Illustration of visual pathways from the retina of the eye to the brain cortex (seen from below). At the back of each eye (at top), the light-sensitive membrane of the retina transforms visual images into nerve impulses. These images are binocular in that the visual field of each eye overlaps. Each eye has a unique field of view too, which is also analysed by the brain. Light that falls on the right side of each retina (blue) from the left field of view, passes as impulses to the right visual cortex of the brain via the optic nerves at centre, and chiasma (cross-point of these nerves). This is reversed for light that falls on the left side of the retina (coloured red).