1. 1-24 of 689 1 2 3 4 ... 27 28 29 »
    1. Detection of progression of glaucomatous retinal nerve fibre layer defects using optical coherence tomography-guided progression analysis

      Detection of progression of glaucomatous retinal nerve fibre layer defects using optical coherence tomography-guided progression analysis

      Purpose The aim was to investigate the agreement for detection of progression of glaucomatous retinal nerve fibre layer defects (RNFLD) between optical coherence tomography-guided progression analysis (OCT GPA) and conventional red-free fundus photography. Methods Four hundred and fifteen glaucomatous eyes that underwent at least four serial red-free photographic and OCT examinations were included in the study. Based on the inspection of the red-free fundus photographs and GPA maps, RNFLD progression was defined as the development of a new defect, widening or deepening of a pre-existing RNFLD in red-free fundus photography (photographic progression) or ‘Likely Loss’ on a GPA map (GPA ...

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    2. Freeze artifact on full-field optical coherence tomography skin imaging

      Freeze artifact on full-field optical coherence tomography skin imaging

      Background/Purpose Full-field optical coherence tomography (FFOCT) is an emerging imaging technique for rapid histological analysis. As FFOCT is introduced into the Mohs workflow, it is important to document the effect of tissue freezing on FFOCT images and any effect FFOCT has on frozen sections. Our study aimed to evaluate the changes on FFOCT images after tissue freezing as well as FFOCT imaging effects on frozen sectioning. Methods Six normal skin specimens were imaged using FFOCT and subsequently frozen using a cryostat. The specimens were then reimaged using FFOCT and compared for any differences. To evaluate the effect of FFOCT ...

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    3. In vivo microvascular imaging of cutaneous actinic keratosis, Bowen's disease and squamous cell carcinoma using Dynamic optical coherence tomography

      In vivo microvascular imaging of cutaneous actinic keratosis, Bowen's disease and squamous cell carcinoma using Dynamic optical coherence tomography

      Background A clear distinction between actinic keratosis (AK), Bowen's disease (BD) and squamous cell carcinoma (SCC) cannot reliably be made by clinical and dermoscopic evaluation alone. Dynamic optical coherence tomography (D-OCT) is a novel angiographic variant of OCT that allows for non-invasive, in vivo evaluation of the cutaneous microvascular morphology. Objective To investigate the microvascular structures of AK, BD and invasive SCC using D-OCT in order to gain insights into the microvascular morphology of lesions in the spectrum of keratinocyte skin cancers. Methods 47 patients with a total of 54 lesions (18 AK, 12 BD and 24 SCC) were ...

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    4. Exploration of peripapillary vessel density in highly myopic eyes with peripapillary intrachoroidal cavitation and its relationship with ocular parameters using optical coherence tomography angiography

      Exploration of peripapillary vessel density in highly myopic eyes with peripapillary intrachoroidal cavitation and its relationship with ocular parameters using optical coherence tomography angiography

      Importance Identifying changes of peripapillary vessel density in highly myopic eyes with peripapillary intrachoroidal cavitation (PICC) by optical coherence tomography angiography (OCTA). Background To investigate peripapillary vessel density and its relationship with other ocular parameters in highly myopic eyes with PICC. Design This was a hospital-based, cross-sectional study. Participants Thirty-five highly myopic eyes with PICC, 46 highly myopic eyes without PICC and 36 normal eyes were included in this study. Methods All participants underwent OCTA to image the retinal vasculature in the peripapillary areas of different sectors, including the radial peripapillary capillaries (RPC) and optic nerve head (ONH) layer. Correlations ...

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    5. Optical coherence elastography for strain dynamics measurements in laser correction of cornea shape

      Optical coherence elastography for strain dynamics measurements in laser correction of cornea shape

      We describe the use of elastographic processing in phase-sensitive optical coherence tomography (OCT) for visualizing dynamics of strain and tissue-shape changes during laser-induced photothermal corneal reshaping, for applications in the emerging field of non-destructive and non-ablative (non-LASIK) laser vision correction. The proposed phase-processing approach based on fairly sparse data acquisition enabled rapid data processing and near-real-time visualization of dynamic strains. The approach avoids conventional phase unwrapping, yet allows for mapping strains even for significantly supra-wavelength inter-frame displacements of scatterers accompanied by multiple phase-wrapping. These developments bode well for real-time feedback systems for controlling the dynamics of corneal deformation with 10 ...

