Tear film lipid layer and ocular surface epithelium

The tear film lipid layer (TFLL) and the ocular surface epithelium represent a complex physiological system rather than a single molecular target. The TFLL is the outermost layer of the tear film, primarily composed of non-polar and polar lipids secreted by the Meibomian glands, which functions to prevent evaporation of the underlying aqueous layer and provide a smooth optical surface for refraction (StatPearls, Physiology, Tear Film, 2023). The ocular surface epithelium, comprising the cornea and conjunctiva, serves as a critical physical and immunological barrier, expressing membrane-associated mucins like MUC1 and MUC16 that maintain hydration and prevent pathogen adherence (NCBI, The Ocular Surface, 2017). Dysfunction in this system is the hallmark of Dry Eye Disease (DED), where lipid deficiency leads to evaporative water loss and subsequent hyperosmolarity, triggering inflammatory cascades on the epithelium. Therapeutic strategies target this system through various modalities: perfluorohexyloctane (Miebo) acts as a surfactant to stabilize the TFLL and reduce evaporation, while immunomodulators like cyclosporine (Restasis) and lifitegrast (Xiidra) target inflammatory pathways on the epithelial surface to restore homeostatic tear production (FDA, Miebo Prescribing Information, 2023; TFOS DEWS II Management and Therapy Report, 2017). Because this entry describes a multi-component anatomical structure and tissue system rather than a specific protein or receptor, it is classified as an incorrect target designation for high-throughput molecular screening.

Other names

Ocular surface systemPre-ocular tear filmCorneal-conjunctival epitheliumTear film unit

Stabilization of the tear film lipid layer to prevent aqueous evaporation and reduction of inflammatory signaling/T-cell activation on the ocular surface epithelium.