Objective: To determine when corneal transplants develop the decreased endothelial cell density that predisposes to late endothelial failure (LEF).
Design: Noted cohort study within a prospective case series.
Participants: The authors compared 21 grafts that developed LEF with the remaining transplants (controls) in a longitudinal cohort study of 500 consecutive penetrating keratoplasties by 1 surgeon. Eyes regrafted during the study, fellow eyes of bilateral cases, and patients who did not want their data used for research purposes were excluded, leaving 389 grafts in 389 patients for analysis.
Intervention: Penetrating keratoplasty.
Main outcome measures: Endothelial cell density before surgery and at 2 months and 1, 3, 5, and 10 years after surgery.
Results: Grafts with LEF had lower median endothelial cell densities than other grafts, both before surgery (2710 cells/mm2 vs. 2991 cells/mm2; P = 0.02) and 2 months after surgery (1895 cells/mm2 vs. 2501 cells/mm2; P < 0.001), a difference that was maintained through 5 postoperative years. Despite having lower preoperative cell densities, the grafts with LEF had larger median endothelial cell losses 2 months after keratoplasty (31% vs. 16%, P = 0.002). The endothelial cell loss subsequent to the 2-month examination, however, was not increased in the grafts with LEF. Risk factors for developing LEF included a low endothelial cell density before surgery (P = 0.007) and 2 months after surgery (P = 0.002), aphakia or pseudophakia (P = 0.04), older recipient age (P = 0.002) and older donor age (P = 0.03), and occurrence of an endothelial rejection episode (P = 0.03).
Conclusions: Corneal grafts with LEF, the major cause of graft failure after 5 postoperative years, fail from low initial endothelial cell density rather than an increased rate of chronic postoperative cell loss. Improved techniques of corneal preservation should decrease the rate of LEF. In addition to low preoperative and 2-month postoperative endothelial cell density, a higher risk of LEF is also seen in patients with aphakia or pseudophakia, older recipient age, older donor age, and occurrence of an endothelial rejection episode.