Pathologic Investigation Failure of Trabeculotomy

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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.