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Background and Objective: The purpose of this article is to demonstrate the optical coherence tomography angiography (OCTA) Analysis Toolkit (OAT), a custom-designed software package, as a repeatable and reproducible tool for computing OCTA metrics across different devices., Materials and Methods: Fourteen participants were imaged using three devices. Foveal avascular zone, vessel index, vessel length index, and vessel diameter index were calculated using the OAT. Repeatability and reproducibility were assessed using the coefficient of variation and interclass correlation coefficient (ICC)., Results: Analysis of identical images demonstrated perfect levels of repeatability for all metrics (coefficient of variation 0%), which was a consequence of the software being deterministic (ie, producing the same outputs for the same inputs). Foveal avascular zone ICC values were in the excellent-to-good range (I CC > 0.6) for all devices. All values for vessel index (VI), vessel length index, and vessel diameter index fell in the good-to-fair (I CC > 0.4) or excellent-to-good range, except for vessel index analysis in the Cirrus device (I CC = 0.34)., Conclusions: The OAT appears to be a reliable tool that may enable comparison between OCTA data sets acquired on different imaging instruments, thereby facilitating a more consistent approach to OCTA analysis. [ Ophthalmic Surg Lasers Imaging Retina 2023;54:114-122.] .

Purpose: Describe the utility of anterior segment optical coherence tomography angiography (AS-OCTA) to assess ocular surface lesions., Methods: Retrospective, case-control study of 10 eyes of 9 patients with malignant lesions and 23 eyes of 22 patients with benign lesions. Lesions included 13 epithelial, 10 pigmented and 10 lymphoid lesions. Graders performed an average of 3 depth and diameter measurements of peri-lesional vessels entering each lesion on AS-OCTA. Statistical models to assess differences between groups accounted for bilateral eye inclusion and lesion thickness (on AS-OCT). Receiver operating characteristic (ROC) curve and area under the curve (AUC) were performed for each parameter., Results: In the benign and malignant groups, age was 49.5 ± 22.4 and 64.3 ± 10.6 years (p = 0.145) with 45% males and 55% males (p = 0.458), in their respective groups. AS-OCTA showed greater peri-lesional vessel depth and diameter in malignant lesions (315.2 ± 73.0 μm, p < 0.001 and 76.4 ± 18.2 μm, p < 0.001; respectively) compared to benign lesions (199.4 ± 34.1 μm and 44.0 ± 9.4 μm, respectively). Malignant lesions showed deep and dilated peri-lesional vessels, which may represent feeder vessels. Vessel depth showed AUC = 0.980, 90.9% sensitivity and 100.0% specificity with a 236.5 μm cutoff. Vessel diameter showed AUC = 0.960, 100.0% sensitivity and 88.9% specificity with a 53.9 μm cutoff., Conclusion: AS-OCTA shows greater peri-lesional vessel depth and diameter of malignant lesions compared to benign lesions. This imaging modality provides novel and non-invasive functional vascular parameters that can potentially aid the assessment of ocular surface lesions., (Copyright © 2021 Elsevier Inc. All rights reserved.)

Purpose: To assess the full-thickness macular hole (FTMH) size using the choroidal hypertransmission signal on spectral-domain optical coherence tomography and to compare this method to the standard aperture measurement of the minimum aperture size at the level of the neurosensory retina., Design: Cross-sectional study of retrospective data., Methods: Eyes with FTMH imaged on spectral-domain optical coherence tomography were included. Two independent masked graders used the device's built-in caliper tool to measure the FTMH minimum aperture size at the level of the neurosensory retina and the size of the corresponding hypertransmission signal below the level of the retinal pigment epithelium/Bruch membrane complex. To assess the reproducibility of the hypertransmission measurement in tilted scans, two measurements were obtained and compared; the first was traced parallel to the retinal pigment epithelium (parallel hypertransmission), and the second was horizontal to the image frame (horizontal hypertransmission), both using Image J software., Results: A total of 31 eyes were enrolled. The mean FTMH minimum aperture size was smaller compared with both the choroidal parallel hypertransmission and horizontal hypertransmission measurements (mean ± SD: 335.7 ± 139.5 µm, 376.7 ± 150.6 µm, 375.1 ± 150.0 µm, respectively. P < 0.001 for both comparisons)., Conclusion: The proposed hypertransmission measurement is a feasible and reproducible alternative to assess FTMH size and could provide the basis for an automated FTMH measurement on cross-sectional spectral-domain optical coherence tomography scans, as presented in this study, or on the spectral-domain optical coherence tomography volumetric data set by using an en face projection.

Purpose: To evaluate the use of swept-source optical coherence tomography angiography 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 swept-source optical coherence tomography angiography (12 × 12 mm). High-risk features including overlying fluid, orange pigment, shaggy photoreceptors, acoustic hollowness, depth >2 mm, and basal diameter >5 mm were assessed. Optical coherence tomography angiography vascular markers included: choroidal vessel visualization, choroidal vessel depth, and choriocapillaris flow signal, assessed qualitatively by comparison with surrounding, unaffected choriocapillaris., Results: Twenty-nine lesions were included in this study, seven flat choroidal nevi, 17 elevated choroidal nevi, and 5 choroidal melanomas. Distinct vascular patterns were noted between flat nevi, elevated nevi, and small choroidal melanomas. Choroidal melanomas displayed two types of vasculature: "nevus-like" vasculature with straight parallel vessels and complex vasculature with vascular loops and crosslinking. Visualized choroidal vessels were significantly deeper in melanomas (110 µm) than elevated (84 µm) or flat nevi (70 µm). In a size-matched subanalysis of 5 elevated choroidal nevi and 5 choroidal melanomas, choroidal melanomas had increased mean choroidal vessel depth (P = 0.015), deepest choroidal vessel visualized (P = 0.034), and presence of a deep choroidal vessel >155 µm (P = 0.048)., Conclusion: Swept-source optical coherence tomography angiography may detect distinct vascular features in choroidal nevi and small choroidal melanomas., (Copyright © 2021 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of the Opthalmic Communications Society, Inc.)

Purpose: 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 OCT angiography (OCTA) that detects relative blood flow speeds, which then can be depicted on a color-coded map. This study used VISTA to analyze relative blood flow speeds in the microvascular changes associated with DR., Design: Cross-sectional study., Participants: Thirteen patients with varying severities of DR treated at New England Eye Center, Boston, Massachusetts., Methods: OCT angiography images centered at the fovea were obtained on a prototype swept-source OCT device, and the VISTA algorithm was applied to visualize relative blood flow speeds., Main Outcome Measures: Descriptive flow analysis of the retinal vascular features of DR was conducted on the VISTA-generated images., Results: Twenty-six eyes were included in this study. Of these, 3 eyes had mild nonproliferative DR (NPDR), 6 eyes had moderate NPDR, 4 eyes had severe NPDR, 9 eyes had proliferative DR, and 4 eyes were normal controls. Microaneurysms, intraretinal microvascular abnormalities (IRMAs), and neovascularization appeared to originate from areas of relatively slow blood flow speeds. Microaneurysms showed relatively slower flow, IRMAs showed turbulent, intermediate to slow flow, and venous beading and looping presented with relatively high flow speeds that tapered progressively. Neovascularization of venous origin demonstrated slower flow speeds, whereas that of arterial origin showed relatively high flow speeds. Additionally, increased disease severity was associated with globally slower flow speeds, with particularly slower flow around the foveal avascular zone., Conclusions: The VISTA algorithm seems to be a useful extension of OCTA that overcomes some of the limitations of normal gray-scale OCTA. It seems to have some potential in providing relevant insight into the pathogenesis of the microvascular changes associated with DR. These findings may assist in improving our understanding of the pathogenic changes that take place in DR., (Copyright © 2020. Published by Elsevier Inc.)

