Abstract
Purpose :
To quantify choriocapillaris (CC) flow deficits in diabetic retinopathy (DR) using projection-resolved optical coherence tomographic angiography (PR-OCTA).
Methods :
We imaged healthy eyes, eyes with diabetes without retinopathy, and several DR severities including mild non-proliferative DR (NPDR), proliferative DR (PDR), and DR with diabetic macular edema (DME). Two repeat scans were acquired on the same eye. OCTA scans were acquired using a commercial system (Solix, Visionix/Optovue, Inc, CA ) in the 6.4×6.4-mm area centered on the foveal avascular zone. A PR-OCTA algorithm was applied to remove the projection artifacts by voxel. En face choriocapillaris angiograms were generated in the slab between Bruch’s membrane (BM) and BM+10 µm. CC deficit area was then detected and quantified according to the following procedure. (1) CC vasculature was enhanced using local contrast (Fig.1 column C); (2) A CC vascular mask was obtained by binarization; (3) An averaging low-pass filter was used to generate the CC density map (Fig.1 column D); (4) CC deficits were detected by thresholding on the CC density map (Fig.1 column E); (5) CC deficits area was measured shadowing artifacts (Fig.1 B2&B3) caused by the hard exudates ((Fig.1 A2&A3)) and large vessels in the inner retina and the floaters in the vitreous excluded.
Results :
We imaged a total of 191 eyes, including 57 normal eyes, 7 eyes with diabetes without retinopathy scans, 31 eyes with NPDR, 28 eyes with PDR, and 66 eyes with DME. The proposed method achieved good repeatability (intraclass correlation coefficient, 0.90). Compared to the normal controls, CC deficit area increased with DR severity (Fig. 1 E1-3). The diagnostic accuracy analysis demonstrated that CC deficits area could be used to diagnose diabetes, DR and DME (Table 1).
Conclusions :
The proposed method could provide accurate measurement of CC deficits with PR-OCTA, which is potentially important for characterizing DR.
This abstract was presented at the 2023 ARVO Imaging in the Eye Conference, held in New Orleans, LA, April 21-22, 2023.