Tear film lipid layer (TFLL) (TFLL)

The tear film lipid layer (TFLL) is the outermost component of the precorneal tear film, primarily composed of non-polar and polar lipids secreted by the meibomian glands [TFOS DEWS II, 2017]. Its primary biological function is to provide a hydrophobic barrier that retards the evaporation of the underlying aqueous layer, maintains a smooth optical surface for clear vision, and acts as a lubricant during blinking [PubMed: 28736335]. Dysfunction of the TFLL, often due to meibomian gland dysfunction (MGD), leads to evaporative dry eye disease, characterized by tear film instability and ocular surface inflammation [StatPearls, 2023]. Therapeutic interventions targeting the TFLL aim to stabilize the lipid layer, reduce evaporation, and restore the homeostatic environment of the ocular surface [PubMed: 33031415]. Recent pharmacological advances include semifluorinated alkanes like perfluorohexyloctane, which form a monolayer at the air-tear interface to prevent water loss [FDA: Miebo Label, 2023]. Other treatments focus on improving the quality of lipid secretion or reducing the inflammatory cycle that compromises the ocular surface environment [PubMed: 31030105].

Other names

Pre-ocular tear film lipid layerOcular surface lipid filmMeibomian lipid layerLipid layer of the tear film

Reduction of aqueous evaporation and stabilization of the tear film interface