BACKGROUND

Recent studies have demonstrated that oxidative stress is involved in pathogenesis of dry eye disease. Raised levels of reactive oxygen species, lipid oxidative stress markers, and inflammatory cells were found in the conjunctiva and tear film of patients with Sj”gren syndrome and dry eye animal and cell models. For most patients with mild dry eye symptoms, over-the-counter dry eye drops (OTC-DED) are the first line of therapy. OTC-DED can help maintain ocular surface homeostasis by reducing oxidative stress. The purpose of this in vitro study was to examine the antioxidant effects of a novel OTC-DED, Blink Nourish (BN), and two other common OTC-DEDs on human corneal epithelial cells (HCECs).

METHOD

Riken-HCECs were pre-exposed to the OTC-DED for 30 minutes and then exposed to CellROX Green (CRG) Reagent for 30 minutes. CRG media were removed, and the cells were then exposed to 0.003% or 0.006% hydrogen peroxide (H2O2) and OTC-DED. Changes in oxidized CRG relative fluorescent units were measured every 15 minutes for 2 hours. Integrated responses of the change in relative fluorescent units were analyzed by calculating the areas under the curve (AUC) for each test well over the time course. Upon completion of the antioxidant experimental time course, cells were assessed for cellular metabolic activity using alamarBlue.

RESULTS

No significant differences were observed with cells exposed to 0.003% H2O2; however, cells exposed to 0.006% H2O2 had significantly lower metabolic activity versus the Hanks' Balanced Salt Solution control. Cells exposed to 0.003% H2O2 and 0.006% H2O2 had increased CRG fluorescence and AUC of fluorescence over time. BN and both BN and Refresh Relieva had significantly lower AUCs versus the cells exposed to

0.003% and 0.006% H2O2 controls, respectively. Systane Hydration and Biotrue Hydration Boost both had significantly higher AUCs versus the 0.003% H2O2 control.

CONCLUSION

These results indicate the antioxidant effects of BN with HCECs compared with common OTC-DED products in this in vitro cell model. The BN formulation exhibits antioxidant activity and demonstrates potential to maintain homeostasis of the ocular surface environment.