Return of human corneal sensitivity after penetrating keratoplasty

To evaluate the reinnervation of corneal grafts, we studied 91 eyes of 79 patients for the return of sensitivity one month to ten years following penetrating keratoplasty for various corneal disorders including keratoconus, Fuchs' dystrophy, herpes simplex keratitis, aphakic and pseudophakic bullous keratopathy, glaucoma, trauma, and interstitial keratitis. Using the Cochet-Bonnet esthesiometer, a sensation was recorded in the center of the graft no earlier than 18 months. We found a progressive return of sensitivity from the periphery toward the center of the graft. Regression analysis indicated a rate of return of sensitivity that averaged 0.029 mm/mo for each diagnostic category except herpes simplex keratitis. The slope of the return of sensitivity in the group with herpes simplex keratitis was essentially flat, showing no central progression. None of the eight patients with herpes simplex keratitis had a sensation recorded further than 0.5 mm from the wound margin.