ARCHITECTURE OF HUMAN CORNEAL NERVES

Purpose. The corneal innervation, mainly analyzed in light microscopic al studies, has been described as radially oriented stromal nerve bund les that ramify as leashes in the subbasal plexus. The current study a ims to determine the orientation, the size, and the postmortem changes of the nerve fibers in the subbasal plexus of the human cornea. Metho ds. Before processing for light and electron microscopy, the position of the corneas within the enucleated eyes of persons with melanoma and pairs of postmortem eyes was marked. The orientation and postmortem c hanges of the fibers were studied in serial ''en face'' semithin secti ons, and the size was determined in random, ultrathin cross-sections. Results. Thirteen and a half hours after death, the majority of the ne rve fibers were degenerated or gone. Nerve fiber bundles in the subbas al plexus run first in the 9-3 hours direction, then after bifurcation in the 12-3 hours direction and after a second bifurcation again in t he 9-3 hours direction. From the main straight bundles, single-beaded fibers branch and run obliquely. Quantification of the nerve fibers sh ows an equally dense innervated central and central-peripheral cornea (mean fiber diameter, 0.4 mu m) and a five to six times lower innervat ed peripheral cornea (mean fiber diameter, 0.67 mu m). Conclusions. Th e nerve bundles in the subbasal plexus of the human cornea form a regu lar dense meshwork with equal density over a large central and central -peripheral area. Because of their size, the majority of the fibers ca n be classified as C-fibers.