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Relationship between Peripapillary Retinal Nerve Fiber Layer Thickness Measured by Optical Coherence Tomography and Visual Field Severity Indices
摘要： Purpose: Though there are many reports regarding the structure-function relationship in glaucoma, they are too complicated to apply to the routine clinical setting. The aim of this study was to investigate the direct relationship between peripapillary retinal nerve fiber layer (RNFL) thickness measured by optical coherence tomography (OCT) and visual field (VF) severity indices computed by standard automated perimetry. Methods: This cross-sectional comparative study included 104 glaucomatous patients and 59 healthy subjects. Peripapillary RNFL thickness was measured by spectral domain (SD) and time domain (TD) OCTs. Four glaucoma VF severity indices, including mean deviation (MD), pattern standard deviation (PSD), Collaborative Initial Glaucoma Treatment Study (CIGTS) VF score, and Advanced Glaucoma Intervention Study (AGIS) VF score, were calculated using standard automated perimetry. The Pearson’s correlation coefficients (r) between the average and quadrants of peripapillary RNFL thicknesses and the four VF severity indices were calculated. Results: In glaucomatous eyes, the r value between the average RNFL thickness measured by SD OCT and each VF severity index were 0.562, -0.514, -0.577, and -0.567 for the MD, PSD, CIGTS VF score, and AGIS VF score, respectively (all p < 0.001). Among each quadrant, the inferior RNFL thickness showed the largest r value; 0.587, -0.552, -0.613, and -0.598 for the MD, PSD, CIGTS VF score, and AGIS VF score, respectively (all p < 0.001). Measurements by TD OCT showed similar strengths of association with SD OCT. Conclusions: Moderate correlation was identified between peripapillary RNFL thicknesses measured by SD/TD OCT and glaucoma VF severity indices. Among each quadrant, the inferior RNFL thickness showed the greatest association with glaucoma VF severity indices. There was no significant difference according to the type of VF severity index or the type of OCTs.
关键词： Glaucoma,Retinal nerve fiber layer thickness,Optical coherence tomography,Visual fields
更新于2025-09-23 15:22:29
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Comparison of Kang's and Littmann's Methods of Correction for Ocular Magnification in Circumpapillary Retinal Nerve Fiber Layer Measurement
摘要： PURPOSE. To assess and compare the accuracy of Kang’s method for ocular magnification correction in circumpapillary retinal nerve fiber layer (cpRNFL) thickness measurement with that of the currently used Littmann’s method. METHODS. A total of 148 eyes of 148 healthy participants underwent cpRNFL measurement without correction and with correction by Littmann’s method using spectral-domain optical coherence tomography. Correction of ocular magnification by Kang’s method is based on the observed uncorrected cpRNFL thickness. The accuracy of Kang’s method was compared with that of Littmann’s method for magnification correction by using the Pearson product-moment correlation coefficient (r) and Bland–Altman analysis. RESULTS. A total of 132 eyes were assessed. The two methods used to correct the global cpRNFL thickness were strongly correlated (r = 0.940, P < 0.01), and the mean difference between the two methods was -0.4 μm, with 95% limits of agreement (LoA) of –6 μm without systemic bias (P > 0.05). Although the cpRNFL thicknesses corrected with the two methods at quadrant and 12-o’clock sectors showed a strong correlation (r > 0.731, P < 0.01), high LoAs ranging from –13.3 to –27.9 and systemic biases were observed at nasal and inferior sectors. CONCLUSION. No difference was found between Kang’s and Littmann’s methods for correction of ocular magnification in global cpRNFL thickness measurement. However, with regard to magnification correction for sectoral cpRNFL thickness, further scrutiny of Kang’s method is warranted, even in healthy participants, because of the high variability between Littmann’s and Kang’s methods.
