scholarly journals In Vivo Imaging of Schlemm's Canal and Limbal Vascular Network in Mouse Using Visible-Light OCT

2020 ◽  
Vol 61 (2) ◽  
pp. 23 ◽  
Author(s):  
Xian Zhang ◽  
Lisa Beckmann ◽  
David A. Miller ◽  
Guangbin Shao ◽  
Zhen Cai ◽  
...  
Keyword(s):  
Visible Light ◽  
In Vivo Imaging ◽  
Vascular Network ◽  
Schlemm’S Canal ◽  
Schlemm's Canal

In vivo imaging of the Schlemm's Canal and the response to Selective laser trabeculoplasty

2021 ◽  
Author(s):  
Toshit Varshney ◽  
Kishan Azmira ◽  
Shikha Gupta ◽  
Karthikeyan Mahalingam ◽  
Abhishek Singh ◽  
...  
Keyword(s):  
In Vivo Imaging ◽  
Selective Laser Trabeculoplasty ◽  
Schlemm’S Canal ◽  
Schlemm's Canal ◽  
Laser Trabeculoplasty

scholarly journals An imaged-based inverse finite element method to determine in-vivo mechanical properties of the human trabecular meshwork

2017 ◽  
Vol 1 (3) ◽  
pp. 100-111
Author(s):  
Anup D. Pant ◽  
Larry Kagemann ◽  
Joel S. Schuman ◽  
Ian A. Sigal ◽  
Rouzbeh Amini
Keyword(s):  
Mechanical Properties ◽  
Finite Element ◽  
Shear Modulus ◽  
Trabecular Meshwork ◽  
Computational Simulation ◽  
Optimization Technique ◽  
Schlemm’S Canal ◽  
Aqueous Humor Outflow ◽  
Schlemm's Canal

Aim/Purpose: Previous studies have shown that the trabecular meshwork (TM) is mechanically stiffer in glaucomatous eyes as compared to normal eyes. It is believed that elevated TM stiffness increases resistance to the aqueous humor outflow, producing increased intraocular pressure (IOP).It would be advantageous to measure TM mechanical properties in vivo, as these properties are believed to play an important role in the pathophysiology of glaucoma and could be useful for identifying potential risk factors.  The purpose of this study was to develop a method to estimate in-vivo TM mechanical properties using clinically available exams and computer simulations.Design: Inverse finite element simulationMethods: A finite element model of the TM was constructed from optical coherence tomography (OCT) images of a healthy volunteer before and during IOP elevation. An axisymmetric model of the TM was then constructed. Images of the TM at a baseline IOP level of 11, and elevated level of 23 mmHg were treated as the undeformed and deformed configurations, respectively. An inverse modeling technique was subsequently used to estimate the TM shear modulus (G). An optimization technique was used to find the shear modulus that minimized the difference between Schlemm’s canal area in the in-vivo images and simulations.Results: Upon completion of inverse finite element modeling, the simulated area of the Schlemm’s canal changed from 8,889 μm2 to 2,088 μm2, similar to the experimentally measured areal change of the canal (from 8,889 μm2 to 2,100 μm2). The calculated value of shear modulus was found to be 1.93 kPa,  (implying an approximate Young’s modulus of 5.75 kPa), which is consistent with previous ex-vivo measurements.Conclusion: The combined imaging and computational simulation technique provides a unique approach to calculate the mechanical properties of the TM in vivo without any surgical intervention. Quantification of such mechanical properties will help us examine the mechanistic role of TM biomechanics in the regulation of IOP in healthy and glaucomatous eyes. 

scholarly journals Anterior Segment Optical Coherence Tomography Signs of Local Dilatation Effect of a Micro-Stent on Schlemm’s Canal

2018 ◽  
Vol 10 (2) ◽  
pp. 184-187
Author(s):  
Kevin Gillmann ◽  
Giorgio Enrico Bravetti ◽  
Kaweh Mansouri ◽  
André Mermoud
Keyword(s):  
Optical Coherence Tomography ◽  
Trabecular Meshwork ◽  
Anterior Segment ◽  
Optical Coherence ◽  
Schlemm’S Canal ◽  
New Device ◽  
Schlemm's Canal ◽  
Canal Diameter ◽  
Trabecular Bypass

Introduction: The iStent inject® (Glaukos Corporation, CA, USA) is a relatively new device designed to be implanted ab-interno through the trabecular meshwork. This is, to the best of our knowledge, the first in-vivo description of a trabecular bypass device visualised with anterior segment optical coherence tomography (AS-OCT), and report of its structural effect on Schlemm’s canal. Case Report: A 74 year-old female patient suffering from long-standing primary open-angle glaucoma and nuclear sclerosis underwent cataract surgery combined with the implantation of two iStent injects®. Surgery was uncomplicated and achieved intraocular pressure (-1 mmHg) and medication (-2 molecules) reduction at 6 months. Under AS-OCT (Spectralis OCT, Heidelberg Engineering AG, Germany) the stent appears as a 300 μm long hyper reflective hollow device within the trabecular meshwork. Approximately a third of it protruded into the anterior chamber. Profound OCT signal loss was notable within the shadow of the device. A second AS-OCT section 500 μm beside the microstent shows a markedly dilated Schlemm’s canal, with a major diameter of 390 μm. Discussions: This report confirms that AS-OCT is a suitable technique to assess microstent positioning, and provides a first report on the in-vivo appearance of a functioning stent. It also indicates that iStent injects® could have a tangible effect on adjacent portions of Schlemm’s canal with, in this case, a 220% increase in canal diameter compared to the observed average (122 μm). This suggests the IOP-lowering effect of trabecular bypass devices could rely on a  dual mechanism involving Schlemm’s canal dilatation.

