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Bingjie Wang, Acner Camino, Shaohua Pi, Yukun Guo, David Huang, Thomas S Hwang, Yali Jia; Three Dimensional Evaluation of Foveal Ischemia in Diabetic Retinopathy. Invest. Ophthalmol. Vis. Sci. 2019;60(9):3034. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
We aim to evaluate the foveal ischemia three dimensionally (3D) and demonstrate its utility in diagnosis of diabetic retinopathy (DR) severity.
Volumetric macular OCTA scans (304×2×304 A-lines covering 3×3 mm2 area) were obtained with a commercial spectral-domain OCT system (RTVue-XR, Optovue, Inc.). OCTA was generated by SSADA and further processed by PR-OCTA and irb-BMS. The anatomic boundary of foveal avascular zone (FAZ) before the onset of DR was obtained using a constant ganglion cell complex (GCC) thickness established by normal references. A para-FAZ volume including regions between inner limiting membrane (ILM) and 15 µm above ellipsoid zone (EZ) in axial direction and annulus regions of 600 µm distance from the anatomic FAZ boundary in the transverse direction was analyzed (Figure 1). Para-FAZ ischemic volume was characterized by 3D vessel density (3D-PFVD, %), defined as the percentage of vascular perfused voxels to the total voxels in the analytic volume. Para-FAZ ischemic area was characterized by 2D vessel density (2D-PFVD, %) in the maximum projection of the corresponding region. The correlations of 2 conventional (FAZ area, perimeter) and 2 new (3D-PFVD and 2D-PFVD) parameters with DR severity and best-corrected visual acuity (VA), as determined by Early Treatment Diabetic Retinopathy Study (ETDRS) vision scores, were assessed. The diagnosis accuracy of DR severity was evaluated with sensitivity at 95% specificity of healthy controls, as well as area under the receiver operating characteristic curve (AROC).
A total of 93 subjects [22 healthy controls, 24 with diabetes without retinopathy, 23 with mild to moderate nonproliferative (NPDR), and 24 with severe NPDR or PDR] were included. Eyes with severe diabetic macular edema (DME) were excluded. In the healthy control eyes, the anatomic FAZ boundary defined by the region with GCC thickness not thicker than 31 µm agreed with FAZ on inner retinal angiograms with Jaccard index of 0.82. Both 2D and 3D-PFVD had much stronger correlation with DR severity and best-corrected VA, and achieved much greater sensitivity in differentiating eyes with varying severity levels from healthy controls (Table 1), compared to 2 conventional methods. The performance of 3D-PFVD is slightly superior to 2D measurement.
By defining anatomic FAZ, 3D para-FAZ vessel density measurment is the most sensitive indicator to evaluate the ischemia in DR.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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