Signal Strength Reduction Effects in OCT Angiography

To compare choroidal neovascularization (CNV) area and vessel density (VD) measurements between two different swept-source optical coherence tomography angiography (SS-OCTA) devices. En face optical coherence tomography angiography (OCTA) images of patients affected by neovascular age-related macular degeneration were collected prospectively from two devices: Zeiss PLEX Elite 9000 (Carl Zeiss Meditec, Dublin, CA) and Topcon DRI OCT Triton SS-OCTA (Topcon, Tokyo, Japan). Choroidal neovascularization area and VD of images were measured and analyzed with ImageJ software by two readers to evaluate the agreement between two devices, with respect to different image size (3 × 3 and 6 × 6 mm) and different image segmentation (automatic vs. manual), and a Topcon equivalent Zeiss segmentation as control (i.e., the equivalent anatomical slab given by Topcon device on the Zeiss device). A total of 30 eyes (30 patients) were analyzed. There was an excellent agreement between the two readers in CNV area measurements intraclass correlation coefficient >0.9 in all analyses. We found excellent agreement in CNV area measurements (manual and automatic segmentations) when comparing 3 × 3-mm or 6 × 6-mm images both for each single device and between the two devices (overall intraclass correlation coefficient > 0.9). Vessel density measurements between manual to automatic segmentation within the same device and same image size had a high intraclass correlation coefficient value, but there was a poor agreement in VD between different image sizes (3 × 3 mm vs. 6 × 6 mm) in the same device and also comparing the two devices (3 × 3 Topcon vs. 3 × 3 Zeiss; 6 × 6 Topcon vs. 6 × 6 Zeiss). There was a poor agreement between the Topcon equivalent Zeiss segmentation and all other segmentations. There was an excellent agreement in CNV area measurements for both swept-source optical coherence tomography angiography devices in automatic and manual segmentations. However, the Topcon equivalent Zeiss segmentation was not comparable with any of the preset segmentations of Topcon and Zeiss devices. There was a poor agreement in CNV VD between different image size and different devices. For these reasons, it seems that, for accurate longitudinal analysis of VD, it is better to use the same device for each individual, even if both devices can be used interchangeably for CNV area measurements using automatic or manual segmentations.

AimTo newly describe a spectral-domain (SD) optical coherence tomography angiography (OCTA) for the cornea and directly compare two OCTA system scans of the same eyes with corneal vascularisation.MethodsCross-sectional, observational, comparative...

Pseudoexfoliation glaucoma eyes had a similar level of peripapillary and superficial macular vessel densities compared with primary open-angle glaucoma eyes matched for age and glaucoma severity when assessed by optical coherence tomography angiography (OCT-A). To compare vessel density (VD) measured by OCT-A between primary open-angle glaucoma (POAG) and pseudoexfoliation glaucoma (PXG) in the peripapillary and macular areas. The circumpapillary (cpVD), parafoveal (pfVD), and perifoveal vessel densities (perifVD) were obtained using OCT-A (AngioVue/RTVue-XR) in 98 eyes from 98 subjects [age, visual acuity, visual field (VF) mean deviation (MD) matched 49 POAG and 49 PXG eyes]. Global and 8 sectoral VDs in the peripapillary capillary layer were compared. In the macula, the superficial and deep layers of the pfVD and perifVD were analyzed globally and in 4 quadrants. Univariate and multivariate linear regression models were built using cpVD, pfVD, and perifVD as dependent variables and covariates [age, intraocular pressure (IOP), axial length, signal strength index (SSI), and retinal nerve fiber layer (RNFL) thickness] were considered independent variables. In the peripapillary region, none of the VDs differed between groups both before and after adjustment. When we adjusted superficial and deep layer macular VDs for age, IOP, SSI, axial length, and RNFL thickness, all of which could affect measurements, the 2 groups did not differ in any sector. The cpVD in POAG eyes significantly correlated with VF MD and RNFL thickness, whereas IOP, VF MD, and RNFL thickness affected cpVD in PXG. The macular VD in the deep layer was associated with only SSI in both groups. Age-matched and glaucoma severity-matched PXG and POAG did not significantly differ in cpVD or in most of the superficial macular VD parameters.

Background/aimsOptical coherence tomography angiography (OCTA) allows the study of vessel density (VD). We intended to perform a systematic review of studies focusing on longitudinal changes in peripapillary and macular VD...

