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Stable Hall voltages in presence of dynamic quasi-continuum bands in poly(3,4-ethylene-dioxythiophene)
摘要： Topological and thermal disorder complicate the mobility characterization in poly(3,4-ethylenedioxythiophene) systems and presently leaves the exact transport mechanisms not fully understood. Here we show that ac-Hall measured by lock-in amplifier is able to resolve the Hall voltage in semimetallic polymers between room temperature and 32 K. These results are evaluated using an organic random phase model. This accounts for the role of tail states and, particularly, for thermal disorder of molecular semiconductors. We report band mobilities up to 3.7 cm2 V?1 s?1 in semimetallic polymers occurring in delocalized bands that originate from significant electron coherence across the polymer chains.
关键词： Weak localization,Conducting polymers,PEDOT,Hall-effect,Organic phase model,Electron coherence
更新于2025-09-04 15:30:14
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Reflectivity and thickness analysis of epiretinal membranes using spectral-domain optical coherence tomography
摘要： · AIM: To compare thickness and reflectivity spectral domain optical coherence tomography (SD-OCT) findings in patients with idiopathic epiretinal membranes (ERMs), before and after ERM peeling surgery, with normal controls. · METHODS: A retrospective study analyzing SD-OCTs of eyes with ERMs undergoing ERM peeling surgery by one surgeon from 2008 to 2010 and normal control eyes. SD-OCTs were analyzed using a customized algorithm to measure reflectivity and thickness. The relationship between the SD-OCT findings and best corrected visual acuity (BCVA) outcomes was also studied. · RESULTS: Thirty-four ERM eyes and 12 normal eyes were identified. Preoperative eyes had high reflectivity and thickness of the group of layers from the internal limiting membrane (ILM) to the retinal pigment epithelium (RPE) and the group of layers from the ILM to the external limiting membrane (ELM). The reflectivity of these two groups of layers decreased postoperatively, but were still higher than normal eyes. In contrast, preoperative eyes had lower reflectivity of two 10 × 15 pixel regions of interest (ROIs) incorporating: 1) ELM + outer nuclear layer (ONL) and 2) photoreceptor layer (PRL) + RPE, compared to controls. The values of reflectivity of these ROIs increased postoperatively, but were still lower than normal. A larger improvement in BCVA postoperatively was correlated with a greater degree of abnormal preoperative reflectivity and thickness findings. · CONCLUSION: Quantitative differences in reflectivity and thickness between preoperative, postoperative, and normal SD-OCTs allow assessment of changes in the retina secondary to ERM. Our study identified hyperreflective inner retinal changes and hyporeflective outer retinal changes in patients with ERMs. SD-OCT quantitative measures of reflectivity and/or thickness of specific groups of retinal layers and/or ROIs correlate with improvement in BCVA.
关键词： epiretinal membranes,retina,imaging,reflectivity,optical coherence tomography,vitrectomy
更新于2025-09-04 15:30:14
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Evaluation of Each Retinal Layer Thickness According to Preoperative OCT Patterns after Idiopathic ERM Removal
摘要： ??: ??? ???????? ? ? ????????? ???? ??? ?? ?? ?? ???? ????? ??? ??? ????, ?????? ????? ????? ???. ??? ??: ??? ?????? ??? ?? 6?? ?? ????? ???? ?? 63? 63?? ???? ????? ?????. ? ? ???????? ?? ????? ??? ???, ???, ????? ???? ?? ?? ???? ????? ??? ??? ????, ?????? ????? ??? ???. ??: ? ? ??? ???, ???, ??? ????, ?????? ??? ????? ???. ???? ?? ? ? ? ??????+????, ????, ?????? ???, ???, ??? ??? ??? ????? ???, ? ? ??????+????? ?????? ???, ???, ??? ??? ????? ??? ??? ???. ? ? ??? ???? ??? ? ? ???? ???, ????? ????? ? ? ??????+????? ?????, ?????? ????? ????? ?? ??? ????. ??: ??? ???????? ????????? ???? ??? ?? ? ? ???? ??? ??? ???. ?? ???? ??? ?? ? ? ??? ???? ?? ? ????? ???? ??? ????? ??? ???? ??? ? ???.
