History of Vision

  A theme common to very early theories of vision was that there had to be some "physical" connection between a person's eye and the object seen.  Rays were emitted by the eye to somehow "touch" the object.  This thinking persisted until the early 1600's.

  Plato (427-347BC) introduced the concept of "ocular beams" as projected from the eye, traveling to objects in straight lines at great speed to somehow interact and cause the sensation of sight.

  Euclid's theory of perspective made the eye the point of origin of the lines of vision, not the object seen.

  Democritus suggested the opposite, that emissions from the object (somehow) entered the eye and formed an image.  However, it couldn't be explained how a single object could produce enough emissions to cause sight in many people viewing the object all at the same time.

  Galen, the great European anatomist, objected, saying that large images could not fit through the tiny pupil of the eye.

  Kepler's explanation of the eye, in 1604, proposed that in fact the lens focuses images onto the retina.

  Scheiner, in 1625, provided direct experimental observation of image formation on the retina.

  Descartes provided the first direct evidence that the retinal image is inverted.  He surgically removed the eye from an ox, and scraped the back of it to make it transparent.  After placing it on a window ledge, he could see that the image on the retina was inverted.

  In 1801, Thomas Young performed experiments to show how the lens forms an image on the retina.  He also showed that astigmatism is the result of an improperly curved cornea.  This is just what modern-day LASIK surgery corrects!

Click on the following link see a chronological history of vision science (1600-1960):