Optical Coherence Tomography Angiography Devices Research Articles

Evaluation of retinal and choroidal vascular structures in obsessive-compulsive disorder.

To evaluate the optical coherence tomography-angiography (OCT-A) findings and choroidal vascularity index (CVI) of patients followed with a diagnosis of obsessive-compulsive disorder (OCD) by comparing them with the healthy control group (HCG). This prospective study included 33 patients diagnosed with OCD and 32 HCG patients who followed up for at least 3 months. OCT-A images were obtained to evaluate the microvascular circulation, and enhanced HD line images were obtained for the CVI calculation of all patients. Statistical analysis results revealed that the rates of superficial vascular density in the fovea region and deep vascular density in the parafovea region decreased in the OCD group compared to the HCG group (P = 0.003 and P = 0.010, respectively). Subfoveal choroidal thickness values of the OCD group were lower than those of the HCG group (P = 0.008). While total choroidal area and lumen area values were lower in the OCD group than in the HCG group (P < 0.001 and P < 0.001, respectively); CVI values were similar in both groups (P = 0.436). The use of the OCT-A device, which is a non-invasive method for detecting retinal and choroidal changes in OCD cases, may provide insight into the pathogenesis of the disease.

Optical coherence tomography angiography analysis methods: a systematic review and meta-analysis

Optical coherence tomography angiography (OCTA) is widely used for non-invasive retinal vascular imaging, but the OCTA methods used to assess retinal perfusion vary. We evaluated the different methods used to assess retinal perfusion between OCTA studies. MEDLINE and Embase were searched from 2014 to August 2021. We included prospective studies including ≥ 50 participants using OCTA to assess retinal perfusion in either global retinal or systemic disorders. Risk of bias was assessed using the National Institute of Health quality assessment tool for observational cohort and cross-sectional studies. Heterogeneity of data was assessed by Q statistics, Chi-square test, and I2 index. Of the 5974 studies identified, 191 studies were included in this evaluation. The selected studies employed seven OCTA devices, six macula volume dimensions, four macula subregions, nine perfusion analyses, and five vessel layer definitions, totalling 197 distinct methods of assessing macula perfusion and over 7000 possible combinations. Meta-analysis was performed on 88 studies reporting vessel density and foveal avascular zone area, showing lower retinal perfusion in patients with diabetes mellitus than in healthy controls, but with high heterogeneity. Heterogeneity was lowest and reported vascular effects strongest in superficial capillary plexus assessments. Systematic review of OCTA studies revealed massive heterogeneity in the methods employed to assess retinal perfusion, supporting calls for standardisation of methodology.

Evaluation and comparison of optical coherence tomography angiography (OCTA) parameters in normal and moderate myopic individuals

ObjectiveThe objective of this study was to evaluate and compare Optical Coherence Tomography Angiography (OCTA) parameters in patients with moderate myopia and healthy individuals retrospectively. MethodsA total of 80 male individuals aged 18–20 years were included in the study with 40 moderate myopic and 40 healthy persons. All participants underwent detailed ocular examination including refraction, intraocular pressure (IOP), visual acuity, biomicroscopy, OCTA measurement and optic biometry measurement. Retinal, retinal nerve fiber layer and choroidal layer thicknesses were evaluated in µm with the help of the software available in the OCTA device. ResultsThe mean axial length (24.32 ± 0.53 mm) was statistically significantly higher in the moderate myopic group (24.32 mm) compared to the healthy group (23.33 ± 0.61 mm) (p < 0.001). Spherical equivalent (SE) was found as -3.79 ± 0.91 D in the moderate myopic group and -0.22 ± 0.32 D in the healthy group (p < 0.05). The mean superficial foveal mean density (FovSupMVD) and the mean deep foveal mean density (FovDepMVD) were statistically significantly lower in the moderate myopic group than in the healthy group (both, p < 0.001). The mean retinal temporal thickness (RTt) was statistically significantly lower in the moderate myopic group (p = 0.017). There was a mild negative correlation between axial length and FovSupMVD, FovDepMVD in myopes. In axial length ROC analysis, the cutoff value for moderate myopes was found to be 24.15 mm. Mean superficial foveal mean density (FovSupMVD) and mean deep foveal mean density (FovDepMVD), mean retinal temporal thickness (RTt) were significantly lower in the group above 24.15 mm axial length compared to the group below 24.15 mm axial length (all three, p < 0.001). Foveal avascular zone was significantly higher in the group above 24.15 mm axial length (p = 0.016) ConclusionThe results of our study indicate that the mean axial length and spherical equivalent were significantly higher, while retinal temporal thickness, the mean superficial foveal mean density and the mean deep foveal mean density were significantly lower in patients with myopia up to -6.0 D compared to the healthy individuals.

