Abstract
Purpose:
To evaluate the effect of different contact lens materials and cases on the disinfection efficacy of Multipurpose Disinfection Solutions (MPDS) following the November 12, 2008 draft standard, Antimicrobial Efficacy Endpoint Methodology to Determine Compatibility of Contact Lens Solutions, Lens Cases and Hydrogel Lenses for Disinfection (AEEMC).
Methods:
AEEMC testing was conducted in manufacturer supplied lens cases. Two silicone hydrogel lenses (balafilcon A and senofilcon A) and one conventional lens (etafilcon A) were inoculated with a test organism (P. aeruginosa, S. marcescens, S. aureus, C. albicans, or F. solani) in the presence of organic soil. After an exposure time of 3-to10-minutes, MPDS was dispensed into each well. Aliquots of the inoculated solutions were removed at the disinfection time (4 or 6 hrs as stated on the product label) and 24 hours for microbial enumeration. Lens cases without lenses inoculated with organisms were included as controls.
Results:
Reduction in efficacy associated with contact lens was most pronounced with C. albicans as a challenge organism at both disinfection time and 24 hrs for all MPDS. Only one solution consistently met > 1 log reduction for all three lenses at disinfection time. Challenges with Fusarium also resulted in reduced efficacy in the presence of contact lens for most of the MPDS at disinfection time, although OPTI-FREE® PureMoist® showed no reduction in efficacy. A reduction in efficacy against S. marcescens was also observed at disinfection time with 2 out of 4 solutions. All MPDS exhibited similar efficacy against P. aeruginosa and S. aureus.
Conclusions:
The AEEMC studies are designed to more closely simulate the conditions during actual use and evaluate the effect of contact lenses in a lens case on the antimicrobial efficacy of MPDS. Reduced efficacy of several MPDS were observed with C. albicans, F. solani, and S. marcescens when tested following AEEMC protocols in conjunction with balafilcon A, senofilcon A and etafilcon A lenses. The current ISO standard 14729 does not address the reduction in MPDS antimicrobial efficacy in the presence of contact lenses. OPTI-FREE® PureMoist® demonstrated a high level of efficacy under these simulated in-use conditions relative to other MPDS.
Keywords: 477 contact lens