Pathologic Investigation Failure of Trabeculotomy

Abstract

To investigate the reason for failure of trabeculotomy using trabeculectomy (TLE) specimens involving the area of previous trabeculotomy. Thirteen TLE specimens from 13 patients with open-angle glaucoma were processed for transmission electron microscopy and light microscopy, involving immunohistochemical staining of thrombomodulin, D2-40 (podoplanin), and CD34. All intraocular pressure after trabeculotomy decreased to normal and then returned to the same or a higher level compared with that before TLE. Eleven and 2 TLE specimens were taken from areas with no peripheral anterior synechia (PAS) and PAS areas, respectively. The 4 types of histologic change in the trabecular meshwork were observed: (1) persistence of a disconnected trabecular meshwork with swelling or degeneration at the cut edge; (2) fusion of the trabecular meshwork; (3) a membrane covering the innermost trabecular meshwork; and (4) pigmented cell invasion into the disconnected trabecular meshwork at the PAS site. Schlemm canal (SC) opening into the anterior chamber and SC occlusion were observed in 2 and 8 eyes, respectively. Opening of SC into the anterior chamber observed in the eyes with failed trabeculotomy suggested that the enhancement of conventional routes may not be important for the intraocular pressure-lowering effect. All 4 types of histologic change in the trabecular meshwork, as mentioned above, may reduce enhancement of the newly created unconventional routes by trabeculotomy.