Investigation of the effects of gestational diabetes and hypertension on retinal and choroidal microvascular circulation using swept-source optical coherence tomography angiography.

PURPOSE: The aim of this study was to investigate the microvascular changes in the retina and choroid in gestational diabetes mellitus (GDM) and pregnancy-induced hypertension (PIH) and to compare the results with those of healthy pregnant subjects. METHODS: Twenty-nine pregnant subjects with coexisting GDM and PIH (group 1) and 36 healthy pregnant subjects (group 2) were enrolled in the study. All subjects were examined by optical coherence tomography (OCT) and angiography (OCTA). The retina, retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), choroidal thickness (CT), superficial capillary plexus (SCP), deep capillary plexus (DCP), choriocapillaris (CC) vascular density (VD), and foveal avascular zone (FAZ) were measured. RESULTS: We observed that the values of CT and VD were lower in group 1 than in group 2. No significant difference was found between groups in RT, FAZ area and CC VD. SCP and DCP VD values were higher in group 2 in all quadrants. We observed a significant increase in FAZ area and CC VD with increasing systolic blood pressure. No correlation was observed between diastolic blood pressure and FBS with other parameters. In group 1, FAZ area was significantly higher in the diet-treated group than in the insulin-treated group. CONCLUSION: Monitoring and treatment of pregnant women with PIH and GDM is important because of the risks that may occur during pregnancy. We believe that changes in microvascular circulation can be detected noninvasively with OCTA, even in the absence of clinical or retinal findings.

Foveal avascular zone area measurement in diabetic patients: Superficial, deep or combined retinal vascular complex?

PURPOSE: To compare differences in the foveal avascular zone (FAZ) area, measured in the Superficial Vascular Complex (SVC), Deep Vascular Complex (DVC) and a combined analysis of both (SDVC), using two Spectral Domain OCT angiography (OCT-A) protocols, High Speed (HS) and High Resolution (HR). METHODS: A total of 26 eyes of diabetic patients, with and without macular oedema, were examined with two different fovea centered OCT-A volume scans. The two protocols were HS and HR volume scans, and the foveal avascular zone was manually measured in the SVC, DVC, and SDVC slabs by two masked investigators. Inter and intraoperator variability was analysed using Intraclass Correlation Coefficient (ICC) and differences were compared between the HR and HS acquisitions throughout the different vascular slabs. RESULTS: Intraoperator variability was low in all slabs (ICC > 0.9) and interoperator variability was lower for HR (ICC 0.835-0.911) compared to HS (ICC between 0.604 and 0.865). Comparing HS and HR measurements for the same slab, the correlation was only moderate in SVC and DVC (ICC was 0.640 and 0.568 respectively) but was good in the SDVC (ICC = 0.823). FAZ area measurement in SDVC also showed the smallest bias (mean difference 0.009 mm2) and the narrowest limits of agreement (-0.175 to 0.193 mm2). CONCLUSIONS: Even in cases of diabetic macular oedema, when measuring the FAZ area, the reproducibility was better between HS and HR protocols when using the SDVC slab, compared to the SVC or DVC slabs alone. Further studies should evaluate the use of the combined SDVC slab for the FAZ assessment, compared to the SVC and DVC slabs alone, in the detection and progression of different retinal diseases.

Optical coherence tomography angiography for detection of microvascular changes in early diabetes: A systematic review and meta-analysis.

AIMS: To evaluate the effectiveness of optical coherence tomography angiography (OCTA) in detecting early intraocular microvascular changes in diabetic patients. MATERIALS AND METHODS: A systematic study search was performed on PubMed, Medline, Embase, and the Cochrane Library, ranging from January 2012 to March 2023. Controlled studies compared diabetes mellitus (DM) patients with non-diabetic retinopathy (NDR) or patients with mild non-proliferative diabetic retinopathy (mild NPDR) to healthy people. These studies included parameters of OCTA such as foveal avascular zone (FAZ), vessel density of superficial capillary plexus (VDscp), vessel density of deep capillary plexus (VDdcp), and peripapillary VD. The relevant effect model was used according to the heterogeneity, and the mean difference and 95% confidence intervals were calculated. RESULTS: A total of 18 studies with 2101 eyes were eventually included in this meta-analysis. Our results demonstrated that early alterations of VDscp, VDdcp, and peripapillary VD in NDR patients had a significant difference compared with healthy people by OCTA (VDscp: WMD = -1.34, 95% CI: -1.99 to -0.68, P < 0.0001. VDdcp: WMD = -2.00, 95% CI: -2.95 to -1.04, P < 0.0001. Peripapillary VD: WMD = -1.07, 95% CI: -1.70 to -0.43, P = 0.0010). However, there was no statistically significant difference in total FAZ between them (WMD = -0.00, 95% CI: -0.02-0.01, P = 0.84). In addition, for patients with mild NPDR, OCTA could illustrate prominent changes in VDscp, VDdcp, and total FAZ compared with healthy people (VDscp: WMD = -6.11, 95% CI: -9.90 to -2.32, P = 0.002. VDdcp: WMD = -4.26, 95% CI: -5.95 to -2.57, P < 0.00001. FAZ: WMD = 0.06, 95% CI: 0.01-0.11, P = 0.03). CONCLUSIONS: In diabetic patients with or without retinopathy, the parameters of OCTA such as VDscp, VDdcp, and peripapillary vessel density were demonstrated as potential biomarkers in monitoring the early alterations of retinal microangiopathy, while total FAZ may have no significant changes in diabetic patients without retinopathy.