To investigate the relationship between the visual field (VF) deterioration and vessel density (VD) around the optic nerve head (ONH) in a sector-wise manner in eyes with retinitis pigmentosa (RP). The present study enrolled the RP patients who demonstrated VF constriction within central 10°. The VD around the ONH was measured with optical coherence tomography angiography (OCTA), using three binarization methods and the relationships between VD and the mean deviation (MD) value were investigated, respectively. Then, the VD in each quadrant (superior, temporal, inferior, nasal) around the ONH was calculated using Otsu method (OVDs: vessel density measured with Otsu method in the superior region, OVDt: vessel density measured with Otsu method in the temporal region, OVDi: vessel density measured with Otsu method in the inferior region, OVDn: vessel density measured with Otsu method in the nasal region). Considering the foveal position relative to the optic disc, angle-corrected binarized OCTA images were created and the VD was measured in each sector (AcOVDs: angle-corrected OVDs, AcOVDt: angle-corrected OVDt, AcOVDi: angle-corrected OVDi, and AcOVDn: angle-corrected OVDn). We investigated the relationship between the MD value and OVDs, OVDt, OVDi and OVDn. Furthermore, the correlation between the MD value and AcOVDs, AcOVDt, AcOVDi and AcOVDn was analyzed. Thirty-six eyes were examined in the current study. Among Niblack, Bernsen and Otsu methods, the VD measured with Otsu method was closely related to the MD value. Among OVDs, OVDt, OVDi and OVDn, the optimal model for the MD value included OVDt and OVDi. On the other hand, among AcOVDs, AcOVDt, AcOVDi and AcOVDn, the optimal model for the MD value included only AcOVDt. The sector-wise VD around the ONH reflects VF deficit severity and is a candidate for improving the assessment of VF deterioration in eyes with RP.

AimsTo compare the intrasession repeatability of peripapillary and macular vessel density measurements of optical coherence tomography angiography (OCTA) in normal and glaucoma eyes, and to evaluate the effect of signal...

The aim of this study was to evaluate the effect of subject-related (age, sex, and systemic hypertension and diabetes), eye-related (refractive error, optic disc size), and technology-related (signal strength index, SSI of the scans) determinants on the peripapillary and macular vessel densities measured with optical coherence tomography angiography (OCTA) in normal eyes. In a cross-sectional study, 181 normal eyes of 107 subjects (45 men, 62 women, median age: 50 y, range: 18 to 77 y) underwent OCTA imaging. Linear mixed models were used to analyze the effect of the determinants on the peripapillary and macular vessel densities measured with OCTA. It was found that age and optic disc size did not affect the vessel densities of any of the regions (P>0.05 for all associations). En face optic disc (coefficient: 1.67, P<0.001) and most of the peripapillary vessel densities were higher in female individuals. En face disc (coefficient=-1.88, P=0.02) and most of the peripapillary vessel densities were lower, whereas the parafoveal vessel density was higher (coefficient=2.32, P=0.01), in subjects with hypertension. Most of the vessel densities were lower in subjects with diabetes. SSI showed a statistically significant association with the vessel densities of all regions (coefficients: 0.14 to 0.27 for peripapillary and 0.20 to 0.27 for macular sectors). Most of the peripapillary vessel densities were higher in female subjects. Hypertension and diabetes also affected the vessel densities. Vessel densities in all the regions were significantly higher in scans with higher SSI. These results should be considered when interpreting the vessel densities in retinal diseases and glaucoma.

Background Glaucoma is a prevalent cause of visual impairment, and early detection is critical to prevent progressive vision loss. Optical coherence tomography angiography (OCT-A) enables visualization of retinal and optic nerve microvasculature and holds promise for early glaucoma detection. Aims This study aims to assess microvasculature density alterations in glaucoma using OCT-A. Methods An observational cross-sectional case–control study was conducted at Benghazi Eye Hospital in Libya from December 2022 to August 2023. It included 160 eyes of 126 patients diagnosed with primary open-angle glaucoma and 120 eyes of 96 control subjects. OCT-A was performed using the Swept-Source OCT DRI Triton. Vessel density measurements were obtained from OCT-A images using new built-in software within the device. The data presented as mean ± standard deviation and percentages were analyzed using SPSS. The statistical significance of the differences between different groups was determined using independent t-tests, and the level of significance was set at p-value less than 0.05. Results OCT-A demonstrated significantly reduced microvasculature density in glaucoma eyes across all optic nerve sectors including the inferior (29.0%), superior (25.2%), central (23.5%), nasal (9.9%), and temporal sectors (9.3%; p &lt; 0.02). Moreover, glaucoma patients exhibited a significant reduction in vessel density in the superior macula (17% reduction), the temporal (15.7%,), nasal (12.9%), and inferior sectors (12.6%) (p &lt; 0.002). No statistical difference was seen with vessel density of the central sector (0.49%, p &gt;0.05). Conclusion OCT-A demonstrated significant reductions in microvasculature density in glaucoma patients compared with healthy controls. These findings support the association between glaucoma and vascular changes. Additionally, the TOPCON Swept-Source OCT DRI Triton new software shows promise as a valuable tool for early detection and monitoring of glaucoma-related vascular changes.

