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Numerical analysis of brilliance and coherent photon flux of segmented undulator radiation based on statistical optics
摘要： A method based on wave optics together with electron tracking is used to analyze synchrotron radiation from a segmented undulator in a double or multi mini-β function lattice storage ring. Radiation brilliance and transverse coherence features are investigated, where the former is calculated with the Wigner distribution function and the latter is evaluated by integrating the photon flux and cross-spectral density to exhibit the coherent flux and overall degree of coherence. To be specific, radiation properties for a single undulator in a typically single mini-β function and a tandem undulator in a double mini-βy lattice are compared in this work. As a result, both, brilliance and coherent flux can be enhanced by a second tandem undulator at the Taiwan Photon Source.
关键词： Wigner distribution function,transverse coherence,segment undulator.,double mini-βy lattice,brilliance
更新于2025-09-23 15:22:29
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A Quantum Field Approach for Advancing Optical Coherence Tomography Part I: First Order Correlations, Single Photon Interference, and Quantum Noise
摘要： Optical coherence tomography has become an important imaging technology in cardiology and ophthalmology, with other applications under investigations. Major advances in optical coherence tomography (OCT) imaging are likely to occur through a quantum field approach to the technology. In this paper, which is the first part in a series on the topic, the quantum basis of OCT first order correlations is expressed in terms of full field quantization. Specifically first order correlations are treated as the linear sum of single photon interferences along indistinguishable paths. Photons and the electromagnetic (EM) field are described in terms of quantum harmonic oscillators. While the author feels the study of quantum second order correlations will lead to greater paradigm shifts in the field, addressed in part II, advances from the study of quantum first order correlations are given. In particular, ranging errors are discussed (with remedies) from vacuum fluctuations through the detector port, photon counting errors, and position probability amplitude uncertainty. In addition, the principles of quantum field theory and first order correlations are needed for studying second order correlations in part II.
关键词： Plaque,Quantum mechanics,Interferometry,Ophthalmology,Noise,Vacuum,Cardiology,Arthritis,Optical coherence tomography
更新于2025-09-23 15:22:29
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Prediction models for different plaque morphology in non-significantly stenosed regions of saphenous vein grafts assessed with optical coherence tomography
摘要： Introduction: Coronary artery bypass grafting (CABG) is a method of choice in treatment of diffuse coronary artery disease (CAD), although it has some limitations such as late saphenous vein graft (SVG) patency loss, which occurs in one fifth of all conduits at 5 years. Since atherosclerosis in SVG has diffuse characteristics, it appears that significantly and non-significantly stenosed lesions may have an equal impact on worse prognosis. Aim: To assess non-significant lesions of SVG by the use of optical coherence tomography (OCT) and investigate the clinical and laboratory findings with the potential impact on plaque composition. Material and methods: Twenty-nine patients with 43 non-significant lesions were enrolled in the study. All variables were assessed using uni- and multivariable logistic regression analysis with each plaque morphology as a dependent variable. Odds ratio (OR) and 95% confidence interval (CI) were computed. Results: Plaque rupture (PRT) was independently associated with age (OR = 1.49, 95% CI: 1.09–2.04, p = 0.015) and lower rates of high-density lipoproteins (HDL) cholesterol (OR = 0.67, 95% CI: 0.49–0.92, p = 0.016). Intimal tearing or rupture (ITR) was related to reduced GFR (OR = 0.52, 95% CI: 0.38–0.72, p = 0.0004). Lipid-rich plaque (LRP) was associated with raised platelet count (PLT) (OR = 1.51, 95% CI: 1.16–1.96, p = 0.004) and increased frequency of smoking (OR = 1.45, 95% CI: 1.12–1.89, p = 0.007). Conclusions: Atherosclerosis of SVG is not restricted to significantly stenosed lesions. Plaque composition is independently associated with different types of clinical and laboratory findings, mostly recognized as risk factors of CAD.
