1. Articles from Nadia K. Waheed

    1-24 of 93 1 2 3 4 »
    1. OCT Angiography-based Evaluation of the Choriocapillaris in Neovascular Age-related Macular Degeneration

      OCT Angiography-based Evaluation of the Choriocapillaris in Neovascular Age-related Macular Degeneration

      Neovascular age-related macular degeneration (AMD) can lead to rapid, irreversible vision loss in untreated eyes. While the pathogenesis of neovascular AMD remains incompletely understood, the choriocapillaris has been hypothesized as the initial site of injury. Due to limitations of dye-based angiography, in vivo imaging of the choriocapillaris has been a longstanding challenge. However, the clinical introduction of optical coherence tomography angiography (OCTA) has enabled researchers and clinicians to noninvasively image the choriocapillaris vasculature, allowing the evaluation of the choriocapillaris in eyes with a variety of pathologies. In this perspective, we review important OCTA-based findings regarding choriocapillaris impairment in neovascular AMD ...

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    2. Multiscale correlation of microvascular changes on optical coherence tomography angiography with retinal sensitivity in diabetic retinopathy

      Multiscale correlation of microvascular changes on optical coherence tomography angiography with retinal sensitivity in diabetic retinopathy

      Purpose: To assess global, zonal, and local correlations between vessel density changes measured by optical coherence tomography angiography (OCTA) and retinal sensitivity measured by microperimetry across diabetic retinopathy severity. Methods: Diabetic patients and non-diabetic controls underwent OCTA imaging and microperimetry testing. Pearson's correlation was used to assess associations between average sensitivity and skeletonized vessel density (SVD) or FAZ area centrally. Linear mixed effects modeling was used to assess relationships between local SVD measurements and their spatially corresponding retinal sensitivity measurements. Results: Thirty-nine eyes from 39 participants were imaged. In all slabs, there was a statistically significant positive correlation between ...

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    3. Analysis of correlations between local geographic atrophy growth rates and local OCT angiography-measured choriocapillaris flow deficits

      Analysis of correlations between local geographic atrophy growth rates and local OCT angiography-measured choriocapillaris flow deficits

      The purpose of this study is to quantitatively assess correlations between local geographic atrophy (GA) growth rates and local optical coherence tomography angiography (OCTA)-measured choriocapillaris (CC) flow deficits. Thirty-eight eyes from 27 patients with GA secondary to age-related macular degeneration (AMD) were imaged with a commercial 1050 nm swept-source OCTA instrument at 3 visits, each separated by ∼6 months. Pearson correlations were computed between local GA growth rates, estimated using a biophysical GA growth model, and local OCTA CC flow deficit percentages measured along the GA margins of the baseline visits. The p-values associated with the null hypothesis of ...

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    4. Macular Vessel Density in Diabetic Retinopathy Patients: How Can We Accurately Measure and What Can It Tell Us?

      Macular Vessel Density in Diabetic Retinopathy Patients: How Can We Accurately Measure and What Can It Tell Us?

      Diabetic retinopathy is one of the leading causes of blindness worldwide. Optical coherence tomography angiography (OCTA) is a non-invasive technology that provides depth-resolved images of the chorioretinal vasculature and allows for the understanding of the changes in vasculature with diabetic retinopathy. Not only can it provide qualitative information, but OCTA can also provide quantitative information about the vasculature in patients with diabetic retinopathy. Macular vessel density is one of the quantitative metrics that can be obtained from OCTA images. This is a repeatable and non-subjective measurement that can provide valuable insight into the pathophysiology of diabetic retinopathy. In this non-systematic ...

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      Mentions: Tufts University
    5. Optical coherence tomography angiography distortion correction in widefield montage images

      Optical coherence tomography angiography distortion correction in widefield montage images

      Background: Optical coherence tomography (OCT) imaging is inherently susceptible to distortion artifacts due to the natural curvature of the eye. This study proposes a novel model for widefield OCT angiography (OCTA) distortion correction and analyzes the effects of this correction on quantification metrics. Methods: Widefield OCTA images were obtained on normal subjects at five fixation spatial positions. Radial and field distortion correction were applied and images stitched together to form a corrected widefield montage image. Vessel area density (VAD), vessel complexity index (VCI), and flow impairment area were quantified on the original and corrected montage images. Results: This model allows ...

