# An In Vitro Evaluation of the Effect and Protection of Artificial Tear Formulations on Human Corneal Epithelial Cells in Normal and Dry Eye Disease States

## TL;DR

This study evaluates how artificial tear solutions protect human corneal cells under dry eye disease conditions using in vitro cell assays.

## Contribution

The study introduces novel in vitro assays to assess the biocompatibility and efficacy of artificial tear solutions containing hyaluronate.

## Key findings

- Artificial tear solutions offer varying levels of protection against desiccation and hyperosmotic stress in corneal cells.
- DED conditions cause significant morphological changes in HCECs, which are mitigated by the tested artificial tear products.
- The developed assays provide a robust method for evaluating next-generation artificial tear formulations.

## Abstract

Background: Dry eye disease (DED) is characterized by tear film instability and a hyperosmolar ocular surface, which significantly impacts ocular health. Artificial tear solutions (ATSs) have been effective frontline treatments for DED, yet current commercially available products often provide only temporary relief, necessitating frequent daily administration. Significant efforts have been made to develop next-generation ATSs that can provide prolonged protective effects for DED. High-molecular-weight sodium hyaluronate (HA) is more commonly used in multi-dose preservative ATSs due to its longer chain lengths and rheological properties that can provide an enhanced retention time and clinical comfort and effects. The current methods to evaluate ATSs have largely focused on human biocompatibility and rheological testing and often overlook the dynamic nature of cellular phenotypes or the protective mechanisms at a cellular level. Therefore, this study developed novel in vitro mammalian cell assays involving human corneal epithelial cells (HCECs) to comprehensively assess ATSs with HA for biocompatibility and efficacy. Methods: We evaluated cellular viability across varying severities in two distinct DED models: desiccation and hyperosmotic stress. Simultaneously, time-lapse imaging coupled with computational image analyses quantified subtle, yet significant, cellular morphological changes under these stress condition. Results: Our assays revealed that ATSs provide significant, yet varying, protection against mild, medium, and harsh desiccation stress, as well as hyperosmotic conditions. This study also made a key insight that was the observation that DED conditions induce drastic HCEC morphological changes, including significant cellular monolayer breakage, which were effectively mitigated by the ATS products used in this work. Conclusions: The assays presented here provide a robust standard for ATS testing, ultimately guiding the selection of more effective next-generation therapies and aiding in a greater understanding of DED pathogenesis.