Optical Coherence Tomography Angiography Measurements Research Articles

Assessment of the impact of low-density lipoprotein cholesterol on retinal vessels using optical coherence tomography angiography

BackgroundLow-density lipoprotein cholesterol (LDL-C) is acknowledged as an independent risk factor (IRF) for atherosclerotic cardiovascular disease. Nevertheless, studies on the impact of LDL-C on microvasculature are still scarce. The retina, abundant in microvasculature, can now be examined for microvascular alterations through the novel, non-invasive, and quantitative optical coherence tomography angiography (OCTA) technique.MethodsIn this cross-sectional study, 243 patients from the geriatric department were recruited (between December 2022 and December 2023). Individuals were classified into four groups based on their LDL-C levels: Group 1 (≤ 1.8 mmol/L), Group 2 (> 1.8 mmol/L to ≤ 2.6 mmol/L), Group 3 (> 2.6 mmol/L to ≤ 3.4 mmol/L), and Group 4 (> 3.4 mmol/L). The OCTA results including retinal vessel density (VD), foveal avascular zone (FAZ) area, macula thickness, and retinal nerve fiber layer (RNFL) thickness were contrasted across these groups. T-tests, analysis of variance, Welch’s tests, or rank-sum tests were employed for statistical comparisons. In cases where significant differences between groups were found, post-hoc multiple comparisons or rank-sum tests were performed for pairwise group comparisons. Spearman’s correlation coefficient was employed to perform bivariate correlation analysis to evaluate the relationship between LDL-C levels and various OCTA measurements. Multivariable regression analysis was used to evaluate the association between LDL-C levels and various OCTA measurements. Linear regression analysis or mixed-effects linear models were applied.ResultsIt was discovered that individuals with LDL-C levels exceeding 2.6 mmol/L (Groups 3 and 4) exhibited reduced VD in the retina, encompassing both the optic disc and macular regions, compared to those with LDL-C levels at or below 2.6 mmol/L (Groups 1 and 2). A negative correlation among LDL-C levels and retinal VD was identified, with r values spanning from − 0.228 to -0.385. Further regression analysis presented β values between − 0.954 and − 2.378. Additionally, no notable disparities were detected among the groups regarding FAZ area, macular thickness, and RNFL thickness.ConclusionsThe outcomes of this study suggest that elevated LDL-C levels constitute an IRF for decreased VD across the entire retina.Trial registrationNCT05644548, December 1, 2022.

Correlation between optical coherence tomography angiography measured vessel density and retinal nerve fiber layer thickness in moderate primary open angle glaucoma cases and normal controls

: Aim of this study was to establish a correlation between findings obtained from Optical Coherence Tomography Angiography (OCT-A) and Retinal Nerve Fiber Layer (RNFL) thickness measurements in a series of moderate Primary Open Angle Glaucoma (POAG) cases and normal controls. In this observational cross-sectional study a total of 100 eyes were included, comprising 50 eyes with glaucoma and 50 control eyes without glaucoma. All participants underwent comprehensive anterior and posterior segment evaluations, intraocular pressure (IOP) measurement using Goldmann applanation tonometer, gonioscopy, visual field testing, and OCT imaging, which included OCT-A. The OCT-A imaging was performed using the RTvue XR Avanti by Optovue. Two types of analysis were conducted: a comparative analysis between the normal and glaucomatous groups using an unpaired t-test to assess differences in RNFL thickness and vessel density values, and a correlation analysis within each group to examine the strength of correlation between RNFL loss and reduction in vascular density. The results showed a significant reduction in vessel density index in all quadrants of glaucomatous eyes compared to normal eyes. Moreover, this reduced vessel density was found to be significantly correlated with the reduction in RNFL thickness in glaucoma patients. Specifically, the uperior and inferior quadrants exhibited the strongest correlation with each other. The severity of vascular compromise demonstrated a significant correlation with the extent of retinal nerve fiber loss in patients with glaucoma. OCT-A can serve as a valuable adjunct in the diagnosis of glaucoma and monitoring its progression.

