Documenting the organization of the retinal capillaries is of importance to understand the visual consequences of vascular diseases which may differentially affect the microvascular layers. Here we detailed the spatial organization of the macular capillaries in ten healthy human subjects using a prototypic adaptive optics-enhanced optical coherence tomography angiography (AO-OCTA) system. Within the central 6° × 6°, the radial peripapillary capillaries and the superficial, intermediate and deep vascular plexuses (SVP, IVP and DVP, respectively) were consistently resolved. In 8 out of the 10 eyes, the capillary segments composing the perifoveal arcade (PFA) were perfused only by the SVP, while drainage of the PFA showed more variability, comprising a case in which the PFA was drained by the DVP. Around the center, a distinct central avascular zone could be documented for each layer in 7 of the 10 cases; in three eyes, the IVP and SVP merged tangentially around the center. In all eyes, the foveal avascular zone was larger in the DVP than in the SVP and IVP. In one eye with incomplete separation of the inner foveal layers, there was continuity of both the SVP and the IVP; a central avascular zone was only present in the DVP. The diversity of perfusion and drainage patterns supported a connectivity scheme combining parallel and serial organizations, the latter being the most commonly observed in perifoveal vessels. Our results thus help to further characterize the diversity of organization patterns of the macular capillaries and to robustly analyze the IVP, which will help to characterize early stages of microvascular diseases.

OBJECTIVE: Radiation-induced optic neuropathy (RION) is rare but may lead to blindness. The mechanisms by which this occurs include endothelial and neuronal damage, but RION has been assessed very little in the case of extraocular tumors treated with high-energy proton therapy, the use of which is expanding worldwide. We assessed peripapillary microvascular changes by optical coherence tomography angiography (OCT-A) in patients undergoing high-energy proton therapy for para-optic intracranial or head and neck tumors.
METHODS: In this prospective institutional review board approved study, patients receiving>40Gy_RBE maximal PBT dose to their optic nerve between 2018 and 2020 underwent quantitative OCT-A analyses. ImageJ software was used to assess changes in the peripapillary superficial vascular complex (SVC) using vascular area density (VAD), vessel length density (VLD) and fractal dimension (FDsk). Uni- and multivariate analyses were performed.
RESULTS: Of 47 patients (78 eyes) with 29±6 months of follow-up (range 18-42), 29 patients (61.7%) had previously undergone surgery and 18 (32.1%) had microvascular abnormalities prior to proton therapy. Total radiotherapy dose was the most relevant factor in decreased peripapillary microvasculature. Duration of follow-up was associated with lower VAD (P=0.005) and mean retinal nerve fiber layer (RNFLm) thickness also decreased. There was no significant correlation between OCT-A changes and mean visual defect.
CONCLUSIONS: Peripapillary microvasculature changes may occur from tumor compression or surgery and proton therapy for extraocular tumors. OCT-A may provide quantitative and mechanistic insights into RION before the occurrence of clinical symptoms.

OBJECTIVE: To study the effect of brimonidine on vascular density and flow index of optic nerve head (ONH) and macula in primary open angle glaucoma (POAG) using optical coherence tomography angiography (OCTA).
METHODS: Twenty-three brimonidine-naïve POAG patients were started on brimonidine. They underwent OCTA ONH and macula before commencing brimonidine and one month thereafter. Systemic arterial blood pressure (SABP) and intraocular pressure (IOP) were measured at each visit to calculate mean ocular perfusion pressure (MOPP). The OCT angiograms were analyzed using ImageJ software to calculate ONH and macular flow indices.
RESULTS: Thirty-seven eyes (23 patients) with a mean age of 56.7 ± 12.49 years were included of whom 60.8% were males. Brimonidine was associated with an increase in the superficial flow index (SFI) (P-value = 0.02) and optic nerve head flow index (ONHFI) (P-value = 0.01). Also, superficial vascular density (SVD) for whole image, superior-hemi and fovea increased (P-value = 0.03, 0.02, 0.03 respectively). ONH inferior-hemi vascular density decreased (P-value = 0.01) despite an increase in inferior quadrant retinal nerve fiber layer thickness (RNFLT) (P-value = 0.03). There was no statistically significant correlation between flow indices and MOPP at baseline and follow-up. A moderate negative correlation was found between SVD and DVD at the fovea and MOPP at baseline and follow-up (P-value = 0.03, 0.05) (P-value = 0.02, 0.01) respectively.
CONCLUSIONS: Brimonidine was associated with an increase in SFI, ONHFI and SVD indicating improved GCC and RNFL perfusion in POAG. Despite the increase in inferior quadrant RNFLT, the concomitant decrease in inferior-hemi ONHVD precluded a conclusion of hemodynamically-mediated improvement of RNFLT.

