Full circumferential morphological analysis of Schlemm’s canal in human eyes using megahertz swept source OCT

Yao, Xinwen; Tan, Bingyao; Ho, Yijie; Liu, Xinyu; Wong, Damon Wing Kee; Chua, Jacqueline; Wong, Tina; Perera, Shamira; Ang, Marcus; Werkmeister, René M.; Schmetterer, Leopold

doi:10.1364/boe.426218

Cited by 10 publications

(9 citation statements)

References 45 publications

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“…To test the 3D imaging capability we showed a 2.5-mm scanning length circumferentially. The latest published techniques for 360° imaging of the SC employed the combination of multiple volumetric scanning 47 , 48 , 53 , which might cause discontinuity between volume scans. A larger field of view could be a solution but the resolution is limited and the direction of OCT beams is not optimal for the angle imaging.…”

Section: Discussionmentioning

confidence: 99%

Iridocorneal angle imaging of a human donor eye by spectral-domain optical coherence tomography

Luo,

Holland,

Khazaeinezhad

et al. 2023

Sci Rep

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Iridocorneal angle (ICA) details particularly the trabecular meshwork (TM), Schlemm’s canal (SC), and collector channels (CCs) play crucial roles in the regulation of the aqueous outflow in the eyes and are closely associated with glaucoma. Current clinical gonioscopy imaging provides no depth information, and studies of 3D high-resolution optical coherence tomography (OCT) imaging of these structures are limited. We developed a custom-built spectral-domain (SD-) OCT imaging system to fully characterize the angle details. Imaging of a human cadaver eye reveals the visibility of details in the TM/SC/CC region via a ’crossline’ scanning and a series of image processing. This shows that ICA imaging can be used for preoperative glaucoma inspections in the clinical setting with the proposed prototype.

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Section: Discussionmentioning

confidence: 99%

Iridocorneal angle imaging of a human donor eye by spectral-domain optical coherence tomography

Luo,

Holland,

Khazaeinezhad

et al. 2023

Sci Rep

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“…Huang et al (Huang et al, 2017) demonstrated the ability to perform a 360 °threedimensional reconstruction of SC in one healthy volunteer eye using a commercial SD-OCT instrument that included an active eye tracker to compensate for motion artifacts. Meanwhile, Yao et al (Yao et al, 2021) utilized SS-OCT to perform complete circumferential imaging of SC in two healthy human eyes. They reconstructed three-dimensional renderings of SC by stitching the segmented SCs from the volumetric datasets.…”

Section: Discussionmentioning

confidence: 99%

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

Huang,

Tian,

Sun

et al. 2023

Front. Physiol.

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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.

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Section: Discussionmentioning

confidence: 99%

“…Thus, repeated serial measurements were performed to reduce random errors and confirm our observations. Thirdly, the AS-OCTA does not directly image the aqueous outflow tracts such as the Schlemm's canal and collector channels ( 49 ). Ideally we should perform aqueous angiography to assess the actual flow through the collector channels—thus the Hydrus implant may not increase the flow in the collector channels.…”

Section: Discussionmentioning

confidence: 99%

Anterior Segment Optical Coherence Tomography Angiography Following Trabecular Bypass Minimally Invasive Glaucoma Surgery

Gan

Sng

et al. 2022

Front. Med.

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ObjectiveTo assess anterior segment optical coherence tomography angiography (AS-OCTA) imaging of the episcleral vessels before and after trabecular bypass minimally invasive glaucoma surgery (MIGS).DesignA prospective, clinical, single-centre, single-arm pilot feasibility study conducted at National University Hospital, Singapore.SubjectsPatients with primary glaucomatous optic neuropathy undergoing Hydrus Microstent (Ivantis Inc., Irvine, CA, USA) implantation, who require at least one intra-ocular pressure-lowering medication. One or two eyes per patient may be enrolled.MethodsWe performed AS-OCTA (Nidek RS-3000 Advance 2, Gamagori, Japan) pre- and up to 6 months post-MIGS implantation using a standard protocol in all cornealimbal quadrants, to derive episcleral vessel densities (VD) using a previously described technique.Main Outcome MeasuresEpiscleral VD pre- and post-surgery, in sectors with and without the implant.ResultsWe obtained serial AS-OCTA images in 25 eyes undergoing MIGS implantation (23 subjects, mean age 70.3 ± 1.5, 61% female) with mean preoperative intraocular pressure (IOP) of 15.5 mmHg ± 4.0. We observed reductions in postoperative episcleral VD compared to preoperative VD at month 1 (mean difference −3.2, p = 0.001), month 3 (mean difference −2.94, p = 0.004) and month 6 (mean difference −2.19, p = 0.039) in sectors with implants (overall 6 month follow-up, p = 0.011). No significant changes were detected in episcleral VD in the sectors without implants (p = 0.910).ConclusionIn our pilot study, AS-OCTA was able to detect changes in the episcleral VD following trabecular bypass MIGS, which may be a useful modality to evaluate surgical outcomes if validated in future studies.

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Full circumferential morphological analysis of Schlemm’s canal in human eyes using megahertz swept source OCT

Cited by 10 publications

References 45 publications

Iridocorneal angle imaging of a human donor eye by spectral-domain optical coherence tomography

Iridocorneal angle imaging of a human donor eye by spectral-domain optical coherence tomography

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

Anterior Segment Optical Coherence Tomography Angiography Following Trabecular Bypass Minimally Invasive Glaucoma Surgery

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