Ocular surface tear film lipid layer (TFLL)

The ocular surface tear film lipid layer (TFLL) is the outermost component of the precorneal tear film, primarily secreted by the meibomian glands located in the eyelids. Its primary biological function is to provide a hydrophobic barrier that retards the evaporation of the underlying aqueous-mucin layer, thereby maintaining ocular surface hydration and stability (StatPearls, 2023). Additionally, the TFLL reduces the surface tension of the tear film, allowing it to spread evenly across the cornea during blinking and providing a smooth optical surface for clear vision (Butovich, 2017). Dysfunction of this layer, often due to meibomian gland dysfunction (MGD), leads to evaporative dry eye disease, characterized by rapid tear film breakup and ocular surface inflammation. Therapeutic interventions target the TFLL by supplementing deficient lipids or using semifluorinated alkanes like perfluorohexyloctane to stabilize the layer and prevent water loss (FDA, 2023). Recent drug development has focused on enhancing the biophysical properties of the TFLL, such as its elasticity and surfactant activity, to restore homeostasis in patients with chronic ocular surface diseases (Eftimov et al., 2020).

Other names

Tear film lipid layerMeibomian lipid layerPrecorneal lipid layerTFLL

Supplementation and stabilization of the lipid barrier to reduce aqueous evaporation and lower surface tension.