Optical Coherence Tomography Angiography Research Articles

Comparative of OCT and OCTA parameters in patients with early chronic angle-closure glaucoma and early pituitary adenoma

Optical coherence tomography (OCT) and optical coherence tomography angiography (OCTA) have the potential application in evaluating pathological structural change of the optic nerve. We aimed to evaluate the value of the OCT and OCTA parameters of the optic disk and macular in differentiating early chronic primary angle-closure glaucoma (CPACG) and early pituitary adenoma (PA) in case of mild visual field defects (the mean defect (MD) > 6 dB). The results showed that regarding OCTA parameters, CPACG patients had lower retinal blood flow density of most layers of the optic disk and macular than PA patients. Regarding OCT parameters, CPACG patients had thinner circumpapillary retinal nerve fiber layer (CP-RNFL) in all quadrants and average CP-RNFL, ganglion cell layer (GCL) and macular ganglion cell complex (GCC) in each quadrant of macular inner and outer rings, and inner plexus layer (IPL) of macular inner ring, superior-outer ring and temporal-outer ring than PA patients. The Z test indicated that OCTA parameters and OCT parameters had similar value in the diagnosis of disease. In conclusion, in the case of similar visual field damage, early CPACG patients have smaller blood flow density and thinner optic disk and macular than early PA. OCTA has similar performance to OCT in diagnosing CPACG and PA.

The Retinal Blood Flow Density Is Related to the Pathological Severity of Diabetic Kidney Disease

Introduction: This study aimed to investigate the correlation between fundus blood flow parameters and the severity of pathological biopsy in patients with diabetic kidney disease (DKD). Methods: Data of patients with type 2 diabetes mellitus who completed renal pathology biopsies and optical coherence tomography angiography (OCTA) examinations, including renal function, 24-h urine protein quantification, and macular flow imaging, were collected. DKD pathology biopsies were graded as stages 1–4, and differences and correlations of the parameters were compared between groups. The grading was transformed into early (stage 1) and late (stages 2–4), and regression analyses were conducted to develop a model, draw a nomogram, and test efficacy. Results: This study included 157 eyes from 157 individuals in total. Urinary microalbumin and to urinary creatinine ratio (mALB/NCR) increased with pathological grading, whereas while glomerular filtration rate was decreased (p < 0.01). Corresponding retinal blood flow in superficial, deep, and full paracentral rings was decreased, which correlated with pathological grading (p < 0.01), with the highest blood flow density in the whole layer (r2 = −0.707). Meaningfully, in the early DKD model (area under the curve = 0.929 [0.889–0.970], p < 0.01), whole-layer blood flow density, mALB/NCR, and diabetes duration were statistically significant. Conclusions: The decrease in macular retinal blood flow density detected by OCTA is closely associated with the increase in pathological grading of DKD and can be used as a noninvasive parameter for monitoring early changes in DKD.

Radiation Optic Neuropathy

Radiation optic neuropathy (RON) is a rapid-onset, severe, challanging optic neuropathy that can cause unilateral or bilateral vision loss, which may occur years after radiotherapy. RON mostly occurs with radiation therapy exceeding 50 Gy to the visual axis. The risk of RON occurring at radiation doses between 50-60 Gy is 5% within 10 years. Since RON can cause acute, irreversible, unilateral or bilateral profound vision loss, patients at risk need to be carefully monitored. Early diagnosis and treatment is very important to prevent serious vision loss. The first test to be performed in patients with suspected RON is fat-suppressed, non-contrast brain MRI, which is recommended to be performed in 3 mm and thinner sections. In addition; lumbar puncture and Optical coherence tomography angiography (OCT-A) are helpful tests in the differential diagnosis. Anti-VEGF molecules have been shown to be effective in treatment, which aim to reduce edema and retinal hemorrhages. Hyperbaric oxygen therapy is not a proven treatment for RON – but there are some studies about it’s speculated effect. Studies presenting the success rates of this treatment are quite limited in number. Systemic corticosteroids, heparin, warfarin and other anticoagulation treatments have not been proven successful in the treatment of RON. RON is one of the optic neuropathies that chronically damages visual function. The prognosis is generally poor. It is important for the patient and the physician to be aware of RON after radiotherapy and to minimize the possibility of permanent damage through preventive measures that can be taken. Since there are no definitive treatments for RON, preventive medicine is of great importance.

