OCT Angiograms Research Articles

Effect of brimonidine on vascular density and imagej-derived flow index of optic nerve head and macula in primary open angle glaucoma.

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). 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. Thirty-seven eyes (23 patients) with a mean age of 56.7 ± 12.49years 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. 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.

Retinal microvascular density analysis in patients with rheumatoid arthritis treated with hydroxychloroquine

PurposeRheumatoid arthritis (RA) is the most common inflammatory joint disease, and hydroxychloroquine (HCQ) is an established treatment. The extent to which HCQ impacts ocular microvascular vessel density (VD) in patients with RA without evidence of HCQ retinopathy has not yet been conclusively clarified. The main aim of this study was to evaluate VD measured by optical coherence tomography angiography (OCTA) in patients with RA treated with HCQ.MethodsThe VD data of the 3 × 3 mm OCT angiogram (RTVue XR Avanti, Optovue Inc., Fremont, California, USA) as well as the retinal thickness (RT) data of patients with RA (n = 30) and healthy controls (n = 30) were extracted and analyzed. The study group was further divided into patients undergoing HCQ treatment for > 5 years (high-risk-group) and < 5 years (low-risk group).ResultsPatients with RA showed no evidence of VD reduction compared to the control group in all obtained regions (p > 0.05). Correlation analysis revealed no dependency between VD, RT, and HCQ therapy duration or cumulative HCQ dose (p > 0.05). High-risk patients showed a decreased VD in the superficial quadrant of the superficial capillary plexus compared to low-risk-patients (p = 0.022). Whole-en-face RT was reduced in the high-risk group compared to the control group (p = 0.019).ConclusionOur study showed no evidence that HCQ diminishes VD in patients with RA without HCQ retinopathy measured by OCTA. However, RA patients with a long duration of therapy showed a significantly reduced RT. Our results suggest that quantitative VD analysis by OCTA may not be suitable for early detection of HCQ retinopathy and that the focus on detecting early HCQ retinopathy should be on intensive and sequential OCT diagnostics.

Comparative study of lipid profile influence on foveal avascular central zone

AbstractPurpose: To evaluate the influence of lipid profile on foveal avascular central zone (ACZ) using Swept Source Optical Coherence Tomography Angiography (SS‐OCT A).Methods: A cross‐sectional, comparative study including 30 eyes of 15 volunteers with no history of ocular disease or surgery was conducted in the department of ophthalmology of Habib Thameur University Hospital, Tunis. SS‐OCT A imaging was performed using the DRI‐OCT Triton (Topcon, Japan). The macula was imaged using 3 × 3 mm scans, and superficial retinal OCT angiograms were extracted and analysed. Foveal ACZ was characterized by its perimeter, its area, its circularity, the aspect ratio (AR), the roundness index (Round), the solidity and the Feret's diameter (Feret). Patients with dyslipemia were compared to a control group using the Mann–Whitney U‐test and the degree of correlation between two variables was expressed as the Spearman's correlation coefficient.Results: Eleven males and four females were included in the study. Sixteen eyes of eight patients (53.3%) with dyslipemia were compared to fourteen eyes of 7 healthy controls (46.7%). Mean age was 53.33 ± 9.73 years. Mean total ACZ measurements were: Perimeter (2.63 ± 0.53), Area (3.98 ± 1.49), Circularity (7.07 ± 0.97), AR (1.23 ± 0.23), Round (8.32 ± 1.18), Solidity (8.86 ± 0.41) and Feret (6.53 ± 3.24). Comparative study revealed that ACZ area was higher in the dyslipemia group than in the control group (4.64 vs. 3.31, p = 0.02). There was no significant difference between the two groups in the other measurements of ACZ.Conclusions: Dyslipemia causes enlargement of the foveal avascular central zone without affecting its form. These results suggest that dyslipemia may affect foveal vascular structure potentially through chronic ischemia mechanisms.

Retinal Vascular Plexuses Are Unequally Affected in Canine Inherited Retinal Degenerations.

