The effectiveness of various cleaning regimens and current guidelines in contact lens case biofilm removal.

PURPOSE Lens case hygiene is important for safe contact lens wear. However, there are no evidence-based data to suggest optimum hygiene regimens. This in vitro study aimed to evaluate and compare the effectiveness of manufacturers' guidelines and several other regimens in removing biofilm using various types of contact lens cases and disinfecting agents. METHODS Biofilms of Staphylococcus aureus ATCC 6538 and Pseudomonas aeruginosa 122 were formed on two types of unused contact lens cases. Subsequently, each contact lens case was subjected to one of four cleaning regimens using two different multipurpose disinfecting solutions or distilled water: "rinse and air-dry (guidelines)," "rub, rinse and air-dry," "tissue-wipe and air-dry," and "rub, rinse, tissue-wipe, and air-dry." The levels of residual biofilm were then quantified using viable counts and compared. RESULTS The manufacturers' guidelines resulted in 1 to 2 log CFU reduction of either biofilm. "Rub, rinse, tissue-wipe, and air-dry" was the most effective cleaning regimen (P < 0.001), capable of removing 4 to 6 log CFUs of bacteria; higher levels of biofilm were removed by mechanical friction from nonridged cases than that of ridged cases (P < 0.001). Biofilm removal varied with multipurpose solution tested. CONCLUSIONS Current manufacturers' guidelines are not adequate in eliminating microbial contamination. Simply incorporating a rubbing/wiping step in daily case hygiene reduces viable organism recovery. Factors such as the cleaning regimen, antimicrobial potency of multipurpose solution, and the interior topography of a lens case may impact the surface detachment of biofilm during the cleaning process.