Purpose: This study aims to characterize quantitative optical-coherence-tomographyangiography (OCTA) features of non-proliferative diabetic-retinopathy (NPDR), and to validate them for computer-aided NPDR staging. Methods: 120 OCTA images from 60 NPDR (mild, moderate and severe stages) patients and 40 images from 20 control subjects were used for this study conducted in a tertiary, subspecialty, academic practice. Both eyes were photographed and all of the OCTAs were 6 mm × 6 mm macular scans. Six quantitative features, i.e., blood vessel tortuosity (BVT), blood vascular caliber (BVC), vessel perimeter index (VPI), blood vessel density (BVD), foveal avascular zone (FAZ) area (FAZ-A), and FAZ contour irregularity (FAZ-CI) were derived from each OCTA image. A support vector machine (SVM) classification model was trained and tested for computer-aided classification of NPDR stages. Sensitivity, specificity and accuracy were used as performancemetrics of computer-aided classification and receiver-operation-characteristics (ROC) curve was plotted to measure the sensitivity-specificity tradeoff of the classification algorithm. Results: Among six individual OCTA features, BVD shows the best classification accuracies, 93.89% and 90.89% for control vs. disease and control vs. mild-NPDR, respectively. Combinedfeature classification achieved improved accuracies, 94.41% and 92.96% respectively. Moreover, the temporal-perifoveal region was the most-sensitive region for early detection of DR. For multiclass classification, SVM algorithm achieved 84% accuracy.

Abstract:Early detection is an essential step for effective intervention of sickle cell retinopathy (SCR). Emerging optical coherence tomography angiography (OCTA) provides excellent three-dimensional (3D) resolution to enable label-free, noninvasive visualization of retinal vascular structures, promising improved sensitivity in detecting SCR. However, quantitative analysis of SCR characteristics in OCTA images is yet to be established. In this study, we conducted comprehensive analysis of six OCTA parameters, including blood vessel tortuosity, vessel diameter, vessel perimeter index (VPI), area of foveal avascular zone (FAZ), contour irregularity of FAZ and parafoveal avascular density. Compared to traditional retinal thickness analysis, five of these six OCTA parameters show improved sensitivity for SCR detection than retinal thickness. It is observed that the most sensitive parameters were the contour irregularity of FAZ in the superficial layer and avascular density in temporal regions, while the area of FAZ, tortuosity and mean diameter of the vessel were moderately sensitive. E2395-E2402 (2015). 12. Z. Chu, J. Lin, C. Gao, C. Xin, Q. Zhang, C. L. Chen, L. Roisman, G. Gregori, P. J. Rosenfeld, and R. K. Wang, "Quantitative assessment of the retinal microvasculature using optical coherence tomography angiography," J.

Transient intrinsic optical signal (IOS) changes have been observed in retinal photoreceptors, suggesting a unique biomarker for eye disease detection. However, clinical deployment of IOS imaging is challenging due to unclear IOS sources and limited signal-to-noise ratios (SNRs). Here, by developing high spatiotemporal resolution optical coherence tomography (OCT) and applying an adaptive algorithm for IOS processing, we were able to record robust IOSs from single-pass measurements. Transient IOSs, which might reflect an early stage of light phototransduction, are consistently observed in the photoreceptor outer segment almost immediately (<4 ms) after retinal stimulation. Comparative studies of dark- and light-adapted retinas have demonstrated the feasibility of functional OCT mapping of rod and cone photoreceptors, promising a new method for early disease detection and improved treatment of diseases such as age-related macular degeneration (AMD) and other eye diseases that can cause photoreceptor damage.