To characterize the progression of vascular changes that occur in each retinal plexus, in three canine models of inherited retinal degeneration. In this retrospective cohort study, we examined the retinal imaging records of 44 dogs from a research colony that had undergone optical coherence tomography angiography (OCTA) imaging. Animals enrolled included crd2/NPHP5 and xlpra2/RPGR mutant dogs imaged at different stages of photoreceptor loss, as well as RHOT4R/+ dogs after acute light-induced rod degeneration. Also included were normal controls imaged at similar ages. OCT angiograms of the superficial vascular plexus combined with the intermediate capillary plexus (SVP + ICP), and the deep capillary plexus (DCP) were analyzed using the AngioTool software to calculate vessel density and other vascular parameters. A reduction in vessel density was seen over time in both the SVP + ICP and DCP in all mutant dogs but was more pronounced in the DCP. Scans were subclassified based on outer nuclear layer (ONL) thinning compared to age-matched normal controls. When ONL loss was 0% to 50%, vessel density in the DCP was significantly lower than in age-matched controls. In all cases, when ONL loss exceeded 87.5%, vessel density in the SVP + ICP was significantly reduced as well. In the acute light-induced rod degeneration model, the vascular regression changes were observed mainly in the DCP. Vessel density reduction in dogs undergoing retinal degeneration is first detected by OCTA in the DCP, and only at later stages in the SVP + ICP.

Altered ocular microvasculature in patients with systemic sclerosis and very early disease of systemic sclerosis using optical coherence tomography angiography

The vascular hypothesis of systemic sclerosis (SSc) would predict microvascular alterations should also affect anatomical regions like ocular microvasculature. The objective of this study was to evaluate retinal and choriocapillary vessel density (VD) in patients with definite SSc and very early disease of systemic sclerosis (VEDOSS) using optical coherence tomography angiography (OCTA). 22 eyes of 22 patients and 22 eyes of 22 healthy subjects were included in this study. Patients were classified into patients with definite SSc and patients with VEDOSS. VD data of the superficial OCT angiogram (OCTA-SCP), deep OCT angiogram (OCTA-DCP) and choriocapillaris (OCTA-CC) were analysed. VD in the OCTA-SCP and OCTA-CC was lower in patients with SSc (p < 0.05). In VEDOSS patients, VD in the OCTA-CC was still reduced compared to controls (p < 0.05). Correlation analysis revealed a positive correlation between nailfold capillaroscopy and VD of OCTA-CC (Spearman correlation coefficient (rSp) 0.456, p < 0.05) and a negative correlation between skin score and VD of OCTA-SCP (p < 0.05). Ocular perfusion seems to be impaired in patients with SSc and even VEDOSS. VD correlated with disease severity. OCTA could be a new useful diagnostic and predictive parameter for monitoring patients with different stages of the disease.

ROLE OF OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY IN DETECTING AND MONITORING INFLAMMATORY CHOROIDAL NEOVASCULARIZATION.

To investigate the utility of optical coherence tomography angiography (OCTA) for the detection of inflammatory choroidal neovascularization (iCNV) and monitoring their response to treatment. A retrospective review of patients with a diagnosis of uveitis and associated iCNV with active exudation was performed. Active iCNV was determined by spectral domain OCT and/or fluorescein angiogram. Spectral domain OCTA outer retina to choriocapillaris slabs was evaluated for the presence of iCNV. Follow-up OCTA images were qualitatively assessed to determine whether regression of iCNV occurred after treatment. Thirteen eyes of 12 patients were included. The etiologies of uveitis include punctate inner choroidopathy (n = 4), multifocal choroiditis (n = 2), presumed sarcoid uveitis (n = 2), tuberculous choroiditis (n = 1), birdshot chorioretinopathy (n = 1), syphilitic uveitis (n = 1), serpiginous choroiditis (n = 1), and idiopathic panuveitis (n = 1). Inflammatory choroidal neovascularization was detected on en face OCTA in 10 of 13 eyes (76.9%). After iCNV treatment, en face OCTA demonstrated complete regression of iCNV in 5 of 10 eyes (50%), partial regression in 2 of 10 eyes (20%), and no regression in 3 of 10 eyes (30%). Optical coherence tomography angiography is an effective modality for detecting iCNV and could provide detailed visualization regarding location, morphologic structure, and flow of the iCNV and its response to therapy.

A Deep Learning Network for Classifying Arteries and Veins in Montaged Widefield OCT Angiograms.