Purpose: To evaluate the repeatability and reproducibility of photoreceptor density assessment with manual cell counting in healthy participants imaged with the Heidelberg Spectralis High Magnification Module (HMM)., Design: Precision study, evaluation of diagnostic test or technology., Participants: Eleven eyes of 8 participants., Methods: Images were acquired using the Spectralis HMM by a single operator during 2 separate imaging sessions. The 3 highest-quality images of each eye from each session were selected for analysis and coregistered. For a subset of participants, a second operator acquired images in 1 session, and images with the best quality were selected for analysis. Photoreceptor densities were obtained by manual counts in squares of 0.0625 mm 2 located in the parafovea. Repeatability (intragrader and intrasession) and reproducibility (interoperator, intergrader, and intersession) were assessed by calculating the intraclass correlation coefficient (ICC) from linear mixed effects models. Bland-Altman plots, coefficients of repeatability, and Pearson correlation results were reported., Main Outcome Measures: Intragrader, intrasession, intersession, interoperator, and intergrader ICC estimates and their 95% confidence intervals for photoreceptor density measurements in the parafovea., Results: Twenty-four eyes of 13 healthy participants were imaged initially. Of these, 11 eyes (45.83%) of 8 participants that had at least 3 acceptable images in each session were included in this study. Mean parafoveal photoreceptor density was 14 988 cells/mm 2 (standard deviation, 1403.15 cells/mm 2 ). Intragrader ICC was 0.84 (95% confidence interval, 0.57-0.95), intrasession ICC was 0.69 (95% confidence interval, 0.17-0.86), intersession ICC was 0.88 (95% confidence interval, 0.53-0.96), interoperator ICC was 0.70 (95% confidence interval, 0-0.95), and intergrader ICC was 0.22 (95% confidence interval, 0-0.71)., Conclusions: Images obtained with the HMM allow for photoreceptor mosaic visualization in the macular area, mainly in the parafovea. Although densities obtained are in accordance with other reported methods in the literature, variability within and between images of the apparent cell mosaic were observed, and this study did not demonstrate high repeatability or reproducibility for quantitative assessments using the manual counting method., (Copyright © 2020 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.)

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 Eye Center from August 1, 2018, to February 28, 2019. Data were primarily analyzed from March 1 to June 20, 2019., Main Outcomes and Measures: Training of the deep learning model, using a model-to-data approach, in recognizing intraretinal fluid (IRF) on OCT B-scans., Results: The model was trained (learning curve Dice coefficient, >80%) using 400 OCT B-scans from 128 participants (69 female [54%] and 59 male [46%]; mean [SD] age, 77.5 [9.1] years). In comparing the model with manual human grading of IRF pockets, no statistically significant difference in Dice coefficients or intersection over union scores was found (P > .05)., Conclusions and Relevance: A model-to-data approach to deep learning applied in ophthalmology avoided many of the traditional hurdles in large-scale deep learning, including data sharing, security, and privacy concerns. Although the clinical relevance of these results is limited at this time, this proof-of-concept study suggests that such a paradigm should be further examined in larger-scale, multicenter deep learning studies.

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., Results: 62 EB patients and 60 age-matched controls were enrolled. Mean BCVA was 1.8 lines worse in patients (p < 0.001). Vision loss was associated with increased stromal thickness. Discrete lesions were seen in 60.2% of patient eyes, averaging 1.71 ± 1.75 lesions in patients and 0.14 ± 0.42 in controls (p < 0.001). Mean primary lesion depth was 151.88 ± 97.49 μm in patients. Patients showed significant stromal thickening versus controls and lesions were most common in the periphery and inferiorly. Differences in frequency and duration of abrasions and severity of pain were all statistically and clinically significant in patients versus controls (p < 0.001)., Conclusions: AS-OCT can visualize and quantify differences in the corneas of EB patients compared with age-matched controls. Novel findings include quantification of average depth, length, and severity of discrete lesions, and sparing of the superior quadrant from stromal thickening in EB patients. These results support use of AS-OCT and a questionnaire in clinical trials for new EB therapies., (Copyright © 2020. Published by Elsevier Inc.)

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 thresholding methods were independently applied. Vessel area density (VAD) and vessel length were calculated for retinal vascular images. Choriocapillaris (CC) images were quantified for VAD and flow deficit metrics. Repeatability, measured using the intra-class correlation coefficient, was inconsistent and generally not high (ICC < 0.8) across binarization thresholds, devices, and plexuses. In retinal vascular images, local thresholds tended to incorrectly binarize the foveal avascular zone as white (i.e., wrongly indicating flow). No image processing technique analyzed consistently resulted in highly repeatable metrics. Across contrast changes, retinal vascular images showed the lowest repeatability and CC images showed the highest.

Purpose: With the increasing prevalence of diabetes, fast, noninvasive identification of proliferative diabetic retinopathy (PDR) becomes essential. This study evaluated the utility of optical coherence tomography angiography (OCTA) to characterize intraretinal microvascular abnormalities (IRMA) and retinal neovascularization (NV)., Methods: Patients with severe non-PDR or PDR were imaged with fluorescein angiography and widefield swept-source OCTA (Zeiss Plex Elite 9000; Carl Zeiss Meditec, Dublin, CA). Regions suspicious for IRMA or retinal NV were identified and the OCTA, including flow overlay on the co-registered structural optical coherence tomography, and fluorescein angiography images were graded by two masked readers., Results: Ninety-six foci of irregular vasculature were analyzed, comprised of 70 IRMA and 26 retinal NV lesions from 14 eyes. Compared with fluorescein angiography, OCTA with flow overlay demonstrated specificity of 99% and sensitivity of 92% in identifying IRMA and NV. Neovascularization differed from IRMA on OCTA by demonstrating supraretinal flow breaching the internal limiting membrane and posterior hyaloid (P < 0.001). Intraretinal microvascular abnormalities were distinguished from NV by outpouching of the internal limiting membrane (P = 0.035). Vascular flow was reduced in the presence of fibrosis., Conclusion: Optical coherence tomography angiography, through flow overlay, has utility to image and differentiate IRMA and NV, which are key features distinguishing severe non-PDR and PDR, respectively. Noninvasive widefield OCTA may be a useful tool to diagnose high-risk diabetic retinopathy eyes.

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 calculated to assess the repeatability of these measurements, and linear mixed models were utilized to assess the reproducibility of these measurements., Results: Forty-four eyes from 27 diabetic patients were imaged. Normalized CoR values ranged between 3.44 and 6.65% when calculated for vessel area density and between 1.35 and 23.39% when calculated for vessel skeleton density. When stratified by disease severity, the swept-source OCTA device consistently produced the smallest CoR values for vessel area density in the full retinal layer. Vessel area density measurements were repeatable across the two spectral-domain devices in the full retinal layer when all severities were combined, as well as in diabetic patients without retinopathy, mild nonproliferative diabetic retinopathy (NPDR), and moderate NPDR., Conclusion: Vessel area density measured in the full retinal layer may be a more precise measure than vessel skeleton density to follow diabetic retinopathy patients both on the same device and across devices.

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 with suspected physiologic and pathophysiologic characteristics, thus demonstrating the principle that, in the absence of gold standards for measurement of choriocapillaris perfusion, the best available approximations of pathophysiology may be used to guide choice of binarization method., Competing Interests: Disclosure: P.X. Braun, None; N. Mehta, None; I. Gendelman, None; A.Y. Alibhai, None; C.R. Baumal, Genentech (C), Carl Zeiss Meditec, Inc. (S); J.S. Duker, Carl Zeiss Meditec, Inc. (F, C), Optovue, Inc. (F, C); N.K. Waheed, Topcon Medical Systems, Inc. (F), Nidek Medical Products, Inc. (F, S), Carl Zeiss Meditec, Inc. (F), Optovue, Inc. (C), (Copyright 2020 The Authors.)

