REACTION OF MULLER CELLS AFTER INCREASED INTRAOCULAR-PRESSURE IN THE VET RETINA

Using light microscopy and immunocytochemistry, we investigated the mo rphological changes of retinal tissues and the reaction of Muller cell s in the ischemic rat retina induced by increasing intraocular pressur e. At early stages (from I h to 24 h after reperfusion), cells in the ganglion cell layer and in the inner nuclear layer showed some degener ative changes, but at later stages (from 72 h to 4 weeks) marked degen erative changes occurred in the outer nuclear layer (ONL). At 4 weeks after reperfusion, the ONL was reduced to 1 or 2 cell layers. Immunore activity for glial fibrillary acidic protein (GFAP) appeared in the en dfeet and distal processes of Muller cells as of 1 h after reperfusion . GFAP immunoreactivity in Muller cells increased up to 2 weeks and th en decreased at 4 weeks after reperfusion. Our Endings suggest that Mu ller cells are involved in the pathophysiology of retinal ischemia thr ough the expression of GFAP. The degree of GFAP expression in Muller c ells closely correlated with that of the degeneration of retinal neuro ns.