Changes of blood flow in macular zone of patients with diabetic retinopathy at different stages evaluated by optical coherence tomography angiography.

To evaluate changes in macular blood flow in patients with various stages of diabetic retinopathy (DR) by optical coherence tomography angiography (OCTA). The data of 94 patients (122 eyes) with type 2 diabetes mellitus admitted from January 2018 to May 2021 were recorded, including 31 patients (42 eyes) with no DR (NDR group), 33 patients (40 eyes) with mild non-proliferative DR (mild NPDR group) and 30 patients (40 eyes) with moderate NPDR (moderate NPDR group). Forty healthy patients (40 eyes) who were examined during the same period were selected as control group. The blood flow densities at the superficial capillary plexus (SCP), deep capillary plexus (DCP) and 300μm-wide region near the foveal avascular zone (FAZ) (FD300), FAZ area, FAZ perimeter and acircularity index (AI) were compared. Correlations of blood flow densities at the SCP, DCP and FD300, FAZ area, FAZ perimeter and AI with the severity of DR were investigated by multivariate regression analysis. A receiver operating characteristic (ROC) curve was plotted to analyze the predictive efficacy of the OCTA indices for early DR. Blood flow densities at the SCP, DCP and FD300 significantly decreased, while FAZ perimeter and AI increased in the NDR and DR groups compared with those of the control group (P<0.05). Blood flow densities at the SCP, DCP and FD300 of the DR group were lower than those of the NDR group, but the FAZ perimeter and AI of the former were larger (P<0.05). Blood flow densities at the SCP, DCP and FD300 in the macular zone of DR patients declined with increasing DR stage, while FAZ perimeter and AI increased (P<0.05), without collinearity among the variables. The area under the curve of FD300 for predicting early DR was highest (0.804), with a sensitivity and specificity of 84.13% and 67.19%, respectively. AI with a cut-off value of 1.05 showed the optimal specificity (87.84%) and sensitivity (73.62%) for predicting early DR. The flow density at FD300 declines, while FAZ perimeter and AI increase in the macular zone of patients with early DR. These three OCTA indicators show close associations with DR stage, and can function as predictors of early DR.

Zhao S ，He J ，Qiu M ，Liang X ... -  《-》

Macular Capillary Perfusion in Chinese Patients With Diabetic Retinopathy Obtained With Optical Coherence Tomography Angiography.

To compare the macular perfusion in the retina and choroidal layer between control subjects and Chinese patients with diabetic retinopathy (DR) using optical coherence tomography angiography (OCTA) and to evaluate the association of OCTA characteristics with the stage of DR. A total of 200 eyes (normal controls = 40; mild non-proliferative diabetic retinopathy [NPDR] = 40; moderate NPDR = 40; severe NPDR = 40; and PDR [proliferative diabetic retinopathy] = 40) underwent OCTA imaging. OCTA parameters were vessel densities in the superficial capillary plexus (SCP), deep capillary plexus (DCP), and choriocapillaris, as well as foveal avascular zone (FAZ) area (mm2) in the SCP. The reduction of macular perfusion in the SCP, DCP, and choriocapillaris was correlated with increasing severity of DR. Vessel density in the SCP, DCP, and choriocapillaris was 55.31% ± 2.56%, 62.40% ± 2.46%, and 66.87% ± 1.30%, respectively, in control subjects; 50.58% ± 3.14%, 56.31% ± 4.24%, and 66.20% ± 1.69%, respectively, in mild NPDR; 46.46% ± 3.09%, 49.40% ± 5.68%, and 64.39% ± 1.94%, respectively, in moderate NPDR; 45.61% ± 3.81%, 49.33% ± 6.14%, and 63.75% ± 2.21%, respectively, in severe NPDR; and 43.78% ± 3.71%, 44.78% ± 6.36%, and 61.32% ± 6.29%, respectively, in PDR. Vessel density in DR groups decreased compared with normal controls (P < .001). FAZ area in the SCP was 0.34 ± 0.09 mm2 in control subjects compared with 0.48 ± 0.17 mm2 (mild NPDR), 0.52 ± 0.13 mm2 (moderate NPDR), 0.62 ± 0.24 mm2 (severe NPDR), and 0.75 ± 0.30 mm2 (PDR). FAZ in the SCP of patients with DR was greater than that in control subjects (P < .001). Vessel density in the DCP shows better ability to identify the severity of DR (area under the curve, sensitivity, and specificity of 0.967, 92.5%, and 93.1%, respectively) than vessel density in the SCP and choriocapillaris. OCTA might be clinically useful to evaluate different stages of DR in a noninvasive manner. Vessel density in DCP could be an objective and reliable indicator for monitoring progression of DR. [Ophthalmic Surg Lasers Imaging Retina. 2019;50:e88-e95.].

Yang D ，Cao D ，Huang Z ，Xie J ，Meng Q ，Dong X ，Hu Y ，Zeng Y ，Zhang L ... -  《-》

Perifoveal capillary changes in diabetic patients and association between severity and type of diabetes, visual acuity, and enlargement of non-flow area in the retinal capillary plexuses.

