Water-Free Eye Drop May Provide Tear Film Lipid Layer Substitute in DED

A water-free eye drop may provide symptomatic dry eye relief and demonstrate a better ability to inhibit tear film evaporation compared with aqueous artificial tears, according to a study published in Current Therapeutic Research. Although the drop has only undergone in vivo testing, the report states that it may be a “functional substitute for the native tear-film lipid-layer in patients with DED.”  

Researchers tested evaporation rates at 25℃ and 35℃. The team layered the water-free eye drop over a phosphate buffered saline solution (11-200 μL perfluorohexyloctane [PFHO]) and compared it with the evaporation rate obtained from artificial tears (100 μL) layered over the same solution. Investigators further evaluated evaporation rates after adding 50 mg/mL mucin to the solution and compared it with meibum lipid collected from a healthy volunteer (White; age, 68 years). 

At 25℃, the in vitro model showed that the water-free eye drop inhibited evaporation of the phosphate buffered saline solution by 81% (P <.0001). Layering with the artificial tears, however, did not affect tear film evaporation. Adding mucin further inhibited evaporation of the phosphate buffered saline solution by 17% (P <.001), the report shows. 

The team obtained similar results at 35℃ — the water-free eye drop inhibited evaporation of the phosphate buffered saline solution by 88% after layering 100 μL and by 28% following a single 11 μL drop. 

The study authors highlight the potential clinical application of this water-free eye drop.

“PFHO may be considered a functional substitute for the native tear film lipid-layer in patients with DED associated with [meibomian gland dysfunction] based on its ability to provide relief of dry eye signs and symptoms, its optical properties, and, as shown in the current study, its superior ability to inhibit evaporation as compared to [meibum lipids] and aqueous artificial tears,” the researchers explain. 

A failure to assess the performance of the water-free eye drops with in vivo trials is an acknowledged limitation to the research. 

Disclosure: This research was supported by Bausch and Lomb. Please see the original reference for a full list of disclosures.