In vivo biometric evaluation of Schlemm's canal with spectral-domain optical coherence tomography in pseuduexfoliation glaucoma

2016 ◽  
Vol 94 (8) ◽  
pp. e688-e692 ◽  
Author(s):  
Serhat Imamoglu ◽  
Mehmet S. Sevim ◽  
Oksan Alpogan ◽  
Nimet Y. Ercalik ◽  
Esra Turkseven Kumral ◽  
...  
Keyword(s):  
Optical Coherence Tomography ◽  
Spectral Domain ◽  
Optical Coherence ◽  
Schlemm’S Canal ◽  
Schlemm's Canal

Endothelia of Schlemm's canal and trabecular meshwork: distinct molecular, functional, and anatomic features

2004 ◽  
Vol 286 (3) ◽  
pp. C621-C634 ◽  
Author(s):  
Jorge A. Alvarado ◽  
Abigail Betanzos ◽  
Linda Franse-Carman ◽  
Janet Chen ◽  
Lorenza González-Mariscal
Keyword(s):  
Trabecular Meshwork ◽  
Flow Direction ◽  
Cell Types ◽  
Human Endothelial Cells ◽  
Rt Pcr ◽  
Schlemm’S Canal ◽  
Phenotypic Properties ◽  
Schlemm's Canal

The purpose of this study was to compare human endothelial cells from Schlemm's canal (SCEs) and the trabecular meshwork (TMEs) in terms of ZO-1 isoform expression, hydraulic conductivity (HC) properties, and “giant” vacuole (GV) formation. The principal study methods were Western blot, RT-PCR, immunofluorescence, and perfusion chambers. Blot signals for α+-and α--isoforms were similar in SCEs but less intense for the α+-relative to the α--signal in TMEs. With the anti-α+ antibody used at 1/50 dilution, binding occurred at cell borders of both cell types, but only to SCEs when used at a ≥1/200 dilution in vitro and in vivo. SCEs were more resistive than TMEs (HC = 0.66 vs. 1.32 μl·min-1·mmHg-1·cm-2; P < 0.001) when perfused from apex to base. When perfused in the other direction, SCEs were again more resistive (5.23 vs. 9.04 μl·min-1·mmHg-1·cm-2; P < 0.01). GV formation occurred only in SCEs as a function of flow direction, perfusion pressure, and time. We conclude that SCEs and TMEs have distinctive phenotypic properties involving their content of ZO-1 isoforms, barrier function, and GV formation.

scholarly journals Fundamental Biomaterial Considerations in the Development of a 3D Model Representative of Primary Open Angle Glaucoma

2021 ◽  
Vol 8 (11) ◽  
pp. 147
Author(s):  
Hannah C. Lamont ◽  
Imran Masood ◽  
Liam M. Grover ◽  
Alicia J. El Haj ◽  
Lisa J. Hill
Keyword(s):  
Primary Open Angle Glaucoma ◽  
Open Angle Glaucoma ◽  
In Vitro Models ◽  
Open Angle ◽  
Schlemm’S Canal ◽  
Schlemm's Canal ◽  
Future Success ◽  
Central Regions

Glaucoma is a leading cause of irreversible blindness globally, with primary open angle glaucoma (POAG) being the most common subset. Raised intraocular pressure is an important risk factor for POAG and is caused by a reduction in aqueous humour (AqH) outflow due to dysfunctional cellular and matrix dynamics in the eye’s main drainage site, the trabecular meshwork (TM) and Schlemm’s canal (SC). The TM/SC are highly specialised tissues that regulate AqH outflow; however, their exact mechanisms of AqH outflow control are still not fully understood. Emulating physiologically relevant 3D TM/S in vitro models poses challenges to accurately mimic the complex biophysical and biochemical cues that take place in healthy and glaucomatous TM/SC in vivo. With development of such models still in its infancy, there is a clear need for more well-defined approaches that will accurately contrast the two central regions that become dysfunctional in POAG; the juxtacanalicular tissue (JCT) region of the TM and inner wall endothelia of the Schlemm’s canal (eSC). This review will discuss the unique biological and biomechanical characteristics that are thought to influence AqH outflow and POAG progression. Further consideration into fundamental biomaterial attributes for the formation of a biomimetic POAG/AqH outflow model will also be explored for future success in pre-clinical drug discovery and disease translation.

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