Abstract: Objective To observe the characteristics of nerve regeneration after penetrating keratoplasty. Methods heidelberg retina laser tomography (HRT3) corneal confocal microscopy was used to observe patients after penetrating keratoplasty. 71 patients were observed at1, 3, 6 and 12 months after the surgery. The characteristics of nerve growth and the associated factors influencing nerve regeneration in corneal grafts including subepithelial nerves and stromal nerves were analyzed. Results There was no regenerated nerves in the grafts at 1 month after the surgery. In all 71 patients, the rate of nerve regeneration, including subepithelial nerves and stromal nerves, at 3,6 and 12 months after penetrating was 26/71 (36.62%) and 11/71 (15.49%), 44/71 (61.97%) and 30/71 (42.25%), 46/71 (64.79%) and 36/71 (50.74%) respectively. At 12 months after the surgery, we found the characteristics of the regenerated nerves was significantly different from that of the normal corneal nerves. The regenerated nerves tended to be smaller in diameter, shorter in length and lower in density. For different etiology, the rate of nerve regeneration at the twelfth month after the surgery was different, among which traumatic corneal walleye was 9/10 (90.00%), keratoconus 10/12 (83.33%), corneal dystrophy 3/4 (75.00%), bullous keratopathy 7/11 (63.63%), viral keratitis 6/12 (50.00%), past PKP/LKP surgery 8/18 (44.44%), congenital corneal walleye 1/4 (25.00%). Regenerated nerves decreased or disappeared in different degrees in the rejected corneal grafts. We also found that regenerated nerves occured unexplained subside or disappear in 5 patients. Conclusion Corneal nerve regeneration after penetrating keratoplasty was affected by many factors and was varied. Confocal microscopy can do a continuous follow-up observation of nerve regeneration after corneal transplantation.

Key words: penetrating keratoplasty, confocal microscope, nerve regeneration