Goblet cells in the conjunctival lid wiper elevation provide a built‐in lubrication system

Abstract

AbstractPurpose The lid wiper is an epithelial elevation at the posterior lid border apposed to the globe that distributes the thin pre‐ocular tear film during the blink. To minimize the high risk of friction it can be assumed that it is provided with an advanced lubrication system.Methods The structure of the lid wiper epithelium is explained together with an overview of historical reports. Theoretical models of lubrication at the lid‐bulbus interface are discussed.Results A thickened epithelium was described early but the immediate functional implications for the distribution of the preocular tear film over the bulbar surface were noticed only much later. More recently “Lid wiper epitheliopathy” (LWE), a respective vital stainable epithelial alteration, was reported as first sign of tear film deficiency and increased friction in dry eye patients. The structure of the lid wiper was generally assumed to consist of a squamous non‐cornified epithelium, however in recent investigations we could show that it has in fact a conjunctival structure with goblet cells and goblet cell crypts that secrete mucins of different types.Conclusion The conjunctival structure of the lid wiper for distribution of the thin pre‐ocular tear film with goblet cells and goblet cell crypts implies the presence of a thick mucin‐water gel at the surface. This provides the structural pre‐requisite for the assumption of a hydrodynamic type of lubrication and can explain how the lid margin continuously travels over the bulbar ocular surface without wounding it. Support: DFG KN 317‐11