Purpose: To examine the effects of enhanced depth imaging (EDI) and en face averaging on global vascular measurements of optical coherence tomography angiography (OCTA) images., Methods: All eyes were imaged with 3 mm × 3 mm fields centered at the fovea using the Carl Zeiss Cirrus 5000 spectral-domain OCTA, with and without EDI, and the Zeiss PLEX Elite 9000 swept-source OCTA. Vessel area density (VAD), vessel length (VL), and vessel diameter index (VDI) were calculated for the superficial capillary plexus (SCP) en face angiograms. For the choriocapillaris (CC), VAD and the number, total area, and average size of flow voids were calculated. These metrics were compared between SD- and SS-OCTA images, with and without en face averaging and EDI., Results: Both averaging and EDI had a significant effect on quantitative metrics. EDI images trended toward a decrease in SCP VAD. In the CC, EDI decreased average flow void size. Averaging increased CC VAD while decreasing number of flow voids, total flow void area, and average flow void size. With both averaging and EDI, SD-OCTA was not able to visualize as many CC flow voids, particularly of a smaller size, compared with SS-OCTA., Conclusions: Averaging and EDI affect quantitative metrics from SCP and CC OCTA images. EDI resulted in a trend toward decreased VAD in SCP images. Averaging had a major effect on CC imaging. Even with the combination of EDI and en face averaging, SD-OCTA images do not appear to approximate SS-OCTA images in terms of quantitative metrics. This has implications for clinical and research use of SD-OCTA for retinal imaging.

Purpose: To develop an optical coherence tomography angiography (OCTA)-based framework for quantitatively analyzing the spatial distribution of choriocapillaris (CC) impairment around choroidal neovascularization (CNV) secondary to age-related macular degeneration., Methods: In a retrospective, cross-sectional study, 400-kHz swept-source OCTA images from 7 eyes of 6 patients with CNV secondary to age-related macular degeneration were quantitatively analyzed using custom software. A lesion-centered zonal OCTA analysis technique-which portioned the field-of-view into zones relative to CNV boundaries-was developed to quantify the spatial dependence of CC flow deficits., Results: Quantitative, lesion-centered zonal analysis of CC OCTA images revealed highest flow-deficit percentages near CNV boundaries, decreasing in zones farther from the boundaries. Optical coherence tomography angiography using shorter (1.5 ms) interscan times revealed more severe flow deficits than OCTA using longer (3.0 ms) interscan times; however, spatial trends were similar for both interscan times. A detailed description of the OCTA processing steps and parameters was provided so as to elucidate their influence on quantitative measurements., Conclusion: Impairment of the CC, assessed by flow-deficit percentages, was most prominent closest to CNV boundaries. The lesion-centered zonal analysis technique enabled quantitative CC measurements relative to focal lesions. Understanding how processing steps, imaging/processing parameters, and artifacts can affect quantitative CC measurements is important for longitudinal, OCTA-based studies of disease progression, and treatment response.

Purpose: To combine advances in high-speed, wide-field optical coherence tomography angiography (OCTA) with image processing methods for semiautomatic quantitative analysis of capillary nonperfusion in patients with diabetic retinopathy (DR)., Methods: Sixty-eight diabetic patients (73 eyes), either without retinopathy or with different degrees of retinopathy, were prospectively recruited for volumetric swept-source OCTA imaging using 12 mm × 12 mm fields centered at the fovea. A custom, semiautomatic software algorithm was used to quantify areas of capillary nonperfusion., Results: The mean percentage of nonperfused area was 0.1% (95% confidence interval: 0.0-0.4) in the eyes without DR; 2.1% (95% confidence interval: 1.2-3.7) in the nonproliferative DR eyes (mild, moderate, and severe), and 8.5% (95% confidence interval: 5.0-14.3) in the proliferative DR eyes. The percentage of nonperfused area increased in a statistically significant manner from eyes without DR, to eyes with nonproliferative DR, to eyes with proliferative DR., Conclusion: Capillary nonperfusion area in the posterior retina increases with increasing DR severity as measured by swept-source OCTA. Quantitative analysis of retinal nonperfusion on wide-field OCTA may be useful for early detection and monitoring of disease in patients with diabetes and DR.

Purpose: Swept-source optical coherence tomography angiography (SS-OCTA) was used to investigate if the clinical stage of dry age-related macular degeneration (AMD) was correlated with global and regional macular choriocapillaris (CC) perfusion., Methods: In this retrospective, cross-sectional study, 6 × 6-mm SS-OCTA images from eyes with early, intermediate, and advanced dry AMD (56 eyes, 41 patients) were analyzed using algorithms described in the literature to assess regional flow deficit percentage (FD%) and average flow deficit size. Regions were defined by concentric areas centered on the fovea: a 1-mm-diameter area, 3-mm-diameter ring, 5-mm-diameter area, 5-mm-diameter ring, and 6 × 6-mm whole image. Data were modeled using the generalized estimating equations approach., Results: The relationship between age and CC FD% and average flow deficit size was statistically significant (P ≤ 0.05) in all regions of analysis by linear modeling. The relationship between dry AMD stage and FD% was statistically significant by linear modeling in the 5-mm ring, and between dry AMD stage and average flow deficit size in the 3-mm ring, 5-mm area, 5-mm ring, and 6 × 6-mm whole image., Conclusions: Linear modeling suggests a statistically significant relationship between dry AMD stage and CC perfusion, most prominent in the more peripheral regions of the macula.

Background/aims: Hydroxychloroquine (HCQ) retinopathy may result in severe and irreversible vision loss, emphasising the importance of screening and early detection. The purpose of this study is to report the novel finding of early optical coherence tomography (OCT) abnormalities due to HCQ toxicity that may develop in the setting of normal Humphrey visual field (HVF) testing., Methods: Data from patients with chronic HCQ exposure was obtained from seven tertiary care retina centres. Ten patients with HCQ-associated OCT abnormalities and normal HVF testing were identified. Detailed analysis of the OCT findings and ancillary tests including colour fundus photography, fundus autofluorescence, multifocal electroretinography and microperimetry was performed in these patients., Results: Seventeen eyes from 10 patients illustrated abnormalities with OCT and normal HVF testing. These OCT alterations included (1) attenuation of the parafoveal ellipsoid zone and (2) loss of a clear continuous interdigitation zone. Several eyes progressed to advanced parafoveal outer retinal disruption and/or paracentral visual field defects., Conclusion: Patients with high risk HCQ exposure and normal HVF testing may develop subtle but characteristic OCT abnormalities. This novel finding indicates that, in some cases of early HCQ toxicity, structural alterations may precede functional impairment. It is therefore important to employ a screening approach that includes OCT to assess for these early findings. Ancillary testing should be considered in cases with suspicious OCT changes and normal HVFs., Competing Interests: Competing interests: NKW is a consultant for Optovue and receives research support from Carl Zeiss Meditec, Topcon Medical Systems and Nidek Medical Products. JSD is a consultant for and receives research support from Carl Zeiss Meditec and Optovue. EHS is a consultant for Novartis, Bayer Schering Pharma, Allergan Inc. and Farmila-Thea. KBF is a consultant to Genentech, Allergan, Optos, Optovue, Zeiss, Heidelberg Engineering and Novartis. He receives research funding from Genentech/Roche. DS is a consultant for Amgen, Bayer, Genentech, Novartis and Optovue and receives research funding from Genentech, Heidelberg, Optovue and Regeneron. All other authors have no conflict of interest to declare., (© Author(s) (or their employer(s)) 2019. No commercial re-use. See rights and permissions. Published by BMJ.)

Purpose: To summarize the results of a consensus meeting aimed at defining terminology for widefield imaging across all retinal imaging methods and to provide recommendations for the nomenclature used to describe related images., Design: An international panel with expertise in retinal imaging was assembled to define consensus terminology for widefield imaging and associated terminology., Participants: A panel of retina specialists with expertise in retinal imaging., Methods: Before the consensus meeting, a set of 7 images acquired with a range of imaging methods and representing both healthy and diseased eyes was circulated to the expert panel for independent assignment of nomenclature for each example. The outputs were assembled and used as the starting point for discussions occurring at a subsequent roundtable meeting. The anatomic location, field of view, and perspective provided by each image example was reviewed. A process of open discussion and negotiation was undertaken until unanimous terminology for widefield imaging was achieved., Main Outcome Measures: Definitions of widefield imaging applicable to multiple imaging methods., Results: Across a range of different imaging methods, the expert panel identified a lack of uniform terminology being used in recent literature to describe widefield images. The panel recommended the term widefield be limited to images depicting retinal anatomic features beyond the posterior pole, but posterior to the vortex vein ampulla, in all 4 quadrants. The term ultra widefield was recommended to describe images showing retinal anatomic features anterior to the vortex vein ampullae in all 4 quadrants. The definitions were recommended over other device-specific terminology., Conclusions: A consistent nomenclature for widefield imaging based on normal anatomic landmarks that is applicable to multiple retinal imaging methods has been proposed by the International Widefield Imaging Study Group. The panel recommends this standardized nomenclature for use in future publications., (Copyright © 2019 American Academy of Ophthalmology. Published by Elsevier Inc. All rights reserved.)

