En face optical coherence tomography detection of Schlemm's canal in primary open angle glaucoma

Haili Huang; Lijia Tian; Xinghuai Sun; Yuhong Chen

doi:10.3389/fphys.2023.1214427

En face optical coherence tomography detection of Schlemm's canal in primary open angle glaucoma

Front Physiol. 2023 Nov 2:14:1214427. doi: 10.3389/fphys.2023.1214427. eCollection 2023.

Authors

Haili Huang^#^{1

2}, Lijia Tian^#^{1

2}, Xinghuai Sun^{1

2

3}, Yuhong Chen^{1

2}

Affiliations

¹ Department of Ophthalmology and Visual Science, Eye and ENT Hospital, Shanghai Medical College, Fudan University, Shanghai, China.
² NHC Key Laboratory of Myopia, Shanghai Key Laboratory of Visual Impairment and Restoration, Chinese Academy of Medical Sciences, Fudan University, Shanghai, China.
³ State Key Laboratory of Medical Neurobiology and MOE Frontiers Center for Brain Science, Institutes of Brain Science, Fudan University, Shanghai, China.

^# Contributed equally.

Abstract

Purpose: 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 en face reconstruction. Methods: 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 en face and cross-sectional images. The diameter and area of SC in cross-sectional images and the visible percentage and area of SC in en face images were measured using ImageJ. Results: SC was observed in 84% of en face images and 81% of cross-sectional images in eyes with POAG but in 92% of en face images and 86% of cross-sectional images in control eyes. Significant differences between the POAG and normal control eyes were found in the en face area (0.35 ± 0.14 mm² vs. 0.56 ± 0.22 mm² in the temporal quadrant and 0.36 ± 0.14 mm² vs. 0.58 ± 0.23 mm² in the nasal quadrant; both p < 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 p < 0.001) in en face images as well as the cross-sectional area (2790.9 ± 942.2 μm² vs. 4138.6 ± 2027.8 μm² in the temporal quadrant and 2805.7 ± 947.2 μm² vs. 4224.0 ± 2002.2 μm² in the nasal quadrant, both p < 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 p < 0.001) in cross-section images. In addition, the mean intraocular pressure (IOP) significantly correlated with the en face area, visible percentage of SC, and cross-sectional area in the temporal and nasal quadrants. Conclusion: SS-OCT can obtain high-quality en face images of SC without post-acquisition processing. Eyes with POAG had a decreased en face SC area compared with normal eyes. A correlation between SC area, visible percentage of en face images, and IOP was also observed.

Keywords: Schlemm’s canal; en face; primary open angle glaucoma; swept source optical coherence tomography; three-dimension.

Grants and funding

This work was generously supported by the funds from the National Natural Science Foundation of China (Grant No. 81870692), the Shanghai Committee of Science and Technology, China (Grant No. 20S31905800), and the Clinical Research Plan of SHDC (Grant No. SHDC2020CR6029).