Effect of Buerger’s disease on ocular microvascular structure

ABSTRACT Clinical relevance Buerger’s disease, being a systemic inflammatory vasculopathy, may present with ocular findings. Background This study aims to understand the potential role of optical coherence tomography and angiography findings in evaluating the course of Buerger’s disease. Methods This was a prospective, cross-sectional study that included 25 patients with Buerger’s disease (Group 1) and 51 healthy control participants, of whom 27 were smokers (Group 2) and 24 were non-smokers (Group 3). Following a detailed ophthalmic examination, optical coherence tomography and angiography measurements were conducted on participants. The values of macular superficial and deep capillary plexus, peripapillary capillary plexus vessel density measurements were taken into account from optical coherence tomography angiography measurements. Furthermore, measurements were taken for the parameters of the foveal avascular zone, including its area, perimeter and acircularity index. Additionally, the choriocapillaris flow area was assessed between radii of 1 mm, 2 mm, and 3 mm. Results In patients with Buerger’s disease, the area and perimeter of the foveal avascular zone were higher than in both smoker and non-smoker healthy groups (p < 0.001 for all). The vessel densities in superficial capillary plexus were found to be lower in patients with Buerger’s disease compared to both smokers and non-smokers in all regions except the parafovea (p < 0.05 for all). The radial peripapillary capillary plexus vessel densities in the whole retina and peripapillary region were lower than those in the non-smoker group (p < 0.001 and p = 0.008). The choriocapillaris flow areas in all three radius were lower in the smoker group than in the non-smoker group (1 mm, p = 0.01; 2 mm, p = 0.005; 3 mm, p = 0.011) Conclusions Buerger’s disease extends beyond the extremities, affecting vascular density and tissue perfusion in the optic disc and macula, making it a systemic condition. This disease can have ocular involvement without causing serious ocular findings.

Assessment of the effects of two commonly used mydriatics on the macular and peripapillary microvascular systems of healthy children: An Optical Coherence Tomography Angiography Study.

To evaluate the effects of pupil dilation caused by topical applications of 2.5% phenylephrine and 0.5% tropicamide on retinal microvascularization using optical coherence tomography angiography (OCTA). Healthy children were included in this prospective observational study. Baseline OCTA measurements were taken for all children before dilatation. Then they were randomly divided into two groups, the tropicamide group given 0.5% tropicamide solution and the phenylephrine group given 2.5% phenylephrine solution. After dilation OCTA images were taken for the second time from all children. The effect of dilation using two different mydriatic agents caused a decrease in mean radial peripapillary capillary density (RPC-VD) and superior RPC-VD (p=0.008 and p=0.001). Remarkably, this reduction due to dilatation was also determined to be caused by the combined effect of both mydriatic agents (p=0.016 and p=0.013). Although phenylephrine showed a slightly greater decrease than tropicamide, the effects of the two mydriatic drugs were not superior to each other (p=0.166 and p=0.167). Dilation with 2.5% phenylephrine or 0.5% tropicamide significantly decreased mean RPC-VD and superior RPC-VD. Although there was no statistically significant difference between the two mydriatic agents, phenylephrine caused a greater reduction than tropicamide. This effect of dilation and phenylephrine on VD should be considered in studies using OCTA and focusing on peripapillary areas.

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

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. 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). 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). 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.

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

BackgroundTo 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).MethodsThis 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.ResultsA 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.ConclusionBased 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.

Study of the impact of the vascular systemic risk factors on peripapillary vascular density by optical coherence tomography angiography.

