Pre-corneal tear film (TF)

The pre-corneal tear film is a sophisticated, multi-layered fluid system that coats the ocular surface, traditionally described as comprising an outer lipid layer, a middle aqueous layer, and an inner mucin layer (StatPearls, 2023). Its primary biological functions include providing a smooth optical surface for light refraction, lubricating the ocular surface during blinking, and protecting the corneal epithelium from desiccation and microbial invasion (TFOS DEWS II, 2017). Disruptions in the composition or stability of these layers lead to Dry Eye Disease (DED), a prevalent condition characterized by tear hyperosmolarity and ocular surface inflammation (NCBI, 2021). Pharmacological treatments target the tear film by either replacing missing components with artificial lubricants, stimulating endogenous production of aqueous and mucin, or stabilizing the lipid layer to prevent excessive evaporation (PubMed, 2022). Modern therapies, such as perfluorohexyloctane, specifically address the lipid layer to restore the film's integrity and alleviate symptoms of evaporative dry eye (FDA, 2023).

Other names

Tear filmOcular surface layersPre-corneal filmLacrimal filmTear film lipid layerMucoaqueous layer

Stabilization of the lipid layer to reduce evaporation (e.g., perfluorohexyloctane), supplementation of aqueous volume (e.g., artificial tears), and enhancement of mucin production or goblet cell density (e.g., cyclosporine) to improve tear film stability and reduce ocular surface inflammation (StatPearls, 2023; TFOS DEWS II, 2017).