The optic nerve (Cranial nerve II) is responsible for transmitting visual information from the retina to the brain. It carries afferent nerve fibers that originate from retinal ganglion cells, conveying *sensory input* essential for vision. Damage to this nerve may result in *visual field defects* or complete vision loss in the affected eye. During surgical interventions near the orbit or intracranial region, preserving the integrity of the optic nerve is critical to maintain visual function. Unlike other cranial nerves, it is purely sensory and does not control eye movement or facial sensation.

Reference: Gray's Anatomy, Susan Standring, 42nd Edition.