PurposeTo propose a deep-learning−based method to differentiate arteries from veins in montaged widefield OCT angiography (OCTA).DesignCross-sectional study.ParticipantsA total of 232 participants, including 109 participants with diabetic retinopathy (DR), 64 participants with branch retinal vein occlusion (BRVO), 27 participants with diabetes but without DR, and 32 healthy participants.MethodsWe propose a convolutional neural network (CAVnet) to classify retinal blood vessels on montaged widefield OCTA en face images as arteries and veins. A total of 240 retinal angiograms from 88 eyes were used to train CAVnet, and 302 retinal angiograms from 144 eyes were used for testing. This method takes the OCTA images as input and outputs the segmentation results with arteries and veins down to the level of precapillary arterioles and postcapillary venules. The network also identifies their intersections. We evaluated the agreement (in pixels) between segmentation results and the manually graded ground truth using sensitivity, specificity, F1-score, and Intersection over Union (IoU). Measurements of arterial and venous caliber or tortuosity are made on our algorithm’s output of healthy and diseased eyes.Main Outcome MeasuresClassification of arteries and veins, arterial and venous caliber, and arterial and venous tortuosity.ResultsFor classification and identification of arteries, the algorithm achieved average sensitivity of 95.3%, specificity of 99.6%, F1 score of 94.2%, and IoU of 89.3%. For veins, the algorithm achieved average sensitivity of 94.4%, specificity of 99.7%, F1 score of 94.1%, and IoU of 89.2%. We also achieved an average sensitivity of 76.3% in identifying intersection points. The results show CAVnet has high accuracy on differentiating arteries and veins in DR and BRVO cases. These classification results are robust across 2 instruments and multiple scan volume sizes. Outputs of CAVnet were used to measure arterial and venous caliber or tortuosity, and pixel-wise caliber and tortuosity maps were generated. Differences between healthy and diseased eyes were demonstrated, indicating potential clinical utility.ConclusionsThe CAVnet can classify arteries and veins and their branches with high accuracy and is potentially useful in the analysis of vessel type-specific features on diseases such as branch retinal artery occlusion and BRVO.

An Open-Source Deep Learning Network for Reconstruction of High-Resolution OCT Angiograms of Retinal Intermediate and Deep Capillary Plexuses.

PurposeWe propose a deep learning–based image reconstruction algorithm to produce high-resolution optical coherence tomographic angiograms (OCTA) of the intermediate capillary plexus (ICP) and deep capillary plexus (DCP).MethodsIn this study, 6-mm × 6-mm macular scans with a 400 × 400 A-line sampling density and 3-mm × 3-mm scans with a 304 × 304 A-line sampling density were acquired on one or both eyes of 180 participants (including 230 eyes with diabetic retinopathy and 44 healthy controls) using a 70-kHz commercial OCT system (RTVue-XR; Optovue, Inc., Fremont, California, USA). Projection-resolved OCTA algorithm removed projection artifacts in voxel. ICP and DCP angiograms were generated by maximum projection of the OCTA signal within the respective plexus. We proposed a deep learning–based method, which receives inputs from registered 3-mm × 3-mm ICP and DCP angiograms with proper sampling density as the ground truth reference to reconstruct 6-mm × 6-mm high-resolution ICP and DCP en face OCTA. We applied the same network on 3-mm × 3-mm angiograms to enhance these images further. We evaluated the reconstructed 3-mm × 3-mm and 6-mm × 6-mm angiograms based on vascular connectivity, Weber contrast, false flow signal (flow signal erroneously generated from background), and the noise intensity in the foveal avascular zone.ResultsCompared to the originals, the Deep Capillary Angiogram Reconstruction Network (DCARnet)–enhanced 6-mm × 6-mm angiograms had significantly reduced noise intensity (ICP, 7.38 ± 25.22, P < 0.001; DCP, 11.20 ± 22.52, P < 0.001), improved vascular connectivity (ICP, 0.95 ± 0.01, P < 0.001; DCP, 0.96 ± 0.01, P < 0.001), and enhanced Weber contrast (ICP, 4.25 ± 0.10, P < 0.001; DCP, 3.84 ± 0.84, P < 0.001), without generating false flow signal when noise intensity lower than 650. The DCARnet-enhanced 3-mm × 3-mm angiograms also reduced noise, improved connectivity, and enhanced Weber contrast in 3-mm × 3-mm ICP and DCP angiograms from 101 eyes. In addition, DCARnet preserved the appearance of the dilated vessels in the reconstructed angiograms in diabetic eyes.ConclusionsDCARnet can enhance 3-mm × 3-mm and 6-mm × 6-mm ICP and DCP angiogram image quality without introducing artifacts.Translational RelevanceThe enhanced 6-mm × 6-mm angiograms may be easier for clinicians to interpret qualitatively.

