Optical coherence tomography angiography (OCTA) is a non-invasive ophthalmic imaging modality that is widely used in clinical practice. Recent technological advances in OCTA allow imaging of blood flow deeper than the retinal layers, at the level of the choriocapillaris (CC), where a granular image is obtained showing a pattern of bright areas, representing blood flow, and a pattern of small dark regions, called flow voids (FVs). Several clinical studies have reported a close correlation between abnormal FVs distribution and multiple diseases, so quantifying changes in FVs distribution in CC has become an area of interest for many clinicians. However, CC OCTA images present very complex features that make it difficult to correctly compare FVs during the monitoring of a patient. In this work, we propose fully automatic approaches for the segmentation and monitoring of FVs in CC OCTA images. First, a baseline approach, in which a fully automatic segmentation methodology based on local contrast enhancement and global thresholding is proposed to segment FVs and measure changes in their distribution in a straightforward manner. Second, a robust approach in which, prior to the use of our segmentation methodology, an unsupervised trained neural network is used to perform a deformable registration that aligns inconsistencies between images acquired at different time instants. The proposed approaches were tested with CC OCTA images collected during a clinical study on the response to photodynamic therapy in patients affected by chronic central serous chorioretinopathy (CSC), demonstrating their clinical utility. The results showed that both approaches are accurate and robust, surpassing the state of the art, therefore improving the efficacy of FVs as a biomarker to monitor the patient treatments. This gives great potential for the clinical use of our methods, with the possibility of extending their use to other pathologies or treatments associated with this type of imaging.

Purpose: To assess the presence of macular intervortex venous anastomosis in central serous chorioretinopathy (CSCR) patients using en face optical coherence tomography (EF-OCT). Methods: A cross-sectional study where EF-OCT 6 × 6 and 12 × 12 mm macular scans of patients with unilateral chronic CSCR were evaluated for anastomosis between vortex vein systems in the central macula. The presence of prominent anastomoses was defined as a connection with a diameter ≥150 µm between the inferotemporal and superotemporal vortex vein systems which crossed the temporal raphe. Three groups were studied: CSCR eyes (with an active disease with the presence of neurosensorial detachment; n = 135), fellow unaffected eyes (n = 135), and healthy eyes as controls (n = 110). Asymmetries, abrupt termination, sausaging, bulbosities and corkscrew appearance were also assessed. Results: In 79.2% of the CSCR eyes there were prominent anastomoses in the central macula between the inferotemporal and superotemporal vortex vein systems, being more frequent than in fellow eyes and controls (51.8% and 58.2% respectively). The number of anastomotic connections was higher in the affected eye group (2.9 ± 1.8) than in the unaffected fellow eye group (2.1 ± 1.7) and the controls (1.5 ± 1.6) (p < 0.001). Asymmetry, abrupt terminations and the corkscrew appearance of the choroidal vessels were more frequent in the affected eyes, although no differences in sausaging or bulbosities were observed. Conclusions: Intervortex venous anastomoses in the macula were common in CSCR, being more frequently observed in affected eyes than in fellow unaffected eyes and healthy controls. This anatomical variation could have important implications concerning the pathogenesis and classification of the disease.

Purpose: To assess the repeatability of flow signal voids (FSV) measurements of the choriocapillaris (CC) and choroid (CH) in central serous chorioretinopathy (CSCR) by Swept-Source optical coherence tomography angiography (SS-OCTA). Methods: Cross-sectional study including 104 eyes of 52 patients with unilateral CSCR. Two consecutive macular 6x6 mm SS-OCTA scans (Plex Elite 9000; Zeiss, Dublin, CA) were obtained from the affected eyes with persistent subretinal fluid (SRF) (CSCR group) and the fellow unaffected eyes (control group). FSV area and the number of contours measurements were analyzed using three slabs: inner CC, outer CC and CH. The repeatability of the measurements was assessed with intraclass correlation coefficients (ICC) and coefficients of variation (CV). Results: In the CSCR group, ICCs for the FSV area in the three slabs were all ≥0.859, observing higher values for the outer CC and the CH (0.959 and 0.964) than for the inner CC (0.859). Similar ICC values were obtained for the FSV area in control eyes, observing the highest values for the outer CC (0.949), followed by the CH (0.932) and inner CC (0.844). Regarding the FSV number of contours measurements, ICCs were higher for the outer CC and CH (0.949 and 0.932) than for inner CC (0.844). CV for the FSV area was 4.7%, 3.8% and 8.6% in the CSCR eyes and 4.8%, 3.9% and 9.3% in the control group for the inner CC, outer CC and CH respectively. Conclusion: SS-OCTA offers good repeatability to quantify macular FSV in CSCR eyes and fellow eyes

Purpose: To describe optical coherence tomography angiography (OCTA) findings in the retina and choroid of patients with neurofibromatosis type 1 (NF1). Methods: We describe a series of four patients diagnosed with NF1 and choroidal nodules who underwent a comprehensive ophthalmic evaluation including a retinal multimodal imaging study based on retinography, near-infrared reflectance imaging (NIR), enhanced depth imaging (EDI) optical coherence tomography (OCT) and OCTA. Results: Patients were three women and one man aged 36–47 years. In all patients, the choroidal nodules were not visible in retinographies but easily detectable with NIR, appearing as multiple bright patches. On OCTA, we observed reduced vessel density in the choriocapillaris in zones where choroidal nodules appeared in OCT images. In one patient, a corkscrew vessel was visible in the superficial capillary plexus. Conclusion: Choriocapillaris vessel density was reduced in zones where choroidal nodules occur in NF1 patients. Further work is needed to clarify the clinical relevance of this finding.