Investigation of the effects of single and two-muscle horizontal rectus surgeries on macular microvasculature.

PURPOSE: To investigate the changes in posterior segment hemodynamics caused by horizontal rectus muscle surgeries using the optic coherence tomography angiography (OCTA). METHODS: Patients who underwent at least one horizontal rectus recession, resection, or combination surgery were included. The patients were evaluated with an OCTA preoperatively and 30 days postoperatively. Postoperative changes in superficial capillary plexus (SCP)-vessel density (VD), deep capillary plexus (DCP)-VD, foveal avascular zone (FAZ) area and choriocapillaris (CC)-flow area parameters were examined. The mean differences (Δ) for the parameters in which significant changes were detected in the whole operated eyes group were compared between the single- and two-muscle surgery groups. RESULTS: Twenty-five eyes of 24 patients with an average age of 16.40 ± 6.75 years (5-29) were included. Of the eyes, 10 underwent single muscle recession surgery. Two-muscle surgeries were performed in 15 eyes. SCP-VD in the superior parafoveal region increased significantly postoperatively (53.23 ± 4.11% vs. 54.54 ± 3.67%, p = 0.032). For DCP-VD, there was a statistically significant increase in all zones, except the superior hemisphere and fovea regions (p < 0.05 for all). FAZ area did not change significantly (p = 0.207). There was a significant increase in the CC-flow area (2.171 ± 0.146 mm2 vs. 2.232 ± 0.115 mm2, p = 0.013). There was a significant difference between the two groups only for the Δ SCP-VD/parafovea superior value (-0.62 ± 0.98 vs. 1.57 ± 3.07, p = 0.019). CONCLUSIONS: Conventional horizontal rectus muscle surgeries may cause alterations in posterior segment hemodynamics. The number of muscles incised does not seem to greatly affect the magnitude of changes that occur. KEY MESSAGES: What is known • After conventional horizontal rectus muscle surgeries, the anterior ciliary arteries are not recanalized, instead, anterior segment blood flow is maintained by increasing the flow in the long posterior ciliary arteries. • Previous studies using Doppler ultrasonography have shown increased flow in the ophthalmic artery, central retinal artery and long posterior ciliary arteries. What is new • In this study, significant increases were observed in superficial and deep capillary plexus-vessel density and choriocapillaris-flow area parameters in the first postoperative month with optic coherence tomography angiography device. • Hemodynamic increases in both retinal and choroidal vasculature were detected in the early period after conventional horizontal rectus muscle surgeries. • The number of muscles incised does not seem to greatly affect the magnitude of changes that occur.

Morphological characteristics of the foveal avascular zone in pathological myopia and its relationship with macular structure and microcirculation.

PURPOSE: To explore the characteristics of macular structure, microcirculation, and foveal avascular zone (FAZ) morphology in pathological myopia and to research the associations between these factors and pathological myopia. METHODS: This is a cross-sectional study. The study included 103 eyes with non-high myopia and 206 eyes with high myopia (139 with simple high myopia and 67 with pathological myopia). Macular structural and microcirculation parameters were determined using optical coherence tomography angiography (OCTA). The FAZ morphological parameters were measured manually using Image J software. Correlations between pathological myopia and various factors were analyzed. RESULTS: Patients with pathological myopia had a thinner retinal thickness (RT) and choroidal thickness (CT) and a lower retinal superficial vascular density (SVD), retinal deep vascular complex density (DVD), choriocapillaris perfusion area (CCPA), and choroidal vascularity index (CVI) (all P < 0.05). Patients with pathological myopia had a larger FAZ area, perimeter, major axis, minor axis, acircularity index (AI), and lower circularity index (CI) (all P < 0.01). The axial length (AL), the major axis of the superficial FAZ, CI, and AI were significantly correlated with myopia severity (all P < 0.05). CONCLUSIONS: Patients with pathological myopia exhibited worse macular microcirculation and thinner macular retina and choroid. The FAZ in pathological myopia was larger and more irregular. The AL, CI, and AI were significantly associated with myopia severity. Thus, CI and AI might serve as new indicators for monitoring the progression of myopia. Further investigations should be performed. TRIAL REGISTRATION: Clinical Trials.gov Identifier: ChiCTR2100046590.

