[Changes in extracellular matrix in the lamina cribosa of patients with secondary glaucoma]

The aim of this study was to analyze the localization and distribution of extracellular matrix in normal and glaucomatous damaged optic discs using immunohistochemical methods. Five eyes donated for corneal allografting without any history of glaucoma and three other eyes with secondary glaucoma were studied. Immunohistochemical reactions were performed with antibodies against collagen types I, III, IV and VI and against laminin, proliferating antigen KI67 and GFAP. In glaucomatous eyes the characteristic arrangement of collagen fibrils is lacking. Septa of the lamina cribrosa appear enlarged. The immunoreactivity of all examined collagen types is stronger in glaucomatous eyes. The axon basement membranes show an irregular and interrupted pattern. The number of proliferating cells with positive GFAP staining in glaucomatous cribriform plates is distinctly higher. We postulate that fibroblasts and astrocytes in the stroma of glaucomatous lamina cribrosa could be stimulated to increased and uncontrolled proliferation. Associated disorganization and raised secretion of extracellular matrix may lead to axon constriction and, secondarily, to neural degeneration.