Optical coherence tomography imaging of the peripheral retina

Abstract: This review critically assesses the applicability of retinal periphery imaging technology, scrutinizing its practical limitations and potential advancements within ophthalmology. It underscores the significant costs and the need to evaluate the clinical utility of optical coherence tomography (OCT) and OCT angiography devices. It emphasizes how clinicians should consider their practice-specific use-cases while investing in devices with capabilities like ultra-widefield OCT, autofluorescence imaging, and angiography. The paper also highlights the challenges associated with image acquisition, such as artifact management and patient cooperation for extended fixation periods. This review outlines the utility of these modalities in various retinal pathologies, as well as their contribution to telemedicine and personalized care, facilitated by artificial intelligence for improved image processing, quantification, and interpretation. These techniques potentially offer a more comprehensive understanding of peripheral retinal conditions and associated pathologies, thus influencing clinical decision-making, particularly in remote regions with limited specialist access.

Evaluation of the retina, choroid and optic disc vascular structures in individuals with a history of COVID-19

In this study, we aimed to detect changes in posterior segment structures and vascular density caused by COVID-19 using an optical coherence tomography angiography (OCTA) device. The study included 20 eyes of 20 patients no systemic or ocular disease who were followed at the Ophthalmology Clinic of Health Sciences University Antalya Training and Research Hospital. The OCTA images of these individuals taken prior to contracting COVID-19 and six months after recovery were examined. The mean choriocapillaris blood flow was 2.00±0.13mm2 before COVID-19 and 2.08±0.23mm2 after the disease, and the mean subfoveal choroidal thickness was 247.33±7.65μm before the disease and 273.08±4.92μm after the disease, indicating a statistically significant difference (P=0.003, P=0.001, respectively). The mean retinal nerve fiber layer thickness before and after COVID-19 were 119.33±3.88 and 117.50±3.92μm, respectively, representing a statistically significant decrease (P<0.001). This is the first study in the literature to evaluate the post-COVID-19 changes in the vascular structures of the eye compared to the pre-disease values. In this study, we found statistically significant changes in choriocapillaris blood flow, subfoveal chroidal thickness and retinal nerve fiber layer thickness after COVID-19 infection. Further research with a greater sample size is needed to explore the effect of COVID-19 on these parameters.

Inference of Capillary Nonperfusion Progression on Widefield OCT Angiography in Diabetic Retinopathy.

The purpose of this study was to explore the spatial patterns of the nonperfusion areas (NPAs) on widefield optical coherence tomography angiography (OCTA) images in diabetic retinopathy (DR) and to investigate their associations with NPA progression and DR severity. We prospectively enrolled 201 eyes from 158 patients with DR. Widefield images were obtained using a swept-source OCTA device (Xephilio OCT-S1), followed by the creation of 20-mm (1614 pixels) en face images. Nonperfusion squares (NPSs) were defined as 10 × 10-pixel squares without retinal vessels. Eyes with high-dimensional spatial data were mapped onto a two-dimensional space using the uniform manifold approximation and projection algorithm and divided by clustering. The patterns of NPA distribution were statistically compared between clusters. All eyes were mapped onto a two-dimensional space and divided into six clusters based on the similarity of NPA distribution. Eyes in clusters 1 and 2 had minimal and small NPAs, respectively. Eyes in clusters 3 and 4 exhibited NPAs in the temporal and inferotemporal regions, respectively. Eyes in cluster 5 displayed NPAs in both superonasal and inferonasal areas. The unique NPA distributions in each cluster encouraged us to propose eight possible pathways of NPA progression. DR severity was not equal between clusters (P < 0.001), for example, 8 (15.7%) of 51 eyes and 15 (65.2%) of 23 eyes had PDR in clusters 1 and 5, respectively. Dimensionality reduction and subsequent clustering based on the NPA distribution on widefield OCTA enabled the inference of possible NPA progression in DR.