The goal of this study was to evaluate the perifoveal capillary bed and to analyze areas of non-flow using optical coherence tomography angiography (OCT-A) in patients presenting with diabetic retinopathy (DR), correlating them to the severity of DR, type of diabetes and visual acuity (VA). The non-flow area (NFA) and foveal avascular zone (FAZ) in the superficial (SCP) and deep capillary plexus (DCP) were calculated using OCT-A imaging of patients with DR followed between July 2015 and March 2016 at the Jules Gonin Eye Hospital (Lausanne, Switzerland). Disease severity was classified using the Early Treatment Diabetic Retinopathy Study (ETDRS) classification. Analysis of variance was used to correct for correlation between eyes. Seventy-eight eyes of 53 patients were included (29 men; 44 right eyes). There were 45 eyes with non-proliferative DR (NPDR; stage 1 [n=14], stage 2 [n=7], and stage 3 [n=24]) and 33 with proliferative DR (PDR; stage 1 [n=17], stage 2 [n=16]) included, among which 26 had type I diabetes and 52 type II diabetes. The mean Best Corrected Visual Acuity (BCVA) was 78.5 letters. The mean NFA in the SCP differed according to diabetes type and stage of DR (type 1 diabetes: NPDR, 0.76±0.3, PDR, 1.24±0.7; type 2 diabetes: NPDR, 1.46±0.7, PDR, 1.57±0.7). The NFA, measured by OCTA, may be a useful indicator of DR severity, especially in the superficial capillary plexus. Loss of visual acuity might be correlated with increasing NFA (excluding the FAZ or not), primarily among patients with type II diabetes and NPDR.

Kuonen A ，Bergin C ，Ambresin A 《-》

Assessment of macular microvasculature features before and after vitrectomy in the idiopathic macular epiretinal membrane using a grading system: An optical coherence tomography angiography study.

To evaluate pre- and postoperative microvasculature features in eyes with different idiopathic macular epiretinal membrane (iERM) classifications using optical coherence tomography angiography (OCTA). In this retrospective study, 100 eyes with iERM were enrolled; 62 eyes underwent pars plana vitrectomy (PPV). All iERM eyes were evaluated and graded using optical coherence tomography (OCT). According to the thickness of the fovea relative to the surrounding macula from OCT radial line scans, we classified iERM into three grades. Optical coherence tomography angiography (OCTA) was used to measure the foveal avascular zone (FAZ)-related parameters and the superficial and deep capillary plexus layers using 3 × 3 mm scans. Measurements were taken at baseline and 3 months postoperatively. Best corrected visual acuity (BCVA), vessel density (VD), FAZ area, FAZ perimeter (PERIM), acircularity index (AI), and foveal vessel density (FD) were evaluated. Idiopathic macular epiretinal membrane (iERM) eyes with a higher grade had a lower FAZ area and perimeter (p < 0.0001), higher foveal vessel density (FVD) both in the superficial capillary plexus (SCP) (p < 0.0001) and in the deep capillary plexus (DCP) (p < 0.05), and a lower parafoveal vessel density (PRVD) in the DCP (p < 0.0001). The macular vessel density ratio (MVR = FVD/PRVD) increased with an increase in grade both in the SCP and in the DCP (p < 0.0001). For grade 1 iERM eyes, only PRVD in the DCP significantly changed before versus after the operation (p < 0.05). For grade 2 iERM eyes, the FAZ area and perimeter became larger after the operation (p < 0.05). The MVR of grade 2 iERM eyes decreased postoperatively both in the SCP (p < 0.05) and in the DCP (p < 0.001). For grade 1 and grade 2 iERM eyes, preoperative LogMAR BCVA was negatively correlated with the FAZ area (p < 0.01) and perimeter (p < 0.01), and was positively correlated with the MVR in the SCP (p < 0.05). Postoperative LogMAR BCVA was positively correlated with the FVD in the DCP (p < 0.05). Idiopathic macular epiretinal membrane (iERM) eyes of different grades have significant differences in microvasculature features. According to OCTA, eyes with higher grades have more serious microvascular changes. Grading plays a part in predicting postoperative microvascular characteristics, and grade 1 iERM eyes have a better visual outcome compared with grade 2 iERM eyes.

Mao J ，Xu Z ，Lao J ，Chen Y ，Xu X ，Wu S ，Zheng Z ，Liu B ，Shen L ... -  《-》

Evaluation of Foveal and Parafoveal Microvascular Changes Using Optical Coherence Tomography Angiography in Type 2 Diabetes Patients without Clinical Diabetic Retinopathy in South Korea.

The aim of this study was to investigate foveal and parafoveal microvascular changes in retinal vascular plexuses in patients with type 2 diabetes mellitus (DM) without clinical diabetic retinopathy (NDR) using optical coherence tomography angiography (OCTA) in South Korea. We included 64 patients in the NDR group and included 48 healthy control subjects for comparison. All subjects underwent ocular examination with visual acuity and wide-field fundus photos. Foveal and parafoveal vessel density and foveal avascular zone (FAZ) area (mm2) in the superficial capillary plexus (SCP) and deep capillary plexus (DCP) were analyzed. Foveal vessel densities in both the SCP and DCP were decreased in the NDR group compared to the controls (p = 0.034 and 0.001, respectively). Vessel densities in the superior and inferior parafoveae in the DCP were decreased in the NDR group compared to the controls (p = 0.006 and 0.034, respectively). The FAZs of the SCP and DCP were significantly different between the NDR group and the controls (p = 0.003 and 0.001, respectively). The average vessel densities of the SCP and DCP were not correlated with HbA1c, serum creatinine, or the duration of DM in the NDR group. We demonstrated that OCTA can identify early-stage DR before the manifestation of clinically apparent retinopathy in diabetic eyes. Diabetic patients without clinical DR have microvascular alterations (foveal vessel density, parts of the parafovea, and enlarged FAZ) in the SCP and DCP. Our results suggest that OCTA might be a promising tool for early detection of eyes with DR.

Park YG ，Kim M ，Roh YJ 《-》