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Soshian Sarrafpour, Edmund Tsui, David Fell, Sherief Raouf, Nicole K Scripsema, Sarwar Zahid, Sarita B Dave, Patricia M. Garcia, Toco Yuen Ping Chui, Richard B Rosen, Rudrani Banik, Joshua A Young; Fractal Analysis of Peripapillary Vasculature In Eyes With Papilledema Using Optical Coherence Tomography Angiography. Invest. Ophthalmol. Vis. Sci. 2017;58(8):3306.
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© ARVO (1962-2015); The Authors (2016-present)
To quantify the fractal dimension (FD) of eyes with papilledema as compared with control eyes using Optical Coherence Tomography Angiography (OCTA).
A retrospective study was performed in 49 eyes with papilledema and 40 control eyes. OCTA images were obtained using the RTVue XR Avanti (Optovue Inc., Fremont, CA, USA). Peripapillary scans of 4.5mm x 4.5mm diameter were obtained. Grayscale OCTA images were standardized and binarized using ImageJ (National Institutes of Health, Bethesda, Maryland, USA). Fractal box-counting analyses were performed using Fractalyse (ThéMA, Besançon Cedex, France). Statistical analysis was performed using one-way analysis of variance with post-hoc Tukey’s multiple comparisons test and two-tailed t-test. Further analyses were performed on papilledema subgroups based on severity (Grade 0, n=12; Grade 1, n=15; Grade 2, n=13; Grade 3, n=5; Grade 4/5, n=4).
The mean FD of all eyes with papilledema (1.677, SD=0.075) was significantly higher (P=0.0021) than control eyes (1.630, SD=0.062). The FD in papilledema subgroups based on severity were Grade 0 (1.707, SD=0.047), Grade 1 (1.675, SD=0.046), Grade 2 (1.674, SD=0.090), Grade 3 (1.610, SD=0.139), Grade 4/5 (1.694, SD=0.060). Analyses between papilledema subgroups demonstrated a significant increase (P<0.05) in FD between Grade 0 papilledema and control eyes. There were no significant differences in pairwise comparisons between other subgroups.
The FD in OCTA of eyes with papilledema was significantly higher compared to control eyes. When analyzed by severity, eyes with Grade 0 papilledema had a higher FD compared to control eyes. Since fractal geometry reflects the branching of the peripapillary microvasculature, an increased FD may correlate with an increase in perfused vessel density as identified by OCTA. Fractal analysis in OCTA has the potential to establish quantitative parameters for peripapillary microvascular pathology in papilledema.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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