Optical coherence tomography angiography evaluation of optic disc and retinal vascular densities in obese patients

BackgroundTo evaluate optic disc and retinal vascular densities in obese patients using optical coherence tomography angiography (OCTA). MethodsThis study included 27 eyes from 27 obese patients with a body mass index (BMI) of ≥35 who were scheduled for bariatric surgery at the general surgery clinic and 26 eyes from 26 healthy individuals with a BMI of 18.5–24.9 kg/m2 who were of similar age and gender to the obese group. The macular vascular densities of the superficial and deep capillary plexuses (SCP and DCP, respectively), choriocapillaris flow area, optic disc peripapillary vascular density, and retinal thicknesses were evaluated using the OCTA device in obese patients and controls. ResultsThe mean age of the obese patients was 35.89 ± 10.93 years, and that of the controls was 32.31 ± 7.88 years (p = 0.199). The mean BMI values of the obese and control groups were 45.04 ± 6.89 kg/m2 and 23.19 ± 1.66 kg/m2, respectively (p < 0.0001). The whole, parafoveal, and perifoveal vascular density values of the SCP and those of the DCP were statistically significantly lower in the obese group than in the control group (p = 0.004, p = 0.011, p = 0.006, p = 0.036, p = 0.029, and p = 0.024, respectively). There was no significant difference between the two groups in terms of optic disc vascular density. Full retinal perifoveal thickness, full retinal perifoveal volume, inner retinal perifoveal thickness, and inner retinal perifoveal volume were statistically significantly lower in obese patients compared to the controls (p = 0.043, p = 0.042, p = 0.027, and p = 0.024, respectively). In addition, statistically significant negative correlations were found between BMI and the whole, parafoveal, and perifoveal vascular densities of the SCP and DCP and the whole vascular density values of the optic disc for all vessels and small vessels ​​(p = 0.017, r = -0.327; p = 0.043, r = -0.280; p = 0.033, r = -0.293; p = 0.034, r = -0.291; p = 0.017, r = -0.327; p = 0.023, r = -0.311; p = 0.031, r = -0.296; and p = 0.047, r = -0.274, respectively). ConclusionWe consider that the decrease in retinal vascular density and retinal thickness in obese patients is responsible for obesity-induced oxidative stress, increased inflammatory cytokines, and microvascular damage.

Evaluation of macula with optical coherence tomography-angiography device in glaucomatous and disease-free individuals with unilateral pseudoexfoliation material.

Amaç: Tek taraflı pseudoekfolyasyon materyali (XFM) izlenen bireylerin; glokom geliştiği ve gelişmediği durumlarda makula vasküler yoğunluğunun gözler arası değişimini gözlemlemek. &#x0D; Gereç ve yöntemler: 38 sayıda tek taraflı pseudoeksfolyasyon sendromlu (XFS) bireyin 76 gözü ve 36 sayıda tek taraflı pseudoeksfolyasyon glokomlu (XFG) hastanın 72 gözü çalışmaya dahil edilmiştir. Her iki grubun XFM olan ve olmayan gözlerinin OCT-A ile incelenen tüm makuler belirteçleri standart ortalama karşılaştırmalı t testi ile değerlendirilmiştir. Her iki gruptaki XFM pozitif ve negatif olan göz grupları birbirleriyle ve gruplar arasında Kruskal-Wallis testi ile kıyaslanmıştır. &#x0D; Bulgular : Tek taraflı XFS olan hastaların gözler arası yüzeyel kapiller pleksus yoğunluğunda anlamlı farklılıklar minimal görülürken tek taraflı XFG’lerin gözler arası makulanın totalinde (p= 0,0004) üst ve alt yarımında (p=0.0018, p=0.0002), fovea (p=0,014), parafovea (p=0,0411) ,parafoveanın inferior yarımı (p=0,0126) ve temporalinde (p=0,0126); glokomlu gözlerde anlamlı düzeyde damar yoğunluğunda azalma dikkati çekmektedir. Derin kapiller pleksusta ise hem grup içi hem gruplar arası kıyaslamalarda anlamlılık, yüzeyel damar tabakasına göre azalmıştır.&#x0D; Sonuç: Medikal tedaviyle kontrol edilen glokom tablolarında makula bölgesindeki özellikle yüzeyel kapiller pleksusun yoğunluğunda azalma olduğu gösterilmiştir. Ancak bu damarsal azalma glokomsuz gözlerde XFM varlığında öncü bulgu olarak gösterilememiştir.