Non-Arteritic Ischemic Optic Neuropathy

Non-arteritic ischemic optic neuropathy (NAION); it is an optic neuropathy that can cause acute unilateral painless vision loss, optic disc edema, relative afferent pupillary defect, peripapillary hemorrhage and visual field defects in individuals over 50 years of age. Although its pathophysiology has not been fully elucidated today; It is widely accepted that it results from hypoperfusion in the short posterior ciliary arteries that supply the optic nerve head. The diagnosis of NAION is made primarily clinically. While there is no vision loss in approximately one-third of the cases, severe vision loss develops in 40-50%. It is thought that there is always a visual field defect from the beginning of NAION, therefore perimetry is the most important diagnostic test. In the differential diagnosis of NAION, vision- and life-threatening diseases, especially arteritic ischemic optic neuropathy, demyelinating, infiltrative and compressive optic neuropathies, should be considered. Perimetry, blood tests, fluorescein angiography, optical coherence tomography (OCT), OCT angiography, brain and orbital MRI provide very useful information in the differential diagnosis. Although many medical and surgical treatments have been tried, unfortunately there is no effective treatment or prophylactic prevention method for NAION today; However, neuroprotective agents, stem cell and gene therapy treatments aimed at stopping or reducing optic nerve damage appear promising in the near future. The purpose of this review is to provide a comprehensive, up-to-date overview of NAION.

Factors Defining Density of Retinal Macrophage-like Cells Displayed with Optical Coherence Tomography.

To study the factors which define the density of MLC of the inner retinal surface in healthy eyes. Healthy individuals, including candidates for LASIK surgery, and post-LASIK patients were included. MLC density was calculated using structural en face projections of OCT angiography scans. The status of the vitreoretinal interface was assessed as the distance from the inner limiting membrane to the posterior hyaloid membrane on cross-sectional scans and as the area of tight posterior vitreous adhesion on en face projections. The correlation between MLC density and various demographic and anatomical parameters, including the status of the vitreoretinal interface was calculated. Fifty-four healthy individuals, 30 post-LASIK patients all without posterior vitreous detachment (PVD) as well as 20 patients with partial PVD were included. MLC density showed a statistically significant correlation with axial length, refractive error, age, subfoveal choroidal thickness, and the status of the vitreoretinal interface (p<0.05) in eyes without PVD. In multiple regression analysis the axial length was the main parameter independently correlated with MLC density (p=0.025). The status of the vitreoretinal interface had a statistically significant correlation with the axial length (p<0.001). Partial PVD was associated with almost complete loss of MLC (p<0.001). The status of the vitreoretinal interface is a characteristic directly defining the density of retinal MLC in healthy eyes. However, axial length appears to be a key anatomical parameter which correlates with MLC density due to its effects on the adhesion of the posterior hyaloid membrane to the retinal surface.

Evaluating the impact of polycythemia vera on retinal and optic nerve head microvascularity: An OCTA study.

