Keratoconus and pellucid marginal degenerations are genetically based ocular conditions and post surgical ectasia is an iatrogenic condition. These diseases are characterized by weakening of the front part of the eye that causes thinning and distortion. This distortion results in unevenness of the cornea and produces progressive near-sightedness and irregularity, which causes loss of vision when using eyeglasses. When eyeglasses fail to give enough vision, the the investigators use rigid contact lenses to create an artificial front eye surface. This improves visual acuity in many patients although they eventually fail either because they cannot be tolerated or the surface irregularity has become so severe that they are rejected. At this stage there is usually thinning and loss of clarity of the eye.