The normal and abnormal human corneal epithelial surface: a scanning electron microscope study.

The surface morphology of 108 corneal buttons obtained at keratoplasty showed specific patterns for each disease process. The surface over a traumatically scarred cornea was identical to that of undamaged sites, showing microvilli and microplicae in various numbers and combinations. Keratoconus specimens showed many dark cells, frequently noted to have surface blebs 0.25 to 3 micrometer in size over the entire cone in the nipple type, and in a broad basal band inside the cone or over the entire button in the sagging-cone type. Some blebs contained cytoplasm and 250 A glycogen-like granules. In larger, dark cells, holes were found in the blebs and the plasma membrane was degenerated. Corneal epithelial edema was manifested by a large irregular surface caused by the anterior bulge of edematous cells, many attached by only a small area, and variable-sized depressions, often the size of epithelial cells. More than a year after stromal scarring from herpetic keratitis, many epithelial cells lay loosely on the surface whereas other epithelial cells were edematous and partially detached from the surface cell sheet. Localized heaping of rounded epithelial and inflammatory cells persisted in some areas.