CELLULAR ASPECTS OF AMYLOID ANGIOPATHIES OF THE IRIS IN OPEN-ANGLE GLAUCOMA

We studied cellular aspects of amyloid angiopathy of the iris upon dec ompensation of ocular pressure and the role of microcirculatory pathol ogy in pathogenesis of the open angle glaucoma. A total of 115 iris bi opsies were studied, which were taken during antiglaucoma operations a nd stained by Congo rot and thioflavine for amyloid and Toluidine blue for glycosaminoglycans. The biopsies from nine patients were studied at the ultrastructural level. Intravasal increase of the concentration of preamyloid proteins during spasms of the arterioles and capillarie s should be considered as a provoking moment of the iris amyloidogenes is. Blockade of reticular structures of the microcirculatory basal mem branes by preamyloid serum proteins, which provides for shedding of am yloid fibrils, dystrophic changes and detachment of the endothelial ce lls from the basal membrane, obliteration of lumens of the capillaries and arterioles, disturbed integrity of the microvascular barrier and accumulation of preamyloid and amyloid proteins in the extracellular m atrix, ischemia and focal microinfarctions of the iris, and dystrophia of the melanocytes, are subsequent key factors. Amyloid angiopathy of the iris is a cause of ischemia of the anterior eye part, thus creati ng conditions for increased intraocular pressure and glaucoma.