Abstract
Purpose: :
Lack of maintenance of contact lens case hygiene has been shown in many epidemiology studies to be associated with an increased risk of developing microbial keratitis. The aim of this study was to examine the microbial colonisation of lens cases during use of lens care products (LCP) containing dual disinfectants.
Methods: :
Two non-contemporaneous prospective, single group, bilateral design, open labelled clinical studies were conducted using the same protocol to evaluate the microbial contamination of contact lens cases when used with balafilcon A lenses in conjunction with either RevitaLens OcuTec® (containing polyquaterium-1 and Alexidine, Abbott Medical Optics, Inc.) in one study or Biotrue™ (polyquaternium-1 and PHMB, Bausch & Lomb) in another. Forty subjects were enrolled in each of the studies, and lens cases (approximately 70 from each trial) were collected after 1 month of use and cultured, using standard techniques, to identify and enumerate the types of microbes within the lens case. The frequency and the types of microbial contamination of cases were evaluated following the same procedures and compared between the two solutions. These data were then compared to the data of other LCP/contact lens combinations previously published by us using the same clinical protocol and laboratory procedures.
Results: :
There was not significantly different (p>0.05) in the case contamination rates between the LCP containing PQ/Alexidine (79%) and PQ/PHMB (84%). There were no significant differences (p>0.05) between PQ/Alexidine and PQ/PHMB for the rates of case contamination with Gram-positive bacteria (77% v 81%), Gram-negative bacteria (12% v 16%) or fungi (9% v 12%). The total number of colony forming units recovered from cases was low with either LCP (median CFU 10 or 20 per case). In comparison to our previous data, the rates of contamination of cases by Gram-positive bacteria was similar regardless of lens or LCP type (from 71% to 84%), and the rate of case contamination by Gram-negative bacteria was significantly less (p<0.05) for either PQ/Alexidine (12%) or PQ/PHMB (16%) compared to the cases in which a brand of LCP containing PQ/ALDOX (45%) was used.
Conclusions: :
Use of the LCP containing PQ/Alexidine or PQ/PHMB resulted in a low frequency of contamination of contact lens cases by Gram-negative bacteria, suggesting these LCP may have potential to reduce the incidence of adverse events associated with the type of bacterial contamination during contact lens wear.
Clinical Trial: :
Australian New Zealand Clinical Trials Registry, ACTRN12609000640202; ACTRN12610001068055
Keywords: contact lens • antibiotics/antifungals/antiparasitics • clinical laboratory testing