Improved microvascular imaging with optical coherence tomography using 3D neural networks and a channel attention mechanism.

Skin microvasculature is vital for human cardiovascular health and thermoregulation, but its imaging and analysis presents significant challenges. Statistical methods such as speckle decorrelation in optical coherence tomography angiography (OCTA) often require multiple co-located B-scans, leading to lengthy acquisitions prone to motion artefacts. Deep learning has shown promise in enhancing accuracy and reducing measurement time by leveraging local information. However, both statistical and deep learning methods typically focus solely on processing individual 2D B-scans, neglecting contextual information from neighbouring B-scans. This limitation compromises spatial context and disregards the 3D features within tissue, potentially affecting OCTA image accuracy. In this study, we propose a novel approach utilising 3D convolutional neural networks (CNNs) to address this limitation. By considering the 3D spatial context, these 3D CNNs mitigate information loss, preserving fine details and boundaries in OCTA images. Our method reduces the required number of B-scans while enhancing accuracy, thereby increasing clinical applicability. This advancement holds promise for improving clinical practices and understanding skin microvascular dynamics crucial for cardiovascular health and thermoregulation.

Extensive macular atrophy with pseudodrusen-like appearance: comprehensive review of the literature.

PURPOSE: This review focuses on extensive macular atrophy with pseudodrusen-like appearance (EMAP), a recently described maculopathy presenting with pseudodrusen-like lesions and chorioretinal atrophy more pronounced in the vertical axis. METHODS: Narrative review of the literature published until May 2024. RESULTS: The early onset age of EMAP (50-55 years) and its distinctive natural history, which includes night blindness followed by severe vision loss, differentiate it from atrophic age-related macular degeneration (AMD). A clear pathogenesis has not been determined, but risk factors include female gender and complement system abnormalities (altered levels of C3 and CH50). Moreover, lifelong exposure to pesticides has been suggested as risk factor for direct neuronal degeneration involving rods and cones. In the early phase of the disease, reticular pseudodrusen-like lesions appear in the superior perifovea and tend to coalescence horizontally into a flat, continuous, reflective material localized between the retinal pigmented epithelium and Bruch's membrane. Over time, EMAP causes profound RPE and outer retinal atrophy in the macular area, with a recent classification reporting a 3-stages evolution pattern. Blue autofluorescence showed rapidly evolving atrophy with either hyperautofluorescent or isoautofluorescent borders. Significant similarities between the diffuse-trickling phenotype of geographic atrophy and EMAP have been reported. Macular neovascularization is a possible complication. CONCLUSION: EMAP is specific form of early-onset atrophic macular degeneration with rapid evolution and no treatment. Further studies are needed to assess the best management.

Effect of magnification error and axial length on circumpapillary capillary density and retinal nerve fiber layer thickness.

This study aimed to evaluate the effect of magnification error and axial length (AL) on circumpapillary capillary density (cpCD) and circumpapillary retinal nerve fiber layer thickness (cpRNFLT) in healthy eyes. Seventy-two healthy eyes of 72 subjects with AL 24.7 ± 1.5 mm (range: 20.9-28.0 mm) were enrolled in this retrospective cross-sectional study and underwent optical coherence tomography angiography scanning. Magnification corrected measurement areas were obtained using AL upon which corrected cpCD, cpRNFLT values were determined. Relationships between AL and the percentage difference between corrected and uncorrected values (ΔcpCD, ΔcpRNFLT) as well as the effect of AL on magnification corrected cpCD, cpRNFLT were evaluated. ΔcpCD significantly increased with AL in the global, inferior nasal and superior nasal sectors (all p < 0.001). ΔcpRNFLT significantly increased with AL in global and all sectors (all p < 0.001) and the correlations were significantly stronger than that of ΔcpCD-AL in all sectors (all p < 0.001). Corrected cpCD did not associate with AL while corrected cpRNFLT demonstrated a significant positive association with AL in the global (p = 0.005) and temporal sector (p < 0.001). Magnification error led to a significant underestimation of cpCD in eyes with longer AL although its underestimation and the effect of AL was smaller in comparison to that of cpRNFLT.