关键词： Littmann’s method,optical coherence tomography,magnification correction,circumpapillary retinal nerve fiber layer,Kang’s method
更新于2025-09-23 15:22:29
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Optical coherence tomography and its use in optical neuritis and multiple sclerosis
摘要： Optical coherence tomography is a relatively new non-invasive imaging technique used for obtaining the images and quantifying the layers of the retina. It also provides information about optic nerve head topography, peripapillary retinal nerve fiber layer thickness, and macular volume which correlates with axonal loss. Until now, this method was used mainly in ophthalmology; now it has emerged as relevant in neurology as well. RNFL thickness is of particular interest in optic neuropathies and in multiple sclerosis. In sclerosis multiplex, axonal loss occurs as early as the first stages and the quantification of the RNFL thickness by OCT provides an indirect measure of axonal and neuronal loss in the anterior visual pathways. Because OCT is noninvasive, easy to obtain, and highly reproducible, it can be used as a marker of axonal loss and as an endpoint in clinical trials. This paper presents a comprehensive summary of the use of this new diagnostic method in multiple sclerosis patients (Fig. 1, Ref. 58). Text in PDF www.elis.sk.
关键词： multiple sclerosis,optical neuritis,optical coherence tomography
更新于2025-09-23 15:22:29
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Design Considerations for Murine Retinal Imaging Using Scattering Angle Resolved Optical Coherence Tomography
摘要： Optical coherence tomography (OCT), an optical imaging approach enabling cross-sectional analysis of turbid samples, is routinely used for retinal imaging in human and animal models of diseases affecting the retina. Scattering angle resolved (SAR-)OCT has previously been demonstrated as offering additional contrast in human studies, but no SAR-OCT system has been reported in detail for imaging the retinas of mice. An optical model of a mouse eye was designed and extended for validity at wavelengths of light around 1310 nm; this model was then utilized to develop a SAR-OCT design for murine retinal imaging. A Monte Carlo technique simulates light scattering from the retina, and the simulation results are confirmed with SAR-OCT images. Various images from the SAR-OCT system are presented and utility of the system is described. SAR-OCT is demonstrated as a viable and robust imaging platform to extend utility of retinal OCT imaging by incorporating scattering data into investigative ophthalmologic analysis.
关键词： angle resolved imaging,retinal imaging,optical coherence tomography,rodent imaging,scattering
更新于2025-09-23 15:22:29
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Practical Challenges of Current Video Rate OCT Elastography: Accounting for Dynamic and Static Tissue Properties
摘要： Optical coherence tomography (OCT) elastography (OCTE) has the potential to be an important diagnostic tool for pathologies including coronary artery disease, osteoarthritis, malignancies, and even dental caries. Many groups have performed OCTE, including our own, using a wide range of approaches. However, we will demonstrate current OCTE approaches are not scalable to real-time, in vivo imaging. As will be discussed, among the most important reasons is current designs focus on the system and not the target. Specifically, tissue dynamic responses are not accounted, with examples being the tissue strain response time, preload variability, and conditioning variability. Tissue dynamic responses, and to a lesser degree static tissue properties, prevent accurate video rate modulus assessments for current embodiments. Accounting for them is the focus of this paper. A top-down approach will be presented to overcome these challenges to real time in vivo tissue characterization. Discussed first is an example clinical scenario where OCTE would be of substantial relevance, the prevention of acute myocardial infarction or heart attacks. Then the principles behind OCTE are examined. Next, constrains on in vivo application of current OCTE are evaluated, focusing on dynamic tissue responses. An example is the tissue strain response, where it takes about 20 msec after a stress is applied to reach plateau. This response delay is not an issue at slow acquisition rates, as most current OCTE approaches are preformed, but it is for video rate OCTE. Since at video rate each frame is only 30 msec, for essentially all current approaches this means the strain for a given stress is changing constantly during the B-scan. Therefore the modulus can’t be accurately assessed. This serious issue is an even greater problem for pulsed techniques as it means the strain/modulus for a given stress (at a location) is unpredictably changing over a B-scan. The paper concludes by introducing a novel video rate approach to overcome these challenges.