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    6. Extended axial imaging range, widefield swept source optical coherence tomography angiography

      Extended axial imaging range, widefield swept source optical coherence tomography angiography

      We developed a high-speed, swept source OCT system for widefield OCT angiography (OCTA) imaging. The system has an extended axial imaging range of 6.6 mm. An electrical lens is used for fast, automatic focusing. The recently developed split-spectrum amplitude and phase-gradient angiography allow high-resolution OCTA imaging with only two B-scan repetitions. An improved post-processing algorithm effectively removed trigger jitter artifacts and reduced noise in the flow signal. We demonstrated high contrast 3 mm×3 mm OCTA image with 400×400 pixels acquired in 3 seconds and high-definition 8 mm×6 mm and 12 mm×6 mm OCTA images with ...

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    7. Robust numerical phase stabilization for long-range swept-source optical coherence tomography

      Robust numerical phase stabilization for long-range swept-source optical coherence tomography

      A novel phase stabilization technique is demonstrated with significant improvement in the phase stability of a micro-electromechanical (MEMS) vertical cavity surface-emitting laser (VCSEL) based swept-source optical coherence tomography (SS-OCT) system. Without any requirements of hardware modifications, the new fully numerical phase stabilization technique features high tolerance to acquisition jitter, and significantly reduced budget in computational effort. We demonstrate that when measured with biological tissue, this technique enables a phase sensitivity of 89 mrad in highly scattering tissue, with image ranging distance of up to 12.5 mm at A-line scan rate of 100.3 kHz. We further compare the performances ...

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    8. Optical coherence tomography morphology and evolution in cblC disease-related maculopathy in a case series of very young patients

      Optical coherence tomography morphology and evolution in cblC disease-related maculopathy in a case series of very young patients

      Purpose To describe the retinal structure of a group of patients affected by methylmalonic aciduria with homocystinuria cblC type, caused by mutations in the MMACHC gene, using spectral domain optical coherence tomography (SD-OCT). Methods Young patients ( n = 11, age 0–74 months) with cblC disease, detected by newborn screening or clinically diagnosed within 40 days of life, underwent molecular analysis and complete ophthalmic examination, including fundus photography and SD-OCT. In one case, we also performed fluorescein angiography (FA) and standard electroretinography (ERG). Results Molecular analysis of the MMACHC gene fully confirmed cblC disease in nine of 11 patients. Two patients ...

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    9. The potential role of in vivo optical coherence tomography for evaluating oral soft tissue: a systematic review

      The potential role of in vivo optical coherence tomography for evaluating oral soft tissue: a systematic review

      Background The introduction of optical coherence tomography (OCT) in dentistry enabled the integration of already existing clinical and laboratory investigations in the study the oral cavity. This systematic review, presents an overview of the literature, to evaluate the usefulness of in vivo OCT for diagnosing oral soft tissues lesions, to compare the OCT results with traditional histology, and to identify limitations in prior studies so as to improve OCT applications. Methods: We performed a review of the literature using different search engines (PubMed, ISI Web of Science, and the Cochrane Library) employing MeSH terms such as “optical coherence tomography” and ...

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    10. Novel ultrahigh molecular weight amorphous PLLA bioresorbable coronary scaffold upsized up to 0.8 mm beyond nominal diameter: An OCT and histopathology study in porcine coronary artery model

      Novel ultrahigh molecular weight amorphous PLLA bioresorbable coronary scaffold upsized up to 0.8 mm beyond nominal diameter: An OCT and histopathology study in porcine coronary artery model

      Objectives The aim of the study was to evaluate the biomechanical properties and healing pattern of novel sirolimus-eluting, ultrahigh molecular weight amorphous poly-L-lactic acid bioresorbable scaffolds (S-BRS) that have been postdilated by 0.55 and 0.8 mm beyond the nominal diameters within the pressure-diameter compliance chart range. Background Due to the inherent limitations of bioabsorbable polymeric materials, overexpansion/upsizing may be very limited for some BRS such as the benchmark Absorb BVS. The unique biomechanical properties of the novel S-BRS may allow it to be safely upsized. Methods and Results 12 coronary arteries of 4 healthy Yucatan mini-swine underwent ...