关键词： Epiretinal membrane,Retinal layer thickness,Optical coherence tomography
更新于2025-09-04 15:30:14
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The Evaluation of Prognostic Factors after Vitrectomy for Lamellar Macular Hole Using Optical Coherence Tomography
摘要： Purpose: To evaluate the prognostic factors that predict visual outcome after vitrectomy for lamellar macular hole using optical coherence tomography (OCT). Methods: This study included 26 eyes that underwent pars plana vitrectomy, epiretinal membrane removal, and internal limiting membrane peeling for lamellar macular hole. The maximum parafoveal thickness, maximum height and diameter of lamellar macular hole, maximum height and diameter of intraretinal splitting, thinnest foveal floor thickness, and inner segment/outer segment disruption length on preoperative OCT image were investigated for prognostic factors that predict visual outcome. Results: The mean follow-up period was 32.2 months and the mean best corrected visual acuity improved significantly after vitrectomy from log MAR 0.47 ± 0.32 to log MAR 0.23 ± 0.23. The postoperative visual acuity correlated significantly with preoperative visual acuity, thinnest foveal floor thickness and inner segment/outer segment disruption length, but not with maximum parafoveal thickness, maximum height and diameter of lamellar macular hole and maximum height and diameter of intraretinal splitting. Conclusions: The thinnest foveal floor thickness and inner segment/outer segment disruption length on preoperative OCT image were significant prognostic factors.
关键词： Lamellar macular hole,Optical coherence tomography,Prognostic factors
更新于2025-09-04 15:30:14
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Role of Tractional Forces and Internal Limiting Membrane in Macular Hole Formation: Insights from Intraoperative Optical Coherence Tomography
摘要： We report the case of a 69-year-old patient who underwent vitrectomy for vitreomacular traction (VMT) and developed a postoperative macular hole that was observed 1 week after surgery. The hole did not close by in-office fluid-gas exchange alone, but was achieved after repeat surgery with internal limiting membrane (ILM) peeling. Intraoperative OCT (iOCT) images from the first surgery revealed an occult macular hole that formed after VMT release. We discuss how iOCT findings provide insight into the role of the ILM in macular hole formation and emphasize the importance of carefully inspecting iOCT images in real time to avoid missing small but important findings.
关键词： Macular hole,Optical coherence tomography,Internal limiting membrane,Vitreomacular traction
更新于2025-09-04 15:30:14
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Spectral-Domain Optical Coherence Tomography Features in Open-Angle Glaucoma With Diabetes Mellitus and Inadequate Glycemic Control
摘要： PURPOSE. To evaluate spectral-domain optical coherence tomography (SD-OCT) features according to glycemic control status in open-angle glaucoma with diabetes mellitus. METHODS. Subjects underwent comprehensive ocular examination, visual ?eld testing, and SD-OCT imaging (Cirrus HD-OCT). The relationship between glycosylated hemoglobin (HbA1c) and OCT measurements was compared between diabetic nonglaucomatous eyes and diabetic glaucomatous eyes. Glaucoma-discriminating ability was assessed using the area under the receiver operating characteristic curves (AUCs) for OCT parameters and compared between groups relative to the glycemic control group. RESULTS. Analysis was performed on 69 nonglaucomatous and 87 glaucomatous eyes in the nondiabetic group, and on 72 nonglaucomatous and 56 glaucomatous eyes in the diabetic group. Average, inferonasal, inferior, and inferotemporal ganglion cell–inner plexiform layer (GCIPL) thicknesses were positively correlated with HbA1c in diabetic nonglaucomatous eyes (P ? 0.040, 0.037, 0.025, and 0.013, respectively). The AUC of the average cup-to-disc area ratio (CDR), vertical CDR, and cup volume in diabetic eyes with poor glycemic control was signi?cantly higher than those in nondiabetic eyes (P ? 0.011, 0.003, and 0.043, respectively). The AUC of cube volume, cube average thickness, and minimal GCIPL thickness in diabetic eyes with poor glycemic control was lower than those in nondiabetic eyes (P ? 0.006, 0.007, and 0.004, respectively). CONCLUSIONS. In this study, optic nerve head parameters had a superior ability to discriminate glaucoma in diabetic eyes with poor glycemic control. Conversely, the ability to discriminate glaucoma using macular parameters tended to be lower for diabetic eyes with inadequate glycemic control.