The focus of therapeutic tools in glaucoma has been mainly to control of intraocular pressure. Recently there has been a growing interest in investigating the relationship of vascular risk factors in the development of glaucoma. The aim of this study was to assess the association between systemic arterial hypertension, diabetes mellitus and hypercholesterolemia, and peripapillary vascularization measured by Optical Coherence Tomography Angiography (OCTA) in glaucoma and healthy subjects. In this unicenter, observational, cross-sectional study, 212 subjects, 118 glaucoma patients and 94 controls were consecutively recruited. Of these, 86 participants were excluded due to poor OCTA image quality. Therefore, 146 subjects were included in the final analysis, 74 glaucoma patients and 72 controls. Using a linear regression model, with 95% confidence and 80% statistical power, the effect of vascular risk factors on OCTA parameters in the 146 subjects included in the final analysis was studied. No significant impact of vascular risk factors on OCTA measurements was found. Diabetic patients tended to show a lower peripapillary perfusion vascular density than subjects without diabetes (β 0.016, 95%CI 0.003;0.030, p 0.016). Similarly, hypercholesterolemia patients appeared to show less peripapillary flow index than non-hypercholesterolaemic patients (β 0.029, 95%CI 0.013;0.046, p 0.001). Glaucoma patients had 0.02% lower peripapillary perfusion vascular density (β 0.020, 95% CI 0.011;0.029, p < 0.001), 0.04% lower peripapillary flow index (β 0.036, 95%CI 0.022;0.051, p < 0.001) and 9.62% thinner retinal nerve fibre layer (β 9.619, 95%CI 5.495;13.744, p < 0.001). In conclusion glaucoma has greater effect on peripapillary vascular density parameters than any of the vascular risk factors analyzed. What is known: • Vascular disfunction plays an important role in the development of glaucoma. • Optical coherence tomography angiography makes it possible to assess the retinal microvasculature and the role that its alterations could have in the development of glaucoma. • Decrease of the peripapillary microcirculation seems to be more related to the increase in intraocular pressure and the glaucoma itself than to the presence of cardiovascular risk factors. • The effect of having diabetes, systemic arterial hypertension or hypercholesterolaemia on vascular parameters or nerve fibre layer thickness was low. • There was also no relevant impact of the systemic medication used for these diseases on the peripapillary vascular parameters studied or on nerve fibre layer thickness.

Optical coherence tomography angiography in patients with bipolar disorder and major depressive disorder

BackgroundCerebral microvascular dysfunction is a promising area for research into the pathogenesis of major depressive disorder (MDD) and bipolar disorder (BD). Despite the scientific and clinical potential of studying microvascular dysfunction, progress in this area has long been hampered by the lack of methods to study microvessels intravitally. AimsThe aim of the present study was to search for potential optical coherence tomography (OCT) and OCT-angiography (OCTA) biomarkers of BD and MDD. MethodsOne hundred and five consecutive patients with a current depressive episode were enrolled in the study (39 – BD and 66 – MDD). In addition, forty-one generally healthy subjects were enrolled as a control group. Only the right eye was examined in all subjects. Structural OCT and OCTA scans with signal strength ≥7 were included. ResultsStructural OCT measurements showed no significant differences between the groups. OCTA measurements of foveal avascular zone (FAZ), area and skeleton density showed a decrease in the retinal capillary bed in BD patients, whereas OCTA values in MDD patients did not differ from the control group. Several significant differences were found between the BD and control groups. In the BD group, the FAZ of the deep capillary plexus was increased, reflecting a reduction in capillary perfusion in the central subfield of this plexus. ConclusionsOCTA measurements of FAZ, area and skeleton density showed a decrease in the retinal capillary bed in BD patients, whereas OCTA values in MDD patients did not differ from the control group.

Changes in vessel density patterns assessed with OCTA in patients with diabetic macular edema treated with anti-VEGF therapy

AimsTo determine the presence of sectoral changes in vessel density (VD) patterns induced by vascular endothelial growth factor inhibitors (anti-VEGF) in patients with diabetic macular edema (DME) using optical coherence tomography angiography (OCTA).MethodsProspective, interventional study. A total of 43 patients (63 eyes) were initially enrolled in the study. We performed swept source (SS) OCT and sectorial OCTA measurement to determine parafoveal VD at baseline and after six months of anti-VEGF treatment. In the locations with statistically significant differences in VD between baseline and month 6, we performed univariate and multivariate analyses to determine which, if any, of the baseline variables were associated with the observed changes.ResultsA total of 34 patients (48 eyes) were included in the final analysis. Mean VD decreased from baseline to month 6 (from 45.2 (± 3.5) to 44.6 (± 3.2) % in the SCP and from 50 (± 3.3) to 49 (± 3.9) % in the DCP). The only significant changes in VD were observed in the nasal sector of the deep capillary plexus, with a decrease of 2.9% (p = 0.001). On univariate and multivariate analyses, the only variable significantly associated with changes in VD in the nasal sector after 6 months of treatment was baseline VD in the same sector.ConclusionsAnti-VEGF therapy has a small impact on VD values over time. These variations observed after treatment seems to be related to changes over areas of vascular anomalies and displaced vessels adjacent to cystic areas, with no significant changes over ischemic areas. No correlation was observed between this trend and other clinical baseline features.

