AUTHOR=Huang Haili , Tian Lijia , Sun Xinghuai , Chen Yuhong 

TITLE=En face optical coherence tomography detection of Schlemm’s canal in primary open angle glaucoma

JOURNAL=Frontiers in Physiology

VOLUME=14

YEAR=2023

URL=https://www.frontiersin.org/journals/physiology/articles/10.3389/fphys.2023.1214427

DOI=10.3389/fphys.2023.1214427

ISSN=1664-042X

ABSTRACT=<p><bold>Purpose:</bold> To compare the morphological characteristics of Schlemm’s canal (SC) in patients with primary open-angle glaucoma (POAG) and healthy controls, using swept-source optical coherence tomography (SS-OCT) with <italic>en face</italic> reconstruction.</p><p><bold>Methods:</bold> In this Prospective comparative study, we included 100 eyes from 50 patients diagnosed with POAG and 50 healthy controls. Three-dimensional cube and line scans of the temporal and nasal quadrants of the anterior segment of the limbus were acquired using SS-OCT. SC was identified using <italic>en face</italic> and cross-sectional images. The diameter and area of SC in cross-sectional images and the visible percentage and area of SC in <italic>en face</italic> images were measured using ImageJ.</p><p><bold>Results:</bold> SC was observed in 84% of <italic>en face</italic> images and 81% of cross-sectional images in eyes with POAG but in 92% of <italic>en face</italic> images and 86% of cross-sectional images in control eyes. Significant differences between the POAG and normal control eyes were found in the <italic>en face</italic> area (0.35 ± 0.14 mm<sup>2</sup> vs. 0.56 ± 0.22 mm<sup>2</sup> in the temporal quadrant and 0.36 ± 0.14 mm<sup>2</sup> vs. 0.58 ± 0.23 mm<sup>2</sup> in the nasal quadrant; both <italic>p</italic> &lt; 0.001) and visible percentage of SC (85.71% vs. 94.91% and 87.10% vs. 95.52% in the temporal and nasal quadrant respectively, both <italic>p</italic> &lt; 0.001) in <italic>en face</italic> images as well as the cross-sectional area (2790.9 ± 942.2 μm<sup>2</sup> vs. 4138.6 ± 2027.8 μm<sup>2</sup> in the temporal quadrant and 2805.7 ± 947.2 μm<sup>2</sup> vs. 4224.0 ± 2002.2 μm<sup>2</sup> in the nasal quadrant, both <italic>p</italic> &lt; 0.001) and diameter of SC (123.1 ± 25.4 μm vs. 149.5 ± 34.7 μm in the temporal quadrant and 126.3 ± 28.9 μm vs. 155.3 ± 36.0 μm in the nasal quadrant, both <italic>p</italic> &lt; 0.001) in cross-section images. In addition, the mean intraocular pressure (IOP) significantly correlated with the <italic>en face</italic> area, visible percentage of SC, and cross-sectional area in the temporal and nasal quadrants.</p><p><bold>Conclusion:</bold> SS-OCT can obtain high-quality <italic>en face</italic> images of SC without post-acquisition processing. Eyes with POAG had a decreased <italic>en face</italic> SC area compared with normal eyes. A correlation between SC area, visible percentage of <italic>en face</italic> images, and IOP was also observed.</p>