关键词： coronary artery disease,optical coherence tomography,saphenous vein graft coronary artery bypass grafting
更新于2025-09-23 15:22:29
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Visual Acuity at Presentation in the Second Eye versus First Eye in Patients with Exudative Age-Related Macular Degeneration
摘要： Purpose: To assess the difference in best-corrected visual acuity (BCVA) at presentation between the first and second eye in patients with bilateral neovascular age-related macular degeneration (AMD). Methods: We reviewed the charts of all patients who had a clinical examination for neovascular AMD at the University Eye Clinic of Creteil in January 2013. We retrospectively analyzed demographic and clinical data for 264 patients. Results: In the fellow eye, choroidal neovascularization (CNV) developed in 75/264 patients (28.4%) with a time interval between the 2 events of 30.3 months (range 6-145). Data were available on 65 patients: 14/65 (21.5%) were asymptomatic, 24/65 (36.9%) had BCVA >20/40, whereas at the time of CNV diagnosis in the first eye, no patient was asymptomatic (p<0.0001), and 11/65 (16.9%) eyes had BCVA >20/40 (p<0.0001). The mean BCVA of the first affected eye was 0.68 (±0.41) logarithm of minimum angle of resolution (logMAR) and the mean BCVA for the second eye was 0.36 (±0.29) logMAR (p<0.0001). Conclusions: The BCVA at the time of diagnosis of CNV was higher in the second eye than in the first affected eye. This was possibly due to several factors including systematic bilateral examination in follow-up of unilateral exudative AMD that allowed detection of 20% of cases.
关键词： Patient management,Optical coherence tomography,Visual acuity,Age-related macular degeneration
更新于2025-09-23 15:22:29
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Combined use of Doppler OCT and en Face OCT Functions for Discrimination of an Aneurysm in the Lamina Cribrosa from a Disc Hemorrhage
摘要： purpose: In addition to retinal nerve fiber layer thickness measurements, the recently introduced AngioVue optical coherence tomography (OCT) offers corresponding layer-by-layer Doppler OCT and en face OCT functions, for simultaneous evaluation of perfusion and structure of the optic nerve head. We investigated the clinical usefulness of combined use of Doppler and en face Fourier-domain OCT functions of the AngioVue Fourier-domain OCT for discrimination of a disc hemorrhage and a disc hemorrhage–like atypical vessel structure located deep in the lamina cribrosa. Case report: We present our findings with AngioVue OCT on a disc hemorrhage and a spatially related retinal nerve fiber layer bundle defect in a glaucomatous eye (case 1). Both alterations were detected on en face OCT images without any Doppler OCT signal. We also report on an aneurysm suggestive for a disc hemorrhage on clinical examination and disc photography in a treated ocular hypertensive eye (case 2). The aneurysm was within the lamina cribrosa tissue at the border of the cup and the neuroretinal rim. This vascular structure produced strong Doppler signals but no structurally detectable signs on the en face OCT images. Conclusions: Combined evaluation of corresponding Doppler OCT and en face OCT images enables ophthalmologists to easily separate true disc hemorrhages from disc hemorrhage–like deep vascular structures. This is of clinical significance in preventing unnecessary intensification of pressure-lowering treatment in glaucoma.
关键词： Doppler optical coherence tomography,Aneurysm,AngioVue OCT,Optic disc hemorrhage,En face Fourier-domain OCT,Glaucoma progression
更新于2025-09-23 15:22:29
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Effect of Refractive Status and Axial Length on Peripapillary Retinal Nerve Fibre Layer Thickness: An Analysis Using 3D OCT
摘要： Background: Accurate measurement of retinal nerve fiber layer (RNFL) is now possible with the high resolution optical coherence tomography (OCT). Effect of refractive status of the eye on RNFL thickness may be relevant in the diagnosis of glaucoma and other optic nerve diseases. Aim: To assess the RNFL thickness and compare its correlation with refractive status and axial length of the eye. Material and Methods: Three hundred eyes of 150 patients were included in this study, who underwent RNFL analysis using TOPCON 3D OCT 2000. Analysis of variance has been used to find the significance of study parameters between the study groups. Results: The study showed that refractive status/axial length affected the peripapillary RNFL thickness significantly. Conclusion: The study suggests that the diagnostic accuracy of OCT may be improved by considering refractive status and axial length of the eye when RNFL is measured.
关键词： Optical coherence tomography,Refractive error
更新于2025-09-23 15:22:29
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Enhanced depth imaging optical coherence tomography of choroidal osteoma with secondary neovascular membranes: report of two cases
摘要： We report enhanced depth imaging optical coherence tomography (EDI-OCT) features based on clinical and imaging data from two newly diagnosed cases of choroidal osteoma presenting with recent visual loss secondary to choroidal neovascular membranes. The features described in the two cases, compression of the choriocapillaris and disorganization of the medium and large vessel layers, are consistent with those of previous reports. We noticed a sponge-like pattern previously reported, but it was subtle. Both lesions had multiple intralesional layers and a typical intrinsic transparency with visibility of the sclerochoroidal junction.