Purpose: To compare the sensitivity of detection and the measured size of choroidal neovascularization (CNV) on two commercially available spectral domain optical coherence tomography angiography (OCTA) devices, the Optovue RTVue XR Avanti with AngioVue and the Zeiss Cirrus HD-OCT with AngioPlex., Methods: Patients with CNV lesions were imaged consecutively on both OCTA devices on the same day of their visit. 3 × 3 mm and 6 × 6 mm scans centered at the fovea were obtained. Two independent masked readers evaluated the OCTA images for CNV identification and its area measurements., Results: No significant differences were observed between the 2 OCTA devices in CNV area measurements on their 3 × 3 mm and 6 × 6 mm scans. However, there was suboptimal performance of their automated segmentation algorithms as compared to manually adjusted segmentation for visualizing CNV lesions., Conclusion: There was no significant difference in the size of the CNV lesion as measured on either commercially available spectral domain OCTA device. Both devices were comparable in their detection of CNV lesions on manual adjustment of segmentation lines. However, their automated segmentation algorithms need improvement to allow for accurate measurement of CNV lesions for routine clinical application.

Purpose: Binarization is a critical technique in optical coherence tomography angiography (OCTA) image analysis, but there is no consistency in the method used in published OCTA studies. This study assessed whether differences in OCTA binarization and brightness and contrast adjustments affect quantification measurements., Design: Prospective cross-sectional validity study., Methods: This was a single-center study examining 21 eyes of 11 healthy individuals. All eyes were imaged using a swept-source OCTA (Zeiss), and quantitative measurements resulting from five binarization thresholding and five brightness/contrast adjustment methods were compared. All measurements were calculated for the superficial plexus and choriocapillaris (CC), as well as unaveraged and averaged en face OCTA images., Results: There were statistically significant differences between measurements from different binarization thresholding methods (P < 0.0001), as well as measurements from different histogram adjustments (P < 0.0001). The binarization thresholds yielded different measurements when combined with variable brightness/contrast adjustments. The method of analysis also affected the directionality of trends in imaging measurements between unaveraged and averaged CC images., Conclusions: The method of OCTA image binarization thresholding and histogram adjustment significantly alters quantitative measurements and the directionality of trends. Results obtained from different OCTA binarization methods should be seen as valid only for that given method. This has significant consequences for clinical trials using OCTA measurements as outcome measurements. A consensus is needed across the research community for a consistent method for OCTA image quantification and greater attention paid to fully describing methods in published studies., (Copyright © 2019. Published by Elsevier Inc.)

The recent clinical adoption of optical coherence tomography (OCT) angiography (OCTA) has enabled non-invasive, volumetric visualization of ocular vasculature at micron-scale resolutions. Initially limited to 3 mm × 3 mm and 6 mm × 6 mm fields-of-view (FOV), commercial OCTA systems now offer 12 mm × 12 mm, or larger, imaging fields. While larger FOVs promise a more complete visualization of retinal disease, they also introduce new challenges to the accurate and reliable interpretation of OCTA data. In particular, because of vignetting, wide-field imaging increases occurrence of low-OCT-signal artifacts, which leads to thresholding and/or segmentation artifacts, complicating OCTA analysis. This study presents theoretical and case-based descriptions of the causes and effects of low-OCT-signal artifacts. Through these descriptions, we demonstrate that OCTA data interpretation can be ambiguous if performed without consulting corresponding OCT data. Furthermore, using wide-field non-perfusion analysis in diabetic retinopathy as a model widefield OCTA usage-case, we show how qualitative and quantitative analysis can be confounded by low-OCT-signal artifacts. Based on these results, we suggest methods and best-practices for preventing and managing low-OCT-signal artifacts, thereby reducing errors in OCTA quantitative analysis of non-perfusion and improving reproducibility. These methods promise to be especially important for longitudinal studies detecting progression and response to therapy.

Purpose: To compare foveal vascular anatomy between patients with and without disorganization of retinal inner layers (DRILs) after resolved diabetic macular edema using optical coherence tomography angiography (OCTA)., Methods: Twenty-four eyes of 21 age- and sex-matched patients with resolved diabetic macular edema were included in this retrospective, cross-sectional study. All eyes were imaged with enhanced high-definition line or cross-line structural B scans and 3 × 3-mm OCTA scans. Optical coherence tomography B scans were analyzed for the presence of DRIL, and based on this, eyes were classified as either DRIL present or DRIL absent. The foveal avascular zone area on OCTA was compared between patients with and without DRIL. The foveal avascular zone area was correlated with visual acuity., Results: Nine eyes with DRIL and resolved diabetic macular edema were compared with 15 control eyes without DRIL and resolved diabetic macular edema. Area of ischemia on OCTA scans corresponded to the area of DRIL as determined on OCT B scans. The foveal avascular zone area in full retina as well as superficial and deep retinal plexuses OCTA slabs were significantly larger in patients with DRIL as compared to those without DRIL (P = 0.005, P < 0.001, and P = 0.004, respectively). The larger foveal avascular zone in full retinal segmentation (r = 0.72, P = 0.03) and superficial plexus (r = 0.74, P = 0.02) were positively correlated with lower visual acuity., Conclusion: Optical coherence tomography angiography can visualize retinal ischemia in patients with and without DRIL. Correspondence of impaired blood flow with DRIL suggests that retinal ischemia and loss of normal vasculature contributes to DRIL.

Background and Objective: To assess variability in vessel density (VD) measurements across three optical coherence tomography angiography (OCTA) devices to identify a methodology that offers the least amount of variation in VD, and to assess the effect of averaging of multiple scans on VD variability., Patients and Methods: Fifteen eyes of eight healthy individuals were imaged consecutively on three OCTA devices. Segmentations at the superficial, deep, and full retinal layers were generated. Repeat scans for each retinal layer were registered and averaged to generate one OCTA image. Two different automated thresholding techniques were used to calculate vessel area density (VAD) from binarized images and vessel skeleton density (VSD) from skeletonized images. Vessel length, a linear measure of the combined lengths of vessels, was calculated. Foveal avascular zone (FAZ) area was measured., Results: All three OCTA devices were significantly different (P < .0001). This finding remained after averaging images (P < .0001). VSD was more repeatable within a device but less reproducible across devices. Conversely, VAD demonstrated less repeatability but greater reproducibility. Differences in VSD between devices were systematic and attributable to differences in resolution. Vessel length, unaffected by resolution, demonstrated no significant differences between the devices (P > .107). There was no significant difference in FAZ area across devices (P = .51). After averaging images, VD was significantly different from the single images for each device and plexus (P < .05) but remained within 1% of the value of a single scan., Conclusions: OCTA devices show variability in VD for healthy individuals. With greater repeatability, VSD appeared useful for following a patient on one device. VAD and vessel length seemed ideal for comparing vessel parameters between OCTA devices. After averaging multiple scans, VSD remained within 1% of a single scan, for which clinical significance remains to be determined. Caution is advised when comparing quantitative analyses across OCTA devices. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:S5-S17.]., (Copyright 2018, SLACK Incorporated.)

Primary vitreoretinal lymphoma (PVRL) can be a diagnostic challenge and commonly presents as a partially steroid-responsive vitritis or as subretinal cream-colored infiltrates. The authors present a patient with PVRL who initially presented with bilateral vitritis; however, after two non-diagnostic vitrectomy specimens and two unremarkable brain MRIs, she was lost to follow-up. She presented 2.5 years later with a white plaque on the posterior capsule of her left intraocular lens, though the vitreous cavity was free of infiltrate. Repeat biopsy revealed diffuse large B-cell lymphoma, and brain MRI demonstrated an enhancing lesion of the cerebellum, consistent with primary central nervous system lymphoma., (Copyright 2018, SLACK Incorporated.)