关键词： spectral-domain optical coherence tomography,diabetes mellitus,ganglion cell-inner plexiform layer,glaucoma
更新于2025-09-04 15:30:14
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Comprehensive Three-Dimensional Analysis of the Neuroretinal Rim in Glaucoma Using High-Density Spectral-Domain Optical Coherence Tomography Volume Scans
摘要： To describe spectral-domain optical coherence tomography (OCT) methods for quantifying neuroretinal rim tissue in glaucoma and to compare these methods to the traditional retinal nerve fiber layer thickness diagnostic parameter. Neuroretinal rim parameters derived from three-dimensional (3D) volume scans were compared with the two-dimensional (2D) Spectralis retinal nerve fiber layer (RNFL) thickness scans for diagnostic capability. This study analyzed one eye per patient of 104 glaucoma patients and 58 healthy subjects. The shortest distances between the cup surface and the OCT-based disc margin were automatically calculated to determine the thickness and area of the minimum distance band (MDB) neuroretinal rim parameter. Traditional 150-lm reference surface–based rim parameters (volume, area, and thickness) were also calculated. The diagnostic capabilities of these five parameters were compared with RNFL thickness using the area under the receiver operating characteristic (AUROC) curves. The MDB thickness had significantly higher diagnostic capability than the RNFL thickness in the nasal (0.913 vs. 0.818, P ? 0.004) and temporal (0.922 vs. 0.858, P ? 0.026) quadrants and the inferonasal (0.950 vs. 0.897, P ? 0.011) and superonasal (0.933 vs. 0.868, P ? 0.012) sectors. The MDB area and the three neuroretinal rim parameters based on the 150-lm reference surface had diagnostic capabilities similar to RNFL thickness. The 3D MDB thickness had a high diagnostic capability for glaucoma and may be of significant clinical utility. It had higher diagnostic capability than the RNFL thickness in the nasal and temporal quadrants and the inferonasal and superonasal sectors.
关键词： neuroretinal rim,spectral-domain optical coherence tomography,glaucoma,optic disc,optic nerve
更新于2025-09-04 15:30:14
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Retinal and Choroidal Imaging With 870-nm Spectral-Domain OCT Compared With 1050-nm Spectral-Domain OCT, With and Without Enhanced Depth Imaging
摘要： The purpose of this study was to compare images of the retina and choroid obtained with Spectralis 1050-nm spectral-domain optical coherence tomography (SD-OCT) with and without enhanced depth imaging (EDI) to the commercially available 870-nm SD-OCT with and without EDI. Methods: Full-length 308 line scans were obtained with both 870- and 1050-nm Spectralis OCT instruments, with and without EDI. Two trained retina physicians masked to wavelength and EDI status assessed the ability to visualize the vitreoretinal interface and full-thickness choroid, and subfoveal choroidal thickness (SFCT) was measured. Results: Included in the study were 21 eyes. The vitreoretinal interface was visualized best with 870-nm OCT without EDI and was diminished with 1050-nm OCT. Graders preferred 1050 nm with EDI over 870 nm with EDI in qualitative comparisons of the choroid; 1050 nm without EDI was slightly preferred over 870 nm with EDI but was not statistically significant. SFCT measurements correlated well among the imaging modalities except for 870 nm without EDI. Conclusions: SD-OCT with EDI at 870 nm provides good visualization of both the vitreoretinal interface and choroid, whereas 1050-nm SD-OCT with or without EDI provides more choroidal detail at the expense of visualization of the vitreoretinal interface.
