Abstract
Abstract: :
Purpose: Corneal innervation is important for maintenance of a healthy cornea. With the use of confocal biomicroscopy, which allows observation of corneal components including epithelial cells, keratocytes, nerve fibers, and endothelial cells, we investigated the relation between functional and morphological recovery of corneal innervation in individuals subjected to penetrating keratoplasty (PK), which results in corneal paralysis. Methods: A total of 67 eyes of 57 post-PK individuals with no apparent pathology detected by slitlamp examination was studied. Corneal sensation at the graft center was measured with a Cochet-Bonnet esthesiometer and regarded as an index of functional recovery. Nerve fibers at the graft center, considered an index of morphological recovery, were imaged with a confocal biomicroscope. Results: Confocal biomicroscopy revealed that morphological recovery of innervation of the corneal stroma preceded that of the subepithelium. Within 1 year after PK, reinnervation of the stroma was apparent in 10 of 14 eyes (71%) examined, whereas reinnervation of the subepithelium was not observed. Reinnervation of the subepithelium was apparent in only 4 of 11 eyes (36%) 3 years after surgery. Measurement of corneal sensation revealed that functional recovery occurred gradually over 2 years. However, even after 3 years, only 4 of 12 eyes (33%) had recovered normal corneal sensation. The mean values of corneal sensation were 31.6 23.2 mm for 25 eyes that exhibited only stromal reinnervation, 33.7 16.7 mm for 15 eyes that exhibited both stromal and subepithelial reinnervation, and 12.8 15.7 mm for 23 eyes in which no nerve fibers were detected. Whereas 4 of the 25 eyes that manifested only stromal reinnervation remained paralyzed, none of the 15 eyes that exhibited stromal and subepithelial reinnervation remained so. Conclusions: Morphological recovery of corneal innervation promotes functional recovery. Whereas optimal recovery of corneal sensation requires reinnervation not only of the stroma but also of the subepithelium, morphological recovery appears not to be sufficient for functional recovery.
Keywords: 369 cornea: clinical science • 442 innervation: sensation • 607 transplantation