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    6. OCT-OCTA segmentation: combining structural and blood flow information to segment Bruch's membrane

      OCT-OCTA segmentation: combining structural and blood flow information to segment Bruch's membrane

      In this paper we present a fully automated graph-based segmentation algorithm that jointly uses optical coherence tomography (OCT) and OCT angiography (OCTA) data to segment Bruch's membrane (BM). This is especially valuable in cases where the spatial correlation between BM, which is usually not visible on OCT scans, and the retinal pigment epithelium (RPE), which is often used as a surrogate for segmenting BM, is distorted by pathology. We validated the performance of our proposed algorithm against manual segmentation in a total of 18 eyes from healthy controls and patients with diabetic retinopathy (DR), non-exudative age-related macular degeneration (AMD ...

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    7. Deliberations of an International Panel of Experts on OCTA Nomenclature of nAMD

      Deliberations of an International Panel of Experts on OCTA Nomenclature of nAMD

      A panel of imaging experts was assembled to review neovascular age-related macular degeneration optical coherence tomography angiography descriptors published to date, and test agreement on use of these terms, which was found to be low. Optical coherence tomography angiography (OCTA) has been used to identify and characterize macular neovascularization (MNV) secondary to age-related macular degeneration (AMD). 1-4 Many studies have explored OCTA morphological features of MNV that might serve as biomarkers to assess disease activity and response to treatment. 1-6 The proliferation of studies however has resulted in an OCTA terminology that has been variable and inconsistent. To address inconsistency ...

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    8. Swept Source Optical Coherence Tomography Angiography in Small Choroidal Melanomas and Choroidal Nevi

      Swept Source Optical Coherence Tomography Angiography in Small Choroidal Melanomas and Choroidal Nevi

      Purpose: To evaluate the use of swept source optical coherence tomography angiography (SS-OCTA) to detect distinct vascular features in small choroidal melanomas and choroidal nevi. Methods: Patients with a choroidal nevus or a treatment-naïve choroidal melanoma were imaged with color fundus photography, ultrasound and SS-OCTA (12x12mm). High-risk features including overlying fluid, orange pigment, shaggy photoreceptors, acoustic hollowness, depth >2mm, and basal diameter >5mm were assessed. OCTA vascular markers included: choroidal vessel visualization, choroidal vessel depth, and choriocapillaris flow signal, assessed qualitatively by comparison to surrounding, unaffected choriocapillaris. Results: Twenty-nine lesions were included in this study, 7 flat choroidal nevi ...

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      Mentions: Tufts University
    9. Efficient and high accuracy 3-D OCT angiography motion correction in pathology

      Efficient and high accuracy 3-D OCT angiography motion correction in pathology

      We describe a novel method for non-rigid 3-D motion correction of orthogonally raster-scanned optical coherence tomography angiography volumes. This is the first approach that aligns predominantly axial structural features such as retinal layers as well as transverse angiographic vascular features in a joint optimization. Combined with orthogonal scanning and favorization of kinematically more plausible displacements, subpixel alignment and micrometer-scale distortion correction is achieved in all 3 dimensions. As no specific structures are segmented, the method is by design robust to pathologic changes. Furthermore, the method is designed for highly parallel implementation and short runtime, allowing its integration into clinical workflow ...

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    10. A practical guide to optical coherence tomography angiography interpretation

      A practical guide to optical coherence tomography angiography interpretation

      Background Optical coherence tomography angiography (OCTA) can image the retinal vasculature in vivo, without the need for contrast dye. This technology has been commercially available since 2014, however, much of its use has been limited to the research setting. Over time, more clinical practices have adopted OCTA imaging. While countless publications detail OCTA’s use for the study of retinal microvasculature, few studies outline OCTA’s clinical utility. Body This review provides an overview of OCTA imaging and details tips for successful interpretation. The review begins with a summary of OCTA technology and artifacts that arise from image acquisition. New ...

