What are the layers of the tear film from outside in?

The correct sequence of the layers of the tear film from outside to inside is indeed lipid, aqueous, and mucin. This structure is essential for maintaining eye health and ensuring that the surface of the cornea remains lubricated and protected.

The lipid layer is the outermost layer and serves primarily to reduce evaporation of the aqueous layer beneath it. Its hydrophobic properties help create a barrier that keeps the tears from drying out too quickly. The next layer is the aqueous phase, which comprises the bulk of the tear film and provides nutrients to the cornea, washes away debris, and contains antimicrobial proteins to help prevent infection. Finally, the mucin layer is located closest to the eye surface. It helps to stabilize the tear film over the corneal surface, allowing the tears to spread evenly and enhance lubrication.

Understanding this arrangement is crucial, as any imbalance in these layers can lead to dry eye symptoms or other ocular surface issues, highlighting the importance of their respective functions in the tear film.