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 full-thickness 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/ mm(3)) 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/mm(3); 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 mu m/mm(2)) was lower than that in normal corneas (7025 mu m/mm(2); 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.