Hycosan Shield offers the unique lipid layer replacement benefits of perfluorohexyloctane. This allows Hycosan Shield to replace the function of the lipid layer, forming an outer shield over the surface of the tear film, reducing evaporation of the watery layer. Spreads easily due to low surface tension properties Replaces the outer lipid layer of the tear film Helps to indirectly re-establish the tear film’s watery layer by preventing its evaporation Increases tear film thickness, as well as lipid layer thickness, over time Preservative & phosphate free