Electron microscopical study of the Fleisher ring

The Fleischer ring of keratoconus was studied with the transmission electron microscope in four corneal buttons. The ring was characterized by accumulations of ferritin particles in the widened intercellular spaces and/or in the cytoplasmic vacuoles of the corneal epithelium. Both changes were prominent in basal layers in three cases; in one case, ferritin-containing vacuoles were noted in wing cell layers. Ferritin particles were also scattered over the corneal epithelium in all cases. For comparison, normal human corneas and conjunctivas were studied. Ferritin particles were scattered over the corneal epithelium and throughout the basal cells of the conjunctiva. They were not found in corneal stroma or endothelium. In conjunctival stroma, numerous ferritin particles were observed in the cytoplasm of some macrophages. Possible origin of these particles and the cause of their deposition are discussed.