Effect of Artificial Tears Used in Contact Lens-wearing Eyes on Human Corneal Epithelial Cells in Vitro

Purpose: To investigate the biologic effects of topical ocular artificial tears used in patients wearing contact lens on in vitro corneal epithelial cells. Methods: The efficacies of the topical artificial tears Iris, Irisplus, Eyemiru contact pure, and Eye2O were evaluated using the MTT and wound healing assays. Cell damage was determined using lactate dehydrogenase (LDH), and the solution ingredients were analyzed. Cellular morphologies were examined by inverted light microscopy and transmission electromicroscopy. Results: Metabolic activity of corneal epithelial cells, as determined by the MTT assay, decreased in the Iris eye drop group, but those of the other groups were similar to that of the control. The LDH titers increased up to one hour after Iris eye drop use, and the increased level was maintained for 24 hours. The other three artificial tears showed similar low LDH titers to that of the control. Cellular migration was not observed, although cellular damage to the corneal epithelial cells, such as chromatin margination and cytoplasmic organelle swelling, was prominent with Iris use. Conclusions: Among four brands of topical artificial tear drops used among patients wearing contact lens, Iris caused markedly more severe damage to cultured human corneal epithelial cells than did Irisplus, Eyemiru contact pure, or Eye2O.