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      Mentions: Juan F. Granada
    11. Influence of scanning area on choroidal vascularity index measurement using optical coherence tomography

      Influence of scanning area on choroidal vascularity index measurement using optical coherence tomography

      Purpose Recently, choroidal vascularity index (CVI) is proposed as a novel tool to evaluate the choroidal vasculature. In this study, we investigate the impact of scanning area on CVI measurement using spectral-domain optical coherence tomography (SD-OCT). Methods Spectral-domain optical coherence tomography (SD-OCT) using enhanced depth imaging mode was performed in 30 eyes from 15 normal subjects. Three scanning areas were compared: dingle foveal scan; central macular scans [scan passing through central 1000 microns circle on Early Treatment Diabetic Retinopathy Study (ETDRS) grid, inner circle]; and total macular cube scans. Binarization of OCT B-scans and segmentation of the binarized choroid layer ...

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    12. Automated ablation of dental composite using an IR pulsed laser coupled to a plume emission spectral feedback system

      Automated ablation of dental composite using an IR pulsed laser coupled to a plume emission spectral feedback system

      Objective The purpose of this study is to assemble a laser system for the selective removal of dental composite from tooth surfaces, that is feasible for clinical use incorporating a spectral feedback system, a scanning system, articulating arm and a clinical hand-piece, and evaluate the performance of that system on extracted teeth. Methods Ten extracted teeth were collected and small fillings were placed on the occlusal surface of each tooth. A clinical system featuring a CO 2 laser operating at 50 Hz and spectral optical feedback was used to remove the composite. Removal was confirmed using a cross polarized optical ...

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    13. Non-invasive diagnostic system and its opto-mechanical probe for combining confocal Raman spectroscopy and optical coherence tomography

      Non-invasive diagnostic system and its opto-mechanical probe for combining confocal Raman spectroscopy and optical coherence tomography

      Non-invasive optical diagnostic methods allow important information about studied systems to be obtained in a non-destructive way. Complete diagnosis requires information about the chemical composition as well as the morphological structure of a sample. We report on the development of an opto-mechanical probe that combines Raman spectroscopy (RS) and optical coherence tomography (OCT), two methods that provide all the crucial information needed for a non-invasive diagnosis. The aim of this paper is to introduce the technical design, construction and optimization of a dual opto-mechanical probe combining two in-house developed devices for confocal RS and OCT. The unique benefit of the ...

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    14. Optical coherence tomography evaluation of patients with macula-off retinal detachment after different postoperative posturing: a randomized pilot study

      Optical coherence tomography evaluation of patients with macula-off retinal detachment after different postoperative posturing: a randomized pilot study

      Purpose To assess the presence of outer and inner retinal folds (RFs) and drop-out of the ellipsoid zone (EZ) occurring after surgical repair of macula-off rhegmatogenous retinal detachment (RRD) with different postoperative posture and preoperative use of adjuvant perfluorocarbon liquid (PFCO). Methods In this prospective study, 56 eyes of 56 consecutive patients affected by RRD were subjected to 23- or 25-gauge pars plana vitrectomy (PPV). The patients were randomized in four groups (14 prone 5 hr without PFCO, 14 supine 5 hr without PFCO, 14 prone 5 hr with PFCO and 14 supine 5 hr with PFCO) and followed up ...