Rate of Initial Optic Nerve Head Capillary Density Loss and Risk of Visual Field Progression

Rapid initial optic nerve head capillary density loss may be used to assess the risk of glaucoma visual field progression. To investigate the association between the rate of initial optic nerve head capillary density loss from optical coherence tomography angiography (OCTA) and visual field progression. This was a retrospective study of a longitudinal cohort at a glaucoma referral center. A total of 167 eyes (96 with primary open-angle glaucoma and 71 with glaucoma suspect) of 109 patients were monitored for a mean (SD) of 5.7 (1.4) years from January 2015 to December 2022. Data analysis was undertaken in April 2023. The rates of initial capillary density and average retinal nerve fiber layer loss were calculated from the first 3 optic nerve head OCTA and OCT scans, respectively, during the initial follow-up (mean [SD], 2.0 [1.0] years). Based on the median rate, eyes were categorized into fast and slow progressor groups. The association between initial capillary density change or retinal nerve fiber layer thinning and visual field progression was evaluated using linear-mixed and time-varying Cox models. A total of 167 eyes of 109 patients (mean [SD] age, 69.0 [11.1] years; 56 [51.4%] female and 53 [48.6%] male) were assessed. Eighty-three eyes were slow OCTA progressors, while 84 eyes were fast with mean capillary density loss of -0.45% per year and -1.17% per year, respectively (mean difference, -0.72%/year; 95% CI,-0.84 to -0.60; P < .001). Similarly, 83 eyes were slow OCT progressors, while 84 eyes were fast with mean retinal nerve fiber layer thinning of -0.09 μm per year and -0.60 μm per year, respectively (mean difference, -0.51 μm/year; 95% CI,-0.59 to -0.43; P < .001). The fast OCTA and OCT progressors were associated with more rapid visual field loss (mean difference, -0.18 dB/year; 95% CI,-0.30 to -0.06; P = .004 and -0.17 dB/year; 95% CI,-0.29 to -0.06; P = .002, respectively). Fast OCTA progressing eyes were more likely to have visual field progression (hazard ratio, 1.96; 95% CI, 1.04-3.69; P = .04). Seventeen of 52 eyes (32.7%; 95% CI, 32.5-32.8) with fast OCTA and OCT progression developed subsequent visual field likely progression. Rapid initial optic nerve head capillary density loss from OCTA was associated with a faster rate of visual field progression and a doubling of the risk of developing event progression in this study. These findings may support clinical use of OCTA and OCT optic nerve head measurements for risk assessment of glaucoma progression.

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.

Reduced Retinal Blood Vessel Densities Measured by Optical Coherence Tomography Angiography in Keratoconus Patients Are Negatively Correlated with Keratoconus Severity.

Keratoconus (KC) is the most common corneal ectasia. Optical coherence tomography angiography (OCT-A) is a relatively new non-invasive imaging technique that allows the visualization and quantification of retinal and choriocapillary blood vessels. The aim of this study is to assess retinal and choriocapillary vessel density (VD) differences between KC patients and healthy controls and to investigate correlations between VD and KC severity. Fifty-two eyes were included in this exploratory study: twenty-six eyes from 26 KC patients and twenty-six eyes from 26 age- and gender-matched healthy controls. All patients underwent Scheimpflug corneal topography with Pentacam, axis lengths measurement and optical coherence tomography angiography (OCT-A). The thinnest spot in corneal pachymetry, maximum K (Kmax) and KC severity indices from the Belin/Ambrósio enhanced ectasia display (BAD) were also assessed. There was a distinct reduction particularly in the retinal VD of the superficial capillary plexus (SCP). Correlation analyses showed strong and moderate negative correlations between the VD in the macular SCP and BAD KC scores and between the SCP VD and Kmax. There was no difference in retinal thickness between the KC and healthy controls. With this study, further evidence for altered VD measurements by OCT-A in KC patients is given. For the first time, we demonstrated negative correlations between BAD KC scores and retinal blood vessel alterations. A major limitation of the study is the relatively small sample size. Since an artefactual reduction of the quantitative OCT-A measurements due to irregular corneal topography in KC must be assumed, it remains to be investigated whether there are also actual changes in the retinal microcirculation in KC.

