Optic nerve. Coloured light micrograph of a section through the optic nerve. The optic nerve (bright pink) collects impulses from the light sensitive cells of the retina and relays them to the brain. The optic nerve is leaving the ocular bulb (eyeball, top) via the optical canal (bottom). The retina (pale pink) contains light sensitive photoreceptor cells (purple) and runs towards the optic nerve. This region is known as the blind spot as there are no photoreceptor cells in this region to receive light. The choroid (black) lines the inside of the eye and prevents light from reflecting and distorting the image. Magnification: x110 when printed at 10cm wide.