We have looked at components in dry eye drops that anchor the drops to the surface epithelial cells, and which also link to the basement tear layer of mucins, and those that thicken the aqueous layer. All of these components, of course, add some extra quantity of fluid to the ocular surface.
But what about aiding that all-important evaporative retarding lipid layer?
More often found in sprays, but becoming available in conventional bottle delivery, are agents such as phospholipids and castor and mineral oils that help reform and mimic the normal outer lipid layer. It is recognised that the over-riding cause of most DED is the reduced efficiency of the lipid layer to reduce evaporation of the underlying, middle, aqueous layers of the tear film. According to research, around 86 per cent of DED patients have meibomian gland dysfunction. (1)