ASTROCYTE RESPONSES IN HUMAN OPTIC-NERVE HEAD WITH PRIMARY OPEN-ANGLEGLAUCOMA

Purpose: To identify and characterize astrocyte responses and reactiva tion in human optic nerve heads from patients with primary open-angle glaucoma. Methods: Fifteen optic nerve heads with primary open-angle g laucoma and 13 normal controls were fixed in 4% paraformaldehyde, para ffin embedded, and stained for immunofluorescence and immunoperoxidase . The antibodies used were against glial fibrillary acidic protein (GF AP) and against neural cell adhesion molecule (NCAM). Results: Two sub populations of type 1 astrocytes exist in the normal optic nerve. Type 1A astrocytes express only glial fibrillary acidic protein and type 1 B express both glial fibrillary acidic protein and neural cell adhesio n molecule. These are the major cell subpopulations in the lamina crib rosa and prelaminar regions. In primary open angle glaucoma, type 1B a strocytes in the prelaminar region showed increased immunoreactivity f or glial fibrillary acidic protein and neural cell adhesion molecule, and cytoplasmic enlargement with thicker and longer cytoplasmic proces ses. At the level of the lamina cribrosa, type 1B astrocytes appeared round and the cell bodies were no longer in the cribriform plates but located in the nerve bundles. Type 1A astrocytes were not observed in the glaucomatous optic nerve head. Conclusions: Astrocyte responses in primary open angle glaucoma may underlie cellular changes that lead t o axonal damage and optic nerve head remodeling. These responses may h ave pathogenic significance for glaucomatous optic neuropathy.