Abstract
Abstract: :
Purpose: To determine changes in the central endothelial cells and thickness of grafted corneas, and the cumulative probability of development of glaucoma, graft rejection and graft failure 15 years after penetrating keratoplasty. Methods: We conducted a longitudinal cohort study of 500 consecutive penetrating keratoplasties performed by one surgeon. Patients were asked to return at 2 months, and at 1, 3, 5, 10 and 15 years after surgery. We excluded eyes that were regrafted, fellow eyes of bilateral cases, and patients not granting research authorization, leaving 388 grafts (388 patients) for analysis. We used specular microscopy to measure central endothelial cell density, coefficient of variation of cell area, percentage of hexagonal cells, and corneal thickness. The presence of glaucoma, graft rejection, and graft failure were determined by clinical examination. Results: At 15 years after keratoplasty, 61 patients attended for examination, which represented 29% of the clear grafts available for follow–up because 107 patients had died and 73 grafts had failed. Endothelial cell loss from preoperative donor levels was 70 ± 12% (mean ± SD, n=61). Twenty–four patients attended all follow–up visits and had no episode of rejection or reoperation affecting the endothelium. For these 24 grafts at 15 years after surgery, endothelial cell loss from preoperative donor levels was 71 ± 9%, endothelial cell density was 872 ± 233 cells/mm2, coefficient of variation of cell area was 0.37 ± 0.09, hexagonality was 53 ± 10%, and central corneal thickness was 0.61 ± 0.05mm. Changes in these parameters between 10 and 15 years (n=49) were not significant except for an increase in corneal thickness (P=0.004). The minimum detectable difference in endothelial cell density between 10 and 15 years was 81 cells/mm2 (α=0.05, ß=0.20, n=49). The mean rate of endothelial cell loss from 10 to 15 years after surgery was –0.4 ± 5.4% per year (n=49). The 15–year cumulative probability for developing glaucoma, graft rejection, graft failure overall, or late endothelial failure was 20%, 23%, 26%, and 9%, respectively. From 10 to 15 years after surgery, no patients developed glaucoma, one patient had a first episode of graft rejection, and 4 of the 5 graft failures were caused by late endothelial failure. Conclusions:From 10 to 15 years after penetrating keratoplasty, the annual rate of endothelial cell loss was close to zero. There were no changes in endothelial cell parameters except for an increase in central corneal thickness. Late endothelial failure was the major cause of graft failure.
Keywords: cornea: endothelium • transplantation • clinical (human) or epidemiologic studies: outcomes/complications