Corneal endothelial overgrowth of angle and iris. Evidence of myoblastic differentiation in three cases

Corneal endothelialization of the anterior chamber angle was observed in three cases of iris neovascularization and one case of post-contusion deformity. Scanning electron microscopy in two cases revealed a sheet composed of confluent fusiform cells forming a regular mosaic, growing in a tissue culture-like fashion, and extending over the anterior iris surface. Electron microscopy revealed an endothelial lining continuous with the corneal endothelium extending over the fibrovascular membrane which covered the anterior iris surface in the cases of iris neovascularization and partially extended over the trabecular meshwork in an eye with post-contusion deformity. These endothelial cells possess junctional complexes, apical villi, and prominent basement membrane. In addition, myoblastic differentiation with intracytoplasmic microfilaments, measuring 5 to 6 nm in diameter and often marginally located with fusiform densities, were observed. The presence of myoblastic features may play a role in the ability of corneal endothelial cells to migrate and participate in production of peripheral anterior synechia and ectropion of the iris.