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      Mentions: Tufts University
    11. Maximum A Posteriori Signal Recovery for Optical Coherence Tomography Angiography Image Generation and Denoising

      Maximum A Posteriori Signal Recovery for Optical Coherence Tomography Angiography Image Generation and Denoising

      Optical coherence tomography angiography (OCTA) is a novel and clinically promising imaging modality to image retinal and sub-retinal vasculature. Based on repeated optical coherence tomography (OCT) scans, intensity changes are observed over time and used to compute OCTA image data. OCTA data are prone to noise and artifacts caused by variations in flow speed and patientmovement. We propose a novel iterativemaximuma posteriori signal recovery algorithm in order to generate OCTA volumes with reduced noise and increased image quality. This algorithm is based on previous work on probabilistic OCTA signal models and maximum likelihood estimates. Reconstruction results using total variation minimization ...

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    12. Choroidal nonperfusion on optical coherence tomography angiography in a case of unilateral posterior segment ocular sarcoidosis misdiagnosed as MEWDS

      Choroidal nonperfusion on optical coherence tomography angiography in a case of unilateral posterior segment ocular sarcoidosis misdiagnosed as MEWDS

      Purpose To report a case of presumed ocular sarcoidosis initially presenting with features of multiple evanescent white dot syndrome (MEWDS) with atypical optical coherence tomography angiography (OCTA) findings. Observations A 23 year-old woman presented with a unilateral central scotoma, photophobia, and decreased visual acuity after a viral illness. Examination of the right eye revealed multiple round white macular spots and stippled granularity at the fovea. Multimodal imaging with fluorescein angiography (FA), indocyanine green angiography (ICG), fundus autofluorescence (FAF), and optical coherence tomography (OCT) was consistent with a diagnosis of MEWDS. However, OCTA demonstrated choriocapillaris (CC) flow deficits, which is not ...

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    13. Anterior-segment spectral domain optical coherence tomography in epidermolysis bullosa

      Anterior-segment spectral domain optical coherence tomography in epidermolysis bullosa

      Purpose Assess epidermolysis bullosa (EB)-related corneal pathology using anterior segment optical coherence tomography (AS-OCT) and correlate imaging with clinical metrics in EB patients versus age-matched controls. Methods EB patients and controls were recruited during an EB conference (July 2018) and at Tufts Medical Center (June–August 2019). Subjects completed a questionnaire, had best corrected visual acuity (BCVA) tested, and underwent AS-OCT scanning. Stromal and epithelial thickness were measured. Depth, length, and type of the three largest lesions were assessed by a masked examiner using a novel pathology grading system. Multivariate analysis of AS-OCT findings and clinical metrics was performed ...

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      Mentions: Tufts University
    14. Repeatability of binarization thresholding methods for optical coherence tomography angiography image quantification

      Repeatability of binarization thresholding methods for optical coherence tomography angiography image quantification

      Binarization is a critical step in analysis of retinal optical coherence tomography angiography (OCTA) images, but the repeatability of metrics produced from various binarization methods has not been fully assessed. This study set out to examine the repeatability of OCTA quantification metrics produced using different binarization thresholding methods, all of which have been applied in previous studies, across multiple devices and plexuses. Successive 3 × 3 mm foveal OCTA images of 13 healthy eyes were obtained on three different devices. For each image, contrast adjustments, 3 image processing techniques (linear registration, histogram normalization, and contrast-limited adaptive histogram equalization), and 11 binarization ...

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    15. Using the Pathophysiology of Dry AMD to Guide Binarization of the Choriocapillaris on OCTA: A Model

      Using the Pathophysiology of Dry AMD to Guide Binarization of the Choriocapillaris on OCTA: A Model

      Especially since the incorporation of swept laser sources, optical coherence tomography angiography (OCTA) has enabled quantification of choriocapillaris perfusion. A critical step in this process is binarization, which makes angiographic images quantifiable in terms of perfusion metrics. It remains challenging to have confidence that choriocapillaris perfusion metrics reflect the reality of pathophysiologic flow, largely because choice of binarization method can result in significantly different perfusion metric outcomes. This commentary discusses a proof-of-concept case involving comparative assessment of binarization methods for a set of dry age-related macular degeneration OCTA data. One of these methods was deemed preferable based on superior agreement ...

