Nimesh A. Patel

A normative database of wide-field swept-source optical coherence tomography angiography quantitative metrics in a large cohort of healthy adults

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Purpose Data from healthy eyes is needed to interpret optical coherence tomography angiography (OCTA) findings. However, very little normative data is available for wide-field swept-source OCTA (WF SS-OCTA), particularly 12 × 12-mm and disc-centered angiograms. Therefore, we aim to report quantitative metrics in a large sample of control eyes. Methods In this cross-sectional observational study, 482 eyes of 375 healthy adults were imaged on the 100 kHz Zeiss PLEX® Elite 9000 using protocols centered on the fovea (3 × 3, 6 × 6, and 12 × 12-mm) and optic disc (6 × 6 and 12 × 12-mm) between December 2018 and January 2022. The ARI Network (Zeiss Portal v5.4) was used to calculate vessel density (VD) and vessel skeletonized density (VSD) in the superficial capillary plexus, deep capillary plexus, and whole retina, as well as foveal avascular zone (FAZ) parameters. Mixed-effect multiple linear regression models were used for statistical analysis. Results The subjects’ m...

Characterising collateral vessels in eyes with branch retinal vein occlusions using widefield swept-source optical coherence tomography angiography

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Background/aims: To characterise the morphology, location and functional significance of both macular and extramacular collateral vessels (CVs) in patients with a history of branch retinal vein occlusion (BRVO) using widefield swept-source optical coherence tomography angiography (WF SS OCTA). Methods: Patients with a history of BRVO underwent WF SS OCTA testing to acquire 12×12 mm images, which were evaluated for CVs and non-perfusion area (NPA). Region of interest analysis of individual CVs was performed to identify correlations between CV size, depth and retinal location. Mixed effects multivariate regression analyses of factors associated with NPA and visual acuity (VA) were performed. Results: Fifty-five CVs were identified in 28 BRVO eyes from 27 patients. CVs were identified in 42.9% (12/28) of eyes with a history of BRVO, and of these, 45.5% (25/55) were extramacular. The majority of CVs (87.3%, 48/55) coursed through both the superficial and the deep capillary plexus ...

Widefield Swept-Source Optical Coherence Tomography Angiography Findings in Wagner Syndrome

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Purpose: To describe novel clinical and angiographic findings in Wagner syndrome. Methods: A retrospective case series of three related patients with Wagner syndrome. Patients underwent standard OCT, B-scan ultrasonography, and fluorescein angiography in addition to wide field swept-source OCT angiography (WF SS-OCTA) (PLEX® Elite 9000, Carl Zeiss Meditec Inc.). Patients underwent genetic testing for a panel of hereditary vitreoretinopathies. Results: Three related patients with Wagner syndrome were identified. All were found to have prominent vitreous strands, abnormal vitreoretinal adhesions, peripheral retinal holes, and varying degrees of myopia. A mid-peripheral tractional ridge was identified in all 6 eyes. All patients were positive for a known pathologic intron variant in the VCAN gene (4004-5T-A). WF SS-OCTA (12 mm x 12 mm) was performed in two patients and demonstrated perivascular capillary loss in the superficial capillary plexus along the arcades bilaterally. One pa...

Intraoperative Optical Coherence Tomography Angiography in Children with Incontinentia Pigmenti

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OCT angiography detects vascular abnormalities in incontinentia pigmenti not apparent on fluorescein angiography, and therefore may serve as helpful tool to detect early macular ischemia in children during examination under anesthesia. ( Read Full Article )

Comparison Between Graders in Detection of Diabetic Neovascularization with Swept Source OCT Angiography and Fluorescein Angiography