Purpose: To illustrate errors in the automated segmentation image analysis of optical coherence tomography angiography after laser photocoagulation therapy for Type 2 neovascularization., Methods: This case report describes a patient with extrafoveal Type 2 neovascularization treated with argon laser photocoagulation evaluated before and after treatment by optical coherence tomography angiography., Results: Disrupted retinal layers after laser photocoagulation therapy lead to segmentation errors., Conclusion: Images of optical coherence tomography angiography are prone to degradation by artifacts in cases in which there is disruption of the retinal layers. Clinicians must be aware of these errors because they can be misinterpreted as active Type 2 neovascularization. Improvement in optical coherence tomography angiography image analysis to minimize automated segmentation errors needs to be further explored.

Background and Objective: To demonstrate the feasibility of retinal and anterior segment intraoperative widefield imaging using an ultrahigh-speed, swept-source optical coherence tomography (SS-OCT) surgical microscope attachment., Patients and Methods: A prototype post-objective SS-OCT using a 1,050-nm wavelength, 400 kHz A-scan rate, vertical cavity surface-emitting laser (VCSEL) light source was integrated to a commercial ophthalmic surgical microscope after the objective. Each widefield OCT data set was acquired in 3 seconds (1,000 × 1,000 A-scans, 12 × 12 mm 2 for retina and 10 × 10 mm 2 for anterior segment)., Results: Intraoperative SS-OCT was performed in 20 eyes of 20 patients. In six of seven membrane peels and five of seven rhegmatogenous retinal detachment repair surgeries, widefield retinal imaging enabled evaluation pre- and postoperatively. In all seven cataract cases, anterior imaging evaluated the integrity of the posterior lens capsule., Conclusions: Ultrahigh-speed SS-OCT enables widefield intraoperative viewing in the posterior and anterior eye. Widefield imaging visualizes ocular structures and pathology without requiring OCT realignment. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:94-102.]., (Copyright 2018, SLACK Incorporated.)

Background: Optical coherence tomography angiography (OCTA) has demonstrated good utility in qualitative analysis of retinal and choroidal vasculature and therefore may be relevant in the diagnostic and treatment efforts surrounding nonarteritic anterior ischemic optic neuropathy (NAION)., Methods: Retrospective, cross-sectional study of 10 eyes of 9 patients with a previous or new diagnosis of NAION that received imaging with OCTA between November 2015 and February 2016. Two independent readers qualitatively analyzed the retinal peripapillary capillaries (RPC) and peripapillary choriocapillaris (PCC) for flow impairment. Findings were compared with automated visual field and structural optical coherence tomography (OCT) studies., Results: Flow impairment seen on OCTA in the RPC corresponded to structural OCT deficits of the retinal nerve fiber layer (RNFL) and ganglion cell layer complex (GCC) in 80% and 100% of eyes, respectively, and to automated visual field deficits in 90% of eyes. Flow impairment seen on OCTA in the PCC corresponded to structural OCT deficits of the RNFL and GCC in 70% and 80% of eyes, respectively, and to visual field deficits in 60%-80% of eyes., Conclusions: OCTA can noninvasively visualize microvascular flow impairment in patients with NAION.

Objective: To describe optical coherence tomography angiography (OCTA) reflectance artifacts secondary to retinal pigment epithelial detachment (RPED)., Design: Retrospective review., Methods: Four eyes from 4 subjects were included. Three presented with RPED and 1 eye was a normal control. Two eyes diagnosed with RPED and the normal eye were evaluated using en face OCTA centred at the fovea acquired using the RTVue XR Avanti (Optovue Inc). In the third eye with RPED, OCTA imaging was performed using a CIRRUS 5000 prototype modified to do OCTA imaging on a spectral domain OCT platform provided by Carl Zeiss Meditec, Inc. The segmented OCTA angiograms were overlaid to determine if the flow patterns seen at the edge of the RPEDs were due to reflectance from the inner retinal vessels, also known as "decorrelation tails.", Results: OCTA projection artifacts were noted when segmentation lines intersected with the boundary of the RPED. The overlaid segmented OCTA from the 3 RPED eyes imaged using each system revealed the same vasculature pattern at the edges of the RPED as that of the inner retina, demonstrating the "decorrelation tails" artifact, which caused the RPED to appear as a bright ring on the segmented OCTA., Conclusions: OCTA images are susceptible to various known artifacts. This series describes the impact of the projection artifact seen at the edges of an RPED that simulates appearance of flow but is actually due to reflectance of the inner retinal vasculature on the RPED., (Copyright © 2017 Canadian Ophthalmological Society. Published by Elsevier Inc. All rights reserved.)

Purpose: To study the changes in the choroidal layers thickness with age in a healthy population using swept-source optical coherence tomography., Methods: Retrospective data analysis of a subgroup of eyes from a previous single-center, prospective, cross-sectional, noninterventional study. One hundred and sixty-nine healthy eyes were evaluated using swept-source optical coherence tomography. Inclusion criteria were best-corrected visual acuity between 20/20 and 20/25, spherical equivalent between ±3 diopters, and no systemic or ocular diseases. Two independent investigators determined the macular horizontal choroidal thickness (CT) and the Haller's layer thickness across a 9 mm line centered at the fovea. Subjects were divided into five age groups., Results: Mean subfoveal choroidal thickness was 305.76 ± 80.59 μm (95% confidence interval: 294.85-319.33). Mean subfoveal thickness for Haller's layer was 215.47 ± 67.70 μm (95% confidence interval: 207.30-227.86) and mean subfoveal thickness for choriocapillaris plus Sattler's layer was 87.31 ± 40.40 μm (95% confidence interval: 83.38-95.65). No significant differences were found due to gender. Choroidal thickness profile was similar between groups with choroidal thickness and Haller's layer thickness decreasing with age (P = 0.002)., Conclusion: Choroidal and Haller's layer thickness profiles are similar between different age groups. Age-related choroidal thinning is mostly at the expense of Haller's layer.

Optical coherence tomography angiography (OCTA) is a noninvasive, rapid imaging technique that generates angiographic images without intravenous dye injections. Cross-sectional studies have described the presence of asymptomatic choroidal neovascularization (CNV) in patients with intermediate age-related macular degeneration (AMD). This case report describes the OCT features on longitudinal follow-up of a patient who started with unilateral asymptomatic CNV and eventually developed symptomatic exudative AMD. [Ophthalmic Surg Lasers Imaging Retina. 2017;48:596-598.]., (Copyright 2017, SLACK Incorporated.)

Importance: Alterations in ocular blood flow play an important role in the pathogenesis and progression of diabetic retinopathy (DR). However, the measurement of retinal blood flow in clinical studies has been challenging. En face Doppler optical coherence tomography (OCT) provides an effective method for measuring total retinal blood flow (TRBF) in the clinic., Objective: To investigate TRBF in eyes with DR of varying severity, with or without diabetic macular edema (DME), using en face Doppler OCT., Design, Setting, and Participants: This was a cross-sectional study conducted from May 23, 2014, to January 11, 2016, which analyzed 41 eyes with DR from 31 diabetic patients, 20 eyes without DR from 11 diabetic patients, and 16 eyes from 12 healthy age-matched controls, all at the New England Eye Center in Boston, Massachusetts., Main Outcomes and Measures: Participants were imaged with a high-speed, swept-source OCT prototype at 1050-nm wavelength using repeated en face Doppler OCT raster scans, comprising 600 × 80 axial scans and covering a 1.5 × 2-mm2 area centered at the optic disc. The TRBF was automatically calculated using custom Matlab software., Results: This study included 41 eyes with DR from 31 diabetic patients (mean [SD] age, 62.8 [13.4] years; 12 were female patients), 20 eyes without DR from 11 diabetic patients (mean [SD] age, 58.8 [10.1] years; 5 were female patients), and 16 eyes from 12 healthy age-matched controls (mean [SD] age, 57.9 [8.1] years; 8 were female participants). The mean (SD) TRBF was 28.0 (8.5) µL/min in the eyes with DME, 48.8 (13.4) µL/min in the eyes with DR but without DME, 40.1 (7.7) µL/min in the diabetic eyes without retinopathy, and 44.4 (8.3) µL/min in age-matched healthy eyes. A difference in TRBF between the eyes with DME that were treated and the eyes with DME that were not treated was not identified. The TRBF was consistently low in the eyes with DME regardless of DR severity. The eyes with moderate nonproliferative DR but without DME exhibited a wide range of TRBF from 31.1 to 75.0 µL/min, with the distribution being highly skewed., Conclusions and Relevance: High-speed en face Doppler OCT can measure TRBF in healthy and diabetic eyes. Diabetic eyes with DME exhibited lower TRBF than healthy eyes (P ≤ .001). Further longitudinal studies of TRBF in eyes with DR would be helpful to determine whether reduced TRBF is a risk factor for DME.