Relationship between long-term visual function and the ratio of foveal avascular zone area in eyes with macular hole and healthy fellow eyes.

PURPOSE: This study is to investigate the relationship between long-term changes in the foveal avascular zone (FAZ) and visual function of eyes with macular hole (MH) and compare the relationship between the FAZ of MH eyes and fellow eyes. METHODS: This study included 31 patients with unilateral MH who underwent vitrectomy and their fellow eyes. Best-corrected visual acuity (BCVA) and metamorphopsia were measured preoperatively and at 1, 3, 6, and 12 months postoperatively. We evaluated retinal parameters using optical coherence tomography (OCT) and the superficial FAZ using OCT angiography. The FAZ ratio was defined as follows: (preoperative FAZ area of the MH eye)/(FAZ area of the fellow eye). RESULTS: The preoperative FAZ area of MH eyes was 0.42 ± 0.08 mm2, which decreased to 0.24 ± 0.07 mm2 1 month postoperatively (p < 0.001) and slightly increased to 0.25 ± 0.06 mm2 12 months postoperatively (p = 1.000). The FAZ area did not differ significantly from that of fellow eyes (0.39 ± 0.06 mm2, p = 0.281). The FAZ area of MH eyes was not associated with visual function at any time point. The FAZ ratio showed a correlation with the preoperative, 6-month, and 12-month BCVA (r = 0.604, p < 0.001; r = 0.510, p = 0.003; and r = 0.475, p = 0.007, respectively). CONCLUSIONS: A larger FAZ in the MH eye than that in the fellow eye is associated with poorer long-term visual acuity. The preoperative comparison of the FAZ of the MH eye with that of the fellow eye may be a biomarker for predicting long-term visual acuity.

Quantitative optical coherence tomography angiography assessments in the fellow eyes of those with central serous chorioretinopathy.

BACKGROUND: To analyze the vessel density (VD) of the retina and choriocapillaris (CC) layer and the structure of the foveal avascular zone (FAZ) in the fellow eyes of central serous chorioretinopathy (CSC) patients by using optical coherence tomography angiography (OCTA). METHODS: This was a case-control study. Unilateral CSC patients and age-matched healthy subjects were recruited from the Affiliated Eye Hospital of Wenzhou Medical University between July 2016 and July 2021. All eyes were divided into three groups: acute CSC (aCSC), chronic CSC (cCSC), and healthy controls. Both aCSC and cCSC were again divided into two subgroups: the affected eyes and the fellow eyes. In this study, all parameters of VD and FAZ were measured by self-software of OCTA. RESULTS: A total of 231 eyes of 137 subjects were included, with 47 aCSC patients, 47 cCSC patients, and 43 healthy controls. In the fellow eyes of CSC, the retinal VD was significantly lower (all P < 0.05), and the FAZ was significantly larger (all P < 0.05) in the cCSC group than in healthy controls, while no difference was detected in the CC layer. There was no significant difference between the aCSC group and healthy controls in all OCTA parameters. In the affected eyes of CSC, the superficial retinal vessel density (SRVD) was significantly higher (all P < 0.05) in healthy controls than in the aCSC and cCSC groups, while the deep retinal vessel density (DRVD) was significantly lower (all P < 0.05) and the FAZ was larger (all P < 0.05) in the cCSC group than in the aCSC group and healthy controls. A liner regression equation was established: Y (BCVA, best corrected visual acuity) = 3.692-0.036✱X1 (DRVD-Fovea)-0.031✱X2 (FD-300, vessel density around the 300 µm width of the FAZ), R2 = 0.427. CONCLUSION: Based on OCTA measurements, this study revealed that the retinal microvascular network was impaired even in the fellow eyes of those with cCSC, which should arouse attention to the observation of unilateral CSC.

Optical coherence tomography angiography evaluation of retinal and choroidal microvascular changes in pregnant women with a history of unexplained recurrent spontaneous abortions.

