Ocular surface epithelia and tear film

The ocular surface epithelia and tear film constitute a complex physiological system comprising the cornea, conjunctiva, and the overlying fluid layers. This system functions as a unified lacrimal functional unit to maintain optical clarity and provide a smooth refractive surface (Source: TFOS DEWS II, 2017). It serves as the primary physical and chemical barrier protecting the eye from environmental and microbial insults. The tear film is a complex structure consisting of lipids, aqueous components, and mucins that lubricate the surface and provide nutrients to the avascular cornea (Source: StatPearls, 2023). Dysfunction in any component of this system leads to ocular surface disease, most notably dry eye disease, which is characterized by a loss of homeostasis, tear film instability, and inflammation (Source: NIH/NEI). While not a single molecular target, this system is the site of action for various pharmacological agents, including immunomodulators like cyclosporine and integrin antagonists like lifitegrast (Source: PubMed, PMID: 28736336). These drugs aim to restore homeostasis and reduce inflammatory damage to the epithelial cells to preserve visual function.

Other names

Ocular surfaceLacrimal functional unitLFUCorneal and conjunctival epithelia

Pharmacological agents targeting this system typically act via immunomodulation (e.g., T-cell inhibition), reduction of inflammation (e.g., corticosteroid action), or by supplementing/stimulating the production of tear film components (e.g., cholinergic agonists or lubricants).