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Patricia A. Parsons-Wingerter, Krishnan Radhakrishnan; Fractal-Based Oscillation of Venous Density Within the Macula During Progression of Diabetic Retinopathy. Invest. Ophthalmol. Vis. Sci. 2012;53(14):5754.
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© ARVO (1962-2015); The Authors (2016-present)
Venous remodeling in the human macula was investigated by a fractal-based analysis. We previously examined fractal-based remodeling of macular arterial vessels with progression of diabetic retinopathy (DR) and concluded that arteriogenesis oscillates with vessel dropout.
A binary (black/white) branching pattern of venous vessels was extracted from the macular region within retinal images obtained by 50 deg fluorescein angiography (FA) of eyes diagnosed with mild, moderate or severe nonproliferative DR (NPDR) or proliferative DR (PDR). A box of 1024 px by 1024 px centered at the fovea centralis was overlayed upon the macular region of each binary image of 2392 px by 2048 px. One representative image of each DR stage was selected for this preliminary study. Using VESsel GENeration (VESGEN) Analysis software, the venous binary pattern was mapped automatically to measure the total vessel length density (Lv) and the fractal dimension (Df) by a box-counting algorithm. VESGEN maps and quantifies vascular pattern as a function of vessel branching generation.
For macular venous vessels, angiogenesis oscillated strongly with vascular dropout during progression of DR. Df and Lv increased from mild NPDR (1.312 and 0.0115 px/px2, respectively) to moderate NPDR (1.336 and 0.0128 px/px2), decreased from moderate NPDR to severe NPDR (1.308 and 0.0109 px/px2), and again increased significantly from severe NPDR to PDR (1.370 and 0.0155 px/px2). Previously we showed by a similar fractal analysis that for the combined density of macular arteries and veins, Df decreased with progression from normal to mild NPDR
By both fractal (Df) and vessel length density (Lv) analysis, macular venous density oscillated with progression from mild NPDR to PDR. Results are consistent with our recent study of the macular arterial tree within 50 deg FA’s by VESGEN analysis. Current and previous results are important for advances in regenerative therapies for early-stage DR, when reversal to a more normal vessel density may be possible. For example, potential use of regenerative angiogenesis stimulators to reverse vascular dropout during mild NPDR is not indicated for treatment of moderate NPDR.
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