Changes in Schlemm’s canal morphology after trabeculectomy in open angle glaucoma assessed using anterior segment optical coherence tomography

Abstract

ABSTRACT Clinical relevance Determining how Schlemm’s canal is affected by trabeculectomy may become a marker for evaluating and monitoring surgical success. Background This study aims to evaluate the morphological changes in Schlemm’s canal after trabeculectomy using anterior segment optical coherence tomography (AS-OCT). Methods Thirty-five eyes of 35 patients who were followed up for open-angle glaucoma and indicated for trabeculectomy were included in the study. AS-OCT was performed preoperatively and at week 1, month 1 and month 3 postoperatively. The coronal and meridional diameters of Schlemm’s canal were measured in the temporal and nasal quadrants via AS-OCT. Results The meridional diameter length of Schlemm’s canal was higher in the nasal quadrant than in the temporal quadrant. Nasally, the mean preoperative meridional diameter length was 326.8 ± 88.5 μm, which increased at postoperative week 1 and month 1. Temporally, it was 271.5 ± 91.5 μm and showed a non-significant change postoperatively. The mean preoperative coronal diameter length was 10.9 ± 6.5 μm and 11.9 ± 6.0 μm in the nasal and temporal quadrants, respectively. A statistically significant increase was found in the measurements of the nasal quadrant at week 1 (p = 0.005) and month 1 (p = 0.049), and in the temporal quadrant at week 1 (p = 0.023). Conclusion A significant enlargement of the canal occurs at the first postoperative week, followed by a gradual reduction thereafter. The increase in size is mostly observed in the coronal diameters, resulting in the expansion of the canal.