Avedro, Inc. announced that it has begun enrolling patients in a pivotal Phase 3 clinical trial to evaluate the safety and efficacy of an epithelium-on (epi-on) corneal collagen cross-linking procedure to treat patients with progressive keratoconus. Keratoconus is a non-inflammatory eye condition in which the typically round dome-shaped cornea progressively thins and weakens and is the leading cause of penetrating keratoplasty (corneal transplant) in the United States. The Phase 3 clinical trial, ACP-KXL-308, is a multicenter, randomized, controlled study of a novel corneal cross-linking procedure of 275 patients with progressive keratoconus across approximately 20 sites in the United States. As is typical for U.S. Food and Drug Administration (FDA) drug trials, investigational treatments are provided at no cost to participating patients. The current list of participating study sites include Massachusetts, Ohio, Utah, Pennsylvania and Virginia.