Endothelial alterations in congenital corneal dystrophies.

We studied the clinical and ultrastructural findings in three different types of congenital endothelial dystrophies: hereditary posterior polymorphous dystrophy, congenital hereditary corneal dystrophy, and a nonhereditary congenital endothelial dystrophy. In the first patient, with hereditary posterior polymorphous dystrophy, a layer of epithelial-like cells was observed adjacent to endothelial cells on the posterior corneal surface. Descemet's membrane displayed a multilaminar pattern and consisted of an anterior, thin (3 mu), PAS-positive layer and a posterior, thicker (25 to 30 mu) zone of abnormal collagen. The second patient, with congenital hereditary endothelial dystrophy, showed a thickened multilaminar Descemet's membrane and scant endothelial cells. In the third patient with nonhereditary congenital endothelial dystrophy, the thickened Descemet's membrane was lined posteriorly by a retrocorneal fibrous membrane. A few degenerated endothelial cells were present. All three cases showed 100- to 110-nm banding posteriorly. In these three clinically distinct entities, electron microscopy was useful in demonstrating the unusual form of endothelial transformation to epithelial-like cells in one patient, in contrast to the more common fibroblast-like metaplasia of endothelial cells seen in the other two patients.