This study aims to assess the impact of polycythemia vera (PV) on retinal and optic nerve head (ONH) vessel density (VD) parameters, macular ganglion cell complex (mGCC) thickness, and retinal nerve fiber layer (RNFL) thickness compared to healthy controls. Forty eyes of 20 patients with PV and 40 eyes of 20 age-gender-matched healthy controls underwent comprehensive ophthalmologic assessments and optic coherence tomography angiography (OCTA). RNFL and macular GCC measurements were obtained simultaneously with vascular parameters by AngioVue OCTA using the single-scan protocol. Peripapillary VD was examined across eight sectors, whereas parameters including RNFL, GCC, and macular VD were analyzed in four quadrants. Patients with PV exhibited significant reductions in the average RNFL thickness (P = 0.014) and RNFL thickness in superior (P < 0.001) and inferior (P = 0.003) quadrants compared to controls. Additionally, mGCC thickness in all quadrants significantly reduced in the PV group (P < 0.001). ONH VD parameters, including whole-image VD (P < 0.001) and peripapillary VD (P < 0.001), were significantly reduced in patients with PV. Similarly, macular VD parameters were significantly lower in the PV group (P < 0.001). This study highlights substantial vascular and structural alterations in the retina and ONH of patients with PV compared to healthy controls. These changes likely stem from microvascular dysfunction associated with PV. These findings suggest further research to understand the underlying mechanisms and develop targeted therapeutic strategies for managing ocular complications in patients with PV.

Foveal avascular zone area measurement in diabetic patients: Superficial, deep or combined retinal vascular complex?

PurposeTo 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). MethodsA 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. ResultsIntraoperator 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). ConclusionsEven 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.

Bibliometric analysis of ophthalmic OCT and OCT angiography research trends over the past 20 years.

Optical coherence tomography (OCT) and OCT angiography (OCTA) are widely used in the diagnosis of ophthalmic diseases. This study aims to provide a comprehensive bibliometric analysis of ophthalmologic OCT and OCT angiography. We retrieved publications on ophthalmic OCT and OCTA from 2003 to 2022 from the Web of Science Core Collection and used bibliometric tools to analyze and visualize the distribution, trend, and hotspots. In total, 20,817 articles written by 48,160 authors from 106 countries were selected. The number of publications has significantly increased. In the last two decades, the USA was the most productive country and received the highest citations. The most productive journal was Investigative Ophthalmology and Visual Science and received the highest number of citations. Moorfields Eye Hospital was the most productive institution. Bandello F published the most papers, while Spaide RF was the highest cited author. SPAIDE RF, 2011, AM J Ophthalmology was the most cited document. "OCT", "glaucoma" and "OCTA" were three hotspots in the last two decades. "Vessel density" and "deep learning" would be research hotspots in the future. The bibliometric analysis of ophthalmic OCT and OCTA research over the past two decades on keywords, authors, citations, hotspots and trends will provide global researchers with valuable information for future research and cooperation.

Optical coherence tomography angiography for microaneurysms in anti-vascular endothelial growth factor treated diabetic macular edema

BackgroundWe aimed to evaluate microaneurysms (MAs) after treatment with anti-vascular endothelial growth factor (anti-VEGF) therapy to understand causes of chronic edema and anti-VEGF resistance.MethodsPatients with non-proliferative diabetic retinopathy, with or without macular edema were recruited. Optical coherence tomography angiography (OCTA) MAs-related parameters were observed, including the maximum diameter of overall dimensions, material presence, and flow signal within the lumen. OCTA parameters also included central macular thickness (CMT), foveal avascular zone, superficial and deep capillary plexuses, and non-flow area measurements on the superficial retinal slab.ResultsOverall, 48 eyes from 43 patients were evaluated. CMT differed significantly between the diabetic macular edema (DME ) and non-DME (NDME) groups at 1st, 2nd, 3rd, and 6th months of follow-up (P < 0.001; <0.001; 0.003; <0.001, respectively). A total of 55 and 59 MAs were observed in the DME (mean = 99.40 ± 3.18 μm) and NDME (mean maximum diameter = 74.70 ± 2.86 μm) groups at baseline, respectively (significant between-group difference: P < 0.001). Blood flow signal was measurable for 46 (83.6%) and 34 (59.3%) eyes in the DME and NDME groups, respectively (significant between-group difference: P < 0.001).ConclusionsCompared to the NDME group, the DME group had larger MAs and a higher blood-flow signal ratio. Following anti-VEGF therapy, changes in the diameter of MAs were observed before changes in CMT thickness.Graphical

Using Multi-Layer Perceptron Driven Diagnosis to Compare Biomarkers for Primary Open Angle Glaucoma.

