In Vitro Safety Evaluation of a Novel Contact Lens Care Solution Containing the Disinfectant Hydrogen Peroxide

Abstract

Purpose: : A battery of in vitro tests evaluating viability and barrier function were used to determine whether residual amounts of H₂O₂ remaining after neutralization of an experimental borate-containing contact lens care solution adversely affects human corneal limbal epithelial cells. Effects of the neutralized test solution were compared to that of H₂O₂ in serum-free culture medium.

Methods: : (1) Stratified HCLE cells were exposed to either H₂O₂ (0.01-0.3%) in culture medium or neutralized lens care solutions (full strength or diluted to 1-50% in culture medium) for 1 or 24 hr, followed by measurement of viability, fluorescein permeability and trans-epithelial resistance; (2) Contact lenses soaked in the test solution or Clear Care^® (Ciba Vision) for 1-15 days (2 cycles/day) were applied to stratified cells in a lens overlay model for 24 hr followed by viability and permeability assays. In the overlay model a lens was placed on cells concave side up in the minimum volume of medium required to cover the lens.

Results: : H₂O₂ in culture medium at concentrations > 0.2% caused a marked decrease in cell viability and loss of barrier function. The permeability of the constructs continued to increase when cells were returned to medium without peroxide. In contrast, residual H₂O₂ (< 0.01%) in the neutralized lens solutions, applied to cells at full (1 hr) or diluted (24 hr) concentrations had no effect on viability or barrier function. In the lens overlay model, lenses that were cycled in lens solutions and neutralized had no adverse effects on viability or permeability of stratified cells.

Conclusions: : The experiments using H₂O₂ at concentrations > 0.2% in culture medium demonstrate that stratified HCLE cells are sensitive to peroxide and that the in vitro tests used in this study can detect cellular damage. Residual H₂O₂ in lens care solutions after neutralization had no cytotoxic effects. A lens overlay model developed for safety evaluation of contact lens-solution pairings confirmed these findings. Together, the results show that following neutralization, H₂O₂ containing lens care products do not adversely affect stratified corneal epithelial cells.

Keywords: contact lens • cornea: epithelium • ocular irritancy/toxicity testing