关键词： Optical Coherence Tomography,Elastography,Thin-capped fibroatheromas
更新于2025-09-23 15:22:29
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Reproducibility of Disc and Macula Optical Coherence Tomography using the Canon OCT-HS100 as Compared with the Zeiss Cirrus HD-OCT
摘要： Purpose: In a clinical setting, the usefulness of optical coherence tomography (OCT) is strongly dependent on reproducibility of the measurement. The aim of the present study was to evaluate macula and optic disc measurement reproducibility with the new spectral-domain OCT (SD-OCT) from Canon (Canon OCT-HS100) and to compare reproducibility and obtained measurements with the Zeiss Cirrus HD-OCT. Methods: Macula and optic disc parameters from the right eyes of 31 subjects were obtained twice with both instruments. Interoperator reproducibility was evaluated by use of the coefficient of repeatability (CR), and the obtained measurements were compared between the instruments. Results: No difference in interoperator reproducibility could be found when comparing the 2 instruments and reproducibility ranged from 3.94% to 12.77% for optic disc parameters and from 1.19% to 3.54% for macula parameters. The lowest reproducibility was found for cup volume and vertical cup/disc ratio with both instruments. For all macula and retinal nerve fiber layer (RNFL) thickness measurements, there was a statistical difference when comparing the 2 instruments, except for RFNL measurements of the superior quadrant, with the Canon OCT-HS100 always evaluating the thickness to be thicker; however, the 2 instruments correlated well. Conclusions: The Canon OCT-HS100 is a reproducible instrument that matches the Zeiss Cirrus HD-OCT well. It remains to be evaluated how sensitive the Canon OCT-HS100 is to detect small subtle changes in optic disc parameters and macular nerve fiber layer thickness. Furthermore, due to the differences in thickness estimation, it is important to emphasize that SD-OCTs are not interchangeable.
关键词： Canon OCT-HS100,Reproducibility,Spectral domain,Optical coherence tomography
更新于2025-09-23 15:22:29
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Autofluorescence and spectral-domain optical coherence tomography of optic disk melanocytoma
摘要： The authors report fundus autofluorescence (FAF) and spectral-domain optical coherence tomography (OCT ) findings of two consecutive patients who presented with optic disk melanocytoma (ODM). A retrospective study was performed by reviewing medical records and ophthalmic imaging examinations. Optical coherence tomography findings were sloped and brightly reflective anterior tumor surface, adjacent retinal desorganization and abrupt posterior optical shadowing. Vitreous seeds were found in one patient. Fundus autofluorescence revealed outstanding hypoautofluorescence at the tumor area and isoautofluorescence at the remaining retina. Optical coherence tomography findings of the reported cases are consistent with those reported in the reviewed literature. Fundus autofluorescence has been used in the assessment of choroidal melanocytic tumors, but not yet in melanocytomas. We assume that this is the first report of these findings and believe that when its pattern has become clearly defined, fundus autofluorescence will be a useful tool to avoid misdiagnosis in suspicious cases and for follow-up.
关键词： Melanoma/diagnosis,Female,Adult,Male,Case reports,Optic nerve neoplasms/diagnosis,Fluorescein angiography,Humans,Tomography, optical coherence
更新于2025-09-23 15:22:29
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Evaluation of choroidal and retinal thickness measurements in adult hemodialysis patients using spectral-domain optical coherence tomography
摘要： Purpose: To assess the effect of hemodialysis on retinal and choroidal thicknesses using spectral-domain optical coherence tomography (SD-OCT). Methods: In this prospective interventional study, 25 hemodialysis patients (17 male, 8 female) were enrolled. All participants underwent high-speed, high-resolution SD-OCT (λ=840 mm; 26.000 A-scans/s; 5 μm resolution) before and after hemodialysis. Choroidal thickness was measured perpendicularly from the outer edge of the retinal pigment epithelium to the choroid-sclera boundary at the fovea and at five additional points: 500 μm and 1000 μm nasal to the fovea and 500 μm, 1000 μm, and 1500 μm temporal to the fovea. Two masked physicians performed the measurements. Choroidal and retinal thicknesses before and after hemodialysis were compared. results: The median choroidal thicknesses before and after hemodialysis were 182 μm (range, 103-374 μm) and 161 μm (range, 90-353 μm), respectively (P<0.001). The median retinal thicknesses were 246 μm (range, 179-296 μm) before and 248 μm (range, 141-299 μm) after hemodialysis (P>0.05). Systolic arterial pressure, diastolic arterial pressure, mean arterial pressure, heart rate, and ocular perfusion pressure significantly decreased after hemodialysis (P<0.001). Intraocular pressure did not vary significantly (P=0.540). conclusion: Hemodialysis seems to cause a significant decrease in choroidal thickness, whereas it has no effect on retinal thickness. This significant decrease in choroidal thickness might be due to the extensive fluid absorption in hemodialysis, which could result in decreased ocular blood flow.
