Parts of the Eye

            
             Of all the components of the eye there are eight aspects, in particular, which are of the utmost importance to visual perception. The world of optical inference is based upon the design, function, and interaction of: the retina, fovea, blind spot, cornea, pupil, optic nerve to the brain's visual cortex, iris, and lens. .
             The retina is the light sensitive inner surface of the eye containing the receptor rods and cones, as well as many layers of neurons that begin the processing of visual information. The retina is an extension of the central nervous system that forms during embryonic development. This is one reason why scientists are interested in retinal processing; the retina is also an accessible part of the brain that can be easily stimulated with light. If it were possible to follow a ray of light as it enters the eye, one would see that the ray makes its way through the retina's outer layer of cells to the buried receptor cells, the rods and cones. Light waves striking the rods and cones bring about chemical changes that generate neural signals. This correlates with the optic nerve, which is the nerve that carries neural impulses from the eye to the brain. Nearly a million messages can be sent by the optic nerve at once. .
             Where the optic nerve leaves the eye there are no receptor cells, creating a blind spot in vision. In everyday vision the blind spot doesn't impair vision because the eyes are constantly moving and one eye will catch what the other misses. The filling in process makes the blind spot less noticeable, especially in a peripheral area of sight that has less visual acuity (the ability to see detail). Cones are clustered around the fovea, the retinas area of central focus. The fovea contains only cones no rods, many cones have their own bipolar cells to help relay their individual messages to the cortex, which devotes a large amount of its area to impulses from the fovea.