Abstract
Purpose:
To evaluate correlations among in vitro models, preservative concentration response and lens preservative uptake-release profiles for assessing cytotoxicity and biocompatibility of multipurpose contact lens solutions (MPS).
Methods:
Four MPS containing different preservatives (polyquaternium-1, polyhexamethylene biguanide, alexidine, and/or myristamidopropyl dimethylamine) were used. The effects of MPS were evaluated by USP Direct Contact Test, Colony Formation Assay (ISO 10993) in hamster fibroblast (V79, 1-10% MPS) and Cell Viability Assay by alamarBlue in human corneal epithelial cells (HCEC, 50-100% MPS). Corneal epithelial barrier function was assessed by Zonula Occludens (ZO-1, 50-100%) immuno-histochemistry staining and transepithelial electrical resistance (TEER, 50% MPS) in HCEC. All tests were performed in triplicate and results were compared to media, PBS, and benzalkonium chloride controls. The dose-dependent effects and uptake-release kinetics of preservatives by silicone hydrogel and hydrogel lenses were also evaluated.
Results:
MPS-induced cytotoxicity in in vitro models are dependent upon the lens-preservative uptake and release kinetics. MPS cytotoxicity effects on V79 fibroblasts showed a concentration-dependent response (p<0.05), where cytotoxicity increased with MPS concentrations after long-term exposure (7 days, p<0.05). MPS concentrations in HCEC showed a shorter time exposure dependency (15-60 minutes, p<0.05) when evaluated by alamarBlue Cell Viability Assay. Membrane integrity assays (ZO-1 IHC and TEER) showed the highest correlations followed by metabolic activity (alamarBlue) and colony forming assays.
Conclusions:
All MPS are demonstrated to be biocompatible by correlating results from in vitro assays showing none to minimal effects on cell cytotoxicity, metabolic activity, and membrane integrity. Results from this study indicated that correlations between preservative concentration-response curves and lens uptake-release profiles are valuable to demonstrate MPS biocompatibility.
Keywords: 477 contact lens •
482 cornea: epithelium •
480 cornea: basic science