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    16. The long-term effects of anti-vascular endothelial growth factor therapy on the optical coherence tomography angiographic appearance of neovascularization in age-related macular degeneration

      The long-term effects of anti-vascular endothelial growth factor therapy on the optical coherence tomography angiographic appearance of neovascularization in age-related macular degeneration

      Background The short-term effects of anti-vascular endothelial growth factor (anti-VEGF) treatment on macular neovascularization (MNV) morphology is well described, but long-term studies on morphologic changes and correlation of such changes to the type of MNV have not been conducted. This study aims to determine if different types of MNVs in neovascular AMD (nAMD) behave differently with anti-VEGF treatment as visualized on optical coherence tomography angiography (OCTA). Methods Treatment-naïve nAMD patients were retrospectively screened for baseline and follow-up OCTA imaging 10 or more months after initial treatment. Images were graded for MNV type, area, activity, mature versus immature vessels, vessel ...

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    17. High-Speed, Ultrahigh-Resolution Spectral-Domain OCT with Extended Imaging Range Using Reference Arm Length Matching

      High-Speed, Ultrahigh-Resolution Spectral-Domain OCT with Extended Imaging Range Using Reference Arm Length Matching

      Purpose : To develop high-speed, extended-range, ultrahigh-resolution spectral-domain optical coherence tomography (UHR SD-OCT) and demonstrate scan protocols for clinical retinal imaging. Methods : A UHR SD-OCT operating at 840-nm with 150-nm bandwidths was developed. The axial imaging range was extended by dynamically matching reference arm length to the retinal contour during acquisition. Two scan protocols were demonstrated for imaging healthy participants and patients with dry age-related macular degeneration. A high-definition raster protocol with intra–B-scan reference arm length matching (ReALM) was used for high-quality cross-sectional imaging. A cube volume scan using horizontal and vertical rasters with inter–B-scan ReALM and software motion ...

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    18. Model-to-Data Approach for Deep Learning in Optical Coherence Tomography Intraretinal Fluid Segmentation

      Model-to-Data Approach for Deep Learning in Optical Coherence Tomography Intraretinal Fluid Segmentation

      Importance Amid an explosion of interest in deep learning in medicine, including within ophthalmology, concerns regarding data privacy, security, and sharing are of increasing importance. A model-to-data approach, in which the model itself is transferred rather than data, can circumvent many of these challenges but has not been previously demonstrated in ophthalmology. Objective To determine whether a model-to-data deep learning approach (ie, validation of the algorithm without any data transfer) can be applied in ophthalmology. Design, Setting, and Participants This single-center cross-sectional study included patients with active exudative age-related macular degeneration undergoing optical coherence tomography (OCT) at the New England ...

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      Mentions: Tufts University
    19. Concerns about the interpretation of OCT and fundus findings in COVID-19 patients in recent Lancet publication

      Concerns about the interpretation of OCT and fundus findings in COVID-19 patients in recent Lancet publication

      We read with great interest the correspondence in Lancet by Marinho et al. [ 1 ] describing purported retinal manifestations of coronavirus disease (COVID-19). While there is great interest to understand potential ocular complications of COVID-19 during this pandemic, we have some concerns regarding the interpretation of the fundus and optical coherence tomography (OCT) findings. Marinho et al. examined 12 COVID-19 patients (all confirmed by PCR or antibody testing) with typical systemic disease but no visual symptoms. The reported cohort was relatively young (25–69 years; no mean or median provided) without severe systemic disease, although 2 were hospitalized. Eleven of the ...

