Pilot study assessing the structural changes in posttrabecular aqueous humor outflow pathway after trabecular meshwork surgery using swept-source optical coherence tomography

Abstract

This study evaluated the morphological change in aqueous humor outflow (AHO) pathways using swept-source optical coherence tomography (SS-OCT) volumetric scans in glaucoma patients before and after glaucoma surgery. In this prospective observational case series, 15 eyes (13 patients) with glaucoma were treated with 120-degree Trabectome or 360-degree suture trabeculotomy and followed up for 3 months. B-scan images of the posttrabecular AHO pathway were reconstructed and the pathway areas were evaluated, before and after surgery. Changes in posttrabecular AHO pathway were qualitatively classified as “increased”, “non-significant change”, and “decreased” on reconstructed B-scan images. Quantitative measurements of the posttrabecular AHO pathway areas were performed pre- and postoperatively. Factors associated with both qualitative and quantitative changes in AHO pathway were investigated. From 30 regions (15 nasal and 15 temporal regions) in the 15 eyes, AHO pathways were analyzable in 20 regions pre- and postoperatively. Qualitative assessments of the pathway changes were “increased” in 8 regions, “non-significant change” in 9 regions, and “decreased” in 3 regions. Quantitative assessments of the average pathway area did not change significantly (from 3155±1633 pixels preoperatively to 3212±1684 pixels postoperatively, P = 0.50). All parameters relating to intraocular pressure changes or the surgical location were not associated with postoperative AHO pathway change. The intrascleral AHO pathway could be well visualized in glaucoma patients pre- and postoperatively using swept-source optical coherence tomography. However, structural changes in the AHO pathway assessed by SS-OCT were not significant after trabecular-targeted glaucoma surgery. Functional assessments of AHO are needed in future studies.