A Retinal Oct-Angiography and Cardiovascular STAtus (RASTA) Dataset of Swept-Source Microvascular Imaging for Cardiovascular Risk Assessment

In the context of exponential demographic growth, the imbalance between human resources and public health problems impels us to envision other solutions to the difficulties faced in the diagnosis, prevention, and large-scale management of the most common diseases. Cardiovascular diseases represent the leading cause of morbidity and mortality worldwide. A large-scale screening program would make it possible to promptly identify patients with high cardiovascular risk in order to manage them adequately. Optical coherence tomography angiography (OCT-A), as a window into the state of the cardiovascular system, is a rapid, reliable, and reproducible imaging examination that enables the prompt identification of at-risk patients through the use of automated classification models. One challenge that limits the development of computer-aided diagnostic programs is the small number of open-source OCT-A acquisitions available. To facilitate the development of such models, we have assembled a set of images of the retinal microvascular system from 499 patients. It consists of 814 angiocubes as well as 2005 en face images. Angiocubes were captured with a swept-source OCT-A device of patients with varying overall cardiovascular risk. To the best of our knowledge, our dataset, Retinal oct-Angiography and cardiovascular STAtus (RASTA), is the only publicly available dataset comprising such a variety of images from healthy and at-risk patients. This dataset will enable the development of generalizable models for screening cardiovascular diseases from OCT-A retinal images.

Evaluation of Optic Disc, Retinal Vascular Structures, and Acircularity Index in Patients with Idiopathic Macular Telangiectasia Type 2.

We aimed to compare the retinal, optic disc vascular density (ODVD) values, and acircularity index (AI) of patients with idiopathic macular telangiectasia type 2 (IMT) and healthy individuals using the optical coherence tomography angiography (OCTA) device. The study included 39 patients with IMT and 37 healthy controls. The OCTA findings of the patients and controls were examined. The total, parafoveal and perifoveal vascular density of the superficial capillary plexus, choriocapillaris blood flow, inside-disc ODVD, retinal nerve fiber layer (RNFL), and retinal thicknesses were found to be statistically significantly lower, and the foveal avascular zone value was statistically significantly higher in the IMT group compared to the control group (p = 0.001, p = 0.01, p = 0.02, p = 0.01, p = 0.009, p = 0.002, p = 0.02, respectively). There was a statistically significant negative correlation between best-corrected visual acuity (BCVA) and AI (p = 0.02), and a statistically significant positive correlation between peripapillary vascular density and BCVA (p = 0.04). We consider that the lower retinal, choriocapillaris, ODVD values, and retinal and RNFL thicknesses in the patients with IMT compared to the controls were due to vascular damage, remodeling, fibrosis, proliferation, and Müller cell damage. Ellipsoid zone defect, AI, and peripapillary vascular density are important indicators in the evaluation of visual acuity in these patients.

Disagreement of Radial Peripapillary Capillary Density Among Four Optical Coherence Tomography Angiography Devices.

