The retina is an area at the back of the eye consisting of seven layers of specialized cells and neurons that convert the light signal, which has entered the eye through the cornea and has been focused by the lens, into an electrical signal. The electrical impulse is routed to the brain for interpretation and construction of an image.

The light to electrical signal transduction is accomplished by cells known as rods and cones, which are located in the outermost of the seven layers. The electrical signal then passes through the outer nuclear layer, outer plexiform layer, inner nuclear layer, inner plexiform layer, ganglion cell layer, and the optic fiber layer. In general, the nuclear layers contain cells while the plexiform, or paler appearing layers, contains axons and dendrites; specialized portions of neurons.

Incoming light contacts the receptor region of a rod...