Corneal epithelial cellular dysfunction from benzalkonium chloride (BAC) in vitro

Purpose: To investigate the functional and morphological toxicity of benzalkonium chloride (BAC) on corneal epithelial cells in vitro. Methods: Primary corneal epithelial cells were cultured from rabbit cornea. Corneal epithelial cells containing radioactive Cr-51 were exposed for 5 min, 10 min, 30 min and 60 min to concentration of BAC 0.001%, 0.005%, 0.01%, 0.05% and 0.1%. Control cells were treated with phosphate buffer solution alone. Cr-51 release from epithelial cells into the supernatant was used as an index of epithelial cell lysis. Cell detachment (index of cell dysfunction) was analysed by measuring Cr-51 activity in the supernatant and wash fluid. Morphological cell damage was investigated with transmission electron microscopy. Results: With the higher concentration and the longer duration of BAC exposure, corneal epithelial cell lysis was increased significantly (P < 0.05). Cells showed severe damage at BAC concentration over 0.05% during 5 min of exposure. Cell dysfunction appeared markedly at BAC concentrations of 0.005% for 30 min of exposure, but decreased with longer exposure times. There was an increase in significant cytoplasmic damage with longer BAC exposure times, although not with a minimal dose of 0.001%. Disrupted cytoplasmic membranes of corneal epithelial cells appeared at the higher BAC concentration of 0.1%, and at the longer exposure time of 30 min with BAC concentration of at least 0.001%. Conclusions: BAC can induce corneal epithelial dysfunction, which can damage the corneal epithelial barrier. This effect occurs when BAC is used frequently or for periods over 30 min, even when the BAC concentration is low (0.001%).