In order to view the video you must have the real player plug-in installed. The human eye functions much like a camera, with a lens in front and a light-sensitive screen, the retina, in the rear.
Images enter the eye through the cornea, a transparent domed window at the front of the eye.
The inability of the cornea to refract incoming images properly causes blurred vision and is a form of refractive disorder. In a nearsighted eye the cornea is too steep, causing an image to be focused in front of the retina, and distant objects to appear blurred. To correct nearsightedness, laser vision correction makes the cornea less steep by removing a microscopic layer of the cornea through a gentle reshaping technique. This allows distant objects to be focused properly on the retina. In a similar fashion, farsightedness and astigmatic refractive errors can be corrected by laser vision correction.