To use neural network machine learning (ML) models to identify the most relevant ocular biomarkers for the diagnosis of primary open-angle glaucoma (POAG). Neural network models, also known as multi-layer perceptrons (MLPs), were trained on a prospectively collected observational dataset comprised of 93 glaucoma patients confirmed by a glaucoma specialist and 113 control subjects. The base model used only intraocular pressure, blood pressure, heart rate, and visual field (VF) parameters to diagnose glaucoma. The following models were given the base parameters in addition to one of the following biomarkers: structural features (optic nerve parameters, retinal nerve fiber layer [RNFL], ganglion cell complex [GCC] and macular thickness), choroidal thickness, and RNFL and GCC thickness only, by optical coherence tomography (OCT); and vascular features by OCT angiography (OCTA). MLPs of three different structures were evaluated with tenfold cross validation. The testing area under the receiver operating characteristic curve (AUC) of the models were compared with independent samples t-tests. The vascular and structural models both had significantly higher accuracies than the base model, with the hemodynamic AUC (0.819) insignificantly outperforming the structural set AUC (0.816). The GCC + RNFL model and the model containing all structural and vascular features were also significantly more accurate than the base model. Neural network models indicate that OCTA optic nerve head vascular biomarkers are equally useful for ML diagnosis of POAG when compared to OCT structural biomarker features alone.

Severity Scale of Diabetic Macular Ischemia Based on the Distribution of Capillary Nonperfusion in OCT Angiography

To evaluate the severity scales of diabetic macular ischemia (DMI) by analyzing the quantity and distribution of capillary nonperfusion using OCT angiography (OCTA) images. A single-center, prospective case series. Three hundred one eyes from 301 patients with diabetic retinopathy. We acquired 3× 3-mm swept-source OCTA images and created en face images within a central 2.5-mm circle. The circle was divided into 15× 15-pixel squares and nonperfusion squares (NPSs) were defined as those without retinal vessels. Eyes with high-dimensional spatial data were arranged on a 2-dimensional space using the uniform manifold approximation and projection (UMAP) algorithm and classified by clustering into 5 groups: Initial, Mild, Superficial, Moderate, and Severe. Development of a severity scale for DMI. Eyes arranged on a 2-dimensional UMAP space were divided into 5 clusters, based on the similarity of nonperfusion area distribution. Nonperfusion square counts in the deep layer increased in eyes of the Initial, Mild, Moderate, and Severe groups in a stepwise manner. In contrast, there were no significant changes in superficial NPS counts between eyes of the Initial and Mild groups. In the intermediate stage, eyes of the Superficial group exhibited higher NPS counts in the central sector of the superficial layer compared with those of the Moderate group. The foveal avascular zone extended into the temporal subfield of the deep layer in eyes of the Moderate group. Eyes of the Severe group had significantly poorer visual acuity that was more frequently accompanied with proliferative diabetic retinopathy. The application of dimensionality reduction and clustering has facilitated the development of a novel severity scale for DMI based on the distribution of capillary nonperfusion in OCTA images. The authors have no proprietary or commercial interest in any materials discussed in this article.

Enhanced microvascular imaging through deep learning-driven OCTA reconstruction with squeeze-and-excitation block integration.

Skin microvasculature is essential for cardiovascular health and thermoregulation in humans, yet its imaging and analysis pose significant challenges. Established methods, such as speckle decorrelation applied to optical coherence tomography (OCT) B-scans for OCT-angiography (OCTA), often require a high number of B-scans, leading to long acquisition times that are prone to motion artifacts. In our study, we propose a novel approach integrating a deep learning algorithm within our OCTA processing. By integrating a convolutional neural network with a squeeze-and-excitation block, we address these challenges in microvascular imaging. Our method enhances accuracy and reduces measurement time by efficiently utilizing local information. The Squeeze-and-Excitation block further improves stability and accuracy by dynamically recalibrating features, highlighting the advantages of deep learning in this domain.

