Effects of Trabecular Meshwork Width and Schlemm's Canal Area on Intraocular Pressure Reduction in Glaucoma Patients

AbstractGlaucoma treatment is usually initiated with topical medication that lowers the intraocular pressure (IOP) by reducing the aqueous production, enhancing the aqueous outflow, or both. However, the effect of topical IOP-lowering medications on the microstructures of the aqueous outflow pathway are relatively unknown. In this retrospective, observational study, 56 treatment-naïve patients with primary open-angle glaucoma were enrolled. Images of the nasal and temporal corneoscleral limbus were obtained using anterior segment optical coherence tomography (AS-OCT). The conjunctival vessels and iris anatomy were used as landmarks to select the same limbal area scan, and the trabecular meshwork (TM) width, TM thickness, and Schlemm’s canal (SC) area were measured before and after using the IOP-lowering agents for 3 months. Among the 56 patients enrolled, 33 patients used prostaglandin (PG) analogues, and 23 patients used dorzolamide/timolol fixed combination (DTFC). After 3 months of DTFC usage, the TM width, TM thickness, and SC area did not show significant changes in either the nasal or temporal sectors. Conversely, after prostaglandin analog usage, the TM thickness significantly increased, and the SC area significantly decreased (all P < 0.01). These findings warrant a deeper investigation into their relationship to aqueous outflow through the conventional and unconventional outflow pathways after treatment with PG analogues.

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Influence of Exercise on Intraocular Pressure, Schlemm's Canal, and the Trabecular Meshwork

Investigative Opthalmology & Visual Science ◽

10.1167/iovs.16-19475 ◽

2016 ◽

Vol 57 (11) ◽

pp. 4733 ◽

Cited By ~ 20

Author(s):

Xiaoqin Yan ◽

Mu Li ◽

Yinwei Song ◽

Jingmin Guo ◽

Yin Zhao ◽

...

Keyword(s):

Intraocular Pressure ◽

Trabecular Meshwork ◽

Schlemm’S Canal ◽

Schlemm's Canal

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Combined Circumferential Canaloplasty and Trabeculotomy Ab Interno with the OMNI Surgical System

Frontiers in Ophthalmology ◽

10.36879/fro.21.000106 ◽

2021 ◽

pp. 1-9

Keyword(s):

Intraocular Pressure ◽

Trabecular Meshwork ◽

New Technology ◽

Schlemm’S Canal ◽

Schlemm's Canal ◽

Surgical Device ◽

Outflow Pathway ◽

Consequent Increase ◽

Surgical System ◽

Ab Interno

In the normal eye the conventional outflow pathway is responsible for the majority of aqueous humor egress and plays a key role in the maintenance of healthy intraocular pressure. However, in the glaucomatous eye pathologic changes to the pathway in the trabecular meshwork, Schlemm’s canal, and collector channel ostia can introduce abnormal resistance to outflow with consequent increase in intraocular pressure. The OMNI Surgical System (Sight Sciences, Menlo Park, CA USA) is a relatively new surgical device and the only one that combines two ab interno minimally invasive treatments in a single procedure, canaloplasty and trabeculotomy. This new technology allows surgeons to address outflow resistance wherever it may be, both proximally (juxtacanalicular trabecular meshwork and inner wall of Schlemm’s canal), and distally (Schlemm’s canal and the collector channels). This review covers several recent clinical studies of the OMNI device with the aim of collating what is known and what remains to be learned.

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Stegmann Canal Expander for canaloplasty: A novel technique

European Journal of Ophthalmology ◽

10.1177/1120672117753699 ◽

2018 ◽

Vol 28 (4) ◽

pp. 472-478 ◽

Cited By ~ 3

Author(s):

Matthias C Grieshaber

Keyword(s):

Intraocular Pressure ◽

Trabecular Meshwork ◽

Deep Sclerectomy ◽

Specific Design ◽

Schlemm’S Canal ◽

Schlemm's Canal ◽

Novel Technique ◽

Dissection Technique ◽

Aqueous Outflow ◽

Outflow System

Introduction: The concept of canaloplasty is to increase aqueous egress through all structures that control the aqueous outflow, such as the trabecular meshwork, Schlemm’s canal, and collector channels, by viscomodulation and by placing of a suture stent into the canal. Clinical studies show canaloplasty to be safe and efficient in lowering the intraocular pressure; however, proper knotting of the tensioning suture is technically challenging and even impossible if circumferential cannulation cannot be achieved; furthermore, protrusion of the suture stent is a potential lifelong risk. Methods: The specific design of the Stegmann Canal Expander allows a permanent expansion of the canal and distension of the trabecular meshwork. Two expanders are implanted on either side of the surgically created ostium of Schlemm’s canal to treat half of the circumferential outflow system. This article describes the technique step by step, provides the clinician with surgical pearls, and highlights the management of adverse events. Results: Technically, implantation of the Stegmann Canal Expander is simple and does not require a long learning curve, compared to placing and knotting a tensioning suture. Most issues are related to the two-flap dissection technique (deep sclerectomy technique) and not to implantation of the Stegmann Canal Expander. Intraocular pressure reduction without medications to the low teens can be achieved. Conclusions: The Stegmann Canal Expander is a novel micro-device that has the potential to make canaloplasty a simplified, more controlled, and reproducible surgical procedure.

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Three-dimensional confocal laser microscopy of fibronectin in normal and glaucomatous eyes

Proceedings, annual meeting, Electron Microscopy Society of America ◽

10.1017/s0424820100086313 ◽

1991 ◽

Vol 49 ◽

pp. 402-403

Author(s):

Annelies W. de Kater ◽

R. Rand Allingham ◽

Doug S. Bowman ◽

Fredric S. Fay

Keyword(s):

Fluid Flow ◽

Intraocular Pressure ◽

Aqueous Humor ◽

Trabecular Meshwork ◽

Open Angle Glaucoma ◽

Confocal Laser ◽

Schlemm’S Canal ◽

Endothelial Lining ◽

Schlemm's Canal ◽

Specific Distribution

Aqueous humor exits the anterior chamber of the eye through the trabecular meshwork into Schlemm's canal, a vessel which drains into the systemic circulatory system. The aqueous humor crosses the endothelial lining of Schlemm's canal by means of focal invaginations which form pores and allow digress of fluid into the canal. The trabecular meshwork provides a resistance to fluid flow resulting in a physiologic intraocular pressure in normal eyes. The region adjacent to Schlemm's canal appears to be the site of highest resistance to fluid flow in both normal and glaucomatous eyes. In eyes with primary open angle glaucoma (POAG) the resistance to fluid flow through the trabecular meshwork is abnormally high, causing an elevated intraocular pressure (IOP), which can lead to irreversible damage of the optic nerve and blindness. A definitive morphologic correlate of this disease has not been discovered. Immunohistochemical studies localizing fibronectin in unfixed frozen sections of human eyes have shown elevated levels of fibronectin in the eyes with glaucoma, however the specific distribution of this protein has not been determined due to poor tissue preservation.

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