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.
There has been no treatment for this other than corneal transplantation, a complex surgical procedure with a significant complication rate and a delay in visual recovery. The treatment the investigators wish to perform strengthens the front of the eye by a chemical reaction using light and riboflavin. This technique has been studied over a decade and is widely used throughout the world. The FDA approved multicenter American clinical study is being analyzed in anticipation of its submission to the FDA for PreMarket approval. Because this is a progressive condition, the investigators wish to be able to offer this on a limited basis to patients in need with vision loss.
Any treatment that can delay or prevent corneal transplantation is of great benefit. The investigators believe the evidence is compelling that this treatment is the sole alternative to surgical transplantation.