PURPOSE: To study retinal and choroidal microcirculation by optical coherence tomography angiography (OCTA) in pregnant women with unexplained recurrent spontaneous abortion (RSA) and to compare them with healthy pregnant and nonpregnant subjects. METHODS: Pregnant women with an unexplained history of RSA (group 1), healthy pregnant (group 2), and healthy non-pregnant women (group 3) were included in the study. After a thorough ophthalmologic examination:best-corrected visual acuity, intraocular pressure,slit-lamp biomicroscopy, fundus examination,autorefractometer, biometry, and axial length measurement; OCT and OCTA measurements were performed with Swept Source OCT-Angiography (Topcon Co, Japan). RESULTS: The nonpregnant group had higher values for central foveal superficial capillary plexus (SCP) and deep capillary plexus (DCP) vessel density (VD) and lower values for superior, inferior, and mean VD compared with pregnant groups (p < 0.001). Choriocapillaris values (CC) VD were higher in groups 1 and 2 than in group 3 (p < 0.001). The group with unexplained RSA had a relatively smaller FAZ (foveal avascular zone) area than the group of healthy pregnant women (p:0.047). There were no statistically significant differences between groups in the retina, retinal nerve fiber layer, ganglion cell layer, and choroidal thickness (p > 0.05). CONCLUSION: Although our study did not identify any etiology in pregnant women with RSA, we observed detectable differences in FAZ area and vessel density values using OCTA, when comparing them with healthy pregnant women and healthy nonpregnant controls. We believe that OCTA, as used in many pathologies such as diabetic and hypertensive retinopathy and retinal vascular occlusion, can also be extended to unexplained RSA both to detect etiology and to monitor treatment in studies with a larger number of patients.

The Framework of Quantifying Biomarkers of OCT and OCTA Images in Retinal Diseases.

Despite the significant advancements facilitated by previous research in introducing a plethora of retinal biomarkers, there is a lack of research addressing the clinical need for quantifying different biomarkers and prioritizing their importance for guiding clinical decision making in the context of retinal diseases. To address this issue, our study introduces a novel framework for quantifying biomarkers derived from optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA) images in retinal diseases. We extract 452 feature parameters from five feature types, including local binary patterns (LBP) features of OCT and OCTA, capillary and large vessel features, and the foveal avascular zone (FAZ) feature. Leveraging this extensive feature set, we construct a classification model using a statistically relevant p value for feature selection to predict retinal diseases. We obtain a high accuracy of 0.912 and F1-score of 0.906 in the task of disease classification using this framework. We find that OCT and OCTA's LBP features provide a significant contribution of 77.12% to the significance of biomarkers in predicting retinal diseases, suggesting their potential as latent indicators for clinical diagnosis. This study employs a quantitative analysis framework to identify potential biomarkers for retinal diseases in OCT and OCTA images. Our findings suggest that LBP parameters, skewness and kurtosis values of capillary, the maximum, mean, median, and standard deviation of large vessel, as well as the eccentricity, compactness, flatness, and anisotropy index of FAZ, may serve as significant indicators of retinal conditions.

Vascular changes in the retinal capillary network in fellow eye of the patients with central retinal artery occlusion.

BACKGROUND: We aimed to evaluate the retinal vascular changes in the superficial and deep retinal vascular networks in the fellow eye of patients with central retinal artery occlusion (CRAO) and compare them with controls using optical coherence tomography angiography (OCT-A). METHODS: In a cross-sectional study, 27 patients with CRAO and 189 normal controls were included. Ophthalmic examination and OCT-A images were performed on all participants. RESULTS: The total vascular density of the superficial capillary network in the 6-mm scan was significantly lower in the fellow eye of patients with CRAO than in the control group (p = 0.02). No significant difference was observed in the FAZ area of the affected eyes and their fellow eyes compared with the controls. Total vascular density at 300 microns around the fovea was lower in the fellow eye compared with the control group (p = 0.034). CONCLUSIONS: The retinal vascular network changes in the fellow eyes of patients with CRAO suggest that persistent microvascular changes may be present before the onset of CRAO. This finding indicates that such changes could serve as an early diagnostic window for systemic vascular changes before catastrophic vascular events occur.

[Vascularized foveal zone: prevalence and structural characteristics]. / Vaskulyarizovannaya foveal'naya zona: rasprostranennost' i strukturnye kharakteristiki.

