.Initial inoculum per lens was established, then the lenses were subjected to either the standard label-claim rinse step or to a rub-and-rinse step, and the resultant log-drops from each step were determined. (The lens- solution soak step was omitted, as only the effects of rinse-and-rub and rinse were evaluated in this study.) The test product contained 1 ppm PHMB.
Results:
Table 1: Log-reductions in cells/lens resulting from the rinse step or a rub-and-rinse step* Total kill of initial inoculum
Keywords: contact lens • keratitis • Acanthamoeba