ALTHOUGH the literature dealing with corneal transplantation now includes more than 600 articles, adequate statistical evaluations of the late visual results of penetrating transplants are very few. Since the number of patients with ocular conditions requiring keratoplasty is relatively small, few ophthalmic surgeons have the opportunity of performing any large number of these operations. For the same reason, few surgeons are able to acquire the degree of technical skill and familiarity with complications in this operation which they are able to develop in procedures which they perform more frequently. This means that small groups of cases can at best have only a doubtful statistical value as concerns the final visual results. Larger, compiled series of operations which have been performed by a number of surgeons, in which each surgeon has contributed a few operations, are subject to the same criticism. The combined statistics are no less erroneous in the evaluation