Vision is an extraordinary sense involving many moving parts. The dome-shaped cornea at the front of your eye works with the natural lens to capture light rays traveling through the eye, similar to a camera taking a photograph. The optic nerve then sends that data to your brain to transform the light into images. However, many people have refractive errors in which a misshapen cornea or a stiffened eye lens disrupts the light rays, causing blurry vision. Nearsightedness, farsightedness and astigmatism are refractive errors caused by the corneal shape. Presbyopia is a different refractive error that happens when the natural eye lens hardens and loses its ability to accommodate changing focal distances. Most everyone will develop presbyopia as they get older, which is why reading glasses are common after age 40.