Addressing excessive evaporation: an unmet need in dry eye disease.

Dry eye disease (DED) is a common condition in which tear film abnormalities result in a damaging cycle of tear hyperosmolarity, desiccating stress, inflammation, and ocular surface injury. In a healthy tear film, meibum produced by the meibomian glands forms a lipid layer that stabilizes the tear film and protects against aqueous tear evaporation. Excessive tear evaporation due to a deficient lipid layer is believed to be the most common cause of DED, and most evaporative DED is associated with meibomian gland dysfunction (MGD); this highlights the pathophysiologic importance of the dysfunctional tear lipid layer. Current treatments for DED may be used to supplement hyperosmolar aqueous tears, lubricate the ocular surface, increase meibum flow, decrease inflammation, promote tear production, or otherwise decrease clinical signs of ocular surface damage and/or improve symptoms. Until now, no prescription eye drop has directly addressed the excessive evaporation that occurs in most patients with DED. Perfluorohexyloctane (PFHO) ophthalmic solution (MIEBO™; Bausch + Lomb) is a preservative-free eye drop that has demonstrated the ability to form a long-lasting barrier that inhibits evaporation in preclinical studies. FDA approval of PFHO was based on results from 2 pivotal clinical trials (GOBI [NCT04139798] and MOJAVE [NCT04567329]) in patients with DED and clinical signs of MGD which demonstrated consistent improvements in both signs and symptoms of disease, with a safety profile similar to that of saline eye drops. PFHO is the first and only FDA-approved eye drop that directly targets tear evaporation in patients with DED, thereby promoting ocular surface healing and providing symptomatic relief.