柯林斯词典optic nerve 1. N the second cranial nerve, which provides a sensory pathway from the retina to the brain 视神经 返回 optic nerve剑桥词典the group of nerve fibres (= structures like threads ) that pass signals from the retina at the back of each eye to the brain 视神经（形如细丝的神经纤维束，将视觉信号从眼后部的视网膜传输至大脑） 返回 optic nerve