What is the primary function of the cornea?

The primary function of the cornea is to focus light onto the retina. The cornea is the transparent, dome-shaped surface that covers the front of the eye and is responsible for a significant portion of the eye's total optical power. It bends (refracts) incoming light rays that enter the eye, ensuring that these rays are properly focused onto the retina, which is the light-sensitive layer at the back of the eye. This precise focusing is essential for clear vision.

While the cornea does provide some protective functions and aids in regulating light, its main role is optical, contributing to the eye's ability to form a clear image. The other options refer to important functions associated with various parts of the eye, such as the pupil's role in regulating light entry or other structures contributing to the eye's defense against particulates, but they do not encapsulate the cornea’s primary role in focusing light for vision.