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Patricia A. Parsons-Wingerter, Krishnan Radhakrishnan, Peter K. Kaiser; Fractal-Based Oscillation of Macular Angiogenesis and Vascular Dropout during Progressive Diabetic Retinopathy. Invest. Ophthalmol. Vis. Sci. 2011;52(14):3578.
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© ARVO (1962-2015); The Authors (2016-present)
To examine fractal-based remodeling of macular arterial vessels with progression of diabetic retinopathy (DR).
Binary (black/white) branching patterns of arterial vessels were extracted from the macular region of retinal images obtained by 50° fluorescein angiography (FA) of eyes diagnosed with mild, moderate, or severe nonproliferative DR (NPDR) or proliferative DR (PDR). A box of 1024 x 1024 pixels was overlayed upon the macular region of each 2392 x 2048 binary image and centered at the fovea centralis. One representative image of each DR stage was selected for this preliminary study. Using VESsel GENeration (VESGEN) Analysis software, the 1024 x 1024 arterial binary image was mapped automatically to measure the density of total vessel length (Lv), as well as the fractal dimension (Df) by a box-counting algorithm. VESGEN maps and quantifies vascular pattern as a function of vessel branching generation.
For macular arterial vessels, angiogenesis oscillated strongly with vascular dropout during progression of DR. Df and Lv increased significantly from mild NPDR (1.28 and 0.0096/px, respectively) to moderate NPDR (1.34 and 0.0130/px), decreased from moderate NPDR to severe NPDR (1.28 and 0.0095/px), and again increased from severe NPDR to PDR (1.30 and 0.0108/px). 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 (Avakian et al, Curr Eye Res 24:274 2002).
By both fractal and generational branching analysis, macular arterial density oscillated with progression from mild NPDR to PDR. Results are important for advances in early-stage regenerative DR therapies, when reversal of DR progression may be possible. For example, potential use of angiogenesis stimulators to reverse vascular dropout during mild and severe NPDR is not indicated for treatment of angiogenesis during moderate NPDR.
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