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Thomas S Hwang, Ahmed M Hagag, Miao Zhang, Andrew Kent Smith, David J Wilson, David Huang, Yali Jia; Automated Quantification of Nonperfusion in 3 Vascular Plexuses with Projection-Resolved Optical Coherence Tomography in Diabetic Eyes. Invest. Ophthalmol. Vis. Sci. 2017;58(8):2007. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Projection artifacts in optical coherence tomography angiography (OCTA) interferes with the accurate evaluation of the deeper retinal plexuses. Our group had developed a projection-resolved (PR) OCTA algorithm, which reduces these artifacts and allows visualization of 3 distinct vascular plexuses in the macula. We hypothesize that this technique may better reveal capillary dropout and other vascular abnormalities.
A commercial 70kHz spectral domain OCT system scanned eyes of diabetics and healthy controls using 3x3mm macular OCTA scans. The data was exported for custom processing with PR-OCTA. A semi-automated algorithm segmented the retina into 3 plexuses (Fig. 1). Foveal avascular zone (FAZ) area, total avascular area (TAA), and extrafoveal avascular area (EAA, outside the 1mm diameter central circle) were automatically quantified based on gaps between capillaries.
Fourteen eyes of healthy participants, 8 eyes with diabetes but no retinopathy, 27 eyes with mild to moderate nonproliferative diabetic retinopathy (NPDR), and 21 eyes with more severe retinopathy were imaged. All nonperfusion metrics trended larger with increasing retinopathy severity. EAA on individual layers using PR-OCTA distinguished the 4 groups better than other parameters (Table I) and was able to detect significant nonperfusion in diabetics without retinopathy (p=0.016) compared to control eyes.
Automatically quantified nonperfusion areas individual plexuses using PR-OCTA is more sensitive than analysis on all plexuses as one slab. Nonperfusion area outside of the FAZ provided more accurate diagnosis than the size of the FAZ. This technique may be useful in detecting retinal changes in diabetics even before clinically visible retinopathy appears.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
The inner retinal OCT angiogram is further segmented into 3 slabs: superficial vascular complex (SVC), intermediate capillary plexus (ICP), and deep capillary plexus (DCP) using PR-OCTA in healthy and diabetic eyes with automatically detected nonperfusion areas in blue. DR: diabetic retinopathy, NPDR: non-proliferative DR.
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