关键词： Choroid neoplasms,Choroidal neovascularization,Osteoma,Tomography, optical coherence
更新于2025-09-23 15:22:29
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Swept source optical coherence tomography analysis of choroidal thickness in macular telangiectasia type 2: a case-control study
摘要： Purpose There has been a recent interest in the association of macular telangiectasia (MacTel) type 2 with central serous choroidopathy and other pachychoroid disorders. This study was performed to assess the subfoveal choroidal thickness (SFCT) in patients with MacTel type 2 and compare it with healthy controls using swept source optical coherence tomography (SS-OCT). Methods It was a retrospective case-control study performed at a tertiary eye care center. The cases constituted patients with MacTel type 2 detected over the last 2 years (April 2016 to March 2018). The controls were healthy adults with no posterior segment pathology. The patients were evaluated with color fundus photography, SS-OCT (Triton, Topcon Inc., Oakland, New Jersey, USA) and fundus fluorescein angiography. The cases were staged based on Gass and Blodi classification. SFCT was compared between the two groups. Results Sixty-five eyes of 33 patients with MacTel were included. The controls consisted of 61 eyes of 33 healthy age-matched (p = 0.81) and sex-matched (p = 0.31) adults. The mean SFCT in cases (353.0 ± 91.2 μm) was higher than controls (289.2 ± 69.0 μm), and this difference was statistically significant (p = 0.0001). The mean SFCT was different in various stages: 346.6 ± 86.3 μm (stage 2), 334.6 ± 90.2 μm (stage 3), 374.6 ± 94.0 μm (stage 4), and 294.8 ± 68.8 μm (stage 5), though this was not statistically significant (p = 0.28). Conclusions The choroid in MacTel type 2 patients was significantly thickened as compared to controls. SFCT may vary as the structural changes worsen over time.
关键词： Macular telangiectasia type 2,Swept source optical coherence tomography,Subfoveal choroidal thickness,Enhanced depth imaging
更新于2025-09-23 15:22:29
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Reproducibility and reliability of retinal and optic disc measurements obtained with swept-source optical coherence tomography in a healthy population
摘要： Purpose To analyze the reproducibility of macular and peripapillary thickness measurements, and optic nerve morphometric data obtained with Triton Optical coherence tomography (OCT) in a healthy population. Study design Observational cross sectional study. Material and methods A total of 108 eyes underwent evaluation using the Triton Swept Source-OCT. A wide protocol was used and measurements in each eye were repeated three times. Morphometric data of the optic nerve head, full macular thickness, ganglion cell layer (GCL) and retinal nerve fiber layer thickness (RNFL) were analyzed. For each parameter, the coefficient of variation (COV) and the intra-class (ICC) correlation values were calculated. Results Measurements were highly reproducible for all morphometric measurements of the optic disc, with a mean COV of 6.36%. Macular full thickness showed good COV and ICC coefficients, with a mean COV value of 1.00%. Macular GCL thickness showed a mean COV value of 3.06%, and ICC higher than 0.787. Peripapillary RNFL thickness showed good COV and ICC coefficients, with a mean COV value of 8.31% and ICC higher than 0.684. The inferotemporal sector showed the lowest ICC (0.685). Conclusions Triton OCT presents good reproducibility values in measurements corresponding to retinal parameters, with macular measurements showing the highest reproducibility rates. Peripapillary RNFL measurements should be evaluated with caution.
关键词： Reproducibility,Optical coherence tomography,Coefficient of variation,Swept source
更新于2025-09-23 15:22:29
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Haab striae: Optical coherence tomographic analysis
摘要： Purpose. — To study Haab striae in adults with primary congenital glaucoma and describe them by anterior segment optical coherence tomography, as well as analyze their evolution over the patient’s lifetime. Material and methods. — Three patients with primary congenital glaucoma were recruited, aged between 17 and 48 years old, with incidentally noted Haab striae on glaucoma consultation. They were studied by: slit lamp; anterior segment optical coherence tomography, Heidelberg Engineering Inc., Germany, (with anterior segment module) and Cirrus HD-OCT, Carl Zeiss Meditec, Dublin, California, USA (with 3D reconstruction); and specular biomicroscopy. The results obtained were contrasted with other studies performed in children. Results. — Rounded excrescences protruding towards the anterior chamber were found, as well as dense, irregular tissue between them. In addition, endothelial abnormalities (polymegathism and polymorphism) were found. These findings fit the evolution of those obtained in pediatric studies and remain stable in adult life. Conclusions. — Through noninvasive methods such as optical coherence tomography and specular biomicroscopy, it is possible to make the diagnosis and follow up these patients. The findings suggest posterior corneal topographic changes; additional studies on this subject may be necessary.
关键词： Haab striae,Primary congenital glaucoma,Anterior segment optical coherence tomography,Corneal endothelium,Specular biomicroscopy
更新于2025-09-23 15:22:29