Corneal superficial unwettable defect. II. Electron microscopic study.

Corneal biopsy specimens of 6 patients with this particular affection were studies with the electron microscope. In addition to the routine electron microscopic methods, staining with ruthenium red was performed on one excised specimen. Marked changes were found in the region of Bowman's membrane, which was altered either superficially or in its total width. Its collagen fibrils became rough and intensively electron-dense, forming a granular or structureless trabecular meshwork. Intertrabecular spaces were filled with special electron-lucent material, which also formed a continuous layer on the surface of the altered Bowman's membrane. Filamentous structures resembling fingerprints were observed in certain areas of these spaces; and after staining with ruthenium red, numerob granules were also visible. Both these structures are considered by the author to be acid mucopolysaccharides. There is further discussed on the correlation of these findings with previous histochemical findings; the author gives special attention to the question whether waxy substances-eye ointment bases-could have been deposited in the pathologically altered Bowman's membrane.