PURPOSE: This study was performed to assess the prevalence of the vascularized foveal zone, including macular-foveal capillaries (MFC) and congenital retinal macrovessels (CRM), and to analyze the structural characteristics of the macular area in patients with MFC. MATERIAL AND METHODS: The first phase of the study evaluated the prevalence of MFC and CRM. Optical coherence tomography angiography (OCT-A) was performed, and OCT-A images of the foveal avascular zone were analyzed. In the second phase, two groups were formed: the MFC group (12 eyes, 9 patients, mean age 43.8±10.7 years) and the control group (18 eyes, 17 patients, mean age 43.0±11.8 years). A comparative analysis was performed assessing central retinal thickness (CRT), thickness of retinal nerve fiber layer (RNFL), ganglion cell layer (GCL), inner plexiform layer (IPL), inner nuclear layer (INL), outer plexiform layer (OPL), outer nuclear layer (ONL), and foveal pit depth. RESULTS: MFCs were detected in 45 eyes from a total sample of 1031 eyes of 536 patients. The presence of CRM was recorded in three eyes of three patients. RNFL thickness was significantly higher in the MFC group in the inferior parafoveal sector (26.50 [26.00; 29.50] and 24.50 [21.75; 26.50] µm; p=0.022) and in the foveal zone (15.50 [14.00; 16.00] and 12.00 [11.00; 14.00] µm; p=0.017). Additionally, patients with MFC had a higher thickness of GCL and IPL in the fovea, inferior, nasal, and temporal parafoveal sectors. The depth of the foveal pit was significantly lower in the MFC group compared to the control group (83.0 [77.4; 101.6] and 128.0 [107.5; 147.05] µm; p=0.001). CONCLUSION: The prevalence of MFC was 4.36% (calculated per number of eyes), while the prevalence of CRM - 0.29%. The macular area in patients with MFC had increased thickness of the inner retinal layers and decreased depth of the foveal pit, suggesting potential disruption in the natural process of ganglion cell migration and apoptosis during embryogenesis.

[Terminology of quantitative optical coherence tomography angiography metrics]. / Osobennosti terminologii kolichestvennykh pokazatelei opticheskoi kogerentnoi tomografii-angiografii.

This review is devoted to the English- and Russian-language terminology of quantitative metrics that are used in the evaluation of images obtained by optical coherence tomography angiography (OCT-A). The paper presents an analysis of the use of terms characterizing intraretinal blood flow (vascular density, perfusion density, skeletonized density, etc.), area and shape of the foveal avascular zone, and choriocapillaris blood flow. The factors causing the heterogeneity of OCT-A terminology are described, including the lack of a unified international nomenclature for OCT-A, features of their Russian translation, inconsistency of the parameters in optical coherence tomography systems of different manufacturers. The article also considers ways to standardize the terminology.

Foveal avascular zone size and mfERG metrics in diabetes and prediabetes: a pilot study of the relationship between structure and function.

PURPOSE: Previous studies have demonstrated functional and structural retinal changes in type 2 diabetes (T2DM). However, less is understood in prediabetes, which is an important precursor to T2DM. Here, we evaluate the microvasculature structure of the foveal avascular zone (FAZ) and how it is correlated with retinal function as measured by the multifocal electroretinogram (mfERG) across levels of glucose dysfunction to uncover how T2DM and prediabetes alter this structure-function relationship. METHODS: 33 subjects were included: 9 controls, 12 prediabetes, 12 T2DM with no retinopathy or edema. Subjects were aged 30-70 years, had BCVA of 20/25 or better, and had no confounding ocular conditions. Blood was collected via fingerstick to determine Hemoglobin A1c (HbA1c), which was used along with previous diagnosis, to determine study grouping. Optical coherence tomography angiography (OCTA) was used to analyze the FAZ area and was corrected for refractive error. FAZ area was measured by hand using the Heidelberg Spectralis software. mfERG (VERIS 6.3) metrics implicit time (IT) and amplitude were evaluated in the foveal region, macular region, and averaged over the posterior pole of the right eye. Regression analysis was performed between each study group parameter to determine relationships, and t tests with corrections were used to compare groups. RESULTS: FAZ area (superficial plexus) was negatively correlated with mfERG posterior pole amplitude (p < 0.01, R2 = 0.30), foveal amp (p = 0.02 R2 = 0.17) and macular amplitude (p = 0.02 R2 = 0.18) across all 33 study subjects. FAZ and mfERG metrics were not significantly different between study groups in this cohort except for IT, which was more delayed in the diabetes group compared to other groups. CONCLUSION: FAZ area is correlated with mfERG amplitudes but not IT. This suggests a link between the structural metrics and retinal function. Longitudinal follow-up work would be helpful to determine the timing of these changes in prediabetes.

Microstructural and hemodynamic changes in the fundus after pars plana vitrectomy for different vitreoretinal diseases.

