Purpose: The purpose of this study is to assess the effects of commercially available contact lens wetting solutions on bacterial binding and cell exfoliation rates in human corneal epithelium.
Methods: The effects of four contact lens care solutions were tested: ReNu Multi Plus (Bausch & Lomb, Rochester, NY) multipurpose solution; OPTI-FREE Express (Alcon, Ft. Worth, TX) multipurpose solution; Complete Blink-N-Clean (Allergan, Irvine, CA) lens drops; and Lens Plus (Allergan) rewetting drops.
Study design: Prospective, double-masked, randomized crossover clinical trial (N = 20 subjects).
Outcome measures: Measures of outcome included binding of Pseudomonas aeruginosa (PA) to exfoliated corneal epithelial cells, and the rate of surface cell exfoliation. Cells were collected at the baseline (pretreatment) examination and 4 days later, after subjects used the assigned solution six times daily and once again immediately before cell collection (posttreatment). Following cell collection, patients underwent 1 week of recovery, during which no drops were used, and random cross-over assignment to the next test solution.
Results: Use of test solutions increased PA binding, with a range of + 11.9% to + 58.2%. Analyzed together, PA binding increased significantly (+ 29%; P = 0.02, paired t-test); Lens Plus solution alone raised PA binding levels significantly (P = 0.022, 2-way ANOVA, Student-Newman-Keuls [SNK] test). Exfoliation rates were decreased from -7% to -52.7%. Analyzed together, cell exfoliation decreased significantly (P = 0.004; Wilcoxon signed rank test). Individual use of OPTI-FREE decreased exfoliation significantly (P = 0.019: 2-way ANOVA, SNK test).
Conclusions: Topical application of common commercial contact lens care solutions increases PA binding and reduces corneal surface cell exfoliation. Similar effects have also been reported with contact lens wear. Taken together, the data suggest that the use of lens solution itself may play a role in increasing PA binding to corneal epithelial cells and, hence, might potentially contribute inadvertently to increased risk for lens-related microbial keratitis.