The morphology of human conjunctival mucus.

Normal human conjuctival mucus was examined by permeable membrane filter (Millipore) surface biopsy and instillation of India ink. It exists in solution in the tear film, as clusters of granules, as granular sheets, and as strands, the latter often arranged as a network. This mucus network entraps exfoliated epithelial cells, miscellaneous surface debris, carbon particles (from the India ink) and bacteria, and stains positively for lipid. Blinking causes both collapse of this mucus network into a single strand and movement of this strand to the medial canthus, where it compacts and is pushed onto the skin surface. There it dries and either falls off or is removed by rubbing. It is suggested that the formation and collapse of this mucus network represents a system for removing exfoliated surface cells and debris, infection and foreign particles, and lipid-contaminated mucus from the surface of the normal eye.