Automated Quantification of Nonperfusion Areas in 3 Vascular Plexuses With Optical Coherence Tomography Angiography in Eyes of Patients With Diabetes

Abstract

IMPORTANCE Diabetic retinopathy (DR) is a leading cause of vision loss that is managed primarily through qualitative clinical examination of the retina. Optical coherence tomography angiography (OCTA) may offer an objective and quantitative method of evaluating DR. OBJECTIVE To quantify capillary nonperfusion in 3 vascular plexuses in the macula of eyes patients with diabetes of various retinopathy severity using projection-resolved OCTA (PR-OCTA). DESIGN, SETTING, AND PARTICIPANTS Cross-sectional study at a tertiary academic center comprising 1 eye each from healthy control individuals and patients with diabetes at different severity stages of retinopathy. Data were acquired and analyzed between January 2015 and December 2017. MAIN OUTCOMES AND MEASURES Foveal avascular zone area, extrafoveal avascular area (EAA), and the sensitivity of detecting levels of retinopathy. RESULTS The study included 39 control individuals (20 women [51%]; mean [SD] age, 43.41 [19.37] years); 16 patients with diabetes without retinopathy (8 women [50%]; mean [SD] age, 56.50 [12.43] years); 23 patients with mild to moderate nonproliferative DR (18 women [78%] ; mean [SD] age, 62.48 [10.55] years); and 32 patients with severe nonproliferative DR or proliferative DR (12 women [38%]; mean age, 53.41 [14.05] years). Mean (SD) foveal avascular zone area was 0.203 (0.103) mm 2 for control individuals, 0.192 (0.084) mm 2 for patients with diabetes without retinopathy, 0.243 [0.079] mm 2 for mild to moderate nonproliferative DR, and 0.359 (0.275) mm 2 for severe nonproliferative DR or proliferative DR. Mean (SD) EAA in whole inner retinal slab in these groups, respectively, were 0.020 (0.031) mm 2 , 0.034 (0.047) mm 2 , 0.038 (0.040) mm 2 , and 0.237 (0.235) mm 2. The mean (SD) sum of EAA from 3 segmented plexuses in each of the respective groups were 0.103 (0.169) mm 2 , 0.213 (0.242) mm 2 , 0.451 (0.243) mm 2 , and 1.325 (1.140) mm 2. With specificity fixed at 95%, using EAA in inner retinal slab, the sensitivity of detecting patients with diabetes from healthy control individuals was 28% (95% CI, 18%-40%), 31% for patients with DR (95% CI, 19%-45%), and 47% for patients with severe DR (95% CI, 29%-65%) from whole inner retinal EAA. With the sum of EAA from 3 individual plexuses, the sensitivities were 69% (95% CI, 57%-80%), 82% (95% CI, 70%-91%), and 97% (95% CI, 85%-100%), respectively. Avascular areas were not associated with signal strength index. The commercial vessel density from the 2-plexus scheme distinguished the groups with lower sensitivity and were dependent on SSI. CONCLUSIONS AND RELEVANCE Automatically quantified avascular areas from a 3-layer segmentation scheme using PR-OCTA distinguished levels of retinopathy with a greater sensitivity than avascular areas from unsegmented inner retinal slab or measurements from a commercially available vessel density in 2-layer scheme. Additional studies are needed to investigate the applicability of nonperfusion parameters in clinical settings.

Retinal Nonperfusion Relationship to Arteries or Veins Observed on Widefield Optical Coherence Tomography Angiography in Diabetic Retinopathy

“…Recent studies using OCTA as well as FA have quantitatively evaluated capillary nonperfusion areas in DR, and have generally demonstrated that capillary nonperfusion increases with increasing DR severity. 13,20,21 The results herein agree with these findings (Table). Furthermore, compared to FA, OCTA can also visualize periarterial capillary-free zones [16][17][18] and vessel connections at the level of precapillary arterioles and venules.…”

Microvascular Changes in the Choriocapillaris of Diabetic Patients Without Retinopathy Investigated by Swept-Source OCT Angiography

“…Using OCTA to assess the retinal vascular density in diabetic eyes without clinically visible DR, researchers have drawn mixed conclusions. For example, Dimitrova et al 16 and Hwang et al 29 showed significantly reduced parafoveal VAD in both the superficial and deep retinal capillary plexuses in diabetic eyes without retinopathy compared to controls, while Simonett et al 30 and Carnevali et al 15 reported significantly reduced parafoveal VAD in the deep but not in the superficial plexus in diabetic eyes without retinopathy. In contrast, other groups demonstrated that no significant differences were found in the superficial, deep, or whole parafoveal VAD between the two groups.…”

“…Moreover, recent studies also showed that additional segmentation and evaluation of the intermediate retinal layer from the superficial and deep retinal layers may enhance the ability of OCTA to detect early microvascular changes in diabetic eyes. 29,32,33 In this study, VAD and VSD were measured on the SRL, IRL, and DRL using our validated semiautomated segmentation algorithm. Our study showed that no significant difference was found in VSD or VAD in diabetic eyes without retinopathy compared to controls within the three vascular plexuses for a 6 × 6-mm scanning protocol.…”

“…Our study showed no statistically significant difference in the FAZ area between the two groups, which was consistent with recent reports. 29,36 However, another report found a small enlargement of the FAZ measured on the full-thickness slab in diabetic eyes without retinopathy. 39 Further studies with larger sample sizes are needed to evaluate whether FAZ measurements would be a useful diagnostic tool for early diabetic microvascular dysfunction.…”

Projection-Resolved Optical Coherence Tomographic Angiography of Retinal Plexuses in Retinitis Pigmentosa

“…Our group has recently developed projection-resolved OCTA (PR-OCTA) algorithm 33,34 to significantly suppress projection artifacts, allowing for proper segmentation of retinal circulation, and in turn more reliable visualization and quantification of microvasculature. [35][36][37][38][39][40][41][42][43][44][45] In this study, we aim to characterize the alterations in perfusion in all three retinal plexuses, as well as the relationship between vascular and structural changes in RP patients.…”