The visual process starts when light meets the retina, it begins by comparing the amount of light striking any small region of the retina with the amount of surrounding light. Visual information from the retina is then relayed through the lateral geniculate nucleus of the thalamus to the primary visual cortex which is a thin sheet of tissue that is located in the occipital lobe in the back of the brain. The primary visual cortex is characterized by a unique layered appearance in Nissl stained tissue.