This prospective study evaluated the agreement among four optical coherence tomography angiography (OCTA) devices in the assessment of radial peripapillary capillary (RPC) density. The study included 48 eyes of 48 subjects (14 healthy, 19 glaucomatous, and 15 non-glaucomatous optic neuropathy). Each participant was scanned using four OCTA devices in a random sequence: RTVue XR Avanti (RTVue), DRI OCT Triton (Triton), Revo NX 130 (Revo), and PLEX Elite 9000 (PlexE). All 6 × 6-mm grayscale OCTA images from each device were analyzed for RPC density using a customized algorithm. Agreement between each pair of devices was assessed using intraclass correlation coefficients (ICCs) and Bland-Altman plots. There was a poor correlation between devices in all comparisons (RTVue-Triton, ICC = 0.34; RTVue-Revo, ICC = 0.31; RTVue-PlexE, ICC = 0.28; Triton-Revo, ICC = 0.31; Triton-PlexE, ICC = 0.17; Revo-PlexE, ICC = 0.34). Significant proportional biases (P < 0.05) and wide limits of agreement with apparent constant biases were identified in all comparisons. The mean difference was greatest for the RTVue-Revo pair (-49.3%; 95% confidence interval [CI], -52.9 to -45.8) and smallest for the Triton-PlexE pair (-7.7%; 95% CI, -10.1 to -5.3). The RPC densities obtained from each device had poor inter-device agreement and significant biases and cannot be used interchangeably. RPC density obtained from different OCTA devices is not interchangeable; thus, the progression of optic neuropathy should be monitored using the same OCTA device.

Quantitative Parameters Relevant for Diabetic Macular Edema Evaluation by Optical Coherence Tomography Angiography.

Diabetic macular edema (DME) is one of the main ocular complications of diabetes mellitus (DM) that can lead to important vision loss in diabetic patients. In clinical practice, there are cases of DME with unsatisfying treatment responses, despite adequate therapeutic management. Diabetic macular ischemia (DMI) is one of the causes suggested to be associated with the persistence of fluid accumulation. Optical coherence tomography angiography (OCTA) is a non-invasive imaging modality, able to give in-depth information about retinal vascularization in a 3-dimensional manner. The OCTA devices currently available can provide various OCTA metrics that quantitatively assess the retinal microvasculature. In this paper, we reviewed the results of multiple studies that investigated the changes in OCTA metrics in the setting of DME and their possible contribution to the diagnosis, therapeutic management, follow-up and prognosis of patients with DME. We analyzed and compared relevant studies that investigated OCTA parameters related to changes in macular perfusion in the setting of DME and we evaluated the correlations between DME and several quantitative parameters, such as vessel density (VD), perfusion density (PD), foveal avascular zone (FAZ)-related parameters, as well as complexity indices of retinal vasculature. The results of our research showed that OCTA metrics, evaluated especially at the level of the deep vascular plexus (DVP), are useful instruments that can contribute to the assessment of patients with DME.

Early Retinal Microvascular Alterations in Young Type 1 Diabetic Patients without Clinical Retinopathy.

