Pellucid Degeneration is a degenerative corneal condition, sometimes confused with Keratoconus. It is characterized by a clear, bilateral thinning (ectasia) in the inferior and peripheral region of the cornea and in some cases affects only one eye. There are no symptoms other than vision loss for most patients. Non-surgical treatment including contact lens or eye glasses is normally recommended. Recent studies suggest that corneal collagen cross-linking may be beneficial for patients with pellucid marginal degeneration.