Association of choroidal thickness and blood flow features with asymmetric axial lengths in children with unilateral myopic anisometropia.

BACKGROUND: Considering that changes in the choroidal thickness are closely related to ocular growth, we studied the choroidal thickness (CT) and the blood flow features in children with unilateral myopic anisometropia (UMA) as well as investigating the relationship between choroidal changes and myopia. METHODS: Subjective refractive, axial length (AL), and biometric parameters were measured in 98 UMA children (age: 8-15 years). CT and choroidal blood-flow features, including the choroidal vessel volume (CVV), choroidal vascularity index (CVI), and choriocapillaris perfusion area (CCPA), were measured through swept-source optical coherence tomography angiography. The macular region was categorized into four concentric circles of diameters 0-1 mm (central fovea), 1-3 mm (parafovea), 3-6 mm (perifovea), and 6-9 mm (extended), and further categorized into superior (S), inferior (I), temporal (T), and nasal (N) quadrants. RESULTS: The aforementioned four regions of myopic eyes displayed significantly lower CT, CVV, and CVI than those of non-myopic eyes. CCPA changes differed across different regions of both the eyes (parts of N and T quadrants). There was an inverse association between CT and the interocular AL difference (central and other regions S, T quadrant). No correlation was noted between CVV and CVI with interocular AL difference. CT and CVV were positively correlated in the 0-6-mm macular region of myopic eyes (Spearman correlation coefficient = 0.763, P < 0.001). CONCLUSIONS: In UMA children, CCT and blood flow may be related to myopia progression. A robust correlation between CT and CVV in the 0-6-mm macular region and reduced CT and diminished blood flow indicated an association with myopia.

Retinal microvascular changes in patients with pancreatitis and their clinical significance.

Acute pancreatitis, a common exocrine inflammatory disease affecting the pancreas, is characterized by intense abdominal pain and multiple organ dysfunction. However, the alterations in retinal blood vessels among individuals with acute pancreatitis remain poorly understood. This study employed optical coherence tomography angiography (OCTA) to examine the superficial and deep retinal blood vessels in patients with pancreatitis. Sixteen patients diagnosed with pancreatitis (32 eyes) and 16 healthy controls (32 eyes) were recruited from the First Affiliated Hospital of Nanchang University for participation in the study. Various ophthalmic parameters, such as visual acuity, intraocular pressure, and OCTA image for retina consisting of the superficial retinal layer (SRL) and the deep retinal layer (DRL), were recorded for each eye. The study observed the superficial and deep retinal microvascular ring (MIR), macrovascular ring (MAR), and total microvessels (TMI) were observed. Changes in retinal vascular density in the macula through annular partitioning (C1-C6), hemispheric quadrant partitioning (SR, SL, IL, and IR), and early diabetic retinopathy treatment studies (ETDRS) partitioning methods (R, S, L, and I). Correlation analysis was employed to investigate the relationship between retinal capillary density and clinical indicators. Our study revealed that in the superficial retinal layer, the vascular density of TMI, MIR, MAR, SR, IR, S, C2, C3 regions were significantly decreased in patients group compared with the normal group. For the deep retinal layer, the vascular density of MIR, SR, S, C1, C2 regions also reduced in patient group. The ROC analysis demonstrated that OCTA possesses significant diagnostic performance for pancreatitis. In conclusion, patients with pancreatitis may have retinal microvascular dysfunction, and OCTA can be a valuable tool for detecting alterations in ocular microcirculation in pancreatitis patients in clinical practice.

The Role of Optical Coherence Tomography Angiography in the Evaluation of Chiasmal and Retrochiasmal Compression.

