Effects of ultrasound on the corneal endothelium: I. The acute lesion

The ultrasonic radiation utilised in phacoemulsification procedures for the removal of cataractous lenses results in the widespread production of discrete lesions in the corneal endothelium. The morphology of this induced damage has been examined in rabbit and man using both scanning and transmission electron microscopy. The illustrated results are related to both the duration of the ultrasonic exposure and to the mechanisms of damage.

[Fuchs' endothelial dystrophy--the appearance of the corneal endothelium under the electron microscope (author's transl)]

Studying the various stages of Fuchs' endothelial dystrophy with transmission and surface electronmicroscopy makes the dystrophic and degenerative changes in the endothelial and Descemet's membrane visible: dystrophic changes by the formation of tuberosities, whose structure is very similar to that Descemet's membrane, and degenerative changes by reduction in the number of endothelial cells through destruction of the intercellular connections and through cell necrosis. The second stage is the reformation of the structure by fibroblastic cells. The dystrophic cells lead to the formation of a fibrillary tissue between the cells and the tuberosity-laden Descemet's membrane, which is different from the primary structure of this tissue. The origin of these cells is unknown.

Contributions of electron microscopy to the study of corneal pathology

Most of the electron microscopic studies of pathological corneas have been done only recently. Keratoplasty has been the most important source of specimens for ultramicroscopic investigation. With the introduction of electron microscopic techniques, we have been able to confirm many light microscopic studies in pathological corneas. This contribution has been most valuable in the identification of the sites and types of pathological changes in corneal dystrophies and degenerations. This review of electron microscopic studies describes the present concepts on the nature of the histological changes in dystrophies and degenerations of the anterior and posterior corneal layers and corneal stroma. It also includes a review of some corneal inflammatory conditions as well as metabolic disorders affecting its transparency.