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.
Обзор посвящен англо- и русскоязычной терминологии количественных показателей, которые применяются при оценке изображений, полученных методом оптической когерентной томографии-ангиографии (ОКТ-А). Проанализирована частота использования терминов, характеризующих интраретинальный кровоток (сосудистая плотность, плотность перфузии, скелетонизированная плотность и др.), площадь и форму фовеальной аваскулярной зоны, хориокапиллярный кровоток. В работе описаны факторы, обусловливающие многообразие связанной с ОКТ-А терминологии: отсутствие единой международной количественной номенклатуры ОКТ-А, особенности русскоязычного перевода, несогласованность показателей оптических когерентных томографов разных производителей. Рассмотрены пути к стандартизации терминологии.

OBJECTIVE: To determine whether there are quantitative changes in macular, choriocapillary, and peripapillary microvascular structures using optical coherence tomography angiography (OCTA) due to the presence of lupus nephritis (LN) in patients with systemic lupus erythematosus (SLE) and to investigate the correlation between these quantitative values and disease duration.
METHODS: Fifty -five patients followed up in the rheumatology clinic with an SLE diagnosis were evaluated. As the control group, 61 eyes of 61 age- and gender-matched healthy individuals were included. The patients with SLE were further divided into two groups: those with LN (29 eyes) and those without LN (26 eyes). Macular, choriocapillary, and peripapillary microvascular structures were quantitatively analyzed with OCTA and compared between the three study groups. A correlation analysis of the measured quantitative values and disease duration was also performed.
RESULTS: In macular microvascular (MMV) analysis, the vessel densities (VDs) of the superficial capillary plexus (SCP) decreased in both SLE groups, while those of the deep capillary plexus (DCP) decreased only in the SLE group with LN. The foveal density significantly decreased in the SLE group with LN compared to the control group, there were no significant differences in terms of the radial peripapillary capillary VDs or the choriocapillaris flow area. Disease duration was not correlated with any of the quantitative parameters measured by OCTA in either SLE group.
CONCLUSIONS: Identifying differences in retinal microvascular circulation in SLE patients with kidney damage helps predict possible nephropathy and therefore guides the treatment process of this patient.

OBJECTIVE: The association between the total macular burden of hyperreflective foci (HRF) in eyes with intermediate AMD (iAMD) and the onset of persistent choroidal hypertransmission defects (hyperTDs) was studied using swept-source optical coherence tomography (SS-OCT).
METHODS: Post hoc subgroup analysis of a prospective study.
METHODS: A retrospective review of iAMD eyes from subjects enrolled in a prospective SS-OCT study was performed. All eyes underwent 6×6 mm SS-OCT angiography (SS-OCTA) imaging at baseline and follow-up visits. En face sub-retinal pigment epithelium (subRPE) slabs with segmentation boundaries positioned 64-400 µm beneath Bruch\'s membrane (BM) were used to identify persistent choroidal hyperTDs. None of the eyes had persistent hyperTDs at baseline. The same subRPE slab was used to identify choroidal hypotransmission defects (hypoTDs) attributable to HRF located either intraretinally (iHRF) or along the RPE (rpeHRF) based on corresponding B-scans. A semiautomated algorithm was used by two independent graders to validate and refine the HRF outlines. The HRF area and the drusen volume within a 5mm fovea-centered circle were measured at each visit.
RESULTS: The median follow-up time for the 171 eyes from 121 patients included in this study was 59.1 months (95%CI: 52.0-67.8 months). Of these, 149 eyes (87%) had HRF, and 82 (48%) developed at least one persistent hyperTD during the follow-up. Although univariable Cox regression analyses showed that both drusen volume and total HRF area were associated with the onset of the first persistent hyperTD, multivariable analysis showed that the area of total HRF was the sole significant predictor for the onset of hyperTDs (P<0.001). ROC analysis identified an HRF area ≥ 0.07 mm² to predict the onset of persistent hyperTDs within one year with an area under the curve (AUC) of 0.661 (0.570-0.753), corresponding to a sensitivity of 55% and a specificity of 74% (P<0.001).
CONCLUSIONS: The total macular burden of HRF, which includes both the HRF along the RPE and within the retina, is an important predictor of disease progression from iAMD to the onset of persistent hyperTDs and should serve as a key OCT biomarker to select iAMD patients at high-risk for disease progression in future clinical trials.

We wanted to evaluate if optical coherence tomography angiography OCTA findings could predict the functional outcome in extracranial carotid artery atherosclerotic disease (ECAD) associated stroke. This exploratory study was performed on adults with acute ischaemic stroke due to ECAD at 3-6 weeks following stroke onset with risk factor matched controls without carotid artery stenosis. Twenty-three stroke patients (cases) and 23 controls were enrolled. There was significant difference between cases and controls in deep vessel density at the macula (p = .0007) and in radial peripapillary capillary perfusion density (RPCPD) at the optic nerve head (ONH) (p = .0007). Statistically significant difference was noted in the total superficial vessel density (SVD) at the macula (SVD within 1 standard deviation [SD] versus SVD beyond 1 SD of control data) in the ipsilateral eye and functional outcome at 3 months (poor versus very good outcome, modified Rankin scale [mRS] 0-1 versus mRS 2-6, respectively; p = .0361). There was statistically insignificant correlation between the RPCPD at the ONH and the National Institutes of Health Stroke Scale score at admission, mRS at discharge, and mRS at 3 months following stroke onset (r = .33, r = .35, r = .39; p = .11, p = .09, p = .06, respectively). The findings of this exploratory study suggested that OCTA findings may predict 3 month outcomes in cases of ECAD-related stroke and could be useful in decision making in future intervention studies as to whether intervene or not in patients having critical or non-critical ECAD for preventing stroke.

