Keratoconus is a progressive eye disease in which the normally round cornea thins and begins to bulge into a cone-like shape. This cone shape deflects light as it enters the eye on its way to the light-sensitive retina, causing distorted vision. There are several factors that cause Keratoconus: an imbalance of enzymes within the cornea, overexposure to ultraviolet rays from the sun, excessive eye rubbing, a history of poorly fitted contact lenses and chronic eye irritation.Keratoconus can result in nearsightedness and/or astigmatism, those are all refractice errors. Eyeglasses cannot help to patient with keratoconus, but contact lenses can. Learn more at http://www.allaboutvision.com/conditions/keratoconus.htm