The tear film is composed of three primary layers: the lipid layer, the aqueous layer, and the mucin layer. The lipid layer, produced by the Meibomian glands, prevents the evaporation of tears. The aqueous layer, secreted by the lacrimal glands, provides moisture and contains proteins, enzymes, and nutrients. The mucin layer, produced by goblet cells, helps in the even distribution of the tear film across the corneal surface. Understanding this composition is vital in toxicology as any disruption can lead to increased ocular irritation and exposure to harmful substances.
