Histological study of frequency-doubled Nd:YAG laser trabeculoplasty on monkey eyes

摘要

Two eyes of a rhesus monkey subject to frequency-doubled Nd:YAG laser LTP were examined by light and electron microscopy twenty-four hours and four weeks postoperatively. Light microscopy demonstrated trabecular meshwork edema, acute inflammatory changes such as the presence of polymorphonuclears and amorphous eosinphilous substance of the Schlemm's canal in the specimen 24 hours after surgery, otherwise, membrane-like extension over the surface of uveal meshwork was found in the tissue four weeks after surgery. Scanning electron microscopy of the specimens excited at earlier stage after irradiation revealed evidences of disruption, coalescence of the trabecular beams and the exudation of deformed erythrocytes among intertrabecular spaces; the specimens excited at later stage showed partial or total occlusion of intertrabecular spaces at laser burn site by a membrane like layer which probably originate from so called trabecular stem cell near the Schwalbe's line. Transmission electron microscopy of the tissue excited at 24 hours post laser showed necrosis of the trabecular cells, collagen fibrils edema, as well a macrophages and pigment cells among intertrabecular spaces; the tissues excited at 4 weeks post laser showed degenerated collagen fibrils and denuded collagen core without superficial trabecular cells.