The Collaborative Corneal Transplantation Studies-Reply

In Reply. —Dr Sugar appropriately emphasizes a point that we made in the Comment section of our article. We also mentioned two additional factors that may have contributed to the relatively high success rate for penetrating keratoplasty in the CCTS: a vigorous educational program to assure medication compliance, and frequent, regular follow-up examinations by the transplanting surgeon. The CCTS patients were outstanding in that only 4% of all visits were missed and only 1% of patients were considered unavailable for follow-up. When we formulated the protocol for the CCTS, we were aware that high doses of postoperative steroids could mask any effect of HLA matching on corneal transplant survival. However, our goal was not to design a study that would maximize the likelihood of observing a beneficial HLA matching. Instead, we sought to determine whether HLA matching would improve graft survival when used in addition to the postoperative immunosuppressive regimen