Cytotoxicity evaluation of soft contact lens care solutions on human conjunctival fibroblasts

Purpose: To determine whether different contact lens care solutions for soft lenses cause damage to human conjunctival cells.

Methods: Primary cultured human conjunctival fibroblasts were incubated with various concentrations of four different commercially available soft contact lens care solutions (OptiFree, Renu, SoloCare, Titmus) at concentrations of 5, 10 and 50 microl/ml medium. Toxicity was examined by determination of (1) the cell viability and mitochondrial activity with the colorimetric MTT test, and (2) the number of living cells with a cell analysis system (CASY 1) as compared with untreated cells.

Results: For all four soft contact lens care solutions at a concentration of 5 mul/ml medium, no significant decrease in mitochondrial activity of the human conjunctival fibroblasts was found by the MTT test. At 10 microl/ml, only OptiFree and Titmus reduced mitochondrial viability significantly. The greatest reduction in mitochondrial activity occurred with all of the four soft contact lens care solutions at a concentration of 50 microl/ml. No significant decrease in the number of living conjunctival fibroblasts was observed by CASY 1 even at higher concentrations of the four solutions investigated.

Conclusion: This in vitro study demonstrates that the examined soft contact lens care solutions induce changes in mitochondria of human conjunctival cells only at higher doses as observed by the MTT test. However, this damage to the mitochondria did not lead to cell death as shown by the cell analysis system.