The purpose of this study is to identify and quantify preclinical changes with the help of optical coherence tomography angiography (OCTA) within the retinal microcirculation of young type 1 diabetes (T1D) patients without clinical signs of diabetic retinopathy (DR) and to compare these results with those obtained from healthy age-matched subjects. OCTA is currently used for monitoring diabetic retinopathy; however, there is no current consensus on which OCTA parameter alterations predict the first clinical signs of diabetic retinopathy. The main challenge that young patients with T1D face during the course of the disease is that they can rapidly progress to the development of DR, especially during adolescence. Moreover, they also present an increased risk of rapid progression toward advanced stages of DR and vision loss compared to type 2 diabetes patients, indicating the importance of early diagnosis and intervention. The limitations of the currently used screening procedures that led to the conceptualization of our study are the difficulties in performing fluorescein angiography tests for diagnosing the clinical signs of DR on young patients, namely the invasive procedure of dye injection, the risk of allergic reactions and the long duration of the examination. Moreover, given the long life expectancy of young T1D patients, it is essential to identify the preclinical changes in retinal microvasculature before reaching the first clinical signs quantifiable by FFA. The clinical study enrolled 119 subjects aged between 4 and 30 years old with a mean age of 13 years old, comprising 61 T1D patients with a mean duration of the disease of 4 years and 8 months and 58 healthy age-matched subjects for the control group. OCTA scans were performed using the RevoNX 130 OCTA device (Optopol) to evaluate the following retinal parameters: foveal avascular zone (FAZ) area, perimeter and circularity, overall foveal thickness, and superficial and deep vessel densities. Statistically significant differences between the two groups were identified for the following parameters: the FAZ area in the T1D group (0.42 ± 0.17) was larger than the control group (0.26 ± 0.080), the FAZ circularity (0.41 ± 0.11) was decreased compared to the control group (0.61 ± 0.08) and the FAZ perimeter was larger (3.63 ± 0.97) compared to the control group (2.30 ± 0.50). The overall foveal thickness was decreased in the T1D group (222.98 ± 17.33) compared to the control group (230.64 ± 20.82). The total vessel density of the superficial capillary plexus (SCP) on an investigated area of 6 X 6 mm centered around the fovea was decreased in the T1D group (37.4164 ± 2.14) compared to the control group (38.0241 ± 2.44). Our data suggest that specific imaging biomarkers such as FAZ perimeter, area and circularity, decreased overall foveal thickness and decreased vessel density in the SCP precede the clinical diagnosis of DR in young T1D patients and represent useful parameters in quantifying capillary nonperfusion in T1D patients without clinical signs of DR.

Evaluation of ocular microvascular characteristics in smokers and patients with chronic obstructive pulmonary disease using an optical coherence tomography angiography

PurposeTo investigate retinal microvascular changes in patients with chronic obstructive pulmonary disease (COPD) using optical coherence tomography angiography (OCTA) and to compare these values with those of smokers and healthy non-smokers. MethodsThis study was performed on 38 eyes of 38 patients with COPD, 30 eyes of 30 smokers, and 31 eyes of 31 healthy non-smokers. Foveal avascular zone (FAZ) area, superficial (SCP) and deep (DCP) capillary plexus (whole image, fovea, parafovea, and perifovea) and radial peripapillary capillary (RPC) vessel densities (whole image, peripapillary, and inside disc) were evaluated via OCTA device (Optovue, Fremont, CA, USA). The forced expiratory volume in the first second (FEV1)/forced vital capacity (FVC) ratio and FEV1 values of patients with COPD were recorded. ResultsThere were statistically similar values in smoking pack-years between the smoker and COPD groups (p = 0.059). Entire SCP and DCP vessel densities were significantly different among the all groups (p < 0.05); for these parameters, the control group had the highest and the COPD group had the lowest vessel density values. Significantly decreased RPC vessel densities in all regions were detected in the COPD group compared with the other groups. Multiple regression analysis showed significant positive correlations between the FEV1 and the SCP, DCP, and RPC vessel densities (for all, p < 0.05). ConclusionsThis study detected lower vessel densities in patients with COPD than in smokers and healthy controls and reported decreased vessel density measurements with increasing COPD severity. COPD patients with or without a history of smoking may benefit from higher prioritization in terms of ophthalmic screening to prevent ocular complications.

Ultra-Widefield OCT Angiography.

Optical Coherence Tomography Angiography (OCTA), a functional extension of OCT, has the potential to replace most invasive fluorescein angiography (FA) exams in ophthalmology. So far, OCTA's field of view is however still lacking behind fluorescence fundus photography techniques. This is problematic, because many retinal diseases manifest at an early stage by changes of the peripheral retinal capillary network. It is therefore desirable to expand OCTA's field of view to match that of ultra-widefield fundus cameras. We present a custom developed clinical high-speed swept-source OCT (SS-OCT) system operating at an acquisition rate 8-16 times faster than today's state-of-the-art commercially available OCTA devices. Its speed allows us to capture ultra-wide fields of view of up to 90 degrees with an unprecedented sampling density and hence extraordinary resolution by merging two single shot scans with 60 degrees in diameter. To further enhance the visual appearance of the angiograms, we developed for the first time a three-dimensional deep learning based algorithm for denoising volumetric OCTA data sets. We showcase its imaging performance and clinical usability by presenting images of patients suffering from diabetic retinopathy.

