Electron microscopy of argon laser therapy in phakic open-angle glaucoma

In 22 subjects with phakic open-angle glaucoma, trabeculectomies were performed at intervals of three hours to one year after argon laser treatment (ALT). In ten patients the ALT was done with informed consent anticipating that trabeculectomy would be performed at a scheduled time (three hours to two weeks following laser therapy). In 12 other patients, trabeculectomies were required for failure of ALT (one month to one year later). Scanning and transmission electron microscopy of the specimens examined at earlier intervals after laser therapy revealed evidence of heat effects with disruption of trabecular beams, fibrinous material, and necrosis of occasional cells, including melanin-containing endothelial cells, followed by shrinkage of the collagenous components of the trabecular meshwork. The specimens excised at longer intervals after laser treatment showed partial or total occlusion of intertrabecular spaces by a cellular layer of abnormal corneal and/or trabecular endothelial cells with widened cellular interdigitations and numerous prominent filopodial processes typical of migrating cells.