Study of the toxic effect of benzalkonium chloride on epithelial cells of the lacrimal canaliculi.

The dynamically decreasing concentration model, which better reflects in vivo conditions, demonstrates that physiological dilution of benzalkonium chloride in tear fluid significantly reduces its cytotoxic effect on lacrimal canalicular cells undergoing partial EMT.

These findings support the hypothesis that dry eye syndrome and impaired tear drainage - conditions that prolong benzalkonium chloride exposure and may promote EMT - increase the risk of secondary lacrimal drainage obstruction in patients receiving long-term benzalkonium chloride-preserved therapy.