New insights in the pathogenic mechanism of multiple sclerosis: Is Epstein-Barr virus associated with optic nerve involvement?

There are no reports in the literature studying the possible relationship between Epstein-Barr virus (EBV) and optic nerve involvement in multiple sclerosis (MS). The aim of our study was to analyze the association between EBV antibodies titres and optical coherence tomography (OCT) and OCT angiography (OCTA) quantitative parameters. We conducted a retrospective study. The study included 98 eyes of 49 patients with MS. Years of MS duration, relapse count, history of optic neuritis (ON), and immunoglobulin (Ig) G antibodies to the EBV viral capsid antigen (VCA) were recorded from each patient. Also, OCT analysis (including retinal nerve fibre layer (RNFL) thickness and ganglion cell-inner plexiform layer (GCIPL) thickness) and OCTA analysis (including perfusion density (PD) and flux index (FI) of the radial peripapillary capillary plexus) were performed in each participant. No significant associations were observed between anti-EBV antibody levels and OCT or OCTA parameters (p > 0,05). Correlation analysis between OCT and OCTA measurements showed a significant positive correlation between RNFL thickness and GCIPL thickness with peripapillary PD and FI (p < 0,035). Subgroup analysis revealed a significant diminution of RNFL thickness, GCIPL thickness and peripapillary PD and FI (p < 0,05) in the ON group. We were unable to demonstrate a significant association between anti-EBV VCA IgG antibody titres and OCT or OCTA parameters. Nonetheless, further longitudinal studies are needed to explore the possible association of EBV with optic nerve involvement in MS.

Repeatability and reproducibility of quantitative OCT angiography measurements from table-top and portable Flex Spectralis devices.

The recent development of a portable investigational handheld OCT-angiography (OCTA) device has allowed for expansion of imaging into the operating room (OR) in addition to standard in-clinic imaging. The aim of this study was to assess intravisit repeatability and intervisit reproducibility of retinal microvasculature measures and central retinal thickness for in-clinic table-top and portable OR compatible OCTA devices. Repeated 10 × 10 OCTA images were acquired in 20 healthy adult participants on two separate visit days using Spectralis spectral-domain OCTA table-top and investigational armature suspended Flex systems. Intravisit and intervisit intraclass correlation coefficients and average absolute percent difference were calculated for quantitative microvasculature measures and CRT. 120 OCTA images were acquired from 20 subjects (n = 20, mean age 26.7 ± 1.61years, range 24-30years) with both devices across two separate imaging days. FAZ and CRT measurements had near complete intravisit and intervisit agreement with ICCs between .97 and 1 for both table-top (FAZ ICC .97, .97; CRT ICC .98-1, .98-.99) and Flex (FAZ ICC .97, .95; CRT ICC .99-1, .98-.99) devices. Vessel density measures demonstrated greater variance with only fair to strong agreement (ICC .32-.75) and average absolute percent differences ranging from 2.96 to 6.63%. FAZ and CRT measures for both devices demonstrated high repeatability and reproducibility; retinal vessel density measures demonstrated less. Differences of less than 7% for retinal microvasculature measurements across time and devices are most likely attributable to expectable variance between repeat scans.

Optical Coherence Tomography Angiography Vessel Density in Healthy, Glaucoma Suspect, and Glaucoma Eyes