Optical coherence tomography angiography measurements in Parkinson's disease: A systematic review and meta-analysis.

Optical coherence tomography angiography (OCT-A) is an ocular imaging technology that has emerged as a non-invasive tool to evaluate retinal microvascular changes in neurodegenerative diseases including Parkinson's disease (PD) and Alzheimer's disease. While several studies have reported on the presence of pathologic retinal microvascular alterations in PD, the utility of OCT-A as a biomarker for PD evaluation is still unclear. A systematic review and meta-analysis were performed to explore the current evidence for the role of OCT-A in PD published up until June 2022. PubMed, Scopus, and Web of Science databases were used to systematically identify relevant papers and a meta-analysis was conducted using Stata16 software according to the level of heterogeneity applying a random- or fixed-effect model. Thirteen studies of 925 eyes in the PD group and 1501 eyes in the control group assessing OCT-A findings in PD patients were included. The meta-analyses revealed that the foveal region of PD patients had a significantly lower vessel density in the superficial capillary plexus (SCP) compared to healthy controls but that there were no significant differences in the foveal avascular zone, the SCP in whole, parafoveal, and perifoveal regions, and deep capillary plexus. OCT-A metrics may act as a potential biomarker for a more accurate and early PD diagnosis. Still, the OCT-A algorithms and interchangeability between OCT-A devices require further standardization to draw clinical conclusions regarding their utility.

Choriocapillary Flow Correlation with Axial Length in High Myopia - An Angiography Study with Optical Coherence Tomography.

To investigate parameters of retinal and choroidal microcirculation quantitatively with optical coherence tomography angiography (OCTA) in high myopic children, and to explore potential correlations with age, axial length (AL), spherical equivalent (SE), and central retinal thickness (CRT). En face angiograms were generated with an OCTA device and evaluated with automated density and flow analyzer algorithms. Perfusion parameters were correlated with age, AL, SE, and CRT using Spearman's rank correlation analysis. Repeatability and reproducibility of perfusion parameter measurements were calculated in a high myopic cohort. Repeatability and reproducibility of OCTA measurements were good, ranging from 3.6 - 6.5%. Strong positive correlation was identified between age and CRT (rho = 0.673, p = 0.00) as well as between AL and SE (rho = 0.844, p = 0.00). There was a strong negative correlation between AL and choriocapillary flow density (CCFD) (rho = - 0.612, p = 0.00), and a moderate negative correlation between age and superficial parafoveal retinal vessel density (SPRVD) as well as CCFD (rho = - 0.497, p = 0.013 and rho = - 0.483, p = 0.023, respectively). OCTA appears to be a reliable tool for the quantitative investigation of retinal and choroidal microcirculation in a high myopic pediatric cohort. CCFD reduction was associated with increasing AL in this cohort.

Evaluation of retinal and optic disc vascular structures in patients with familial Mediterranean fever (FMF) via optical coherence tomography angiography.

Familial Mediterranean fever (FMF) is an auto-immune disease characterized by fever and serositis. With this study, we aimed at comparing the retinal vascular structures of FMF patients and healthy individuals using optical coherence tomography angiography (OCTA) device. Sixty-nine patients with FMF and 52 healthy controls who were matched by age and sex, didn't have any comorbidities and were admitted to our clinic for routine ophthalmic examination were enrolled in the study. Sixty-nine eyes of 69 patients and 52 eyes of 52 healthy controls that were not disqualified due to the exclusion criteria were included in the study. OCTA images of the patients and controls were analyzed. The mean average age (± SD) of 69 FMF patients included in the study was 39.86 ± 13.16. Forty-nine patients were female, and twenty patients were male. Total vascular density of deep capillary plexus (DCP) and vascular density of DCP parafovea of the FMF patients were found to be statistically significantly lower than those of the controls (p = 0.045, p = 0.034, respectively), while total retinal parafoveal thickness, total retinal perifoveal thickness, outer retinal parafoveal thickness and outer retinal perifoveal thickness were statistically significantly higher in the patient group compared with the control group (p = 0.012, p = 0.014, p = 0.013, p = 0.009, respectively). This study found reduced vascular density and increased retinal thickness in patients with FMF compared to controls. Larger studies are required to further explore the effect of FMF on the retina.