BACKGROUND: Pars plana vitrectomy is the standard treatment for several vitreoretinal diseases. Continuous improvements in ophthalmic surgical techniques have led to excellent postoperative recovery of the anatomic structure of the fundus. However, postoperative visual outcomes are not always satisfactory. METHODS: A literature search of articles published before 31 December 2022 was conducted on PubMed using the following keywords: "diabetic retinopathy," "rhegmatogenous retinal detachment," "idiopathic epiretinal membrane," "idiopathic macular hole," "vitrectomy," "optical coherence tomography," "optical coherence tomography angiography," "microstructure," "microstructural," "hemodynamic," "hemodynamics," and "microcirculation." Additional studies were identified by hand-searching references for relevant studies. Articles were screened for language, repetition, and relevance to the direction of study. Studies with a sample size ≥ 7 and the final follow-up time ≥ 4 weeks after vitrectomy were included in this review. Only articles published in English were included. Articles not related to our topic were excluded. Reviews and single case reports were excluded. We structured this review by disease category. The thickness of the retina and choroid, the area of the foveal avascular zone, the vessel density of the retinal and choroidal capillary plexus, and the potential association of related parameters with postoperative visual outcomes are the main outcome measures of studies included in this review. RESULTS: A total of 48 studies were included in this review. There were contradictory results regarding the association between postoperative microcirculatory parameters and visual acuity in patients with diabetic macular edema, with some studies concluding that improvement in perimacular microcirculation may be an important factor that affects visual acuity, and others concluded that postoperative improvement in visual acuity was not related to changes in macular blood flow. The results of studies on the relationship between postoperative microstructural and microcirculatory parameters and visual acuity in rhegmatogenous retinal detachment, idiopathic epiretinal membrane, and idiopathic macular hole eyes have been inconsistent. In gas tamponade macula-off rhegmatogenous retinal detachment eyes, postoperative best-corrected visual acuity has been reported to correlate positively with vessel density of deep capillary plexus and negatively with foveal avascular zone area of superficial capillary plexus and deep capillary plexus. In silicone oil tamponade macula-off rhegmatogenous retinal detachment eyes, best-corrected visual acuity has been reported to be positively correlated with the retinal thickness of the parafoveal 3 mm temporal quadrant and positively correlated with the vessel density of the superficial capillary plexus in the foveal, parafoveal, and perifoveal area. In addition, best-corrected visual acuity was worse and associated with reduced thickness of the inner retina, ganglion cell layer, outer plexiform layer, and outer nuclear layer in silicone oil tamponade rhegmatogenous retinal detachment eyes compared to gas tamponade. Postoperative best-corrected visual acuity in idiopathic epiretinal membrane eyes was positively correlated with the foveal avascular zone area but negatively correlated with full retinal thickness and inner retinal thickness in the foveal and parafoveal areas. Improvement in postoperative best-corrected visual acuity in idiopathic macular hole eyes was associated with reduced inner retinal thickness and reduced foveal avascular zone area. CONCLUSIONS: Microstructural and hemodynamic changes are involved in the recovery process after PPV for different vitreoretinal diseases. The thickness of each retinal layer in different regions of the macula, foveal avascular zone area, and vessel density of different retinal capillary plexuses in different macular regions may be potential prognostic factors for postoperative visual recovery. However, the results of the existing literature are inconsistent and require further study.

Optical Coherence Tomography Angiography in Diabetic Macular Edema Treated with Intravitreal Aflibercept: A 48-Week Observational Study (the DOCTA Study).

INTRODUCTION: Central vision loss due to diabetic macular edema (DME) is related to the macular edema itself but also, in some cases, to alterations of the foveal avascular zone (FAZ). The aim of this trial was to study changes in macular vessels in eyes with DME treated with aflibercept using optical coherence tomography angiography (OCTA). METHODS: This was a longitudinal, prospective, noncontrolled, single-arm study. The primary objective was the quantitative assessment of macular vessels over time in patients with DME treated with intravitreal aflibercept during a 48-week follow-up using OCTA. RESULTS: Twenty-six DME eyes from 26 patients were included (mean age, 64.6 years; women, 53.8%; prior anti-VEGF treatment, 46.1%). Each eye received a mean (SD) of 7.2 (2.2) injections. The following parameters of the FAZ did not change during the 48-week follow-up: the mean (SD) FAZ area varied from 0.19 (0.19) mm2 at baseline (n = 22) to 0.23 (0.20) mm2 at week 48 (n = 15), boundary from 1.54 (1.21) to 2.04 (1.20) mm, and circularity from 0.45 (0.33)% to 0.57 (0.20)%. There was no change in perfusion density and vessel density of the macula in the 3-mm circle. As expected, mean central retinal thickness, macular volume, and visual acuity improved during follow-up. CONCLUSION: No change in macular perfusion was observed in eyes with DME during a 48-week follow-up after intravitreal injections of aflibercept. Randomized controlled trials using OCT angiography in large populations with extended observation periods are needed to assess changes in macular vessels after intravitreal anti-VEGF treatment.