Correlation between Macular Non-Perfusion and Patterns of Corresponding Retinal Layers in Diabetic Patients

Background: Diabetic retinopathy is a common deficiency of diabetes mellitus. Diabetic macular ischemia [DMI] is a permanent form of diabetic maculopathy, and its presence reduces the potential benefits of diabetic retinopathy management. Optical coherence tomography [OCT] is used to precisely and reliably measure the macular thickness and outline the retinal layers. Optical coherence tomography angiography [OCTA] can be utilized as a reliable tool to classify the superficial capillary plexus [SCP], the deep capillary plexus [DCP] and the capillary non-perfusion [NP]. Aim of the work: The current research aimed to investigate the correlation between macular non-perfusion that diagnosed by OCTA and patterns of macular layers that diagnosed by OCT scans through the same parts, in a trial to help in the evaluation of both structural and vascular integrity. Patients and Methods: The study included 250 eyes of 125 diabetic patients. All study participants were scanned by OCTA. OCT angiograms were re-sampled with OCT scans from the same region, permitting synchronous evaluation of structure and blood flow. Results: 250 of 125 diabetic patients were categorized into two groups according to capillary NP, ischemic [G1] and non-ischemic [G2]. In current study the incidence of DMI was 40%. The incidence of DCPNP was 100% in eyes with DMI while the incidence of SCPNP was 71%. The incidence of foveal avascular zone [FAZ] irregularity, disorganization of the retinal inner layers [DRIL], inner/outer segment IS/OS and external limiting membrane ELM disruptions were 100%, 83%, 95%, 71% respectively among eyes with DMI. DCPNP was more found in all eyes with FAZ irregularity, DRIL, IS/OS and ELM disruption than SCP NP which makes it as the central cause of structural changes in the retina during ischemia. There was a strong positive correlation between the appearance of FAZ irregularity, DRIL, IS/OS and ELM disruption with each of the duration and severity of DR. Conclusion: FAZ irregularity, DRIL, IS/OS and ELM disruption are considered reliable OCT/OCTA findings that reflect an underling DMI and their existence can influence the visual prognosis.

Decreased Retinal Vascular Density in Alzheimer's Disease (AD) and Mild Cognitive Impairment (MCI): An Optical Coherence Tomography Angiography (OCTA) Study.

BackgroundTo explore the retinal vascular density changes in Alzheimer’s disease (AD) and mild cognitive impairment (MCI) patients using optical coherence tomography angiography (OCTA).MethodsWe recruit 62 AD patients, 47 MCI patients, and 49 cognitively healthy controls (HC) in this study. All participants in the study received a comprehensive ophthalmological and neurological evaluation, including global cognitive screening, as well as the Mini-Mental State Examination (MMSE), and completed the following eye examinations: visual acuity (VA), intraocular pressure (IOP), examination with slit-lamp, fundus photography (Version 1.5.0.0, NIDEK CO, LTD) and Optical coherence tomography imaging (software ReVue version 2017.1.0.155, Optovue Inc., Fremont, CA, United States). The visual rating scales for atrophy and white matter lesion in MRI was evaluated for all the patients with AD and MCI.ResultsIn the AD patient group, the superficial vascular density in the superior, inferior and whole retina was 44.64 ± 3.34, 44.65 ± 3.55, and 44.66 ± 3.36, respectively. These values were 44.24 ± 3.15, 43.72 ± 3.16, and 44 ± 3.07, respectively, in the MCI patient group. After multivariate analysis of the generalized linear model, adjustments for the confounding factors of sex, age, hypertension, diabetes and the quality index of OCTA image, the superficial vascular density in the AD and MCI patient groups was significantly lower than that in the HC group (P < 0.05): 46.94 ± 2.04, 46.67 ± 2.26, and 46.82 ± 2.08, respectively. No difference in the area of the FAZ among the three groups was observed (AD group: 0.34 ± 0.11 mm2; MCI group: 0.36 ± 0.12 mm2; control group: 0.33 ± 0.12 mm2, p > 0.05). The ganglion cell complex (GCC) thickness, inner parafovea thickness, and peripapillary retinal nerve fiber layer (p-RNFL) thickness were associated with the superficial vascular density. We found no significant correlation between the global cognition (MMSE scores) or between the Fazekas score and retinal OCT angiogram flow density.ConclusionThe superficial vascular density in the AD and MCI patient groups was significantly lower than that in the HC group. Our findings suggest the retinal microvascular dysfunction occurred in MCI and AD.