The compression of the visual pathway is associated with structural retinal changes due to retrograde neurodegeneration. It was brought into question whether visual pathway compression is also associated with retinal vascular changes as assessed by optical coherence tomography angiography (OCT-A). The objective of this review is to discuss the role of OCT-A in the evaluation of patients with tumours of the sellar, parasellar, and retrochiasmal regions. The reported OCT-A parameters were the vessel densities of radial peripapillary capillary network, macular superficial vascular plexus and/or macular deep vascular complex. Optic nerve and macular OCT-A parameters were impaired in patients versus controls. These changes were associated with altered structural OCT parameters and visual field defects. OCT-A could be considered a marker of neurodegeneration in addition to structural OCT, and it has the potential to become a visual prognostic tool in patients with visual pathway compression.

Neuroretinal and microvascular retinal features in dementia with Lewy body assessed by optical coherence tomography angiography.

OBJECTIVE: To explore retinal changes in patients with Dementia with Lewy Bodies (DLB) using Spectral Domain-Optical Coherence Tomography (SD-OCT) and Optical Coherence Tomography Angiography (OCTA), aiming to identify potential biomarkers for diagnosis and monitoring. METHODS: A cross-sectional study analyzed 15 DLB patients and 18 matched controls. Participants underwent physical, neurological, neuropsychological, and ophthalmological evaluations, including SD-OCT and OCTA. Logistic regression, adjusted for age, sex, and inter-eye correlation, was employed to identify retinal alterations in patients affected by DLB. RESULTS: OCTA revealed that DLB is associated with reduced superficial and deep vessel densities (SVD and DVD) in the macula (p < 0.01), as well as decreased peripapillary vessel density (ppVD, p < 0.01). SD-OCT parameters showed correlations with DLB, including reduced central macular thickness (CMT, p < 0.001) and thinning of the ganglion cell layer-inner plexiform layer (GCL-IPL, p < 0.01). Logistic regression (R²=0.26) identified reduced ppVD as a significant predictor of DLB (p = 0.030). CONCLUSIONS: Impairments in retinal capillaries, especially lower ppVD, might mirror cerebral hypoperfusion in DLB, potentially due to reduced Vascular Endothelial Growth Factor (VEGF) levels and increased α-synuclein. Further investigations are warranted to confirm the causal relationship between these observations, disease severity, and progression, as well as their potential role as biomarkers for DLB.

Association of outer retinal and choroidal alterations with neuroimaging and clinical features in posterior cortical atrophy.

BACKGROUND: Posterior cortical atrophy (PCA) is a rare condition characterized by early-onset and progressive visual impairment. Individuals with PCA have relatively early-onset and progressive dementia, posing certain needs for early detection. Hence, this study aimed to investigate the association of alterations in outer retinal and choroidal structure and microvasculature with PCA neuroimaging and clinical features and the possible effects of apolipoprotein E(APOE) ε4 allele on outer retinal and choroidal alterations in participants with PCA, to detect potential ocular biomarkers for PCA screening. METHODS: This cross-sectional study included PCA and age- and sex-matched healthy control participants from June 2022 to December 2023. All participants with PCA completed a comprehensive neurological evaluation. All participants were recorded baseline information and underwent an ophthalmic evaluation. Quantitative analyses were performed using swept-source optical coherence tomography (SS-OCT) and angiography (SS-OCTA). Adaptive optics scanning laser ophthalmoscopy (AO-SLO) was performed in some patients. In participants with PCA, the influence of APOE ε4 on outer retinal and choroidal alterations and the correlation of outer retinal and choroidal alterations with PCA neuroimaging and clinical features in participants with PCA were investigated. RESULTS: A total of 28 participants (53 eyes) with PCA and 56 healthy control participants (112 eyes) were included in the current study. Compared with healthy control participants, participants with PCA had significantly reduced outer retinal thickness (ORT) (p < 0.001), choriocapillaris vessel density (VD) (p = 0.007), choroidal vascular index (CVI) (p = 0.005) and choroidal vascular volume (CVV) (p = 0.003). In participants with PCA, APOE ε4 carriers showed thinner ORT (p = 0.009), and increased choriocapillaris VD (p = 0.004) and CVI (p = 0.004). The PCA neuroimaging features were positively associated with the ORT, CVI and CVV. Furthermore, differential correlations were observed of PCA clinical features with the CRT, CVV and CVI. CONCLUSIONS: Our findings highlighted the association of outer retinal and choroidal alterations with PCA neuroimaging and clinical features in participants with PCA. Noninvasive SS-OCT and SS-OCTA can provide potential biomarkers for the diagnosis and management of PCA, improving awareness of PCA syndrome among ophthalmologists, neurologists, and primary care providers.

