What is the primary function of tear film?

The primary function of the tear film is to lubricate and protect the surface of the eye. Tear film consists of three layers: an outer lipid layer, a middle aqueous layer, and an inner mucin layer. This structure serves several crucial roles in maintaining eye health.

Firstly, the lubrication provided by the tear film reduces friction between the eyelids and the surface of the eye during blinking, which is essential for comfort and function. Without adequate lubrication, the eye can become dry, leading to discomfort and potential damage to the cornea and conjunctiva.

Secondly, the tear film acts as a protective barrier against environmental irritants such as dust, smoke, and allergens, as well as helping to clear debris from the eye. It contains antimicrobial properties thanks to various proteins and enzymes, which help prevent infections.

Additionally, while the tear film does indirectly assist in providing some nutrients to the cornea and has a role in maintaining corneal hydration, its primary and most critical purpose is indeed lubrication and protection. The other options focus on functions that are secondary or specific rather than the core role of the tear film.