关键词： Choroidal thickness,Hemodialysis,Optical coherence tomography
更新于2025-09-23 15:22:29
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Semi-supervised Automatic Segmentation of Layer and fluid region in Retinal Optical Coherence Tomography Images Using Adversarial Learning
摘要： Optical coherence tomography (OCT) is a primary imaging technique for ophthalmic diagnosis due to its advantages in high resolution and non-invasiveness. Diabetes is a chronic disease, which could cause retinal layer deformation and fluid accumulation. It might increase the risk of blindness, and thus, it is important to monitor the morphology change of the retinal layer and fluid accumulation for diabetes patients. Due to the existence of deformation and fluid accumulation, the retinal layer and fluid region segmentation in the OCT image is a challenging task. Machine learning-based segmentation methods have been proposed, but they depend on a significant number of pixel-level annotated data, which is often unavailable. In this paper, we proposed a new semi-supervised fully convolutional deep learning method for segmenting retinal layers and fluid regions in retinal OCT B-scans. The proposed semi-supervised method leverages the unlabeled data through an adversarial learning strategy. The segmentation method includes a segmentation network and a discriminator network, and both the networks are with U-Net alike fully convolutional architecture. The objective function of the segmentation network is a joint loss function, including multi-class cross entropy loss, dice overlap loss, adversarial loss, and semi-supervised loss. We show that the discriminator network and the use of unlabeled data can improve the performance of segmentation. The proposed method is investigated on the duke Diabetic Macular Edema dataset and the POne dataset, and the experiment results demonstrate that our method is more effective than the other state-of-the-art methods for layers and fluid segmentation in the OCT images.
关键词： image processing,optical coherence tomography,layer segmentation,Adversarial learning,convolutional neural networks
更新于2025-09-23 15:22:29
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Polarization-Sensitive Optical Coherence Tomography for Brain Tumor Characterization
摘要： Complete removal of brain tumor is of the most interest to a surgeon because the resection area directly relates to recurrence rate. Although there are many biomedical imaging modalities applied to locate the positions of tumors, they lack the spatial resolution to precisely delineate the boundary between brain tumor and normal brain tissues and are also inconvenient to be used intraoperatively. This study aims to examine the feasibility of label-free, polarization-sensitive optical coherence tomography (PS-OCT) for distinguishing brain tumors from normal brain tissues. Ex vivo samples were obtained from two patients with grade II and II-III glioma; healthy porcine brain tissues were utilized as the control group. In the results obtained from normal porcine brain, white matter contains significantly higher birefringent property over grey matter indicated by phase retardation. Based on the knowledge obtained from porcine brain experiment, a similar high-birefringent tissue is observed partially on the edge of the sliced glioma, and such tissue is considered as white matter because glioma originates through the mutation of the healthy white matter's glia cells. Additionally, differences between grey matter and brain tumor are not apparent based on phase retardation images and further histogram analysis. The capability of PS-OCT for distinguishing glioma from white matter is demonstrated. It could be a potential system to facilitate safe and maximum resection area, and finally, lead to ameliorated outcomes.
关键词： optical polarization,white matter,Brain tumor,optical coherence tomography
更新于2025-09-23 15:22:29