Although the 5-year results indicated no difference in the success rate of moderate-risk transplants according to donor age, results from the SMAS indicated that among the successful cases, there was a slight association between donor age and endothelial cell loss, with the cell loss after 5 years being slightly lower in corneas from younger donors (r adjusted for baseline endothelial cell density = -0.19, 95% confidence interval -0.29 to -0.08). Whether this slight association between cell loss and donor age is of clinical importance is not known. Of perhaps even greater importance, however, was the finding that irrespective of donor age, endothelial cell loss was substantial over the first five years after transplant even when the graft had been successful. Half of the successful cases experienced a cell loss of 70% or more, and at five years more than half had an endothelial cell density <800 cells/mm2.