Retina. Confocal light micrograph of a section through a healthy retina. Neurons (nerve cells) have been stained red and glial cells (support cells) are yellow. The retina is the light- sensitive membrane that lines the back of the eyeball. Light falls onto the retina from the top and passes through the nerve cells before hitting the photoreceptor cells at the bottom. The absorption of light by photoreceptor cells triggers electrical impulses in neurons in the retina. The impulses are passed via the optic nerve to the brain for processing. Glial cells provide structural support, nutrients and oxygen for the neurons. For an image of a detached retina see M155/551.