What is the primary role of the optic nerve?

The primary role of the optic nerve is to transmit visual information from the retina to the brain. This nerve is crucial for vision, as it carries signals generated by photoreceptors in the retina—specifically, rods and cones—after they convert light into electrical impulses. These impulses travel along the optic nerve to the visual cortex of the brain, where they are interpreted as images.

The other options involve functions that are not performed by the optic nerve. Controlling eye movement is the responsibility of the ocular muscles and their associated nerves, which allow for precise movements of the eyeball. Regulating light entering the eye is managed by the pupil's size, controlled by muscles in the iris. Maintaining eye shape is primarily the role of structures like the cornea, lens, and various fluids within the eye, which help maintain intraocular pressure and overall eye integrity. Therefore, the designation of the optic nerve's role as a transmitter of visual information signifies its essential function in the visual system.