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    20. Analyzing Relative Flow Speeds in Diabetic Retinopathy Using Variable Interscan Time Analysis Optical Coherence Tomography Angiography

      Analyzing Relative Flow Speeds in Diabetic Retinopathy Using Variable Interscan Time Analysis Optical Coherence Tomography Angiography

      Objective Further insight into the flow characteristics of the vascular features associated with diabetic retinopathy (DR) may improve assessment and treatment of disease progression. The variable interscan time analysis (VISTA) algorithm is an extension of optical coherence tomography angiography (OCTA) that detects relative blood flow speeds which can then be depicted on a color-coded map. This study utilized VISTA to analyze relative blood flow speeds in the microvascular changes associated with DR. Design and Participants: In this cross-sectional study at New England Eye Center, Boston, Massachusetts, thirteen patients of varying severities of DR were enrolled. Methods OCTA images centered at ...

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    21. Macular and Peripapillary OCTA Metrics Predict Progression in Diabetic Retinopathy: A Sub-analysis of TIME-2b Study Data

      Macular and Peripapillary OCTA Metrics Predict Progression in Diabetic Retinopathy: A Sub-analysis of TIME-2b Study Data

      Purpose To identify optical coherence tomography angiography (OCTA) derived vessel metrics of the macula and optic nerve head (ONH) that predict diabetic retinopathy (DR) disease progression. Design Secondary analysis of clinical trial data Methods This was a sub-analysis of prospectively collected data from 73 subjects that participated in the TIME-2b Study (Aerpio Pharmaceuticals), a multi-center clinical trial for patients with moderate to severe DR treated with AKB-9778 and followed over a 12-month period. Eligible subjects were tested every 3 months with color fundus photography, spectral domain OCT and slit-lamp biomicroscopy. OCTA of the macula and ONH was obtained for a ...

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    22. Morphological changes in intraretinal microvascular abnormalities after anti-VEGF therapy visualized on optical coherence tomography angiography

      Morphological changes in intraretinal microvascular abnormalities after anti-VEGF therapy visualized on optical coherence tomography angiography

      Background To examine the baseline morphological characteristics and alterations in intraretinal microvascular abnormalities (IRMAs) in response to anti-vascular endothelial growth factor (anti-VEGF) treatment, documented by optical coherence tomography angiography (OCTA) in diabetic eyes. Methods In this retrospective study, IRMAs were evaluated with multimodal imaging (fundus photography, fluorescein angiography, OCTA) in treatment-naïve diabetic eyes before and after anti-VEGF treatment for diabetic macular edema (DME) and/or proliferative diabetic retinopathy (PDR) and compared to diabetic control eyes with similar diabetic retinopathy (DR) severity that did not receive anti-VEGF therapy. The morphological characteristics of IRMAs on enface OCTA imaging were graded by ...

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    23. Repeatability and reproducibility of vessel density measurements on optical coherence tomography angiography in diabetic retinopathy

      Repeatability and reproducibility of vessel density measurements on optical coherence tomography angiography in diabetic retinopathy

      Purpose Understanding the precision of measurements on and across optical coherence tomography angiography (OCTA) devices is critical for tracking meaningful change in disease. The purpose of this study is to investigate the repeatability and reproducibility of vessel area density and vessel skeleton density measurements from various commercial OCTA devices in diabetic eyes. Methods Patients were imaged three consecutive times each on three different OCTA devices. En face OCTA images of the superficial capillary plexus, deep capillary plexus, and full retinal layer were exported for analysis. Vessel area density and vessel skeleton density were calculated. The coefficient of repeatability (CoR) was ...

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      Mentions: Tufts University
    24. Correction propagation for user-assisted optical coherence tomography segmentation: general framework and application to Bruch’s membrane segmentation

      Correction propagation for user-assisted optical coherence tomography segmentation: general framework and application to Bruch’s membrane segmentation

      Optical coherence tomography (OCT) is a commonly used ophthalmic imaging modality. While OCT has traditionally been viewed cross-sectionally (i.e., as a sequence of B-scans), higher A-scan rates have increased interest in en face OCT visualization and analysis. The recent clinical introduction of OCT angiography (OCTA) has further spurred this interest, with chorioretinal OCTA being predominantly displayed via en face projections. Although en face visualization and quantitation are natural for many retinal features (e.g., drusen and vasculature), it requires segmentation. Because manual segmentation of volumetric OCT data is prohibitively laborious in many settings, there has been significant research and ...

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