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Regionally discrete aqueous humor outflow quantification using fluorescein canalograms

Loewen, RT and Brown, EN and Roy, P and Schuman, JS and Sigal, IA and Loewen, NA (2016) Regionally discrete aqueous humor outflow quantification using fluorescein canalograms. PLoS ONE, 11 (3).

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Purpose To visualize and quantify conventional outflow directly in its anatomic location. Methods We obtained fluorescein canalograms in six porcine whole eyes and six porcine anterior segment cultures. Eyes were perfused with a constant pressure of 15 mmHg using media containing 0.017 mg/ml fluorescein. Flow patterns were visualized using a stereo dissecting microscope equipped for fluorescent imaging. Images were captured every 30 seconds for 20 minutes for time lapse analysis. Anterior chamber cultures were imaged again on day three of culture. Canalograms were first analyzed for filling time per quadrant. We then wrote a program to automatically compute focal flow fits for each macropixel and to detect convergent perilimbal flow patterns with macropixels grouped into 3 equal-radial width rings around the cornea. A generalized additive model was used to determine fluorescence changes of individual macropixels. Results The resulting imaging algorithm deployed 1024 macropixels that were fit to determine maximum intensity and time to fill. These individual fits highlighted the focal flow function. In whole eyes, significantly faster flow was seen in the inferonasal (IN) and superonasal (SN) quadrants compared to the superotemporal (ST) and inferotemporal (IT) ones (p<0.05). In anterior chamber cultures, reduced flow on day 1 increased in all quadrants on day 3 except in IT (p<0.05). Perilimbal ring analysis uncovered convergent perilimbal flow. Conclusions An algorithm was developed that analyzes regional and circumferential outflow patterns. This algorithm found flow patterns that changed over time and differ in whole eyes and anterior segment cultures.


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Item Type: Article
Status: Published
CreatorsEmailPitt UsernameORCID
Loewen, RTrtl13@pitt.eduRTL13
Brown, EN
Roy, P
Schuman, JSjss28@pitt.eduJSS280000-0002-8885-3766
Sigal, IAian.sigal@pitt.eduIAS6
Loewen, NANAL58@pitt.eduNAL58
ContributionContributors NameEmailPitt UsernameORCID
Centers: Other Centers, Institutes, Offices, or Units > Louis J. Fox Center for Vision Restoration
Date: 1 March 2016
Date Type: Publication
Access Restriction: No restriction; Release the ETD for access worldwide immediately.
Journal or Publication Title: PLoS ONE
Volume: 11
Number: 3
DOI or Unique Handle: 10.1371/journal.pone.0151754
Institution: University of Pittsburgh
Schools and Programs: School of Medicine > Ophthalmology
Refereed: Yes
Date Deposited: 23 Aug 2016 15:12
Last Modified: 30 Mar 2021 15:55


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