Correlation of Ultra-Widefield Fluorescein Angiography and OCT Angiography in Sickle Cell Retinopathy

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Optical coherence tomography angiography features of optic nerve head drusen and nonarteritic anterior ischemic optic neuropathy

To compare optical coherence tomography angiography (OCTA) findings in cases with migraine and healthy controls. Thirty-eight eyes of 19 patients with migraine with aura and 38 eyes of 19 healthy subjects were enrolled in this prospective and comparative study. All patients and healthy controls were evaluated with OCTA (Triton, Topcon®, Tokyo, Japan). Central macular thickness (CMT), optic disc parameters (such as retinal nerve fibre layer [RNFL] thickness and rim and disc areas), foveal avascular zone (FAZ) and parafoveal superficial vessel density (VD) measurements were analysed. The optic disc rim area was significantly larger in the migraine group compared to the control group (p = 0.009). In OCTA measurements, the FAZ area was significantly larger in migraine patients (p = 0.001). The parafoveal superficial VD measurements were found to be lower in the migraine patients in all quadrants, but not statistically significant. Weak negative correlations were found between superior parafoveal VD and disease duration in migraine patients. Migraine with aura was associated with optic disc rim changes, but without any remarkable foveal vascular decrements. It is possible for migraine to cause structural changes due to its chronic nature.

To investigate the hypothesis that macular structure, function, and vessel density (VD) measurements can predict foveal threshold (FT) outcomes in glaucomatous eyes. One hundred ninety-five eyes from 195 subjects (134 subjects with early-to-moderate stage open-angle glaucoma and 61 healthy controls) who underwent optical coherence tomography angiography imaging and 24-2 visual field (VF) testing with FT measurements on the same day were retrospectively enrolled in this study. The association of FT with macular structural/functional/VD measurements was evaluated using partial correlation analyses with adjustment for age and linear regression analyses. FT showed significant correlations between the thickness of the macular ganglion cell-inner plexiform layer (mGCIPL) (r=0.330, P<0.001) and the mean sensitivity (MS) of the central 5 and 10 degrees VF points (r=0.448, P<0.001 and r=0.361, P<0.001). Significant correlations were also found between FT and VD measurements at the inferior and superior parafoveal sectors (r=0.455, P<0.001 and r=0.438, P<0.001). In multivariate linear regression analyses controlling the covariates, the thickness of the mGCIPL, central 5 degrees VF MS, and parafoveal VD were significantly associated with FT (all P<0.001). There was also a significant association between FT and logMAR best-corrected visual acuity (β=-5.647, P<0.001). Macular VD along with mGCIPL thickness and central 5 degrees VF MS independently predict FT outcomes even in the eyes of patients with early-to-moderate stage open-angle glaucoma.

PurposeThe purpose of this study was to evaluate specifically in type 1 diabetes mellitus (DM) individuals the relationship between perifoveal superficial capillary plexus (SCP) parameters assessed by optical coherence tomography angiography (OCTA) and diabetic retinopathy (DR) grade.MethodsCross-sectional analysis of a large scale prospective OCTA trial cohort (ClinicalTrials.gov NCT03422965). A total of 1186 eyes (593 individuals), 956 type 1 DM eyes (478 patients), and 230 control eyes (115 healthy volunteers) were included in this study. DR stage was graded according to the International Classification. OCTA imaging was performed with a commercially available device (Cirrus HD-OCT). Vessel density (VD), perfusion density (PD), and foveal avascular zone (FAZ) area, perimeter and circularity measurements were quantified in the SCP and receiver operating characteristic (ROC) curves were constructed for each OCTA parameter.ResultsVD and PD (in both 3 × 3 and 6 × 6 mm captures) were inversely associated with DR stage (P < 0.001 in all cases) in a multiple regression analysis after controlling by age, gender, signal strength index, axial length, and DM duration. Greater FAZ area and perimeter and conversely lower circularity measurements were observed as DR severity increased in both scanning protocols (P < 0.05 in all cases).ConclusionsIn type 1 DM individuals, OCTA provides an objective, continuous, and reliable method for accurate quantification of VD, PD, and FAZ parameters in the SCP, which ultimately correlate with DR stages.Translational RelevanceObjective OCTA measurements of the retinal microvasculature could substitute the clinical DR classification in patients with type 1 DM, identify patients at risk of DR progression, and inform treatment decisions to modify the evolution of the disease.

Macular and Optic Nerve Head Vessel Density and Progressive Retinal Nerve Fiber Layer Loss in Glaucoma