June 2015
Volume 56, Issue 7
Free
ARVO Annual Meeting Abstract  |   June 2015
OCT Imaging Shows Collector Channels Rapidly Open & Close with Pressure Changes: A Mechanism Regulating Control of Distal Resistance?
Author Affiliations & Notes
  • Murray A Johnstone
    Ophthalmology, University of Washington, Seattle, WA
  • Sepideh Hariri
    Department of Bioengineering, University of Washington, Seattle, WA
  • Yi Jiang
    Ophthalmology, University of Washington, Seattle, WA
  • Steven Padilla
    Ophthalmology, University of Washington, Seattle, WA
  • Zhehai Zhou
    Department of Bioengineering, University of Washington, Seattle, WA
  • Ruikang K Wang
    Department of Bioengineering, University of Washington, Seattle, WA
  • Footnotes
    Commercial Relationships Murray Johnstone, Alcon (C), Allergan (P), Healonics (C), Ivantis (C), Sensimed (C); Sepideh Hariri, None; Yi Jiang, None; Steven Padilla, None; Zhehai Zhou, None; Ruikang Wang, None
  • Footnotes
    Support None
Investigative Ophthalmology & Visual Science June 2015, Vol.56, 3539. doi:
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      Murray A Johnstone, Sepideh Hariri, Yi Jiang, Steven Padilla, Zhehai Zhou, Ruikang K Wang; OCT Imaging Shows Collector Channels Rapidly Open & Close with Pressure Changes: A Mechanism Regulating Control of Distal Resistance?. Invest. Ophthalmol. Vis. Sci. 2015;56(7 ):3539.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract
 
Purpose
 

To Describe a New OCT Platform That Demonstrates Rapid Pressure-dependent Opening and Closing of Collector Channels.

 
Methods
 

Radial limbal segments of ex vivo non-human primate (NHP) nemestrina (2) and human (4) eyes imaged by SD-OCT from the surface of the TM. Segments mounted in a Petri dish under BSS. Cannula insertion using an optical microscope and micromanipulator ensure placement and retention in Schlemm’s canal (SC). Paired reservoirs provide controlled pressure ∆s (5,10,20,30 mm Hg). A perfusion pump provides pulse transients. Assembly into 3D volumes uses a Matlab algorithm to binarize 2D images using a set threshold. Quantification of SC height and area uses manual delineation followed by segmentation with FIJI (ImageJ software). Anatomic appearance by SEM under comparable conditions (SC dilation by using viscoelastic) is assessed in radial sections cut to a thickness of ~100 μm from each quadrant of the limbus of 19 NHPs and 8 humans (6739 total SEM images).

 
Results
 

Dilation of SC with BSS for OCT or with viscoelastic for SEM reveals SC and CC relationships. Collagen septa at collector channel ostia (CCO) generally attach at only one end resulting in a flap-like arrangement that permits mobility (Fig.1D). After perpendicular scleral entry, the lumen of CCO abruptly turns circumferentially forming intrascleral collector channels (CC) parallel to SC; thin collagen septum between the SC and CC lumens result (Fig.1E). Cylindrical attachment structures (CAS) arise from the TM, and then course across SC where they attach to flaps at CCO entrances and to thin CC septa. At each of 10 CCO, SC pressure ∆s induced SC, CCO and CC lumen dimension ∆s in msec as illustrated in (Fig.2) Visible CCO lumen opening and closing occurred with as little as 5 mm ∆P.

 
Conclusions
 

The new high resolution OCT platform permits imaging and quantification of pulse-dependent ∆s in SC, CCO and CC lumen dimensions. Identification of rapid pressure-dependent opening and closing of the lumen of CCO and CC can determine distal outflow system resistance suggesting the region can also play a role in the glaucoma process and be a target for glaucoma management.  

 

 
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