Multilayer Retinal Correspondence of the Structural and Vascular Anomalies in Eyes With Early Macular Telangiectasia Type 2.

To assess the correspondence between interdigitation zone (IZ) reflectivity, ellipsoid zone (EZ) loss, inner retinal layer reflectivity, patterns of capillary dilation, and telangiectasia in eyes with early macular telangiectasia type 2 (MacTel). Twenty-eight eyes of 22 patients with grade 0-2 MacTel (according to the MacTel project classification) and 28 healthy control eyes were included in this study. Multimodal imaging, including optical coherence tomography (OCT) angiography, adaptive optics flood illumination ophthalmoscopy (AO-FIO) and blue light reflectance (BLR), was performed. The EZ, IZ, and outer plexiform layer (OPL) were analyzed on the structural OCT C-scans. The vascular density (VD) was measured on the binarized and skeletonized angiograms of the superficial vascular plexus and deep capillary complex. The vascular diameter index (VDI) was calculated by dividing the binarized VD by the skeletonized VD. On AO-FIO, cone density in the MacTel zone was significantly lower in MacTel eyes than in controls, even in areas located outside the EZ loss (P < 0.001). A distinctive pattern of IZ reflectivity attenuation extended beyond the area of EZ attenuation. The shape and size of a strong OPL hyper-reflectivity corresponded to the MacTel white area (MacTel zone) seen on BLR. Capillary dilation and rarefaction were colocalized with this area, extending beyond visible telangiectasia. The VDI was higher in MacTel eyes than in controls (P < 0.001). These findings suggest that in early MacTel eyes, photoreceptor signal alteration, OPL hyper-reflectivity, and capillary dilation, potentially associated with Müller cell dysfunction, precede the EZ loss.

Impact of acquisition area on deep-learning-based glaucoma detection in different plexuses in OCTA

Glaucoma is a group of neurodegenerative diseases that can lead to irreversible blindness. Yet, the progression can be slowed down if diagnosed and treated early enough. Optical coherence tomography angiography (OCTA) can non-invasively provide valuable information about the retinal microcirculation that has shown to be correlated with the onset of the disease. The vessel density (VD) is the most commonly used biomarker to quantify this vascular information. However, different studies showed that there is a great impact of the acquisition area on the performance of the VD to distinguish between glaucoma patients and a healthy control group. It also seems that the separate capillary plexuses are differently affected by the disease and therefore also influence the results. So in this study we investigate the impact of the acquisition area (3 ×\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ imes $$\\end{document} 3 mm\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ extrm{mm}$$\\end{document} macular scan, 6.44 ×\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ imes $$\\end{document} 6.4 mm\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ extrm{mm}$$\\end{document} macular scan, 6 ×\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ imes $$\\end{document} 6 mm\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ extrm{mm}$$\\end{document} optic nerve head (ONH) scan) and the different plexuses on the machine-learning-based distinction between glaucoma patients and healthy controls. The results yielded that the 6 ×\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ imes $$\\end{document} 6 mm\\documentclass[12pt]{minimal} \\usepackage{amsmath} \\usepackage{wasysym} \\usepackage{amsfonts} \\usepackage{amssymb} \\usepackage{amsbsy} \\usepackage{mathrsfs} \\usepackage{upgreek} \\setlength{\\oddsidemargin}{-69pt} \\begin{document}$$\ extrm{mm}$$\\end{document} ONH show the best performance over all plexuses. Moreover the deep learning-based approach outperforms the VD as a biomarker on every acquisition area and plexus. In addition to that, it also performs better than traditional biomarkers obtained from the OCT scans that are used in the clinical routine for diagnosis and progression tracking of glaucoma. Consequently, OCTA scans of the ONH might be a useful addition to OCT when studying glaucoma.

