January 30, 2012 
How do we see what we see…
Light rays from objects that we see come into our eye passing through almost all its structures. After passing through the cornea, anterior eye chamber and pupil rays pass through the ocular lens.
The lens is capable of accommodation or focusing the light rays directly on the retina or the place of the clearest sight-a yellow spot. The central part of the retina has cells which are called cones and there is a total of about 6.5 million of them helping us to see colors and shapes of objects, while in a peripheral part cells are called sticks (a total of about 130 million) and they are responsible for the sensation of light and movement.
Both types of cells contain the visual pigment (sticks have the rodopsin and cones jodopsin) which is activated under the influence of light and thus initiates chemical changes. This is a key element in creating vision because light energy is converted into chemical. After a series of chemical changes nerve cells of the retina are activated. Nerve cells conduct electrical signals that go to the visual center of the brain through the optic nerve. The center is located in the posterior (occipital) part of the brain in his so-called gray matter, which eventually creates a picture which the person uses to analyze the external world. Accordingly, the eye as an organ is just one part of the whole system by which one sees.
Check out the video
Taken from: www.kontaktne-lece.eu