Ocular tear film (OTF)

The ocular tear film is a complex, multi-layered fluid structure covering the conjunctiva and cornea, essential for maintaining ocular surface health and clear vision (StatPearls, 2023). It traditionally consists of three layers: an inner mucin layer that adheres to the corneal epithelium, a middle aqueous layer providing hydration and nutrients, and an outer lipid layer that prevents evaporation, though modern models suggest a more integrated muco-aqueous phase (TFOS DEWS II, 2017). Dysfunction of the tear film, characterized by instability or hyperosmolarity, leads to dry eye disease (DED), a prevalent condition causing discomfort and visual impairment (NIH/NEI, 2023). Therapeutic interventions aim to restore tear film homeostasis through mechanisms such as lubrication, inflammation reduction (e.g., cyclosporine), and stimulation of natural tear production (e.g., varenicline) (FDA, 2021). While not a single molecular target, the tear film serves as the primary environment for topical drug delivery and a critical physiological system for ophthalmic drug development (Journal of Ocular Pharmacology and Therapeutics, 2020).

Other names

Precorneal tear filmTear filmLacrimal film

Lubrication, osmolarity reduction, lipid layer stabilization, and stimulation of aqueous/mucin secretion.