Iridocorneal endothelial syndrome with contralateral guttate endothelial dystrophy. A light and electron microscopic study.

Both eyes from a 75-year-old woman who had unilateral closed-angle glaucoma, characteristic endothelial specular microscopic findings, and slowly progressive tractional iris abnormalities consistent with essential iris atrophy were obtained postmortem and studied by light, scanning, and transmission electron microscopy. Clinically, the nonglaucomatous right eye had an open-angle, normal iris, and severe endothelial dystrophy with three-plus corneal guttae. In this eye, results of histopathologic examination disclosed marked endothelial degeneration and typical guttate excrescences on Descemet's membrane. In contrast, the endothelium in the fellow eye with the essential iris atrophy variant of the iridocorneal endothelial (ICE) syndrome was strikingly different. The endothelial cells were relatively well preserved and exhibited marked pleomorphism, anisocytosis, and flat, occasionally paired oval nuclei. Binucleate cells also were observed. The endothelial monolayer had secreted a new layer of fibrillar extracellular matrix material on the posterior surface of Descemet's membrane. Extracellular matrix material was found interposed between the iris and cornea in zones of synechial closure, and an endothelial membrane was present on the anterior surface of the iris. These observations support the hypothesis that the iris abnormalities in essential iris atrophy are secondary to endothelial proliferation. The endothelial cells displayed neither tonofilaments nor abundant apical microvilli. The latter observation suggests that increased numbers of endothelial microvilli are not responsible for the characteristic specular microscopic picture seen in the ICE syndrome.