ExCrossV Multi Site Trial for Vascularized High Risk Keratoplasty

This is a randomized, double-masked, multi site clinical trial to determine the safety of Ex Vivo CXL of donor corneal tissue in 96 participants who have undergone high-risk penetrating keratoplasty. Participants will be randomized to receive either a corneal tissue that has been untreated vs. a corneal tissue that has been treated with Photrexa® Viscous \& Photrexa® and UV light. The tissue will be prepared by a Corneal Tissue Bank under Current-Good-Tissue-Practice (CGTP) and delivered to the respective institutions for transplantation. Participants will be monitored up to 24 months post-transplantation to assess for adverse events of the randomized tissue.