Altered microvascular density in patients with systemic lupus erythematosus treated with hydroxychloroquine\u2014an optical coherence tomography angiography study

PurposeTo evaluate the retinal microvascular density using optical coherence tomography angiography (OCTA) in patients with systemic lupus erythematosus (SLE) treated with hydroxychloroquine (HCQ).MethodsNineteen eyes of 19 patients with SLE (study group) without HCQ retinopathy and 19 eyes of 19 healthy subjects (control group) were included in this study. The study group was divided into patients using HCQ for > 5 years (high-risk group) and < 5 years (low-risk group). The VD data of the 3 × 3 mm OCT angiogram of the superficial capillary plexus (SCP) and the choriocapillaris (VD-CC), the foveal avascular zone (FAZ) area and the central retinal thickness (CRT) were extracted and analyzed.ResultsVD in the en face SCP was significantly reduced in the high-risk group and the low-risk group compared with that in the control group (p < 0.001, p = 0.001) and in the high-risk group compared with the low-risk group (p = 0.007). Correlation analysis between the cumulative dose of HCQ and the VD of the study group revealed a negative correlation, but no statistical significance (p = 0.074). However, a significant positive correlation was observed for the low-risk group (p = 0.035). In patients with SLE, VD-CC was lower (p = 0.042) and the FAZ area larger (p = 0.019). CRT showed no difference between the groups (p = 0.183).ConclusionIn this study, SLE patients showed a reduced VD in both groups. In patients treated with HCQ < 5 years, HCQ might have a protective effect on retinal microvasculature. Analysis of retinal microvascular density using OCTA could be useful in the diagnosis and monitoring of vascular alteration in patients with SLE.

Reconstruction of high-resolution 6×6-mm OCT angiograms using deep learning.

Typical optical coherence tomographic angiography (OCTA) acquisition areas on commercial devices are 3×3- or 6×6-mm. Compared to 3×3-mm angiograms with proper sampling density, 6×6-mm angiograms have significantly lower scan quality, with reduced signal-to-noise ratio and worse shadow artifacts due to undersampling. Here, we propose a deep-learning-based high-resolution angiogram reconstruction network (HARNet) to generate enhanced 6×6-mm superficial vascular complex (SVC) angiograms. The network was trained on data from 3×3-mm and 6×6-mm angiograms from the same eyes. The reconstructed 6×6-mm angiograms have significantly lower noise intensity, stronger contrast and better vascular connectivity than the original images. The algorithm did not generate false flow signal at the noise level presented by the original angiograms. The image enhancement produced by our algorithm may improve biomarker measurements and qualitative clinical assessment of 6×6-mm OCTA.

Altered Retinal Perfusion in Patients with Inactive Graves Ophthalmopathy Using Optical Coherence Tomography Angiography

