The term retina refers to the layer of neural tissue at the back of the inner surface of the eye that detects light. In the functional model of central nervous system organization it is classified as part of the subcortical visual system ( Swanson-2004 ). In the classical model, where neural structures are classified according to location relative to the cranial vault and spinal canal, it is part of the peripheral nervous system. In the developmental model, where structures are grouped based upon the part of the embryonic nervous system from which they are derived, it is part of the Telencephalon. The optics of the eye focus an upside-down image of the visual world on the retina, which serves much the same function as the array of microscopic light sensors in a digital camera. Light striking the retina initiates a cascade of chemical and electrical events that ultimately trigger nerve impulses to the brain. Note that the rods and cones, the color sensitive cells of the retina, face the back of the eye; so light reaching them passes first through multiple thin layers of neurons before stimulating them.