How many layers comprise the tear film?

The tear film that covers the surface of the eye is composed of three distinct layers: the outer lipid layer, the middle aqueous layer, and the inner mucin layer. Each of these layers plays a crucial role in maintaining the health and function of the eye.

The outer lipid layer helps to reduce evaporation of the aqueous layer beneath it, while the middle aqueous layer provides hydration and contains essential nutrients and antibacterial properties. Finally, the mucin layer ensures that the tear film adheres evenly to the surface of the cornea and provides lubrication during blinking. This tri-layer structure is vital for clear vision and the overall health of the eye, making the selection of three layers the correct answer.