How does the optic nerve work?
The optic nerve is a cable of nerve fibers that carry electrical impulses from the retina to the brain (see diagram on this page). A layer of cells on the retina, called retinal ganglion cells, is one end of this “cable.” Photoreceptors in the retina convert light into electrical impulses, which are then transmitted to the retinal ganglion cells. The ganglion cells in turn transmit visual information along their axons to the visual centers of the brain. It is there that the electrical impulses are interpreted into sight. Damage to the optic nerve interrupts this flow of visual information. In glaucoma, researchers believe that the ganglion cells of the retina, as well as the support cells within the optic nerve, can die for various reasons. Some possible reasons include excessive fluid pressure within the eye, lack of blood flow or oxygen, or naturally occurring toxins within the eye. With sufficient damage, sight is lost. Damage to the optic nerve is irreversible because the cable of
