The surface of the corneal graft: in vivo color specular microscopic study in the human.

An in vivo microscopic study of the cellular morphology of the corneal graft surface, employing CSM, has been presented. The following epithelial cellular abnormalities have been noted on the graft surface: a high prevalence (70%) of central vortex keratopathy in the postoperative graft; a redirection of cells in a palisading pattern around sutures; a piling up of cells at the wound junction, with redirection parallel to the wound; cellular evidence of filaments and coarse mucus plaques near the suture line. Vortex keratopathy was not seen in grafts after sutures had been removed, and palisading of cells around sutures disappeared after suture removal. Central epithelial cell morphology in grafts 2 years or more after surgery resembled that of normal patients. A discussion of possible causative factors in the induction of epithelial abnormalities included sutures, corneal denervation, topographical changes, lid pressure, and tension effects on epithelial mitosis. Based on the observations of this CSM study, and based on other laboratory and clinical reports, a new hypothesis concerning epithelial cell movement in the cornea has been presented. It is proposed that there is a differential sliding of epithelium from the periphery to the center, and that epithelium is drawn centripetally by preferential loss of surface cells at the corneal center. Shearing forces of the upper lid cause maximal surface cell loss at the corneal center; shearing forces of the lid are lesser inferiorly and at the limbus. In areas of less lid force, as with depressions near graft sutures, areas of epithelial cell stability are created. Vortex patterns represent an exaggeration of normal cellular pathways of movement, occurring when differential sliding of cells is pronounced, as in corneal grafts.