The visual system is arguably the most important system through which our brain gathers information about our surroundings and forms one of our most complex physiological systems. In vertebrates, light entering the eye through the lens is detected by photosensitive pigment in the photoreceptors Photoreceptors, converted to an electrical signal, and passed back through the layers of the retina to the optic nerve Optic nerve and, from there, through the visual nuclei, to the visual cortex .Visual cortex At each stage, the signal passes through an elaborate system of biochemical and neural feedbacks, the vast majority of which are poorly, if at all, understood. Visual processing accounts for about 44% of the brain’s energy consumption.