Ocular surface membrane-associated mucins

The term "ocular surface/lubrication barrier" does not refer to a single molecular target or receptor but rather describes a **functional barrier** on the eye's anterior segment formed primarily by **membrane-associated and secreted mucins**. The main membrane-associated mucins—MUC1, MUC4, and MUC16—are large glycoproteins produced by corneal and conjunctival epithelial cells. These molecules form the glycocalyx that extends into the tear film to provide a hydrophilic protective layer for lubrication and defense against pathogens[1][3]. Secreted gel-forming or soluble mucins such as **MUC5AC**, produced by conjunctival goblet cells, further contribute to lubrication by maintaining tear film stability[4]. Disruption or deficiency in these components is implicated in dry eye disease. Some drugs used for dry eye therapy act indirectly on this system by stimulating production or secretion of these protective molecules rather than targeting a specific receptor[4]. Because "ocular surface/lubrication barrier" is not itself a discrete molecule or therapeutic target but instead refers collectively to several molecular components with overlapping functions—including both membrane-bound and secreted forms—the entry is considered incorrect as a canonical drug target designation. The most accurate approach would be to specify individual targets such as "Membrane-associated mucin 16" or "Secretory gel-forming mucin 5AC".

Other names

Ocular surface glycocalyxocular surface mucinstransmembrane mucins (MUC1, MUC4, MUC16)secreted mucins (MUC5AC)

Stimulation of tear and mucin secretion from conjunctival epithelial cells and goblet cells (diquafosol)[4] Increase in goblet cell number and promotion of mucin secretion (rebamipide)[4]