Temperature instability of ReNu with MoistureLoc: a new theory to explain the worldwide Fusarium keratitis epidemic of 2004-2006.

Purpose: A 2006 US Food and Drug Administration (FDA) inspection of Bausch & Lomb's (B&L's) Greenville, South Carolina, manufacturing site indicated that B&L failed to regulate storage and transport temperatures of their products. The present study investigated the effect of storage temperature on the ability of contact lens solutions to inhibit growth of Fusarium species.

Methods: SIX CONTACT LENS SOLUTIONS WERE STUDIED: ReNu with MoistureLoc (ReNu ML), ReNu MultiPlus, Complete Moistureplus, AQuify, Clear Care, and OPTI-FREE RepleniSH. Two bottles of each solution were separately stored at room temperature and 60 degrees C for 4 weeks, serially diluted, then tested for their ability to inhibit growth of 11 Fusarium isolates (7 of which were associated with the keratitis epidemic).

Results: ReNu ML demonstrated the greatest decline in efficacy after 60 degrees C storage. Clear Care and ReNu MultiPlus performed the best. Regarding the keratitis epidemic isolates only, the ReNu ML bottle stored at room temperature allowed growth in 27 of 84 combinations vs 67 of 84 combinations with the 60 degrees C stored bottle.

Conclusions: When exposed to prolonged temperature elevation, ReNu ML loses its in vitro fungistatic activity to a much greater extent than other products. Improper temperature control of ReNu ML may have contributed to the Fusarium keratitis epidemic of 2004-2006.