Corneal epithelial cell movement in humans.

Evidence is presented which supports the centripetal movement of epithelial cells in the normal corneal epithelium. This movement is not, however, uniform and is influenced by various factors including corneal topography, surface disease states and lid shearing forces. We have studied epithelial morphology with corneal specular microscopy and have demonstrated altered morphology in keratoconjunctivitis sicca, neurotrophic keratitis, and contact lens wearing. Following penetrating keratoplasty, we found a vortex keratopathy in 70 per cent of patients up to two years after surgery. We also found pallisading of epithelial cells around sutures which indicated centripetal movement of epithelial cells around islands of stability created by obstructions. The eyelid also alters epithelial migration and turnover by increasing exfoliation from shearing forces. We advance a new hypothesis that the driving force in the central epithelial cell movement is the preferential loss of surface cells by exfoliation from the central apex secondary to the shearing forces of the upper lid.