Purpose: To investigate the utility of ultrahigh speed, swept source optical coherence tomography angiography in visualizing retinal microvascular and choriocapillaris (CC) changes in diabetic patients., Methods: The study was prospective and cross-sectional. A 1,050 nm wavelength, 400 kHz A-scan rate swept source optical coherence tomography prototype was used to perform volumetric optical coherence tomography angiography of the retinal and CC vasculatures in diabetic patients and normal subjects. Sixty-three eyes from 32 normal subjects, 9 eyes from 7 patients with proliferative diabetic retinopathy, 29 eyes from 16 patients with nonproliferative diabetic retinopathy, and 51 eyes from 28 diabetic patients without retinopathy were imaged., Results: Retinal and CC microvascular abnormalities were observed in all stages of diabetic retinopathy. In nonproliferative diabetic retinopathy and proliferative diabetic retinopathy, optical coherence tomography angiography visualized a variety of vascular abnormalities, including clustered capillaries, dilated capillary segments, tortuous capillaries, regions of capillary dropout, reduced capillary density, abnormal capillary loops, and foveal avascular zone enlargement. In proliferative diabetic retinopathy, retinal neovascularization above the inner limiting membrane was visualized. Regions of CC flow impairment in patients with proliferative diabetic retinopathy and nonproliferative diabetic retinopathy were also observed. In 18 of the 51 of eyes from diabetic patients without retinopathy, retinal mircrovascular abnormalities were observed and CC flow impairment was found in 24 of the 51 diabetic eyes without retinopathy., Conclusion: The ability of optical coherence tomography angiography to visualize retinal and CC microvascular abnormalities suggests it may be a useful tool for understanding pathogenesis, evaluating treatment response, and earlier detection of vascular abnormalities in patients with diabetes.

Purpose: To investigate choriocapillaris (CC) alteration in patients with nascent geographic atrophy (nGA) and/or drusen-associated geographic atrophy (DAGA) using swept-source optical coherence tomography angiography (OCTA)., Methods: A 1,050-nm wavelength, 400 kHz A-scan rate swept-source optical coherence tomography prototype was used to perform volumetric swept-source optical coherence tomography angiography over 6 mm × 6 mm fields of view in patients with nGA and/or DAGA. The resulting optical coherence tomography (OCT) and OCTA data were analyzed using a combination of en face and cross-sectional techniques. Variable interscan time analysis (VISTA) was used to differentiate CC flow impairment from complete CC atrophy., Results: A total of 7 eyes from 6 patients (mean age: 73.8 ± 5.7 years) were scanned. Seven areas of nGA and three areas of DAGA were identified. Analysis of cross-sectional OCT and OCTA images identified focal alterations of the CC underlying all seven areas of nGA and all three areas of DAGA. En face OCTA analysis of the CC revealed diffuse CC alterations in all eyes. Variable interscan time analysis processing suggested that the observed CC flow alterations predominantly corresponded to flow impairment rather than complete CC atrophy., Conclusion: The OCTA imaging of the CC revealed focal CC flow impairment associated with areas of nGA and DAGA, as well as diffuse CC flow impairment throughout the imaged field. En face OCT analysis should prove useful for understanding the pathogenesis of nGA and DAGA and for identifying the formation of nGA and DAGA as endpoints in therapeutic trials., Competing Interests: There are no conflicting relationships for any other author.

Purpose: To characterize the features of choroidal neovascularization (CNV) in neovascular age-related macular degeneration with spectral domain optical coherence tomography angiography (OCTA) and to determine whether OCTA can be used to determine clinical activity of CNV., Methods: Observational, retrospective, consecutive case series., Results: Optical coherence tomography angiography revealed CNV in 28 eyes (62.2%) while 17 eyes (37.8%) did not demonstrate CNV vessels. Choroidal neovascularization was classified as well circumscribed in 12 eyes (42.8%) and poorly circumscribed in 16 eyes (57.2%). Twenty-two eyes with a CNV on OCTA were clinically active, whereas six eyes with visible CNV on OCTA were clinically inactive. Of the 17 eyes that did not have evidence of CNV on OCTA imaging, 14 were clinically inactive and 3 were clinically active. Presence of CNV on OCTA correlated with clinical activity and absence of CNV correlated with inactivity (P < 0.0001)., Conclusion: Optical coherence tomography angiography is a noninvasive imaging technique that can be used to visualize blood flow comprising CNV. Optical coherence tomography angiography detects CNV vessels in some albeit not all eyes with neovascular age-related macular degeneration. Although the presence or absence of CNV vessels on OCTA highly correlated with clinical activity of CNV, the morphologic appearance of CNV on OCTA did not have significant correlation with clinical activity.

Background and Objective: To compare the visualization of microaneurysms (MA) and the foveal avascular zone (FAZ) area using optical coherence tomography angiography (OCTA) versus fluorescein angiography (FA) in patients with diabetic macular edema (DME)., Patients and Methods: Patients were prospectively recruited for same-day imaging on spectral-domain OCTA and FA. OCTA images were automatically segmented into superficial (sOCTA) and deep (dOCTA) capillary plexuses. The number of visible MAs and the FAZ area were compared between the two imaging modalities., Results: Nineteen eyes of 10 patients were included. There was a statistically significant difference between MA counts for FA, sOCTA, and dOCTA (P = .002), and median MA counts were 14.5 (range: 2-43), 9.75 (range: 0-37.5), and 22.5 (range: 5.5-46.5), respectively. dOCTA showed significantly more MAs than sOCTA (P < .001). Although not significant statistically, dOCTA revealed more MAs than FA (P = .06). There was a statistically significant difference between FAZ area for FA, sOCTA, and dOCTA (P = .046), and median FAZ areas were 0.444 (range: 0.1-0.689), 0.224 (range: 0.335-0.806), and 0.345 (range: 0.106-0.881), respectively. FA showed a significantly larger FAZ area than sOCTA (P = .04)., Conclusions: Deep plexus OCTA can better identify microaneurysms compared to either sOCTA or FA. The FAZ area appears larger on FA in contrast to OCTA of both plexuses. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:1013-1019.]., (Copyright 2016, SLACK Incorporated.)

To describe the appearance of a scleral-derived feeder vessel in a highly myopic eye with secondary choroidal neovascularization (CNV) as visualized on both en face high-speed swept-source (SS) optical coherence tomography angiography (OCTA) prototype, and a commercially available spectral-domain (SD) OCTA, with the corresponding en face and cross-sectional structural OCT images. In this case report, a 60-year-old white male presented with high myopia and secondary CNV in the right eye, previously treated with anti-vascular endothelial growth factor, and was imaged on both SD-OCT and SS-OCT. The neovascular complex could be visualized on both devices. Structural en face SS-OCT images demonstrated a large choroidal-scleral feeder vessel that was not visualized with SD-OCT. The authors concluded that structural en face SS-OCT better visualizes scleral feeder vessel compared to SD-OCT due to the longer wavelength (∼1,050 nm) with increased choroidal penetration and decreased sensitivity roll-off in the SS-OCT system. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:960-964.]., (Copyright 2016, SLACK Incorporated.)