Objective: The aim of this study was to evaluate retinal and optic nerve head (ONH) perfusion in patients with inactive Graves ophthalmopathy (GO) and compare it to healthy controls using optical coherence tomography angiography (OCTA). Methods: Twenty-nine eyes of 29 patients with inactive GO (study group) and 29 eyes of 29 healthy subjects (control group) were included in this study. The vessel density (VD) data in the superficial and deep retinal OCT angiogram of the macula and the radial peripapillary capillary network (RPC) were extracted and analyzed. OCTA was performed using RTVue XR Avanti with AngioVue (Optovue Inc, Fremont, CA). Clinical activity was evaluated using the clinical activity score, the severity assessment using the NOSPECS classification. Results: The VD in the superficial OCT angiogram and in the OCT angiogram of the ONH was significantly lower in the GO group when compared to the control group (whole en face, P = .016; parafovea, P = .026; RPC peripapillary, P = .027). There was no significant correlation between VD and functional parameters or the NOSPECS classification. Conclusion: Macular VD and ONH capillary density measured using OCTA were significantly lower in the study group compared to healthy controls. Noninvasive quantitative analysis of retinal perfusion using OCTA could be useful in monitoring patients with GO. Abbreviations: CAS = clinical activity score; GO = Graves ophthalmopathy; OCTA = optical coherence tomography angiography; ONH = optic nerve head; RPC = radial peripapillary capillary; rSp = Spearman's correlation coefficient; VD = vessel density.

Fractal Analysis of Peripapillary Vasculature in Eyes with Papilledema Using Optical Coherence Tomography Angiography

Background: Papilledema is swelling of the optic nerve secondary to increased intracranial pressure. Optical coherence tomography angiography (OCTA) is a technique that allows for fast and non-invasive imaging of the peripapillary microvasculature. Here, we evaluate a novel way of analyzing OCTA images of eyes with papilledema through the use of fractals to estimate vascular complexity through fractal dimension. Methods: A retrospective clinical chart review of papilledema patients imaged with OCTA was performed. En face OCT angiograms identifying peripapillary vessels were obtained using a spectral-domain OCT system. Default automated peripapillary scans of 4.5 mm × 4.5 mm diameter were processed with ImageJ. Fractal analysis was performed with Fractalyse software. Results: Fifty-six eyes with papilledema and 40 eyes from healthy controls were analyzed. The fractal dimension of eyes with papilledema (1.677, SD=0.075) was significantly higher than that of control eyes (1.630, SD=0.062; P=0.002). Subgroup analysis demonstrated significantly higher fractal dimension in Grade 0 papilledema (1.707, SD=0.047) as compared to controls. Conclusion: Increases in fractal dimension of peripapillary vasculature for papilledema may reflect potential increases in microvasculature, particularly during early stages. OCTA fractal dimension analysis has potential to establish quantitative parameters for peripapillary microvascular pathology in papilledema.

Robust non-perfusion area detection in three retinal plexuses using convolutional neural network in OCT angiography.

Non-perfusion area (NPA) is a quantitative biomarker useful for characterizing ischemia in diabetic retinopathy (DR). Projection-resolved optical coherence tomographic angiography (PR-OCTA) allows visualization of retinal capillaries and quantify NPA in individual plexuses. However, poor scan quality can make current NPA detection algorithms unreliable and inaccurate. In this work, we present a robust NPA detection algorithm using convolutional neural network (CNN). By merging information from OCT angiograms and OCT reflectance images, the CNN could exclude signal reduction and motion artifacts and detect the avascular features from local to global with the resolution preserved. Across a wide range of signal strength indices, and on both healthy and DR eyes, the algorithm achieved high accuracy and repeatability.

Relationship of Geographic Altitude with Foveal Avascular Zone Metrics and Vascular Density Values Assessed by OCT Angiography

To evaluate variations in vascular density (VD) and foveal avascular zone (FAZ) metrics in relation to geographic altitude in healthy subjects from 6 Latin American cities. Cross-sectional study. Healthy volunteers from 6 Latin American cities. One hundred eighty-five volunteers were recruited over a 3-month period. The RTVue-XR Avanti system (Optovue, Inc, Fremont, CA) was used along with split-spectrum amplitude-decorrelation angiography (SSADA) software 7.1 to obtain OCT angiography (OCTA) images from fovea-centered 3× 3-mm2 and 6× 6-mm2 angioscans for both the superficial and deep capillary plexuses (SCP and DCP, respectively). FAZ measurements were performed in a full retina slab based on the full retina vasculature using OCT angiograms. Analyses of variance were performed for all variables, and P < 0.05 indicated statistical significance. Retinal SCP and DCP VD; FAZ area, perimeter, and parafoveal density at 300 μm (FD-300). Three hundred seventy eyes of 185 participants (71 males and 114 females; mean age, 39.09±15.06 years; age range, 20-80 years) were assessed. The mean VD in the SCP and DCP was 46.94% (±3.11%) and 52.48% (±3.14%), respectively, with 3 × 3-mm2 scans and 50.62% (±3.13%) and 52.87% (±5.5%), respectively, with 6 × 6-mm2 scans. Mean FAZ area, perimeter, and FD-300 were 0.31 (± 0.11 mm2), 2.18 (± 0.43 mm), and 51.44 (± 3.64%), respectively. Mean SCP VD values in 3× 3-mm2 scans were significantly higher and lower in La Paz and Lima, respectively, compared to those in the other cities (P= 0.001). VD in the 6 × 6 mm2 SCP scans, the DCP (all scans), and FAZ metrics showed no significant differences. VD showed a direct relationship with geographic altitude in SCP 3× 3-mm2 scans in this group of healthy Hispanic volunteers. These findings indicate that geographic altitude should be accounted for when performing retinal OCTA evaluation of VD values.