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Purpose To compare the ability of ophthalmologists to identify neovascularization (NV) in patients with proliferative diabetic retinopathy (PDR) using swept source optical coherence tomography angiography (SS-OCTA) and fluorescein angiography (FA). Design Retrospective study comparing diagnostic instruments. Methods Eyes with PDR or severe non-proliferative diabetic retinopathy and a high suspicion of NV based on clinical examination were imaged using SS-OCTA and FA at the same visit. Two separate grading sets consisting of scrambled, anonymized SS-OCTA and FA images were created. The ground truth for presence of NV was established by consensus of two graders with OCTA experience who did not participate in the subsequent assessment of NV in this study. The two anonymized image sets were graded for presence or absence of NV by 12 other graders that included two residents, six vitreoretinal fellows, and four vitreoretinal attending physicians. The percentage of correct grading of NV u...

Correlations between Different Choriocapillaris Flow Deficit Parameters in Normal Eyes using Swept Source OCT Angiography

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Purpose Choriocapillaris (CC) imaging of normal eyes with swept-source optical coherence tomography SS-OCTA was performed, and the percentage of CC flow deficits (FD%) and the average area of CC flow deficits (FDa) were compared within given macular regions. Design A prospective, cross-sectional study. Methods Subjects with normal eyes ranging in age from their 20s through their 80s were imaged with SS-OCTA (PLEX Elite 9000, Carl Zeiss Meditec, Dublin, CA) using both 3x3 mm and 6x6 mm macular scan patterns. The CC images were generated using a previously published and validated algorithm. In both 3x3 mm and 6x6 mm scans, the CC FD% and FDa were measured in circular regions centered on the fovea with diameters as 1mm and 2.5 mm (C1 and C2.5). In 6x6 mm scans, the FD% and FDa were measured within an additional circular region with diameter as 5 mm (C5). The correlations between FD% and FDa from each region were analyzed with Pearson’s correlation coefficients. Results A total of...

Differentiating veins from arteries on optical coherence tomography angiography by identifying deep capillary plexus vortices

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Purpose To introduce a simple method for differentiating retinal veins from arteries on optical coherence tomography angiography (OCTA). Design Cross-sectional pilot study. Methods Four default en face slabs including color depth encoded, greyscale full-thickness retina, superficial plexus, and deep capillary plexus (DCP) from 9 3x3 mm and 9 6x6 mm OCTA scans were exported and aligned. Nine ophthalmologists with minimum OCTA experience from 2 eye institutions were instructed to classify labeled vessels as arteries or veins in 3 stages. Classification was performed based on graders’ own assessment at Stage 1. Graders were taught that a capillary-free zone was an anatomic feature of arteries at Stage 2 and were trained to identify veins originating from vortices within the DCP at Stage 3. Grading accuracy was analyzed and correlated with grading time and graders’ years in practice. Results Overall grading accuracy in Stages 1, 2, and 3 was (50.4 ± 17.0) %, (75.4 &pl...

Age-Dependent Changes in the Macular Choriocapillaris of Normal Eyes Imaged with Swept-Source OCT Angiography

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Purpose Swept source optical coherence tomography angiography (SS-OCTA) was used to measure the age-dependent changes in macular choriocapillaris (CC) flow deficits (FDs) in normal eyes. Design A prospective, cross-sectional study. Methods Subjects with normal eyes ranging in age from their 20s to their 80s were imaged using a 100-kHz SS-OCTA instrument (PLEX ® Elite 9000, Carl Zeiss Meditec). Both 3x3 mm and 6x6 mm scans were used to image the macular CC. Visualization of the CC and quantification of FDs were performed using a previously validated algorithm. The percentage of FDs (FD%) in the central 1 mm circle (C 1 ), 1.5 mm rim (R 1.5 ), and 2.5 mm circle (C 2.5 ) from the 3x3 mm and 6x6 mm scans and FD% in the 2.5 mm rim (R 2.5 ) and 5 mm circle (C 5 ) from the 6x6 mm scans were measured and correlated with age and axial length. Results A total of 164 subjects were enrolled with at least 10 subjects from each decade of life. No meaningful correlations were found between FD%...


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