关键词： longer wavelength,optical coherence tomography (OCT),choroid,retina
更新于2025-09-04 15:30:14
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Automated Analysis of Vitreous Inflammation Using Spectral-Domain Optical Coherence Tomography
摘要： Purpose: To develop an automated method for quantifying vitreous signal intensity on optical coherence tomography (OCT), with particular application for use in the assessment of vitreous inflammation. Methods: This retrospective, observational case-control series comprised 30 patients (30 eyes), with vitreous haze secondary to intermediate, posterior, or panuveitis; 12 patients (12 eyes) with uveitis without evidence of vitreous haze; and 18 patients (18 eyes) without intraocular inflammation or vitreoretinal disease. The presence and severity of vitreous haze was classified according to the National Eye Institute system; other inflammatory indices and clinical parameters were also documented. Spectral-domain OCT images were analyzed using custom VITreous ANalysis software (termed ‘VITAN’), which is fully automated and avoids the need for manual segmentation. Results: VITAN performed accurate segmentation in all scans. Automated measurements of the vitreous:retinal pigment epithelium (RPE) signal ratio showed a moderate correlation with clinical vitreous haze scores (r ? 0.585, P , 0.001), comparable to that reported using manual segmentation in our previous study (r ? 0.566, P ? 0.0001). The novel parameter of vitreous:RPE textural ratio showed a marginally stronger correlation (r ? 0.604, P , 0.001) with clinical vitreous haze scores than the Vitreous:RPE signal ratio. Conclusions: The custom OCT image analysis software (VITAN) allows rapid and automated measurement of vitreous parameters, that is comparable to our previously reported vitreous:RPE index, and correlates with clinically measured disease activity. Such OCT-based indices may provide the much needed objective markers of vitreous activity, which may be used in both clinical assessment, and as outcome measures in clinical trials for intermediate, posterior, and panuveitis.
关键词： optical coherence tomography,vitreous inflammation,uveitis automated segmentation
更新于2025-09-04 15:30:14
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Virtual Averaging Making Nonframe-Averaged Optical Coherence Tomography Images Comparable to Frame-Averaged Images
摘要： Developing a novel image enhancement method so that nonframe-averaged optical coherence tomography (OCT) images become comparable to active eye-tracking frame-averaged OCT images. Twenty-one eyes of 21 healthy volunteers were scanned with noneye-tracking nonframe-averaged OCT device and active eye-tracking frame-averaged OCT device. Virtual averaging was applied to nonframe-averaged images with voxel resampling and adding amplitude deviation with 15-time repetitions. Signal-to-noise (SNR), contrast-to-noise ratios (CNR), and the distance between the end of visible nasal retinal nerve fiber layer (RNFL) and the foveola were assessed to evaluate the image enhancement effect and retinal layer visibility. Retinal thicknesses before and after processing were also measured. All virtual-averaged nonframe-averaged images showed notable improvement and clear resemblance to active eye-tracking frame-averaged images. Signal-to-noise and CNR were significantly improved (SNR: 30.5 vs. 47.6 dB, CNR: 4.4 vs. 6.4 dB, original versus processed, P , 0.0001, paired t-test). The distance between the end of visible nasal RNFL and the foveola was significantly different before (681.4 vs. 446.5 lm, Cirrus versus Spectralis, P , 0.0001) but not after processing (442.9 vs. 446.5 lm, P ? 0.76). Sectoral macular total retinal and circumpapillary RNFL thicknesses showed systematic differences between Cirrus and Spectralis that became not significant after processing. The virtual averaging method successfully improved nontracking nonframe-averaged OCT image quality and made the images comparable to active eye-tracking frame-averaged OCT images. Virtual averaging may enable detailed retinal structure studies on images acquired using a mixture of nonframe-averaged and frame-averaged OCT devices without concerning about systematic differences in both qualitative and quantitative aspects.
关键词： optical coherence tomography,retina,image processing
更新于2025-09-04 15:30:14