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OCT-A is an exam that allows visualization of the retinal and choroidal vascularization as well as the three-dimensional visualization of the vascular plexuses at different depths, providing functional information about the blood flow in the vessels, and areas of non-perfusion or neovascularization. The foveal avascular zone corresponds to an area deprived of capillaries in the foveolar region that can be detected and measured using OCT-A. When performing the exam, it is possible to choose between two methods with different resolution and acquisition times, so it is important to assess whether the measurements are comparable between methods. The objective of this study was to see if there are differences in the measurement of the foveal avascular zone between two different OCT-A scanning protocols. The conducted study was a case-control cross-sectional study. The sample consisted of 26 participants with diabetes mellitus. The instrument used was the SD-OCT HRA+OCT SPECTRALIS Heidelberg Engineering. The patient assessment consisted of collecting 10° x 10° high-resolution and 20° x 20° high-speed OCT-A scans. These were manually measured by two observers, who each took two measurements of the foveal avascular zone of each scan (high-speed and high-resolution) in each complex (superficial and deep). Statistical analysis was performed using the SPSS program. There were no statistically significant differences between the different measurements, and it can be stated that the evaluation of the two protocols is repeatable and reproducible, with good agreement between the methods. However, the use of both retinal plexuses together to evaluate the foveal avascular zone may be more appropriate. [ABSTRACT FROM AUTHOR]

To compare differences in the foveal avascular zone (FAZ) area, measured in the Superficial Vascular Complex (SVC), Deep Vascular Complex (DVC) and a combined analysis of both (SDVC), using two Spectral Domain OCT angiography (OCT-A) protocols, High Speed (HS) and High Resolution (HR). A total of 26 eyes of diabetic patients, with and without macular oedema, were examined with two different fovea centered OCT-A volume scans. The two protocols were HS and HR volume scans, and the foveal avascular zone was manually measured in the SVC, DVC, and SDVC slabs by two masked investigators. Inter and intraoperator variability was analysed using Intraclass Correlation Coefficient (ICC) and differences were compared between the HR and HS acquisitions throughout the different vascular slabs. Intraoperator variability was low in all slabs (ICC > 0.9) and interoperator variability was lower for HR (ICC 0.835–0.911) compared to HS (ICC between 0.604 and 0.865). Comparing HS and HR measurements for the same slab, the correlation was only moderate in SVC and DVC (ICC was 0.640 and 0.568 respectively) but was good in the SDVC (ICC = 0.823). FAZ area measurement in SDVC also showed the smallest bias (mean difference 0.009 mm2) and the narrowest limits of agreement (−0.175 to 0.193 mm2). Even in cases of diabetic macular oedema, when measuring the FAZ area, the reproducibility was better between HS and HR protocols when using the SDVC slab, compared to the SVC or DVC slabs alone. Further studies should evaluate the use of the combined SDVC slab for the FAZ assessment, compared to the SVC and DVC slabs alone, in the detection and progression of different retinal diseases. • Assessing the Foveal Avascular Zone in combined capillary plexus yields reliable results. • But literature often evaluates FAZ in either superficial or deep vascular plexus separately. • We compared FAZ area using two OCTA scan resolutions in different vascular slabs. • Combined capillary plexus analysis provides the most accurate FAZ area measurements. • Optimizing FAZ analysis can enhance global clinical practice and eye health diagnostics. [ABSTRACT FROM AUTHOR]

This paper aims to study adaptative vascular arrangements in idiopathic fovea plana with volume-rendered optical coherence tomography angiography (OCTA). A retrospective review of two cases of idiopathic fovea plana (mean age: 26.5 years) and two age-matched controls imaged with OCTA was conducted using spectral-domain OCTA (RTVue XR Avanti, Optovue, Inc., Fremont, CA) equipped with the AngioVue software. Both en face OCTA slabs and OCTA b scans were processed through Fiji software (http://fiji.sc; software version 2.0.0-rc-68/1.52e), and then extracted as image sequences for volume rendering reconstructions using the ImageVis3D volume rendering system (3.1.0 release). Eyes with idiopathic fovea plana demonstrated a regular superficial vascular plexus connecting to a single vascular monolayer representing the deeper vascular plexuses. At this location, several vertical short path connections were demonstrated, in contraposition with normal eyes where short path connections were infrequently observed. Advances in three-dimensional OCTA reconstruction increase the understanding of vascular connections and arrangement in retinal plexuses and possible anatomical variations that cannot be detected with conventional two-dimensional b scans.

