The Human Eye


                                                        The Camera                                   vs.                           The Human Eye

The individual components of the eye work in a manner similar to a camera. Each part plays a vital role in providing clear vision. So think of the eye as a camera with the cornea, behaving much like a lens cover. As the eye's main focusing element, the cornea takes widely diverging rays of light and bends them through the pupil, the dark, round opening in the center of the colored iris. The iris and pupil act like the aperture of a camera.

Next in line is the
lens which acts like the lens in a camera, helping to focus light to the back of the eye. The very back of the eye is lined with a layer called the retina which acts very much like the film of the camera. The retina is a membrane containing photoreceptor nerve cells that lines the inside back wall of the eye. The photoreceptor nerve cells of the retina change the light rays into electrical impulses and send them through the optic nerve to the brain where an image is perceived.

Because the light rays cross while going through the cornea, the retina reads the image upside downóbut the brain readjusts so you stay properly oriented. It is believed that for the first few days, babies see everything upside-down. This is because they have not become used to vision.

Your brain CAN be retrained though. In one psychological study, participants were asked to wear inverting lenses - lenses that invert the image BEFORE they get to your eye, so that when your eye inverts it, it's right side up. At first, everything appeared upside-down to the participants. But, after a few days, people began to report that everything appeared right side up! As a second part of the study, the people were asked to take the glasses off. Because they were now used to the lenses, their NORMAL vision appeared upside-down!! Within a day, though, their vision returned to normal. The reason you don't see everything upside-down, then, is simply because it's easier to think about right side up!