Hyperosmolarity and Benzalkonium Chloride Differently Stimulate Inflammatory Markers in Conjunctiva-Derived Epithelial Cells in vitro.

Tear hyperosmolarity is known to cause ocular surface inflammation in dry eye syndrome. Benzalkonium chloride (BAK), an eyedrop preservative, is known to induce dry eye in long-term-treated patients. Analyzing the modulation of the proinflammatory potential of hyperosmolarity in the presence of BAK on the conjunctiva could give new insights into the effect of this preservative on the disease.

Hyperosmolarity potentiates toxic effects of benzalkonium chloride on conjunctival epithelial cells in vitro.

Purpose: Benzalkonium chloride (BAK), the most commonly used preservative in eye drops, is known to induce ocular irritation symptoms and dry eye in long-term treated patients and animal models. As tear film hyperosmolarity is diagnostic of some types of dry eye disease, we determined in vitro on conjunctival epithelial cells the cytoxicity of BAK in hyperosmolar conditions through cell viability, apoptosis, and oxidative stress assays.

Methods: The Wong Kilbourne derivative of Chang conjunctival epithelial cells were cultured for 24 h or 48 h either in NaCl-induced hyperosmolar conditions (400-425-500 mOsM), in low concentrations of BAK (10(-4)%, 3.