PURPOSE: This study examined the concentration-dependent effects of hyaluronic acid (HA) on cellular metabolic activity in transformed human conjunctival and corneal epithelial cells exposed to desiccation stress.

METHODS: Human corneal epithelial cells from the American Type Culture Collection (ATCC-HCEC) and the Riken Cell Bank (Riken-HCEC), as well as human conjunctival epithelial cells (HConjEC), were cultured until confluent. Five concentrations of HA were tested against 50% Hank's Balanced Salt Solution (HBSS) as a negative (no-protection) control. Cells were pre-exposed to test articles for one hour, after which the solutions were removed. Plates were left uncovered in a tissue culture hood with airflow exposure for 0, 15, 30, or 45 minutes to induce air desiccation. Metabolic activity was assessed using the alamarBlue assay and measured in relative fluorescence units (RFUs). Integrated responses of normalized RFUs (NR) were quantified by calculating area under the curve (AUC) for each well over the time course.

RESULTS: Minimal differences were observed between HA-pretreated cells and the HBSS control at the 0-minute time point across all cell lines. Under desiccation exposure, HConjEC (0.02–0.1% HA), Riken-HCEC (0.05–0.1% HA), and ATCC-HCEC (0.1% HA) demonstrated significantly higher AUC values of normalized metabolic activity with HA compared with the HBSS control.

CONCLUSIONS: Across the three cell lines, HA concentrations ranging from 0.02% to 0.1% exhibited protective effects against air-induced desiccation. These findings suggest that HA may contribute to protection from desiccation stress in topical ophthalmic formulations and support ocular surface homeostasis.