Video Color OCT Angiography for Myopic Choroidal Neovascularization

To investigate the myopic macular neovascularization (mMNV) features on dynamic video-color optical coherence tomography (OCT) angiography (OCTA) and the diagnostic rate versus the static, four-segmentations visualization mode. Retrospective cohort study PARTICIPANTS: Fifty-four patients with mMNV METHODS: Sixty-two eyes with high myopia complicated by mMNV were included. Clinical charts, fluorescein angiography and structural OCT were used as standard reference to assess lesion activity. Static and video-color OCTA were then analysed and compared by two independent reviewers. Morphology description of mMNV on video-color OCTA and differences in the proportion of diagnosis between video-colour and static OCTA. 62 eyes from 54 patients (mean age 63,22 years) were enrolled. Thirty-four (55%) mMNV were active and 28 (45%) inactive. Twenty-two (65%) active mMNV presented on video-color OCTA as an interlacing vascular network in the outer retina and the choriocapillaris. A tapered form was the prevalent size (72,7%). In 3 eyes (9%) an abnormal and irregular vascular network (AVN) was disclosed and in 5 (15%) only some blood flow alteration. All the lesions extended both in the outer retinal and the choriocapillaris. Eleven (39%) inactive mMNV presented on video-color OCTA as an interlacing vascular network too, in the outer retina and the choriocapillaris. Eight (29%) had some AVN and 6 (21%) only some blood flow alteration. The diagnostic rate of video-color vs static OCTA was 95% (IC 95% 86% to 99%) vs 77% (IC 95% 86% to 99%, p= 0.0009), and shows an advantage in favour of video-colour OCTA of 15% (CI 95%, 3%-27%) and 22% (CI 95%, 7%-38%) in active and inactive lesions, respectively (p<0.026). Lesion extension within both the outer retina and the choriocapillaris was present in 90% and 69% of cases on dynamic OCTA and static OCTA, respectively, with a proportion difference of 20% (CI 95%, 10%-31%, p= 0.0005). Concordance between the two examiners was high: 0.95 (95%, CI 0.88 to 1.00) and 0.96 (0.91 to 1.00) for active and inactive lesions, respectively. Video color-enhanced OCTA may help in diagnosing mMNV and should be considered by clinicians in addition to structural OCT and static OCTA.

OCTA: Essential or Gimmick?

This commentary article delves into the transformative role of optical coherence tomography angiography (OCTA) in diagnosing and managing a wide array of eye conditions, including diabetic retinopathy, age-related macular degeneration, retinal vein occlusions, and white dot syndromes. Developed in 2005, OCTA has emerged as a non-invasive, high-resolution imaging technique that offers advantages over traditional fluorescein angiography (FA), providing quicker and safer monitoring of ocular conditions with similar diagnostic accuracy. In diabetic retinopathy, OCTA has been instrumental in early identification of retinal changes, offering quantifiable metrics including perfused capillary density (PCD) for assessing vascular alterations. For age-related macular degeneration (AMD), OCTA has deepened our understanding of non-exudative neovascular AMD, allowing for more effective monitoring and potential earlier initiation of treatment. In cases of retinal vein occlusions, OCTA can reveal specific microvascular features and allow for depth-resolved measurements of the foveal avascular zone, providing significant prognostic implications. OCTA has also been invaluable in studying rare white dot syndromes, enabling nuanced differentiation between conditions that often present similarly. Emerging research also suggests that OCTA can have potential utility in neurodegenerative diseases like Alzheimer's, where retinal vascular patterns could offer diagnostic insights. While OCTA is revolutionizing ophthalmic care, further clinical trials and standardization are needed for its broader adoption into clinical practice.

