Corneal innervation and cellular changes after corneal transplantation: an in vivo confocal microscopy study.

PURPOSE Although penetrating keratoplasty is generally considered a successful procedure, transplanted corneal tissue may exhibit abnormal epithelium, decreased sensation, and declining endothelial cell counts after surgery. This study aimed to use in vivo confocal microscopy to correlate corneal microstructure and recovery of the subbasal nerve plexus of the transplanted cornea with indications for, and time from, surgery. METHODS This was a cross-sectional study comparing corneas from 42 patients after penetrating keratoplasty with those of 30 controls. Subjects were assessed by ophthalmic history and clinical examination, computerized corneal topography, and laser scanning in vivo confocal microscopy. RESULTS Time from surgery ranged from 1 month to 40 years (mean, 85 +/- 105 months). Significant reductions in epithelial (P < 0.001), keratocyte (P < 0.001), and endothelial (P < 0.001) cell densities were noted in comparison with control corneas. Significant reductions in subbasal nerve fiber density (P < 0.001) and nerve branching (P < 0.001) were also noted. Endothelial cell density decreased with time after surgery (r = -0.472; P = 0.003), and nerve fiber density (r = .328; P = 0.034) increased. Keratoconus as an indication for transplantation was associated with higher subbasal nerve fiber densities (P = 0.003) than other indications for corneal transplantation. Neither nerve fiber nor cell density was correlated with best-corrected visual acuity. CONCLUSIONS Laser scanning in vivo confocal microscopy highlights profound reductions in cell density at every level of the transplanted cornea and alterations to the subbasal plexus that are still apparent up to 40 years after penetrating keratoplasty.