Purpose: The range of subretinal hyperreflective material (SHRM) seen in macular disease includes type 2 macular neovascularization, fibrosis, exudation, vitelliform material, and hemorrhage. The prognostic significance of SHRM has been evaluated retrospectively in clinical trials, but discriminating SHRM subtypes traditionally requires multiple imaging modalities. The purpose of this study is to describe optical coherence tomography angiography (OCTA) flow characteristics and artifacts that might help to distinguish SHRM subtypes., Design: Validity analysis., Methods: Patients with age-related macular degeneration (AMD), myopia, pachychoroid disease, and macular dystrophy, manifesting SHRM on optical coherence tomography (OCT), were recruited. Clinical chart review and multimodal imaging established the SHRM subtype. All patients underwent OCTA. OCT and OCTA images were examined together for (1) intrinsic flow, (2) retinal projection onto the anterior SHRM surface (strong, weak, absent), (3) retinal projection through SHRM onto retinal pigment epithelium (RPE), and (4) masking of choriocapillaris flow., Results: Thirty-three eyes of 25 patients were included (type 2 neovascularization ×3; fibrosis ×4; exudation ×10; hemorrhage ×5; vitelliform ×17). Mean age per eye was 76 years (standard deviation: 12). Intrinsic flow was strongest in type 2 neovascularization. Subretinal fibrosis showed limited flow in residual large-caliber vessels and branches. Flow was not detected within foci of exudation, hemorrhage, or vitelliform lesions. Retina-SHRM surface projection was strongest onto smooth-surfaced SHRM and weaker onto exudation. Retinal projection was weakest on the surface of vitelliform lesions. Retina-RPE projection was masked by dense hemorrhage and vitelliform material. In compound SHRM, OCTA distinguished between vascular and avascular components., Conclusion: Optical coherence tomography angiography can distinguish vascular from avascular SHRM components. OCTA artifacts may distinguish certain avascular SHRM components., (Copyright © 2016 Elsevier Inc. All rights reserved.)

Fluorescein angiography (FA) and indocyanine green angiography (ICGA) have been the gold standard for the evaluation of retinal and choroidal vasculature in the last three decades and have revolutionized the diagnosis of retinal and choroidal vascular diseases. The advantage of these imaging modalities lies in their ability to document retinal and choroidal vasculature through the dynamic assessment of contrast transit over time in the intravascular and extravascular spaces. However, disadvantages include the absence of depth resolution, blurring of details by contrast leakage, and the inability to selectively evaluate different levels of the retinal and choroidal microvasculature. In addition, these angiographic methods require intravenous dye, which may cause adverse reactions such as nausea, vomiting, and rarely, anaphylaxis. Optical coherence tomography angiography (OCTA) is a noninvasive imaging technique that, in contrast to dye-based angiography, is faster and depth-resolved, allowing in some cases for more precise evaluation of the vascular plexuses of the retina and choroid. The method has been demonstrated in the assessment of various vascular diseases such as venous occlusions, diabetic retinopathy, macular neovascularization, and others. Limitations of this imaging modality include a small registered field of view and the inability to visualize leakage and dye transit over time. It is also subject to a variety of artifacts, including those generated by blinking and eye movement during image acquisition. However, more than an alternative for FA and ICGA, OCTA is bringing new insights to our understanding of retinal and choroidal vascular structure and is changing fundamental paradigms in the clinical management of pathologic conditions. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:848-861.]., (Copyright 2016, SLACK Incorporated.)

Purpose: To determine the sensitivity of the combination of optical coherence tomography angiography (OCTA) and structural optical coherence tomography (OCT) for detecting type 1 neovascularization (NV) and to determine significant factors that preclude visualization of type 1 NV using OCTA., Methods: Multicenter, retrospective cohort study of 115 eyes from 100 patients with type 1 NV. A retrospective review of fluorescein (FA), OCT, and OCTA imaging was performed on a consecutive series of eyes with type 1 NV from five institutions. Unmasked graders utilized FA and structural OCT data to determine the diagnosis of type 1 NV. Masked graders evaluated FA data alone, en face OCTA data alone and combined en face OCTA and structural OCT data to determine the presence of type 1 NV. Sensitivity analyses were performed using combined FA and OCT data as the reference standard., Results: A total of 105 eyes were diagnosed with type 1 NV using the reference. Of these, 90 (85.7%) could be detected using en face OCTA and structural OCT. The sensitivities of FA data alone and en face OCTA data alone for visualizing type 1 NV were the same (66.7%). Significant factors that precluded visualization of NV using en face OCTA included the height of pigment epithelial detachment, low signal strength, and treatment-naïve disease (P < 0.05, respectively)., Conclusions: En face OCTA and structural OCT showed better detection of type 1 NV than either FA alone or en face OCTA alone. Combining en face OCTA and structural OCT information may therefore be a useful way to noninvasively diagnose and monitor the treatment of type 1 NV.

Purpose: To evaluate the perifoveolar retinal capillary network at different depths and to quantify the foveal avascular zone (FAZ) in eyes with retinal vein occlusion (RVO) compared with their fellow eyes and healthy controls using spectral-domain optical coherence tomography angiography (SD-OCTA)., Methods: We prospectively recruited 23 patients with RVO including 15 eyes with central RVO (CRVO) and 8 eyes with branch RVO (BRVO), their fellow eyes, and 8 age-matched healthy controls (8 eyes) for imaging on prototype OCTA software within RTVue-XR Avanti. The 3 × 3 mm and 6 × 6 mm en face angiograms of superficial and deep retinal capillary plexuses were segmented. Perifoveolar retinal capillary network was analyzed and FAZ was quantified., Results: Decrease in vascular perfusion at the deep plexus was observed in all eyes with CRVO (8/8, 100%) and BRVO (6/6, 100%) without cystoid macular edema, and in 8 of 15 (53%) and 2 of 8 (25%) of the fellow eyes, respectively. Vascular tortuosity was observed in 13 of 15 (87%) CRVO and 5 of 8 (63%) BRVO eyes. Collaterals were seen in 10 of 15 (67%) CRVO and 5 of 8 (63%) BRVO eyes. Mean FAZ area was larger in eyes with RVO than their fellow eyes (1.13 ± 0.25 mm2 versus 0.58 ± 0.28 mm2; P = 0.007) and controls (1.13 ± 0.25 mm2 versus 0.30 ± 0.09 mm2; P < 0.0001), and in fellow eyes of RVO patients when compared to controls (0.58 ± 0.28 mm2 versus 0.30 ± 0.09 mm2; P = 0.01)., Conclusions: Spectral-domain OCTA reveals abnormalities at different levels of perifoveolar retinal capillary network and is able to quantify the FAZ in RVO. Longitudinal studies may be considered to evaluate the clinical utility of OCTA in RVO and other retinal vascular diseases.

Purpose: To utilize optical coherence tomography (OCT) and OCT angiography (OCTA) to describe alterations in the retinal and choriocapillaris vasculature following remote laser photocoagulation. Lesions are classified on the basis of choriocapillaris alteration as evaluated on en face OCTA., Methods: This was a retrospective, cross-sectional study analyzing 28 laser photocoagulation scars from 8 patients treated for diabetic macular edema. All eyes were analyzed using a combination of OCTA, en face and cross-sectional OCT, and fundus photography. Two masked readers scored images for alterations at the level of the retinal pigment epithelium (RPE), choroid, and choriocapillaris. Laser photocoagulation lesions were classified as deep if choriocapillaris alteration was present on OCTA; lesions were classified as superficial if no choriocapillaris alteration was present on OCTA., Results: Optical coherence tomography angiography was found to be useful for evaluation of choriocapillaris alteration underlying regions of laser scarring. Of the 28 analyzed laser scars, 13 were classified as superficial and 15 were classified as deep., Conclusions: Optical coherence tomography angiography can be used to visualize choriocapillaris alterations associated with focal laser photocoagulation treatment.