In this study, we aimed to identify the features of indeterminate choroidal melanocytic lesions visualized on optical coherence tomography angiography (OCTA) and to identify the predictors of growth. We retrospectively evaluated 86 patients with indeterminate lesions treated at our centre from 2016 to 2021. Clinical management involved active surveillance followed by brachytherapy if growth was detected. The lesions were classified into two groups according to whether they grew (small melanomas) or remained stable (choroidal nevi). Growth was detected in 19 (22.1%) lesions. All patients underwent OCTA at baseline. These images were compared to identify the possible predictors of growth. Significant between-group differences were observed in thickness (p = 0.00), greatest basal diameter (p = 0.00), number of risk factors (p = 0.00), symptoms (p = 0.001; relative risk [RR]: 4.3), orange pigment (p = 0.00; RR: 6.02), and ultrasonographic hollowness (Kappa sign); p = 0.000; RR: 5.3). The melanomas had significantly more vessels with a diameter ≥ 76.3 µm (p = 0.02; RR: 2.46). The time to growth in these lesions was significantly shorter (p = 0.05) than in lesions with smaller vessels. These findings show that vessel diameter quantified by OCTA can help differentiate between choroidal nevi and small melanomas, when considered together with clinical risk factors.

OBJECTIVE: The aim of this study is to analyse whether optical coherence tomography angiography (angio-OCT, OCTA) measurements can be a useful tool to differentiate central nervous system (CNS) involvement in rheumatic disorders (RD) from multiple sclerosis (MS).
METHODS: A total of 85 patients- 41 with MS, 21 with RD with CNS involvement and 23 healthy controls were included in the study. All individuals underwent OCTA and the following parameters were measured in each eye separately: average foveal and parafoveal vessel density (VD), average foveal and parafoveal vessel length (VL) of the superficial capillary plexus (SCP) and deep capillary plexus (DCP), as well as area, perimeter, and circularity of the foveal avascular zone.
RESULTS: OCTA showed a VD reduction in the foveal region of the SCP in eyes of RD patients when compared to MS patients (21.96 ± 3.39 vs.23.88 ± 3.05 (p = 0.003)). There have been no significant differences in any of the assessed parameters that is average VD and total average VL in the foveal area of the SCP as well as of the DCP in the general population comprising healthy controls, MS and RD groups (p > 0.05 for all).
CONCLUSIONS: Our results suggest that an OCTA finding of decreased VD in the foveal region of the SCP may be considered as a potentially useful biomarker of RD in comparison with MS patients.

OBJECTIVE: To investigate the formation and absorption of avascular subretinal hyperreflective material (avSHRM) in neovascular age-related macular degeneration (nAMD) based on optical coherence tomography angiography (OCTA) characteristics.
METHODS: Prospective cohort study METHODS: This study included patients with treatment-naïve nAMD and followed up for 3 months. Subjects were classified into avSHRM group and non-avSHRM group based on the presence of avSHRM at baseline. Quantitative OCTA characteristics including explant area, perimeter, vessel area, density, length, junctions, endpoints, lacunarity, maximum vessel caliber, vessel dispersion, and fractal dimension were assessed, three-dimensional volume and optical density ratio (ODR) of avSHRM were measured. Comparison analyses, correlate coefficients and regression models were applied to explore factors associated with avSHRM formation and absorption.
RESULTS: 88 eyes from 88 patients (39 females) were enrolled. Compared to non-avSHRM group, avSHRM group exhibit a more intricate vasculature, characterized by higher value of macular neovascularization (MNV) perimeter, vessel area, total vessel length, total number of junctions and total number of endpoints (all P < 0.05), as well as the maximum vessel caliber (P < 0.001). In the multivariate model, which has been adjusted for age, gender, and types of medications, avSHRM absorption was correlated with baseline average vessel length, maximum vessel caliber and avSHRM ODR (standardized β = 0.274, -0.367 and -0.334; P = 0.049, 0.010 and 0.018, respectively), with an adjusted R² of 0.453.
CONCLUSIONS: Quantitative OCTA measurements can be utilized for assessing the dynamics of avSHRM in nAMD. Patients with more complex vasculature are at a higher risk of avSHRM formation. Average vessel length, maximum vessel diameter and avSHRM ODR play a role in its absorption.