Effect of Buerger's disease on ocular microvascular structure.

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.

Long-term functional, anatomical outcome, and qualitative analysis by OCTA, as a predictor of disease recurrences in patients with choroidal neovascularization secondary to angioid streaks.

BACKGROUND: To report the risk of exudation recurrence and long-term outcomes in patients with choroidal neovascularization secondary to angioid streaks, according to its morphology and characteristics by optical coherence tomography angiography. METHODS: Retrospective analysis of electronic medical records from three hospitals. We enrolled patients with a clinical diagnosis of angioid streaks choroidal neovascularization that had a minimum follow-up of 12 months. From each record, we extracted general demographic data, best corrected visual acuity (baseline, before and after each disease recurrence and last on file), type of treatment, time between last intravitreal injection and disease recurrence, and classification of the neovascular lesion morphology by optical coherence tomography, and optical coherence tomography angiography. Patients with myopic choroidal neovascularization were used as controls. Interobserver agreement was assessed with a Cohen-Kappa test. The Odds ratio was calculated with a chi2 test for significance. Visual acuity change through time was evaluated with an ANOVA for repeated measurements with an alpha value of 0.05 for statistical significance. RESULTS: We enrolled 30 patients in the study group and 14 in the control group. In the study group, the baseline and final BCVA were 0.861 ± 0.59 and 1.095 ± 0.61 logMAR (p = 0.1) respectively. CONTROL GROUP: 1.045 ± 0.57 and 0.617 ± 0.53 logMAR (p < 0.05). In the study group, the predominant CNV type by OCTA was mixed (37%), and interlacing (57%) in the control group. Mixed and cog-wheel patterns at baseline had increased Odds for recurrence in the study group (p = 0.09). Patients in the study group required more intravitreal injections on each recurrence episode to achieve disease control (3.5 ± 1.5 vs.1.4 ± 0.2, p < 0.01). CONCLUSIONS: The benefits of anti-VEGF treatment are lost over time in patients with angioid streaks and CNV. Lesion characteristics by optical coherence tomography angiography could help physicians predict the risk of recurrence. TRIAL REGISTRATION: Retrospective registered, and IRB approved.

Probe fusion all-optic OCT-PAM dual-mode imaging system for biomedical imaging.

We proposed a non-contact photoacoustic (PA) detection method using spectral domain optical coherence tomography (SDOCT). Two interference spectrums (A-lines) were acquired before and after the PA excitation with SDOCT. PA signal propagated within the sample causing the vibration. The vibration inner the sample introduced phase change between the acquired two A-lines. Thus, the PA signal can be detected by evaluating the difference in phase between the two A-lines. Based on the method, an OCT-PAM dual-mode imaging system was constructed. In the system, SDOCT served as the detection unit for PAM. Thus, the combination of the two imaging modalities was simplified. Another advantage of the system is that it realizes non-contact all-optic detection, which is attractive for biomedical imaging. Using the system, we imaged phantoms of carbon fibers, asparagus leaves and human hairs. Furthermore, the cortical vasculature of rat was imaged in vivo and the flow status was evaluated quantitatively.

Developing quantitative analysis program of blood flow velocity according to vessel diameter for neovascular age-related macular degeneration using OCTA-VISTA.