The Influence of Myopia on the Foveal Avascular Zone and Density of Blood Vessels of the Macula-An OCTA Study.

Background and Objectives: Myopia is the most common refractive eye anomaly with a prevalence that is constantly increasing. High myopia is associated with numerous complications that can lead to permanent vision loss. It is believed that the basis of these complications lies in changes in the microvasculature of the retina caused by an increase in the longitudinal axis of the eye. Materials and Methods: Optical coherence tomography angiography (OCTA) was used to analyze differences in macular zone vascular and perfusion density and foveal avascular zone (FAZ) parameters in myopic subjects. The following OCTA parameters were analyzed: the vessel and perfusion density of retinal blood vessels in the superficial plexus; the area, perimeter, and index of circularity of the foveal avascular zone (FAZ); and foveal and ganglion cell complex (GCC) thickness. Results: Subjects with low myopia did not show statistically significant differences compared to the control for any of the analyzed parameters. Groups with moderate and high myopia showed a significant decrease in vessel and perfusion density in the parafoveal and the entire 3 × 3 mm analyzed field. Foveal vessel and perfusion densities in the myopic groups were similar to those of the control regardless of the degree of myopia. The area and perimeter of the FAZ, as well as foveal and mean GCC thickness, did not differ significantly no matter the degree of myopia, while the index of circularity was lower in highly myopic subjects. The minimal thickness of the GCC was also lower in the high myopia group. Conclusions: High and moderate myopia led to a loss of blood vessels in the macular region. Perfusion and vascular densities were preserved in the foveal region and were not affected by different degrees of myopia. The FAZ was not significantly larger in myopic subjects, but its circularity was lower in subjects with high myopia.

Quantitative vessel density analysis of macular and peripapillary areas by optical coherence tomography angiography in adults with primary nephrotic syndrome.

PURPOSE: To compare the microvascular parameters of macular and peripapillary areas in adults with primary nephrotic syndrome (PNS) and healthy controls (HCs). METHODS: In this cross-sectional study, optical coherence tomography angiography (OCTA) was used to evaluate the changes in retinal microvascular in 37 adult patients with PNS and 30 HCs in this study. All subjects underwent OCTA for measuring vascular density (VD), perfusion density (PD), and foveal avascular zone (FAZ) in the superficial capillary plexus (SCP) and optical coherence tomography (OCT) for measuring central macular thickness (CMT) and retinal nerve fiber layer (RNFL) thickness. The following clinical data of the PNS group were collected: hemoglobin, platelet, total protein, albumin, prealbumin, creatinine, urea nitrogen, glomerular filtration rate, blood lipid, urinary protein, urine microalbumin, urine microalbumin/creatinine, 24-h urine volume, and 24-h urine protein quantification. The OCTA data were compared between patients with PNS and HCs, and the correlation between the OCTA data and clinical data was analyzed in the PNS group. RESULTS: VD and PD in the macular area of the PNS group were significantly lower than those in the HC group (VD: 17.025 ± 2.229 vs. 18.290 ± 0.721, P = 0.001; PD: 0.417 ± 0.058 vs. 0.450 ± 0.019, P = 0.003). No significant differences in the FAZ area and perioptic disc microvascular parameters were observed between the two groups, and patients in the PNS group showed consistent changes in the left and right eyes. VD and PD in the central macular area were positively correlated with plasma prealbumin level (VD: ρ = 0.541, P = 0.001; PD: ρ = 0.562, P < 0.001) and negatively correlated with urinary protein level (VD: ρ = -0.579, P < 0.001; PD: ρ = -0.596, P < 0.001). CONCLUSIONS: In adult patients with PNS, the decrease in VD and PD was mainly occurred in the macular area. Partly vascular density of the macular area was positively correlated with plasma prealbumin level and negatively correlated with urinary protein level. OCTA provides a convenient, non-invasive and effective method for evaluating and monitoring retinal microcirculation damage in patients with PNS.

Analysis of macular blood flow changes in thyroid associated ophthalmopathy.

