What is the function of the precorneal tear film?

The precorneal tear film plays a critical role in maintaining the health and function of the eye. One of its primary functions is to provide oxygen and moisture, which are essential for the survival of the corneal cells. The tear film forms a continuous layer that covers the surface of the cornea, ensuring it remains hydrated and that the cells receive adequate oxygen, which is vital for their metabolism and overall eye health.

In addition to providing moisture, the tear film also creates a smooth optical surface, which contributes to the clarity of vision. However, while improving visual acuity is a secondary benefit, the more fundamental role of the tear film is in maintaining moisture and oxygen levels.

The other options listed, while relevant to different aspects of eye protection and function, do not capture the primary role of the precorneal tear film as effectively as providing oxygen and moisture does. For instance, while the tear film offers some level of protection against dust and debris, its primary function is moisture provision and oxygenation.