Background and Objective: To describe morphology and vascular layer thickness of the choroid in eyes with neovascular age-related macular degeneration (AMD) using spectral-domain optical coherence tomography (SD-OCT)., Patients and Methods: Cross-sectional, retrospective analysis of 15 eyes with neovascular AMD and 11 healthy age-matched eyes that underwent single horizontal, high-definition raster line imaging using high-definition SD-OCT. Two independent graders assessed choroid morphology and measured the thickness of individual vascular layers of the choroid beneath the fovea., Results: Normal concave choroidal contour was found in 13.3% of eyes with neovascular AMD and 100% of healthy eyes. The thickest point of the choroid was located beneath the foveal center in 20% of eyes and focal thinning was observed in 40% of eyes with neovascular AMD, compared to 91% and 0% of healthy eyes, respectively. Subfoveal total choroidal thickness, large choroidal vessel layer thickness, and the medium choroidal vessel/choriocapillaris layer thickness were reduced in eyes with neovascular AMD compared to healthy eyes (205.7 µm ± 17.08 µm versus 281.3 µm ± 19.29 µm, P = .007; 174.1 µm ± 16.34 µm versus 244.5 µm ± 19.51 µm, P = .01; and 31.53 µm ± 3.67 µm verus 51.9 µm ± 1.94 µm, P = .0002, respectively)., Conclusion: Choroidal morphology is altered in eyes with neovascular AMD as assessed on SDOCT. Choroidal thinning in neovascular AMD involves all its vascular layers. These morphological and vascular changes may have clinical implications in the diagnosis and monitoring of eyes with neovascular AMD. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:618-625.]., (Copyright 2016, SLACK Incorporated.)

Background and Objective: To describe optical coherence tomography angiography (OCTA) findings in patients with unilateral Coats' disease., Patients and Methods: Retrospective, observational case series of four patients with unilateral Coats' disease who underwent bilateral OCTA imaging., Results: Bilateral macular OCTA findings of eight eyes are described. An abnormal foveal avascular zone (FAZ) with inner retinal vessels traversing the avascular zone in the superficial capillary plexus was visible on OCTA in the affected eye of all four patients. A similarly abnormal FAZ was noted on OCTA in the clinically normal fellow eye in two of the four patients (50%)., Conclusion: OCTA may demonstrate an abnormal foveal avascular zone in both the affected eye and the clinically unaffected fellow eye, suggesting widespread pathology of the retinal vasculature in Coats' disease. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:632-635.]., (Copyright 2016, SLACK Incorporated.)

Purpose: To investigate the appearance of choriocapillaris (CC) flow under drusen by comparing long-wavelength (1050 nm) swept-source optical coherence tomography (SS-OCT) angiography with shorter-wavelength (840 nm) spectral-domain (SD) OCT angiography., Methods: Patients with drusen imaged on both devices on the same day were selected and graded. Ambiguous OCT angiography (OCTA) signal loss was defined as low OCTA signal on the en face OCTA CC image that also had low OCT signal in the corresponding area on the en face OCT CC image and OCT B-scans. Unambiguous OCTA signal loss was defined as low OCTA signal on the en face OCTA CC image that did not have low OCT signal in the corresponding area on the en face OCT CC image and OCT B-scans. False-positive flow impairment on SS-OCTA was defined as ambiguous OCTA signal loss on SS-OCTA but no OCTA signal loss on SD-OCTA. False-positive flow impairment on SD-OCTA was defined as ambiguous OCTA signal loss on SD-OCTA but no OCTA signal loss on SS-OCTA., Results: Nine eyes from seven patients were enrolled, 23 drusen were analyzed. On 840-nm SD-OCTA, 17 drusen (73.9%) exhibited OCTA signal loss. Fourteen (82.4%) were classified as ambiguous, and three (17.6%) were classified as unambiguous; 10 (58.8%) were classified as having false-positive flow impairment. On 1050-nm SS-OCTA, seven drusen (30.4%) exhibited OCTA signal loss and were classified as unambiguous; none were classified as having false-positive flow impairment., Conclusions: Results showed that 1050-nm SS-OCTA appears less prone to producing areas of false-positive flow impairment under drusen.

Importance: Optical coherence tomographic angiography (OCTA) is a recently developed noninvasive imaging technique that can visualize the retinal and choroidal microvasculature without the injection of exogenous dyes., Objective: To evaluate the potential clinical utility of OCTA using a prototype swept-source OCT (SS-OCT) device and compare it with fluorescein angiography (FA) for analysis of the retinal microvasculature in diabetic retinopathy., Design, Setting, and Participants: Prospective, observational cross-sectional study conducted at a tertiary care academic retina practice from November 2013 through November 2014. A cohort of diabetic and normal control eyes were imaged with a prototype SS-OCT system. The stage of diabetic retinopathy was determined by clinical examination. Imaging was performed using angiographic 3 × 3-mm and 6 × 6-mm SS-OCT scans to generate 3-dimensional en-face OCT angiograms for each eye. Two trained Boston Image Reading Center readers reviewed and graded FA and OCTA images independently., Main Outcomes and Measures: The size of the foveal nonflow zone and the perifoveal intercapillary area on OCTA were measured in both normal and diabetic eyes using Boston Image Reading Center image analysis software., Results: The study included 30 patients with diabetes (mean [SD] age, 55.7 [10] years) and 6 control individuals (mean [SD] age, 55.1 [6.4] years). A total of 43 diabetic and 11 normal control eyes were evaluated with OCTA. Fluorescein angiography was performed in 17 of 43 diabetic eyes within 8 weeks of the OCTA. Optical coherence tomographic angiography was able to identify a mean (SD) of 6.4 (4.0) microaneurysms (95% CI, 4.4-8.5), while FA identified a mean (SD) of 10 (6.9) microaneurysms (95% CI, 6.4-13.5). The exact intraretinal depth of microaneurysms on OCTA was localized in all cases (100%). The sensitivity of OCTA in detecting microaneuryms when compared with FA was 85% (95% CI, 53-97), while the specificity was 75% (95% CI, 21-98). The positive predictive value and the negative predictive value were 91% (95% CI, 59-99) and 60% (95% CI, 17-92), respectively., Conclusions and Relevance: Optical coherence tomographic angiography enables noninvasive visualization of macular microvascular pathology in eyes with diabetic retinopathy. It identified fewer microaneurysms than FA, but located their exact intraretinal depth. Optical coherence tomographic angiography also allowed the precise and reproducible delineation of the foveal nonflow zone and perifoveal intercapillary area. Evaluation of OCTA may be of clinical utility in the evaluation and grading of diabetic eye disease.

The body of knowledge of in vivo investigation of the choroid has been markedly enhanced by recent technological advances in optical coherence tomography (OCT). New insights elucidating the morphological features of the choriocapillaris and choroidal vasculature, in both physiological and pathological conditions, indicate that the choroid plays a pivotal role in many posterior segment diseases. In this article, a review of the histological characteristics of the choroid, which must be considered for the proper interpretation of in vivo imaging, is followed by a comprehensive discussion of fundamental principles of the current state-of-the-art in OCT, including cross-sectional OCT, en face OCT, and OCT angiography using both spectral domain OCT and swept source OCT technologies. A detailed review of the tomographic features of the choroid in the normal eye is followed by relevant findings in prevalent chorioretinal diseases, focusing on major causes of vision loss such as typical early and advanced age-related macular degeneration, polypoidal choroidal vasculopathy, central serous chorioretinopathy, pachychoroid spectrum disorders, diabetic choroidopathy, and myopia., (Copyright © 2015 Elsevier Ltd. All rights reserved.)

Background and Objective: To present novel software algorithms applied to spectral-domain optical coherence tomography (SD-OCT) for automated detection of diabetic retinopathy (DR)., Patients and Methods: Thirty-one diabetic patients (44 eyes) and 18 healthy, nondiabetic controls (20 eyes) who underwent volumetric SD-OCT imaging and fundus photography were retrospectively identified. A retina specialist independently graded DR stage. Trained automated software generated a retinal thickness score signifying macular edema and a cluster score signifying microaneurysms and/or hard exudates for each volumetric SD-OCT., Results: Of 44 diabetic eyes, 38 had DR and six eyes did not have DR. Leave-one-out cross-validation using a linear discriminant at missed detection/false alarm ratio of 3.00 computed software sensitivity and specificity of 92% and 69%, respectively, for DR detection when compared to clinical assessment., Conclusion: Novel software algorithms applied to commercially available SD-OCT can successfully detect DR and may have potential as a viable screening tool for DR in future. [Ophthalmic Surg Lasers Imaging Retina. 2016;47:410-417.]., (Copyright 2016, SLACK Incorporated.)