What are the three layers of the classic pre-corneal tear film?

The three layers of the classic pre-corneal tear film are the lipid, aqueous, and mucin layers. This composition is essential for maintaining a stable tear film that provides lubrication, nourishment, and protection for the corneal surface.

The lipid layer, which is the outermost layer, plays a critical role in reducing tear evaporation and providing a smooth surface for the eyelid to glide over the eye. It also helps to stabilize the tear film. The aqueous layer, situated in the middle, is the thickest layer and contains water, electrolytes, and proteins that help nourish and protect the corneal epithelium and provide antimicrobial properties. Lastly, the mucin layer is the innermost layer that facilitates the spread of tears over the eye and ensures that the aqueous tear film adheres to the corneal surface, promoting an even and stable coverage.

Understanding these layers helps in identifying issues related to dry eye disease and informs proper management strategies for maintaining ocular health.