Intrapapillary vessel density using optical coherence tomography angiography in primary open-angle glaucoma and normal eyes

Background: Optical coherence tomography angiography (OCTA) is used to quantify optic nerve blood flow in patients with primary open-angle glaucoma (POAG). Intrapapillary vessel density (iVD) has a high diagnostic accuracy for differentiating healthy from glaucomatous eyes. We compared the iVD of patients with POAG with that of healthy controls in an Egyptian tertiary referral center. Methods: This cross-sectional study consecutively recruited patients with medically controlled POAG and age- and sex-matched healthy individuals. All study participants underwent a detailed medical history evaluation and comprehensive ophthalmic examination, with recording of the cup-to-disc ratio (C/D ratio) and intraocular pressure (IOP). Humphrey visual field evaluation using the standard 24-2 program was performed and global indices, including mean deviation (MD) and pattern standard deviation (PSD), were extracted. OCTA and spectral-domain (SD) OCT images were obtained. Average thickness of the retinal nerve fiber layer (RNFL) and thicknesses in the superior, inferior, nasal, and temporal quadrants were recorded. OCTA imaging was used to measure vessel density, and the automatically processed data for iVD were extracted. Results: We included 86 eyes, 43 in the POAG and 43 in the healthy control group, with male predominance in both groups and mean (standard deviation [SD]) ages of 42.1 (9.4) and 39.3 (9.6) years, respectively. The two groups were comparable in terms of mean age, sex ratio, laterality of the included eyes, and mean IOP (all P &gt; 0.05). The mean (SD) C/D ratio, MD, and PSD were significantly higher in the POAG group than in the control group (all P &lt; 0.01). The mean (SD) average RNFL thickness and RNFL thicknesses in the four quadrants were significantly less in glaucomatous eyes than in healthy control eyes (all P &lt; 0.05). Eyes with POAG had a significantly lower mean (SD) iVD than healthy control eyes (P &lt; 0.01). Linear regression analysis revealed a significant positive correlation between iVD and average RNFL thickness (r = + 0.52; P &lt; 0.001) and a significant negative correlation between iVD and PSD (r = - 0.31; P = 0.042) in eyes with POAG. Conclusions: The structural, vascular, and functional parameters measured in this study deteriorated in eyes with POAG compared to controls. Significant circumpapillary RNFL thinning correlated well with reduced iVD in eyes with POAG. Similarly, a lower iVD detected using OCTA had a significant inverse correlation with PSD in the perimetry of eyes with POAG. Further studies with additional parameters and longer follow-up periods are required to verify our preliminary findings.

Diameter-dependent classification of dermal vasculature using optical coherence tomography angiography.

Dermal blood vessels beneath the epidermis play critical roles in epidermal homeostasis and are functionally divided into several types, such as capillaries. Optical coherence tomography angiography (OCTA) is a powerful tool for the non-invasive assessment of dermal vasculature. However, the classification of vessel types has been limited. To address this issue, we proposed an algorithm for diameter-dependent classification that preserves three-dimensional (3D) information using OCTA. OCTA data were acquired by a prototype swept-source-type optical coherence tomography (OCT) system, which was processed through several imaging filters: an optical microangiography (OMAG) imaging filter, a vesselness imaging filter, and a diameter map filter. All vessels were visually classified into three types based on their diameters, as micro-vessels, intermediate vessels, and thick vessels. Aging-related alterations and their association with the epidermis were investigated for each vessel type. The measurements were conducted on the cheeks of 124 female subjects aged 20-79 years. The 3D vascular structure was visualized by applying our proposed post-processing filters. Based on visual assessment, the thresholds for the diameters of the micro, intermediate and thick vessels were set at 80 and 160 µm. It was found that micro-vessels were predominantly located in the upper layer of the dermis and thick vessels in the deeper layer. Analysis of vessel metrics revealed that the volume density of the micro-vessels decreased significantly with age (r=-0.36, P<0.001) and was positively correlated with epidermal thickness (r=0.50, P<0.001). In contrast, the volume density of thick vessels significantly increased with age (r=0.2, P<0.05) and was not significantly correlated with epidermal thickness (r=0.13, P≥0.05). In this study, we proposed a 3D quantification method using OCTA for dermal blood vessels and various vessel metrics, such as vessel volume density. This proposed classification will be beneficial for determining the function of the dermal vasculature and its diagnostic applications.