Abstract Purpose: To evaluate and compare optical coherence tomography angiography (OCTA) retinal vasculature measurements in healthy, glaucoma suspect (GS), and glaucoma patients. Methods: One hundred fourteen eyes with good quality OCTA pictures were included from 38 healthy, 38 GS, 38 and primary open-angle glaucoma (POAG) participants. The information on retinal vasculature was summarized as a vessel density map and as vessel density (%), which is the fraction of the flowing vessel area over the total area examined. The superior, inferior, nasal, and temporal quadrants, as well as whole vessel density (wVD) and peripapillary vessel density (ppVD) data taken from the retinal nerve fiber layer, were studied. Global indices of the visual field were correlated with vessel density measurement. Results: Mean vessel density was significantly lower in POAG eyes compared with GSs and healthy eyes (wVD) 45.34% ± 6.64%, 50.06% ± 1.97% and 53.06% ± 2.12%, respectively (P &lt; 0.001), and ppVD 47.42% ± 7.73%, 47.42% ± 7.73% and 56.074% ± 2.71%, respectively (P &lt; 0.001). A linear relationship between vessel density (wVD and ppVD) and global indices of the visual field (mean deviation [MD] and pattern standard deviation [PSD]) shows a significant (P &lt; 0.001) relation. R 2 is 0.35, 0.36, 0.36, and 0.33 for MD and wVD, PSD and wVD, PSD and ppVD, and MD and ppVD, respectively. Conclusions: For distinguishing between healthy and glaucoma eyes, OCTA vessel density demonstrated near similar diagnostic accuracy to visual field tests. These findings imply that OCTA measurements reflect damage to tissues important in the pathogenesis of POAG.

CHANGES IN OPTICAL COHERENCE TOMOGRAPHY ANGIOGRAPHY MEASURES THROUGHOUT THE DAY: Diurnal Variation or Test-Retest Variability?

To evaluate the repeatability and diurnal variation of the retinal vessel density and foveal avascular zone parameters using optical coherence tomography angiography. Forty-one healthy individuals were measured twice in the morning and once in the evening. Foveal avascular zone area, perimetry, foveal density; superficial and deep capillary plexus (superficial capillary plexus, deep capillary plexus) vessel density, and central macular thickness were evaluated with the intraclass correlation coefficient, coefficient of repeatability, and Bland-Altman plots. Repeatability was evaluated with two consecutive scans taken in the morning. The coefficient of repeatabilities (%) was 5.4; 4.3, and 8.8 for the foveal avascular zone area, perimetry, and foveal density, respectively, with excellent intraclass correlation coefficients. Intraclass correlation coefficient was poor for parafovea (0.33), whereas excellent for fovea (0.97) in superficial capillary plexus-vessel density. Coefficient of repeatability for fovea and parafovea was 19.19% and 10.43%, respectively. Intraclass correlation coefficient values were poor (0.3-0.4) with 10% to 16% measurement differences in deep capillary plexus-vessel density parameters. Coefficient of repeatabilities for central macular thickness was between 1% and 2% with excellent intraclass correlation coefficient. The analysis on diurnal variation yielded comparable results. Except for the parafoveal vessel density, optical coherence tomography angiography is a highly reproducible device for measuring foveal avascular zone and vessel density using 6 × 6 scans with undilated pupils. However, variation in optical coherence tomography angiography parameters observed throughout the day could be attributed to test-retest variation rather than diurnal rhythm.

Evaluation of retinal and peripapillary vessel density and subfoveal choroidal thickness changes in patients undergoing cardiopulmonary bypass: An OCTA study.

We aimed to investigate hemodynamic changes in the retina, peripapillary area, and choroid in patients undergoing coronary artery bypass grafting (CABG). This prospective case series included 35 eyes of 35 patients. Vessel density (VD) of superficial capillary plexus, deep capillary plexus, radial peripapillary capillary, foveal avascular zone area, and subfoveal choroidal thickness changes were evaluated using optical coherence tomography angiography (OCTA) 1 day before and 2 weeks after surgery. The correlation of these parameters with aortic cross-clamp (ACC) duration and cardiopulmonary bypass (CPB) duration was evaluated. There were no differences in the OCTA measurements of the patients after CABG compared to before surgery (P > 0.05). Inside-disc VD showed a negative correlation with both ACC (P = 0.036) and CPB duration (P = 0.048); peripapillary inferior hernia showed a negative correlation with both ACC (P = 0.042) and CPB duration (P = 0.027). Another negative correlation was observed between mean peripapillary VD and CPB duration (P = 0.039). The CPB procedure had no permanent effect on retinal choroid and optic disc blood flow postoperatively. Prolonged ACC and CPB times seem to be important in terms of optic nerve blood flow. Clinicians should be alert for postoperative ocular complications after long surgeries.