FLOW AND GEOMETRICAL ALTERATIONS IN RETINAL MICROVASCULATURE CORRELATED WITH THE OCCURRENCE OF DIABETIC RETINOPATHY: Evidence from a Longitudinal Study.

To assess the relationship between flow and geometric parameters in optical coherence tomography angiography images and the risk of incident diabetic retinopathy (DR). This prospective, observational cohort study recruited patients with Type 2 diabetes without DR in Guangzhou, China, and followed up annually. A commercially available optical coherence tomography angiography device (DRI OCT Triton; Topcon Inc, Tokyo, Japan) was used to obtain a variety of flow (foveal avascular zone area, vessel density, and vessel length density) and geometric (fractal dimension and blood vessel tortuosity) parameters in superficial capillary plexus (SCP) and deep capillary plexus. The odds ratio (OR) and its 95% confidence interval (CI) were calculated per 1-SD increase in each optical coherence tomography angiography parameter. Over a follow-up of 1 year, 182 of 1,698 participants (10.7%) developed incident DR. After adjusting for conventional risk factors and image quality score, the higher risk of DR onset was significantly associated with the reduced parafoveal vessel density of SCP (OR = 0.81; 95% CI: 0.69, 0.96; P = 0.016), reduced parafoveal vessel length density of SCP (OR = 0.73; 95% CI: 0.59, 0.90; P = 0.003), reduced fractal dimension of SCP (OR = 0.73; 95% CI: 0.61, 0.87; P < 0.001), increased blood vessel tortuosity of SCP (OR = 1.39; 95% CI: 1.18, 1.64; P < 0.001), and increased blood vessel tortuosity of deep capillary plexus (OR = 1.19; 95% CI: 1.01, 1.40; P = 0.033). Reduced vessel density and impaired vessel geometry posed higher susceptibility for DR onset in patients with Type 2 diabetes, supporting the adoption of optical coherence tomography angiography parameters as early monitoring indicators of the newly incident DR.

Retinal Microvasculature and Choriocapillaris Flow Deficit in Relation to Serum Uric Acid Using Swept-Source Optical Coherence Tomography Angiography.

PurposeTo explore the relationship between serum uric acid (SUA) and retinochoroidal microcirculation in the Chinese population.MethodsThis prospective cross-sectional study was conducted among the residents of Guangzhou, southern China. A commercially available optical coherence tomography angiography (OCTA) device was used to obtain the superficial vessel density (SVD) and deep vessel density in the retina and the choriocapillaris flow deficit (CFD) in the macular region. Univariable and multivariable linear regression models were used to assess the association of hyperuricemia and SUA levels with OCTA parameters.ResultsA total of 638 participants with normal SUA and 296 participants with hyperuricemia were included in the study. Parafoveal SVD was significantly reduced among the participants with hyperuricemia compared to participants with normal SUA (P < 0.001), while the parafoveal CFD was higher in hyperuricemic participants than those of normal SUA levels (P = 0.007). After adjusting for potential confounders, greater SUA levels was associated with lower SVD (β = −0.078; P < 0.001) and greater CFD (β = 0.015; P = 0.011). Gender difference analysis indicated that a 10-µmol/L increase in SUA levels among the female participants led to a 0.144 decrease in SVD (P < 0.001), but it was not statistically significant for the male participants (P = 0.653).ConclusionsAn elevated uric acid level and its fluctuations were independently associated with impaired retinal and choroidal microcirculation using OCTA in the study population. Women appear to be more sensitive to high SUA levels than men.Translational RelevanceElevating uric acid concentration may play a role in the development and progression of cardiovascular diseases through microvascular alteration, as demonstrated by OCTA parameters.