What is the primary function of mucin in the tear film?

The primary function of mucin in the tear film is to convert the corneal epithelial surface to hydrophilic. Mucins are glycoproteins that play a crucial role in maintaining an effective tear film by providing lubrication and ensuring that the tears adhere to the eye's surface. This hydrophilic property of the mucin allows for better spreading of the tear film across the cornea, helping to prevent dryness and ensuring that the eye remains moist and comfortable.

Additionally, a hydrophilic surface enhances the eye's ability to interact with the aqueous layer of the tear film, facilitating the transport of nutrients and reducing friction during blinking. This is fundamental for maintaining overall eye health and comfort, as well as for the protection of the cornea.

In contrast, other options do not accurately describe the primary function of mucin. While nourishment of the cornea is essential, it is primarily provided by the aqueous layer of the tear film rather than by mucin. The creation of a hydrophobic surface is contrary to what mucins do, as they are vital for promoting wettability. While mucins can assist in the removal of debris, that is not their primary role compared to their function in maintaining a stable, hydrated ocular surface.