Textural Properties of Choriocapillaris on OCTA in Healed Inflammatory Choriocapillaropathies.

To evaluate the flow characteristics and textural properties of choriocapillaris (CC) on optical coherence tomography angiography in eyes with resolved inflammatory choriocapillaropathies and Vogt-Koyanagi-Harada (VKH) disease. A cohort of eyes with healed acute posterior multifocal placoid pigment epitheliopathy (APMPPE), serpiginous choroiditis (SC), and VKH disease were included. A 3 mm × 3 mm OCT angiogram of CC was acquired and graded for flow characteristics and textural properties. This study included 16 patients. Texture was heterogeneous in all eyes in the SC and VKH groups, and in four eyes (40%) in the APMPPE group. Most of the eyes with VKH disease had severe low flow, whereas most of the SC and APMPPE eyes demonstrated mild low flow. Heal duration had a strong negative correlation with severity of CC low flow and a weak, statistically nonsignificant correlation with texture heterogeneity. Despite the resolution of active inflammation, partial CC hypoperfusion and texture disruptions persist for longer durations and may resolve in a time dependent manner. [Ophthalmic Surg Lasers Imaging Retina. 2019;50:566-572.].

Automatic Characterization of Retinal Blood Flow Using OCT Angiograms.

PurposeTo quantitatively characterize the retinal vascular network in healthy and pathological cases using optical coherence tomography angiography (OCTA) images.MethodsThe study included 56 eyes of 28 patients as follows: 26 healthy, 20 with diabetic retinopathy (DR), 6 with age-related macular degeneration (AMD), and 4 with retinal vein occlusion (RVO). For 33 eyes (16 healthy and 17 with DR), vessel density maps were provided by the OCTA machine. An automatic algorithm classified the image (as healthy, DR, AMD, or RVO) and provided quantitative information obtained from the angiograms, including global vessel density, global fractal dimension, and fovea avascular zone (FAZ) area. Classification results were compared with the diagnosis made by a retina specialist. The quantitative values were compared with the literature and to values provided by the OCTA machine.ResultsThe success rate of classification was 83.9%. Vessel densities obtained by our algorithm (in healthy and DR cases) were significantly lower than the values reported in previous studies using OCTA. Similarly, they were much lower than the values provided by the OCTA machine. However, vessel densities in the healthy cases were similar to or higher than (depending on the retinal layer) the recently published values that may be considered as gold standard. Our values of fractal dimension were similar to those previously reported.ConclusionsOur algorithm provides significantly improved vessel density values compared with previous studies. We believe our algorithm successfully omits false vessels.Translational RelevanceAccurately assessing retinal vessel density enables better evaluation of retinal disorders.

Simulating vascular leakage on optical coherence tomography angiography using an overlay technique with corresponding thickness maps

BackgroundTo demonstrate a technique for using optical coherence tomography angiography (OCTA) to simulate leakage in eyes with diabetic macular oedema and determine the sensitivity and positive predictive value of detecting...

Characterisation of microvascular abnormalities using OCT angiography in patients with biallelic variants in USH2A and MYO7A

AimsUsing optical coherence tomography angiography (OCTA) to characterise microvascular changes in the retinal plexuses and choriocapillaris (CC) of patients with MYO7A and USH2A mutations and correlate with genotype, retinal structure...