Essential Iris Atrophy: A Clinical, Immunohistologic, and Electron Microscopic Study in an Enucleated Eye

Abstract

A 29-year-old woman had unilateral essential iris atrophy, corneal endothelial changes, and absolute glaucoma. The enucleated eye was examined by routine light microscopy. Separate portions of unfixed fresh frozen cornea were sectioned and reacted with monoclonal antibodies against keratins, vimentin, and inflammatory cell markers. Stains for filamentous actin (factin) were performed using the 7-nitro-benz-2-oxa-1,3-diazolylphalIacid in (NBD phallacidin) probe. In addition, portions of cornea and iris were examined by scanning and transmission electron microscopy. Immunocytochemical stains with anti-keratin antibodies showed reactivity only in the corneal epithelium of the patient and normal control. Immunoreactivity with anti-vimentin antibodies was observed in corneal endothelium and keratocytes of the patient and control, but was negative in the epithelium. Staining for f-actin appeared more pronounced in the corneal endothelium of the patient. Scanning electron microscopy of the corneal endothelium showed irregularity in cell size and shape and filopodial processes characteristic of migrating cells. Transmission electron microscopy disclosed abnormalities of Descemet's membrane and endothelium with a posterior collagenous layer. The corneal endothelium displayed normal junctional complexes without desmosomal junctions or increased microvillus projections. Increased 10-nm cytoplasmic filaments were noted consistent with the expression of vimentin. Occasional chronic inflammatory cells perturbed the corneal endothelium and were detected within the endothelial layer. Alterations in the endothelium and Descemet's membrane suggest the acquired nature of this disease.