This study aimed to develop a quantitative analysis program of blood flow velocity by vessel diameter in neovascular age-related macular degeneration (nAMD) subjects using high-speed swept-source optical coherence tomography angiography. This retrospective, observational, cross-sectional study included 10 eyes of healthy volunteers and 4 eyes of patients with representative nAMD. Novel scan patterns and variable interscan time analysis were utilized to measure the flow parameter, a surrogate marker of blood flow velocity, by vessel diameter within different depths. Detected vessels at superficial and deep as well as outer retinal regions were categorized into three vessel diameters (major vessels (> 40 µm), medium vessels (20-40 µm), and capillaries (< 20 µm)). The flow parameter increased with enlarged vessel diameter in all participants at superficial and deep layer. All nAMD subjects, except for type 3 macular neovascularization (MNV), contained a structure dominated by medium vessels at outer retinal region. The mean flow parameter at outer retinal region was type 1 MNV (1.46 ms-1), type 1 + 2 MNV (0.98 ms-1), and polypoidal choroidal vasculopathy, including branching vascular networks (1.46 ms-1). This program provides the possibility to extract the blood flow information at different depths by vessel diameter types, which is considered to be useful tool for evaluating nAMD pathology and activity.

Comparison between indocyanine green angiography and optical coherence tomography angiography for the detection of nonexudative macular neovascularization.

PURPOSE: Patients with unilateral treatment-naïve exudative neovascular age-related macular degeneration (nAMD) were examined for the presence of nonexudative macular neovascularization (neMNV) in their fellow eye using a multimodal imaging approach. This is intended to determine the sensitivity of individual imaging methods, namely, indocyanine green angiography (ICGA) and optical coherence tomography angiography (OCTA). METHODS: In this retrospective cross-sectional study, ICGA images of the nonexudative eye were analyzed for the presence of plaques. SS-OCTA outer retinal segmentations were evaluated for neovascular flow in en-face scans and/or color-coded flow in B-scans. The findings were matched with a double-layer sign (DLS) or pigment epithelium detachment (PED) on conventional OCT. RESULTS: In total, neMNV was diagnosed in the fellow eye of 40 of 241 patients (17%) using a multimodal imaging approach employing both ICGA and SS-OCTA. 25 eyes (10%) showed neMNV in both modalities, while 7 (3%) were only detected by ICGA and 8 (3%) by OCTA alone. The sensitivities of ICGA therefore were 80% (32/40) and 83% (33/40) for OCTA. Of the 40 eyes with neMNV, OCT revealed DLS in 25/40 (63%) and PED in 17/40 (43%) of the cases. CONCLUSION: None of the modalities alone could detect all neMNV in the partner eye of Caucasians with unilateral treatment-naïve exudative nAMD. ICGA and OCTA showed comparable sensitivity. The combination of ICGA, OCTA, and OCT provides the most comprehensive screening for this AMD subtype.

Association between three-dimensional morphological features and functional indicators of neovascular age-related macular degeneration.

PURPOSE: To investigate the correlation between morphological lesions and functional indicators in eyes with neovascular age-related macular degeneration (nAMD). METHODS: This was a prospective observational study of treatment-naïve nAMD eyes. Various morphological lesions and impaired retinal structures were manually measured at baseline and month-3 in three-dimensional optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA) images, including the volumes (mm3) of macular neovascularization (MNV), avascular subretinal hyperreflective material (avascular SHRM), subretinal fluid (SRF), intraretinal fluid (IRF), serous pigment epithelial detachment (sPED) and the impaired area (mm2) of ellipsoid zone (EZ), external limiting membrane (ELM) and outer nuclear layer (ONL). RESULTS: Sixty-three eyes were included. The volume of avascular SHRM showed persistent positive associations with the area of EZ damage, both at baseline, month-3, and change values (all P < 0.001). Poor BCVA (month-3) was associated with larger volumes of baseline IRF (ß = 0.377, P < 0.001), avascular SHRM (ß = 0.306, P = 0.032), and ELM impairment area (ß = 0.301, P = 0.036) in multivariate model. EZ and ELM impairment were primarily associated with baseline avascular SHRM (ß = 0.374, p = 0.003; ß = 0.388, P < 0.001, respectively), while ONL impairment primarily associated with MNV (ß = 0.475, P < 0.001). CONCLUSION: The utilization of three-dimensional measurements elucidates the intrinsic connections among various lesions and functional outcomes. In particular, avascular SHRM plays an important role in prognosis of nAMD.