Acute Macular Neuroretinopathy Associated with COVID-19 Pandemic: A Real-world Observation Study

PurposeTo evaluate the clinical and retinal imaging features of Chinese patients with acute macular neuroretinopathy (AMN) associated with COVID-19. DesignA prospective observational study. MethodsRetinal imaging, including color fundus photography, near-infrared imaging (NIR), swept-source optical coherence tomography (SS-OCT), optical coherence tomography angiography (OCTA), and Humphrey perimetry, were conducted for each case. ResultsAll cases were included within the first three months following the pandemic outbreak. A total of 12 male patients (36.36 %) and 21 female patients (63.64 %) were prospectively recruited, and 29 cases (87.88 %) were bilaterally affected. The median interval between the onset of fever and the appearance of ocular symptoms was two days (range, 0.5–5.0 days). Apart from the outer retinal changes typical of AMN, changes in the inner retinal layers were observed, including intraretinal hemorrhage (8.06 %), cotton wool spots (9.68 %), and paracentral acute middle maculopathy (PAMM) (8.06 %). Smaller retinal inner nuclear layer hyperreflective speckles (RIHS) (41.94 %) were identified as a distinguishing feature from typical PAMM. Voids of vessel signals were found in the superficial (11.54 %), intermediate (82.69 %), and deep capillary plexus (98.08 %), and in the choriocapillaris (19.23 %) on OCTA. Humphrey perimetry illustrated central, paracentral, and peripheral scotomas. The occult lesions associated with AMN, PAMM, and some of the RIHS illustrated by OCT were visualized topographically and further confirmed by OCTA as perfusion defects. ConclusionAn increase in AMN cases correlated with the SARS-CoV-2 outbreak. Additional features, including widespread inner retinal perfusion deficits, were observed and may serve as potential biomarkers for systemic microcirculation dysregulation in COVID-19.

Conjunctival microvascular alteration in patients with coronary artery disease assessed using optical coherence tomographic angiography

BackgroundTo quantify conjunctival microvascular characteristics obtained by optical coherence tomographic angiography (OCTA) and investigate their relationship with the presence and severity of coronary artery disease (CAD). MethodsThis cross-sectional study included 103 consecutive CAD patients confirmed by coronary angiography and 125 non-CAD controls. The temporal conjunctivas along the limbus of each participant were scanned using OCTA. Quantification of conjunctival microvasculature was performed by AngioTool software. The severity of the disease was evaluated using SYNTAX and Gensini scores. ResultsCompared to the controls, the CAD group exhibited significantly lower vessel area density (30.22 ± 3.34 vs. 26.70 ± 4.43 %, p < 0.001), lower vessel length density (6.39 ± 0.77 vs. 5.71 ± 0.89/m, p < 0.001), lower junction density (3.44 ± 0.56 vs. 3.05 ± 0.63/m, p < 0.001), and higher lacunarity (0.11 ± 0.03 vs. 0.14 ± 0.05, p < 0.001). Among all participants, lower vessel area density, lower vessel length density, lower junction density, and higher lacunarity were associated with greater odds of having CAD; the adjusted ORs (95 % confidence intervals) per one SD decrease were 2.71 (1.71, 4.29), 2.51(1.61, 3.90), 2.06 (1.39, 3.05), and 0.36 (0.23, 0.58), respectively. Among CAD patients, junction density was negatively associated with the Gensini score (r = −0.359, p = 0.037) and the Syntax score (r = −0.350, p = 0.042) in women but not in men (p > 0.05). ConclusionsConjunctival microvascular characteristics were significantly associated with the presence of CAD. Junction density significantly associated with the severity of CAD among women patients.