BACKGROUND: To evaluate the changes in macular superficial retinal vessel density and their relation with visual acuity in thyroid-associated ophthalmopathy (TAO) patients with different severity. METHODS: This cross-sectional observational study included 70 TAO patients and 70 healthy controls. Only data from the right eyes were analyzed. TAO patients were divided into 7 subgroups according to the NOSPECS score. Foveal avascular zone (FAZ), vascular density (VD), and perfusion density (PD) of macular 1 mm diameter and 6 mm diameter areas were measured by optical coherence tomography angiography (OCTA). RESULTS: In TAO patients, significant increases were found in macular and foveal vascular densities (FVD) and perfusion densities (FPD) while a significant decrease was found in the FAZ area when compared with the control group (p < 0.05). Spearman correlation analysis and multiple linear regression analysis showed that TAO severity grade was negatively correlated with FVD (ß = -1.150, p = 0.032), FPD (ß = -0.024, p = 0.042), MVD (ß = -0.583, p = 0.020) and MPD (ß = -0.011, p = 0.010). Clinical activity score (CAS) score showed positive correlation with FVD (ß = 0.794, p = 0.035) and FPD(ß = 0.017, p = 0.041). FVD (ß = -0.009, p = 0.033), MVD(ß = -0.034, p < 0.001), FPD(ß = -0.416, p = 0.039) and MPD(ß = -2.428, p < 0.001) all showed negative correlation with best corrected visual acuity (BCVA). CONCLUSIONS: There was an overall increase in superficial macular blood flow in TAO patients compared with healthy controls and the blood flow decreased as TAO got worse. Superficial macular flow density was negatively correlated with BCVA.

Optical coherence tomographic angiography in children with anisometropic amblyopia.

OBJECTIVES: To observe and compare the difference in retinal perfusion using optical coherence tomography angiography (OCTA) between anisometropic amblyopia in children and fellow eyes as well as age-matched controls. METHODS: A total of 16 children with anisometropic amblyopia and 19 age-matched healthy subjects were enrolled. All participants underwent OCTA examination, with 3 mm × 3 mm and 6 mm × 6 mm scans in the macular region. Perfusion parameters of the superficial retinal layer were measured by built-in software, including the macular foveal avascular zone (FAZ) area, perimeter and circularity, as well as the vessel length density (VLD) and perfusion density (PD) of the foveal, parafoveal and perifoveal regions. RESULTS: Among the 16 patients with anisometropic amblyopia, the FAZ area was significantly higher in diseased eyes (P = 0.027) than in fellow eyes. The VLD and PD of the foveal average and the VLD of the nasal quadrant of the perifoveal region in anisometropic amblyopic eyes were significantly lower than those in fellow eyes (P < 0.05). The VLD of the parafoveal average, the superior, temporal, inferior and nasal quadrants of the parafoveal region, and the nasal quadrant of the perifoveal region in anisometropic amblyopic eyes were significantly lower than those in healthy controls (P < 0.05). The PD of the parafoveal average, and the inferior quadrant of the parafoveal region in anisometropic amblyopic eyes were significantly lower than those in healthy controls (P < 0.05). The VLD of the parafoveal average, the superior, inferior and nasal quadrants of the parafoveal region, and the nasal quadrant of the perifoveal region in fellow eyes were significantly lower than those in healthy controls (P < 0.05). The PD of the parafoveal average, and the inferior quadrant of the parafoveal region in fellow eyes were significantly lower than those in healthy controls (P < 0.05). CONCLUSIONS: The macular vessel density of the superficial capillary plexus is lower in anisometropic amblyopic children than in age-matched healthy children. Compared with the fellow eye, the perfusion of the amblyopic eye in children with anisometropic amblyopia also decreases.

Assessment of macular findings by OCT angiography in patients without clinical signs of diabetic retinopathy: radiomics features for early screening of diabetic retinopathy.

This cross-sectional study aimed to quantitatively analyze the optical coherence tomography angiography (OCTA) images using MATLAB-based software and evaluate the initial changes in macular vascular density and the distortion of the foveal avascular zone (FAZ), before the clinical appearance of diabetic retinopathy. For this purpose, 21 diabetic patients without any clinical features indicating DR, and 21 healthy individuals matched with patients based on their demographic characteristics were included. Macular thickness, macular vascular density, and morphological changes of FAZ were assessed using OCTA. The diagnostic ability of morphological parameters was evaluated by receiver operating curve analysis. The intraclass correlation coefficient (ICCC) index was used to check the consistency of the extracted values. There was no significant difference in age, gender, LogMAR visual acuity, spherical equivalent, and intra-ocular pressure amongst patients and controls. No correlation was found between age and the FAZ area as well as vascular density. The vascular structure of the superficial layer showed FAZ enlargement, reduced vascular density in the macular area, and significant deviations of FAZ shape parameters (convexity and Frequency Domain Irregularity) in patients compared with healthy individuals. Measurements were highly correlated between separate imaging sessions with ICCC of over 0.85 for all parameters. The represented data suggests that radiomics parameters can be applied as both an early screening tool and guidance for better follow-up of diabetic patients who have not had any sign of DR in fundoscopic exams.