OCTA quantitative assessment of exercise-induced variations and recovery in retinal microvasculature of healthy subjects with or without masks.

PURPOSE: To investigate the impact of exercise and mask-wearing on retinal microvasculature using optical coherence tomography angiography (OCTA). METHODS: A total of 30 healthy volunteers were enrolled and tasked with physical exercise to reach 75-80 % maximum heart rates. Swept-source OCTA was performed on the macular region and optic nerve head (ONH) in participants with no mask, surgical mask, or N95 mask at quiescent conditions (Step 1) and 0 min, 10 min, 20 min, and 30 min post-exercise (Steps 2-5, respectively). The functional vessel density (VD), including the superficial and deep plex (SP and DP) in the macular area and the superficial plex (SP), nerve fiber plex, and small vessels in the optic nerve head, were measured. RESULTS: Under quiescent conditions, the functional VD of SP and DP exhibited significant reduction with surgical and N95 masks in the foveal area (P < 0.05). In step 2 (immediately after training) with or without masks, functional VD of SP and nerve fiber both showed significant reduction in the inside disc and peripapillary area, small functional VD of nerve fiber in the ONH showed significant reduction in peripapillary area (P < 0.05). These changes had been recovered in Step 5 (30 min post-exercise) in all groups (no-mask, surgical mask and N95 mask groups) (P > 0.05). CONCLUSIONS: Mask-wearing and physical exercise reduce retinal functional VD in macular and ONH areas. The retinal vasoconstriction induced by exercise tends to recover after rest for approximately 30 min. Our research provides insights into mask-wearing and physical exercise's immediate retinal microvasculature effects, hinting at systemic microvascular changes.

Skeleton density and ellipsoid zone loss are prognostic for progression in Macular Telangiectasia Type 2.

Macular Telangiectasia Type 2 (MacTel) is a chronic, progressive disease of the central retina characterized by vascular and neurodegenerative changes. As there is currently no treatment for non-neovascular MacTel, there is a dearth for biomarkers identifying eyes with an increased risk for disease progression for patient counseling and clinical trial recruitment. Eyes were classified to be stable or progressive, defined by the fundus photography-based grading system by Gass and Blodi. First, structural differences between these two groups were assessed, employing optical coherence tomography (OCT) and OCT-angiography. Univariate regression analyses revealed evidence towards a lower superficial retinal layer (SRL) vessel density (VD), skeleton density (SD) and deep retinal layer (DRL) SD in progressing compared to stable eyes (p = 0.05, p = 0.05, p = 0.07). Second, a multivariable predictive model was employed to examine the predictive value of structural and functional parameters for disease progression. Baseline best corrected visual acuity (BCVA) and SRL SD are prognostic for disease progression (p < 0.001, p = 0.05). The presence of ellipsoid zone (EZ) loss is prognostic for future central retinal thickness (p < 0.01). We propose SRL SD, BCVA, and EZ loss as prognostic biomarkers and as possible outcome measures in future interventional studies in MacTel.

Evaluation of retinal perfusion density and foveal avascular zone in migraine subjects with and without aura.