This paper aims to study adaptative vascular arrangements in idiopathic fovea plana with volume-rendered optical coherence tomography angiography (OCTA). A retrospective review of two cases of idiopathic fovea plana (mean age: 26.5 years) and two age-matched controls imaged with OCTA was conducted using spectral-domain OCTA (RTVue XR Avanti, Optovue, Inc., Fremont, CA) equipped with the AngioVue software. Both en face OCTA slabs and OCTA b scans were processed through Fiji software (http://fiji.sc; software version 2.0.0-rc-68/1.52e), and then extracted as image sequences for volume rendering reconstructions using the ImageVis3D volume rendering system (3.1.0 release). Eyes with idiopathic fovea plana demonstrated a regular superficial vascular plexus connecting to a single vascular monolayer representing the deeper vascular plexuses. At this location, several vertical short path connections were demonstrated, in contraposition with normal eyes where short path connections were infrequently observed. Advances in three-dimensional OCTA reconstruction increase the understanding of vascular connections and arrangement in retinal plexuses and possible anatomical variations that cannot be detected with conventional two-dimensional b scans. [ABSTRACT FROM AUTHOR]

Crumbs proteins are transmembrane proteins that regulate cellular apico-basal polarity. Animals carrying mutated crb1 present retinal vascular abnormalities; this mutation is associated with progressive retinal degeneration with intraretinal cystoid fluid collection in humans. This study aimed to evaluate a potential role of crumbs proteins in retinal vascular development and maintenance. We demonstrated that crumbs homologues (CRBs) were differentially expressed and changed dramatically during mouse retinal vascular development. Intravitreal injection of CRB1 and CRB2 siRNA induced delayed development of the deep capillary plexus and premature development of the intermediate capillary plexus, resulting in disrupted vascular integrity. However, microfluidic chip assay using human retinal endothelial cells revealed that CRBs do not directly affect in vitro retinal angiogenesis. CRBs control retinal angiogenesis by regulating neuroglial vascular endothelial growth factor-A (VEGFA) and matrix metalloproteinase-3 expression. These findings demonstrate a pivotal role of CRBs in providing critical neurotrophic support through normal layered vascular network development and maintenance. This implies that preserving CRBs and restoring layered retinal vascular networks could be novel targets for preventing vision-threatening retinal diseases. • Expression of crumbs proteins changes greatly during retinal vascular development. • Crumbs proteins regulate the development of deep and intermediate capillary plexus. • Loss of crumbs proteins causes disorganized retinal vascular development. • Crumbs protein loss subsequently leads to retinal hemorrhage and neuronal dysfunction. • Crumbs proteins control retinal angiogenesis by regulating VEGFA and MMP-3. [ABSTRACT FROM AUTHOR]

Aims: To investigate alterations in deep retinal vascular complex (DVC) in patients with non-neovascular intermediate AMD (iAMD), treatment-naïve quiescent macular neovascularization (qMNV), exudative AMD (eAMD) by means of OCT angiography (OCTA)., Methods: Patients with iAMD, qMNV, eAMD and healthy controls presenting in the Department of Ophthalmology of the Centre Hospitalier Intercommunal de Créteil between January 2016 and January 2018, were retrospectively included. 3 × 3-mm OCTA (AngioVue RTVue XR Avanti) perfusion density (PD) of DVC was computed in all groups at baseline and follow up (12.0 ± 1.1 months)., Results: A total of 46 eyes of 45 patients were enrolled: 11/46 iAMD, 10/46 qMNV, 13/46 eAMD, 12/46 control eyes. PD showed a significant decrease during follow-up in qMNV ( p  = 0.0059) and iAMD ( p  = 0.0076) eyes. PD in eAMD and healthy controls didn't show significant changes., Conclusion: PD decreases at the level of DVC in eyes with qMNV and iAMD, while in eAMD eyes, PD is stable throughout follow up, suggesting that repeated anti-vascular endothelial growth factor (VEGF) injections do not impact on the DVC PD.