The eye is often compared to a camera. Light comes in through the cornea, pupil, and lens at the front of the eye just as the lens of the camera lets in light to the film. This picture is then sent to the brain along the optic nerve which connects the eye to the brain. We see properly when all of these parts of the eye and brain are working together. The optic nerve is made up of a million tiny, delicate nerve fibers which are like wires.
Many blood vessels nourish the optic nerve with blood rich in oxygen and nutrition.
Vision actually takes place in the brain when the messages from the eye travel to the brain along the optic nerve, but the nerve has to be healthy to transmit these messages. How much vision is lost depends on how much the retina or the optic nerve is affected. In this website we are discussing only the stroke of the optic nerve and not that of the retina. Ischemia is a decrease in the blood supply to a tissue in the body which in turn decreases oxygen and nutrition. Without sufficient oxygen and nutrition, nerves cannot function properly and will eventually die.