Migraine, classified as a neurovascular disease, has been identified as a potential risk factor for ocular vascular complications. Our study aimed to compare retinal vessel density and perfusion density between subjects with migraine and healthy subjects using optical coherence tomography angiography (OCTA). In this cross-sectional case-control study, we enrolled 30 migraine subjects with aura (MWA), 30 migraine subjects without aura (MWOA) and 30 age and gender-matched healthy controls (HC). The foveal avascular zone (FAZ) in superficial capillary plexus (SCP), Vessel density (VD) and perfusion density (PD) in SCP and deep capillary plexus (DCP) were assessed in a 3 × 3 mm scan of the macula with the swept source OCT. Results indicated that the FAZ of MWA and MWOA subjects was significantly larger from HC. Also, FAZ of MWA was larger from MWOA. VD and PD in both SCP and DCP were significantly reduced in both MWA and MWOA groups compared to HC. However, VD and PD did not show significant differences among MWA and MWOA. Additionally, the duration of disease was the main determinant of the FAZ. In conclusion, the FAZ in the SCP, VD and PD in the SCP and DCP of the macula were affected in both MWA and MWOA. FAZ, specifically, was increased with the evolution of the disease. These findings might contribute to an increased risk of ocular vascular complications among subjects with migraine and could potentially use OCTA as a biomarker for this population.

Characteristics of the radial peripapillary capillary network in patients with COVID-19 based on optical coherence tomography angiography: A literature review.

PURPOSE: This review aimed to evaluate the significance of assessing radial peripheral capillary (RPC) network parameters by optical coherence tomography angiography (OCTA) in patients with severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection confirmed by polymerase chain reaction. METHODS: A literature search was conducted in the PubMed database to select high-quality reviews and original articles on the use of OCTA for visualizing the RPC network and calculating RPC parameters. RESULTS: The study revealed that systemic hypoxia, hypercoagulable state, and inflammation affect the RPC network in patients with coronavirus disease 2019 (COVID-19). Reduced RPC parameters were observed early in the course of SARS-CoV-2 infection and after several months of follow-up. Additionally, there was a correlation between reduced RPC parameters and subsequent thinning of the retinal nerve fiber layer. CONCLUSIONS: The OCTA examination of the retina and optic disc should be considered in patients with a history of COVID-19 to assess the impact of systemic hypoxia and inflammation on ocular function. Follow-up assessment of these patients is also necessary to understand the potential consequences of ischemia affecting the optic nerve, retina, and choroid.

The diagnostic ability of peripapillary vessel density in primary open-angle glaucoma suspects.

OBJECTIVE: To assess the diagnostic ability of peripapillary vessel density (pVD) in primary open-angle glaucoma suspect (GS) patients. METHODS: Sixteen primary open-angle GS patients (22 eyes) and 20 normal controls (22 eyes) were included. In the GS group, OCTA measurements of pVD (superior, inferior, nasal, temporal, and global), OCT measurements of retinal nerve fiber layer (RNFL) thickness, disc area, rim area and ganglion cell complex (GCC) thickness were examined. In the control group, pVD measurements were performed. The vessel density between the two groups was compared. The correlation between OCTA and OCT parameters was evaluated. The receiver operating characteristic curve (ROC) was used to evaluate the diagnostic efficacy of OCTA measurements. RESULTS: The global (P<0.001), nasal (P=0.003), and inferior (P=0.002) quadrant pVD in GS group was considerably lower than the control group. The global pVD was positively correlated with the inferior RNFL thickness (r=0.492, P=0.023) and rim area (r=0.483, P=0.027). The inferior pVD was positively correlated with the inferior RNFL thickness (r=0.648, P=0.001), the nasal RNFL thickness (r=0.441, P=0.045), the rim area (r=0.439, P=0.046) and the GCC thickness (r=0.472, P=0.048). The global pVD had the best diagnostic value (AUC=0.825, sensitivity 86.36%, specificity 72.73%, cutoff value 45%), followed by the inferior (AUC=0.749) and nasal (AUC=0.748) quadrant pVD. CONCLUSION: In primary open-angle GS patients, the global and inferior quadrant pVD was lower than that of normal people, and it was positively correlated with the inferior RNFL thickness and rim area. The diagnostic value of pVD for discriminating GS from normal people was excellent with high sensitivity and specificity.