Purpose: To correlate quantitative OCT angiography (OCTA) biomarkers with clinical features and to predict the extent of visual improvement after ranibizumab treatment for diabetic macular edema (DME) with OCTA biomarkers. Design: Retrospective, longitudinal study in Taiwan. Participants: Fifty eyes of 50 patients with DME and 22 eyes of 22 healthy persons, with the exception of cataract and refractive error, from 1 hospital. Methods: Each eye underwent OCT angiography (RTVue XR Avanti System with AngioVue software version 2017.1; Optovue, Fremont, CA), and 3 × 3-mm2 en face OCTA images of the superficial layer and the deep layer were obtained at baseline and after 3 monthly injections of ranibizumab in the study group. OCT angiography images also were acquired from the control group. Main Outcome Measures: Five OCTA biomarkers, including foveal avascular zone (FAZ) area (FAZ-A), FAZ contour irregularity (FAZ-CI), average vessel caliber (AVC), vessel tortuosity (VT), and vessel density (VD), were analyzed comprehensively. Best-corrected visual acuity (BCVA) and central retinal thickness (CRT) also were obtained. Student t tests were used to compare the OCTA biomarkers between the study group and the control group. Linear regression models were used to evaluate the correlations between the baseline OCTA biomarkers and the changes of BCVA and CRT after treatment. Results: Eyes with DME had larger AVC, VT, FAZ-A, and FAZ-CI and lower VD than those in the control group (P < 0.001 for all). After the loading ranibizumab treatment, these OCTA biomarkers improved but did not return to normal levels. Among all biomarkers, higher inner parafoveal VD in the superficial layer at baseline correlated most significantly with visual gain after treatment in the multiple regression model with adjustment for CRT and ellipsoid zone disruption (P < 0.001). To predict visual improvement, outer parafoveal VD in the superficial layer at the baseline showed the largest area under the receiver operating characteristic curve (0.787; P = 0.004). No baseline OCTA biomarkers showed any significant correlation specifically with anatomic improvement. Conclusions: For eyes with DME, parafoveal VD in the superficial layer at baseline was an independent predictor for visual improvement after the loading ranibizumab treatment.

Application of two-dimensional MXene materials in photovoltaics has attracted increasing attention since the first report in 2018 due to their metallic electrical conductivity, high carrier mobility, excellent transparency, tunable work function and superior mechanical property. In this review, all developments and applications of the Ti3C2Tx MXene (here, it is noteworthy that there are still no reports on other MXenes’ application in photovoltaics by far) as additive, electrode and hole/electron transport layer in solar cells are detailedly summarized, and meanwhile, the problems existing in the related studies are also discussed. In view of these problems, some suggestions are given for pushing exploration of the MXenes’ application in solar cells. It is believed that this review can provide a comprehensive and deep understanding into the research status and, moreover, helps widen a new situation for the study of MXenes in photovoltaics.

A two-dimensional Ising-like model for a triangular spin-chain lattice, where each spin-chain is treated as a rigid giant spin, is proposed to investigate the magnetization of a triangular spin-chain lattice by Monte Carlo simulation. The simulations show the steplike evolution of the magnetization at low temperature against an external magnetic field, namely two steps above 10 K and four steps below 10 K, in quantitative agreement with experiments on a Ca 3 Co 2 O 6 compound. It is argued that the interchain interaction and magnetic inhomogeneity of the lattice are two important ingredients to induce the intriguing steplike feature of the magnetization below 10 K.

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As a new optical coherence tomography (OCT) modality, OCT angiography (OCTA) provides a noninvasive method to detect microvascular distortions correlated with eye conditions. By providing unparalleled capability to differentiate individual plexus layers in the retina, OCTA has demonstrated its excellence in clinical management of diabetic retinopathy, glaucoma, sickle cell retinopathy, diabetic macular edema, and other eye diseases. Quantitative OCTA analysis of retinal and choroidal vasculatures is essential to standardize objective interpretations of clinical outcome. Quantitative features, including blood vessel tortuosity, blood vessel caliber, blood vessel density, vessel perimeter index, fovea avascular zone area, fovea avascular zone contour irregularity, vessel branching coefficient, vessel branching angle, branching width ratio, and choroidal vascular analysis have been established for objective OCTA assessment. Moreover, differential artery–vein analysis has been recently demonstrated to improve OCTA performance for objective detection and classification of eye diseases. In this review, technical rationales and clinical applications of these quantitative OCTA features are summarized, and future prospects for using these quantitative OCTA features for artificial intelligence classification of eye conditions are discussed. Impact statement OCT angiography (OCTA) provides a noninvasive method to detect microvascular distortions correlated with eye conditions. Quantitative analysis of OCTA is essential to standardize objective interpretations of clinical outcome. This review summarizes technical rationales and clinical applications of quantitative OCTA features.