September 2016
Volume 57, Issue 12
Open Access
ARVO Annual Meeting Abstract  |   September 2016
Quantification of Focal Outflow Enhancement using Differential Canalograms
Author Affiliations & Notes
  • Ralitsa Loewen
    Ophthalmology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
  • Eric N Brown
    Ophthalmology, University of Vanderbilt, Nashville, Tennessee, United States
  • Gordon Scott
    School of Medicine, University of Pittsburgh , Pittsburgh, Pennsylvania, United States
  • Hardik Parikh
    Ophthalmology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
    New Jersey Medical School, Rutgers State University of New Jersey, Newark, New Jersey, United States
  • Joel S Schuman
    Ophthalmology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
    Ophthalmology, New York University, New York , New York, United States
  • Nils A Loewen
    Ophthalmology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
  • Footnotes
    Commercial Relationships   Ralitsa Loewen, Neomedix (R); Eric Brown, None; Gordon Scott, None; Hardik Parikh, None; Joel Schuman, None; Nils Loewen, Neomedix (R)
  • Footnotes
    Support  NEI Grant K08 EY022737 (NAL), American Glaucoma Society (NAL), P30-EY08099 (JSS), Research to Prevent Blindness (JSS), CORE P30AEY08098, Alpha Omega Alpha Carolyn L. Kuckein Student Research Fellowship (HAP)
Investigative Ophthalmology & Visual Science September 2016, Vol.57, 5114. doi:
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    • Get Citation

      Ralitsa Loewen, Eric N Brown, Gordon Scott, Hardik Parikh, Joel S Schuman, Nils A Loewen; Quantification of Focal Outflow Enhancement using Differential Canalograms. Invest. Ophthalmol. Vis. Sci. 2016;57(12):5114.

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

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Abstract

Purpose : To quantify focal changes of conventional outflow caused by ab interno trabeculectomy (AIT).

Methods : Gonioscopic, plasma-mediated ab interno trabeculectomy (AIT; Trabectome, Neomedix, Tustin, CA) was established in enucleated pig eyes. We developed a program to automatically quantify outflow changes (R, package eye-canalogram, github.com) using a fluorescent tracer reperfusion technique. Trabecular meshwork (TM) ablation was demonstrated with fluorescent microspheres in 6 eyes before formal outflow quantification was performed with two dye reperfusion canalograms (fluorescein followed by Texas red) in 6 further eyes. Eyes were perfused with a central, intracameral needle at 15 mmHg. Canalograms and histology were correlated for each eye.

Results : The pig eye provided a model with high similarity to AIT in human patients. Histology indicated ablation of TM and unroofing of most Schlemm’s canal segments. Microspheres highlighted additional circumferential and radial outflow beyond the immediate area of ablation. Differential canalograms showed that AIT caused an increase in outflow of 17±5 fold inferonasally (IN), 14±3 fold superonasally (SN) and also an increase in the opposite quadrants with a 2±1 fold increase superotemporally (ST) and 3±3 inferotemporally (IT). Perilimbal specific flow image analysis showed an accelerated nasal filling with additional perilimbal flow directed into adjacent quadrants.

Conclusions : In this quantitative canalography model, supraphysiological outflow enhancement by AIT could be measured in the area of TM ablation and beyond. These new tools are now available as open source software to aid the investigation of outflow tract bioengineering and design of new devices.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.

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