Parapapillary choroidal microvasculature in retrobulbar optic neuritis: An optical coherence tomography angiography study

PurposeTo compare superficial and deep vascular characteristics of the optic disc in retrobulbar optic neuritis using optical coherence tomography angiography (OCT-A). MethodsNineteen patients with unilateral non-infectious retrobulbar neuritis were included in the study. The contralateral eyes of each patient were served as controls. OCT-A scans of the optic discs were performed in a 4.5 × 4.5 mm rectangular area, while macular OCT-A scans were performed in a 6 × 6 mm rectangular area. Various parameters, including radial peripapillary capillary (RPC) density, peripapillary retinal nerve fibre layer (pRNFL) thickness, cup volume, rim area, disc area, cup-to-disc (c/d) area ratio, and vertical and horizontal c/d ratios were automatically obtained using the instrument software. The density for superficial capillary plexus (SCP) and deep capillary plexus (DCP) were assessed using macular OCT-A. Parapapillary choroidal microvascular (PPCMv) density was calculated using MATLAB software. ResultsParafoveal inferior, perifoveal total and inferior SCP densities were significantly decreased in eyes with optic neuritis when compared with contralateral control eyes in OCT-A measurements (respectively, p = 0.027, p = 0.041, p = 0.045). The axial lengths, (p = 0.72), vertical and horizontal cup-disc ratios, and disc area, cup-disc areas, cup volumes, and pRNFL thicknesses between the groups were similar (for each, p>0.05). ConclusionsThis study demonstrated for the first time that patients with retrobulbar optic neuritis had decreased SCP densities, though it did not cause any changes in PPCMv density.

Does SarsCoV-2 infection really cause damage to retinal microcirculation in mild cases of COVID-19?

Aim To evaluate changes of retinal microcirculation in mild cases of recovered COVID-19 patients at least three months after the infection by optical coherence tomography angiography (OCTA) non-invasive method. Methods In this prospective cross-sectional study, 50 right eyes of 50 recovered COVID-19 patients were compared with 50 right eyes of age and gender-matched healthy controls. After the complete ophthalmological examination, all participants underwent OCTA measurements (RTVue XR Avanti, Optovue, Fremont, CA, USA). Results The time between the initial onset of symptoms, and ophthalmologic examination was 479.20 ±197.10 (126-754) days. Findings of ophthalmic examination of all eyes of the recovered COVID-19 patients were within normal range. Significantly reduced superficial (p=0.046) and deep (p=0.044) macular vessel density (VD) in foveal region in the eyes of the recovered COVID-19 patients was found compared with healthy controls. Significantly enlarged foveal avascular zone (FAZ) area and perimeter in the eyes of the recovered COVID-19 patients (p<0.001) were found too. Conclusion Recovered COVID-19 patients have impaired retinal microcirculation, which can be a cause of the development of retinal vascular diseases.

Optical coherence tomography angiography parameters in patients taking hydroxychloroquine therapy.

The aim of this study is to measure retinal vessel density and flow rate area by optical coherence tomography angiography (OCTA) in patients with autoimmune diseases taking hydroxychloroquine (HCQ). The cross-sectional study included 98 patients divided into three groups. Group I included patients with the diagnosis of an autoimmune disease, for whom the introduction of HCQ was planned. Group II implied low-risk patients for retinal toxicity (≤5 years of HCQ use), whereas Group III implied patients that were at high-risk (>5 years of drug use). All patients underwent a computerized visual field, central macular thickness by optical coherence tomography, and OCTA measurements. The vascular density was found to be statistically significantly decreased in the high-risk group compared to the control group in the superficial parafoveal zone (P = 0.030), whereas it was decreased compared to the low-risk and control groups in the deep layers whole (P = 0.006, P = 0.010, respectively) and perifoveal zones (P = 0.003, P = 0.010, respectively). The foveal avascular zone was significantly enlarged in the high-risk group compared to the control (P < 0.018). Retinal flow rates did not show statistically significant differences between the groups (P > 0.05). Patients treated with HCQ for more than 5 appear have a significant loss of vascular density in the parafoveal and perifoveal regions, and FAZ area is significantly increased compared to low-risk patients and controls. These findings indicate that OCTA may be beneficial for monitoring high-risk patients and may stratify their risk of further retinal damage.