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Joel Kaluzny, Yali Jia, Thomas S Hwang; Optical coherence tomography angiography-quantified vascular metrics in diabetic eyes without retinopathy: a systematic review. Invest. Ophthalmol. Vis. Sci. 2019;60(9):3033.
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To present a systematic review of optical coherence topography angiography (OCTA) vascular metrics in the evaluation of diabetic eyes with no retinopathy (NDR).
Using the PRISMA guidelines (Figure 1), we searched PubMed and Google Scholar with the terms: "Optical coherence tomography angiography" AND ("diabetes" OR "diabetic retinopathy" OR "quantification") published before 10/7/2018. We included English-language full-text publications that compared OCTA-derived quantitative vascular metrics between healthy controls and NDR eyes, tabulating the study design and size, metrics examined, segmentation strategy, device type, conclusions made, and statistical adjustment for multiple comparisons.
Of 333 initially identified publications, 21 met the inclusion criteria. Seven compared healthy controls vs. NDR only and 14 also compared eyes with diabetic retinopathy. The device used included 17 by Optovue, 3 by Zeiss, and 1 by Topcon. Eighteen studies segmented the macula in 2 layers, 2 in 3 layers, and 1 as a single slab. Four studies examined the superficial vascular complex (SVC) only. Twenty one studies used 3x3mm scans, 4 used 6x6mm, and 1 used 12x12mm. The studies analyzed vessel area density (19), intercapillary or avascular areas (2), vessel length density (2), fractal dimension (2) and other metrics (8).Fifteen of 21 studies found a significant difference in at least 1 metric. Nine of 18 studies reported a difference in SVC vessel area density (VAD), and 10 of 15 in deep capillary plexus (DCP) VAD. Of 15 studies that examined the VAD of both layers, 5 concluded that the DCP changes were more sensitive and 4 concluded the opposite.
The majority of reviewed studies found a significant difference in at least 1 OCTA-quantified vascular metric between healthy eyes and NDR. No apparent consensus exists on segmentation schemes, vascular metrics, image processing methods, or terminology. Studies disagree on whether vascular metrics derived from superficial or deep vascular layers are more sensitive in detecting early vascular changes in diabetes. The differences strategies for quantification, segmentation, and artifact processing are likely responsible for the disagreement. Statistical analysis was variable, and studies that reported a significant difference between healthy and NDR had a larger average size than those that did not.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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