The cornea surgeon (investigator) and patient were masked to donor age and characteristics of the donor cornea. Preoperative management, surgical technique, and postoperative care, including prescription of medications, were provided according to each investigator's customary routine. The follow-up visit schedule for the initial six months was left to each investigator's discretion and after this time the minimum follow-up visit schedule included a visit between six and 12 months and then one visit every 12 months through five years. The primary study outcome was graft survival at five years. The definition of graft failure, based on the definition used in Collaborative Corneal Transplantation Studies, was a regraft or, in the absence of regraft, a cloudy cornea in which there was loss of central graft clarity sufficient to compromise vision for a minimum of three consecutive months. Follow-up in the initial phase of the study continued for five years unless the patient had a regraft of the study eye.