Tear film mucin layer and ocular surface (TFML)

The tear film mucin layer and ocular surface constitute a complex physiological system essential for maintaining the health and clarity of the eye. This layer is primarily composed of membrane-associated mucins (such as MUC1, MUC4, and MUC16) that form the glycocalyx on the corneal and conjunctival epithelium, and secreted gel-forming mucins (predominantly MUC5AC) produced by conjunctival goblet cells (Gipson, I. K., 2004, PubMed: 15570592). Its primary biological function is to convert the naturally hydrophobic ocular surface into a hydrophilic one, allowing the aqueous tear layer to spread evenly and remain stable, while also providing a protective barrier against pathogens and mechanical friction (Mantelli, F. & Argüeso, P., 2008, PubMed: 18554540). In pathological states like Dry Eye Disease (DED), the mucin layer is often compromised due to inflammation or goblet cell loss, leading to tear film instability and ocular surface damage. Therapeutic interventions target this system through various mechanisms: mucin secretagogues like Diquafosol act as P2Y2 receptor agonists to stimulate secretion, while Rebamipide increases the expression of mucin genes to restore the glycocalyx (Koh, S., 2016, PubMed: 27582811). Additionally, anti-inflammatory agents like Cyclosporine help maintain the integrity of the ocular surface by preventing the immune-mediated destruction of mucin-producing cells. This target is considered 'incorrect' in a strict molecular sense because it describes a multi-component anatomical structure rather than a single protein or receptor.

Other names

Ocular surface glycocalyxMucous layer of the tear filmPrecorneal mucin layerCorneal-conjunctival glycocalyx

Stimulation of P2Y2 receptors to increase mucin and water secretion; induction of mucin gene expression (MUC1, MUC4, MUC5AC); reduction of T-cell mediated inflammation to preserve goblet cell density; physical replacement of the lubricant layer.