To investigate the biologic effects of preservative-free artificial tear drops on cultured human corneal epithelial cells in vitro.

The effects of preservative-free artificial tear drops (sodium hyaluronate 0.1% (Kynex®, Alcon, Seoul, Korea), sodium hyaluronate 0.18% (Kynex2®, Alcon, Seoul, Korea), and sodium hyaluronate 0.3% (Hyaluni eye drops 0.3%®, Taejoon, Seoul, Korea)) on human corneal epithelial cells were evaluated. Cellular proliferation was determined using MTT (3- (4,5-dimethylthiazol-2yl)-2,5-diphenyl-2H-tetrazolium bromide) and Ki-67 assays. Cellular migration was determined using CD44 and scratch wound assays. Cell damage was determined using the lactate dehydrogenase (LDH) assay and cellular morphologies using electronic microscopy and inverted microscopy.

Proliferation of corneal epithelial cells, as determined by the MTT and Ki-67 assays, was not significantly different between the different eye drops ( p > 0.05). The measured value of cellular migration after exposure of the sodium hyaluronate 0.3%, as determined by mean CD44 percentage and scratch wound assay, was higher than that of the sodium hyaluronate 0.1% and sodium hyaluronate 0.18%, but the CD44 value was not significantly different ( p > 0.05). The LDH titer tended to increase as the concentration of sodium hyaluronate increased ( p > 0.05), but influence on cytoplasm, as determined by electronic microscopy, was not different.

Among 3 preservative-free artificial tear drops, sodium hyaluronate 0.3% demonstrated increased migration of corneal epithelial cells. As the concentration of sodium hyaluronate in eye drops increased, the corneal cytotoxicity of corneal epithelial cells also increased. However, there was no significant difference among the 3 tear drops.