Gonioscopic Assessment of Blood in Schlemm's Canal

Schirmer, K. E.

doi:10.1001/archopht.1971.00990050265001

Cited by 23 publications

(31 citation statements)

References 2 publications

Supporting

Mentioning

Contrasting

Unclassified

Order By: Relevance

“…Normally, the SC lumen is little more than a potential space. However, in normal subjects gonioscopy studies have shown that a reversal of pressure relationships results in IOP lower than EVP and causes blood to rapidly dilate and fill the lumen of SC [1,5,69,70]. Dilation of SC results from the TM rapidly collapsing toward the AC, increasing the dimensions of the SC lumen [8,9].…”

Section: Discussionmentioning

confidence: 99%

See 1 more Smart Citation

OCT Study of Mechanical Properties Associated with Trabecular Meshwork and Collector Channel Motion in Human Eyes

2016

View full text Add to dashboard Cite

We report the use of a high-resolution optical coherence tomography (OCT) imaging platform to identify and quantify pressure-dependent aqueous outflow system (AOS) tissue relationships and to infer mechanical stiffness through examination of tissue properties in ex vivo human eyes. Five enucleated human eyes are included in this study, with each eye prepared with four equal-sized quadrants, each encompassing 90 degrees of the limbal circumference. In radial limbal segments perfusion pressure within Schlemm’s canal (SC) is controlled by means of a perfusion cannula inserted into the canal lumen, while the other end of the cannula leads to a reservoir at a height that can control the pressure in the cannula. The OCT system images the sample with a spatial resolution of about 5 μm from the trabecular meshwork (TM) surface. Geometric parameters are quantified from the 2D OCT images acquired from the sample subjected to controlled changes in perfusion pressures; parameters include area and height of the lumen of SC, collector channel entrances (CCE) and intrascleral collector channels (ISCC). We show that 3D OCT imaging permits the identification of 3-D relationships of the SC, CCE and ISCC lumen dimensions. Collagen flaps or leaflets are found at CCE that are attached or hinged at only one end, whilst the flaps are connected to the TM by cylindrical structures spanning SC. Increasing static SC pressures resulted in SC lumen enlargement with corresponding enlargement of the CCE and ISCC lumen. Pressure-dependent SC lumen area and height changes are significant at the 0.01 levels for ANOVA, and at the 0.05 for both polynomial curves and Tukey paired comparisons. Dynamic measurements demonstrate a synchronous increase in SC, CCE and ISCC lumen height in response to pressure changes from 0 to 10, 30 or 50 mm Hg, respectively, and the response time is within the 50-millisecond range. From the measured SC volume and corresponding IOP values, we demonstrate that an elastance curve can be developed to infer the mechanical stiffness of the TM by means of quantifying pressure-dependent SC volume changes over a 2 mm radial region of SC. Our study finds pressure-dependent motion of the TM that corresponds to collagen leaflet configuration motion at CCE; the synchronous tissue motion also corresponds with synchrony of SC and CCE lumen dimension changes.

show abstract

Section: Discussionmentioning

confidence: 99%

“…In mild glaucoma, blood fills and empties from SC slowly. In more advanced glaucoma, there is only patchy filling of the canal with blood and in far advanced glaucoma SC filling with pressure reversal is absent [1,5,69,70]. …”

Section: Discussionmentioning

confidence: 99%

OCT Study of Mechanical Properties Associated with Trabecular Meshwork and Collector Channel Motion in Human Eyes

2016

View full text Add to dashboard Cite

show abstract

“…[34][35][36][37][38] Physiologic positions, such as those commonly occurring in physical fitness activities, can cause pressure reversal with pressure in SC being higher than IOP. 39 During the physical activities involving body inversion, episcleral venous pressure rapidly rises.…”

Section: Discussionmentioning

confidence: 99%

“…In the later stages of the disease, some regions of the canal no longer fill with blood, while in far advanced disease, no SC blood filling is observed. [34][35][36][37][38] Altered blood reflux into SC represents the only directly observable abnormality of the TM and SC regions in glaucoma.…”

Section: Discussionmentioning

confidence: 99%

Platform to investigate aqueous outflow system structure and pressure-dependent motion using high-resolution spectral domain optical coherence tomography

et al. 2014

View full text Add to dashboard Cite

Abstract. The aqueous outflow system (AOS) is responsible for maintaining normal intraocular pressure (IOP) in the eye. Structures of the AOS have an active role in regulating IOP in healthy eyes and these structures become abnormal in the eyes with glaucoma. We describe a newly developed system platform to obtain high-resolution images of the AOS structures. By incorporating spectral domain optical coherence tomography (SD-OCT), the platform allows us to systematically control, image, and quantitate the responses of AOS tissue to pressure with a millisecond resolution of pulsed flow. We use SD-OCT to image radial limbal segments from the surface of the trabecular meshwork (TM) with a spatial resolution of ∼5 μm in ex vivo nonhuman primate eyes. We carefully insert a cannula into Schlemm's canal (SC) to control both pressures and flow rates. The experimental results demonstrate the capability of the platform to visualize the unprecedented details of AOS tissue components comparable to that delivered by scanning electron microscopy, as well as to delineate the complex pressure-dependent relationships among the TM, structures within the SC, and collector channel ostia. The described technique provides a new means to characterize the anatomic and pressure-dependent relationships of SC structures, particularly the active motion of collagenous elements at collector channel ostia; such relationships have not previously been amenable to study. Experimental findings suggest that continuing improvements in the OCT imaging of the AOS may provide both insights into the glaucoma enigma and improvements in its management.

show abstract

“…Die Untersuchung der Patienten mit einem Kontaktglas, das mit Unterdruck an das Auge gesaugt wird, fuhrt ebenfaUs w~ihrend der Gonioskopie leichter zu Bluteintritt in den Schlemmschen Kanal. Suson (1965), Suson & Schultz (1969), Schirmer (1969Schirmer ( , 1971 und Mikuni & Iwata (1965) wandten eine modifizierte Koeppelinse an und pref$ten mit Unterdruck das Kontaktglas gegen die perilimbale Sklera.…”

unclassified

Untersuchungen zur Indikationsstellung der Trabekulotomie bei glaucoma simplex

Grote

1978

Doc Ophthalmol

View full text Add to dashboard Cite

Following trabeculotomy, about 30% of glaucomatous eyes are not normalized in pressure without additional therapy. In these cases, it was not possible to remove the resistance of outflow completely. Before deciding to perform trabeculotomy it is, therefore, necessary to localize the resistance of outflow. The inspection of the blood pattern in Schlemm's canal gives no indication where to localize the resistance of outflow. The same holds true for the haemorrhage deriving from Schlemm's canal, in the operating field (trabeculotomy window), which appears in 19.2% of cases. After trabeculotomy the blood outflow into the anterior chamber is significantly higher (63.6%) using the suction cup, then following pressure of the gonioscopy lens (28.1%). The differences between these findings are discussed. Our results indicate the necessity to search for other methods in localizing the resistance of outflow pre-operatively.

show abstract

Gonioscopic Assessment of Blood in Schlemm's Canal

Cited by 23 publications

References 2 publications

OCT Study of Mechanical Properties Associated with Trabecular Meshwork and Collector Channel Motion in Human Eyes

OCT Study of Mechanical Properties Associated with Trabecular Meshwork and Collector Channel Motion in Human Eyes

Platform to investigate aqueous outflow system structure and pressure-dependent motion using high-resolution spectral domain optical coherence tomography

Untersuchungen zur Indikationsstellung der Trabekulotomie bei glaucoma simplex

Contact Info

Product

Resources

About