What is the primary role of the lens in the eye?

The primary role of the lens in the eye is to focus light onto the retina. The lens is a flexible, transparent structure located behind the iris and pupil. Its shape can be modified by the ciliary muscles, allowing it to adjust its curvature to focus light rays from objects at various distances. This process, known as accommodation, is crucial for clear vision. When light rays enter the eye, the lens refracts (bends) them so that they converge precisely on the retina, where photoreceptor cells can convert this light into electrical signals that are sent to the brain for visual processing.

In contrast, the other options do not reflect the primary function of the lens. The eye's protection from injury is primarily the role of the eyelids and cornea, while the regulation of light entering the eye is mainly the responsibility of the iris and pupil. Tear production for lubrication is performed by the lacrimal glands, not the lens. Thus, the lens's unique and vital function in focusing light onto the retina is what distinguishes its primary role in the visual system.