Keratocyte density and recovery of subbasal nerves after penetrating keratoplasty and in late endothelial failure

Objective: To determine central keratocyte and subbasal nerve densities in clear and failed grafts after penetrating keratoplasty. Methods: Clear grafts and grafts with late endothelial failure (LEF) were examined using confocal microscopy 1 to 31 years after penetrating keratoplasty. Keratocyte density, number of keratocytes in a fullthickness column of stroma, and subbasal nerve density were determined from images. Comparisons were made with normal corneas. Results: The mean±SD keratocyte density in clear grafts (22 101±3799 cells/mm³) was lower than that in normal corneas (26 610±3683 cells/mm³; P<.001) but did not differ from that in grafts with LEF (21 268±3298 cells/mm³; P=.47). The mean±SD number of keratocytes in clear grafts (10 325±1708 cells) was lower than that in normal corneas (11 466±1503 cells; P<.001) but did not differ from that in grafts with LEF (10 778±1760 cells; P=.39). Median subbasal nerve density in clear grafts (150 μm/mm²) was lower than that in normal corneas (7025 μm/mm²; P<.001), and nerve recovery correlated with time after surgery (r=0.36; P<.001). Conclusions: Keratocyte density and number are decreased in penetrating grafts compared with normal corneas. Subbasal nerve density does not recover to normal through 3 decades.