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    15. 3D in vivo imaging with extended-focus optical coherence microscopy

      3D in vivo imaging with extended-focus optical coherence microscopy

      Optical coherence microscopy (OCM) has unique advantages of non-invasive 3D imaging without the need of exogenous labels for studying biological samples. However, the imaging depth of this technique is limited by the tradeoff between the depth of focus (DOF) and high lateral resolution in Gaussian optics. To overcome this limitation, we have developed an extended-focus OCM (xf-OCM) imaging system using quasi-Bessel beam illumination to extend the DOF to ∼100 μm, about 3-fold greater than standard OCM. High lateral resolution of 1.6 μm ensured detailed identification of structures within live animal samples. The insensitivity to spherical aberrations strengthened the capability ...

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    16. Imaging collector channel entrance with a new intraocular micro-probe swept-source optical coherence tomography

      Imaging collector channel entrance with a new intraocular micro-probe swept-source optical coherence tomography

      Purpose To describe the use of a newly developed side-viewing catheter probe to provide the cross-sectional images of collector channel entrance (CCE), achieved by swept-source optical coherence tomography (SS-OCT). Methods A side-viewing SS-OCT catheter probe was developed that has a core probe diameter of 0.15 mm and an outer diameter of 0.25 mm, for the purpose of imaging CCEs within eye globe. Cadaver eyes harvested from swine and human were used to demonstrate its feasibility. For porcine eyes, the probe imaged the CCE by accessing the region of the aqueous plexus (AP) as well as along the inner ...

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    17. Quantitative depth resolved microcirculation imaging with optical coherence tomography angiography (Part Ι): Blood flow velocity imaging

      Quantitative depth resolved microcirculation imaging with optical coherence tomography angiography (Part Ι): Blood flow velocity imaging

      The research goal of the microvascular network imaging with optical coherence tomography (OCT) angiography is to achieve depth resolved blood flow and vessel imaging in vivo in the clinical management of patents. In this review, we review the main phenomena that have been explored in OCT to image the blood flow velocity vector and the vessels of the microcirculation within living tissues. Parameters that limit the accurate measurements of blood flow velocity are then condisered. Finally, initial Clinic diagnosis applications of and future developments are discussed.

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    18. Quantitative depth resolved microcirculation imaging with optical coherence tomography angiography (Part ΙΙ): Microvascular network imaging

      Quantitative depth resolved microcirculation imaging with optical coherence tomography angiography (Part ΙΙ): Microvascular network imaging

      In this work, we review the main phenomena that have been explored in OCT angiography to image the vessels of the microcirculation within living tissues with the emphasis on how the different processing algorithms were derived to circumvent specific limitations. Parameters are then discussed that can quantitatively describe the depth-resolved microvascular network for possible clinic diagnosis applications. Finally,future directions in continuing OCT development are discussed.

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    19. Speckle variance optical coherence tomography of blood flow in the beating mouse embryonic heart

      Speckle variance optical coherence tomography of blood flow in the beating mouse embryonic heart

      Efficient separation of blood and cardiac wall in the beating embryonic heart is essential and critical for experiment-based computational modelling and analysis of early-stage cardiac biomechanics. Although speckle variance optical coherence tomography (SV-OCT) relying on calculation of intensity variance over consecutively acquired frames is a powerful approach for segmentation of fluid flow from static tissue, application of this method in the beating embryonic heart remains challenging because moving structures generate SV signal indistinguishable from the blood. Here, we demonstrate a modified four-dimensional SV-OCT approach that effectively separates the blood flow from the dynamic heart wall in the beating mouse embryonic ...

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    20. Heisenberg strikes again

      Heisenberg strikes again

      Systematic randomized clinical outcome data in BVS has largely been reported in straightforward lesions, and BVS performance in more complex anatomy is not well defined In this study, OCT-analysis of imaging outcomes in lesions with variable degrees of calcification demonstrated similar acute performance between second-generation DES and BVS Open questions as to the unintended effect of OCT-guidance on the results of the study as well as the longer-term clinical outcomes in these lesions remain

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    21. Factors affecting signal strength in spectral-domain optical coherence tomography

      Factors affecting signal strength in spectral-domain optical coherence tomography

      Purpose To identify ocular factors that affect signal strength in spectral-domain optical coherence tomography (SD-OCT). Methods Data from 1312 participants of the population-based Singapore Malay Eye Study-2 (SiMES-2) were included in the analysis. All participants underwent standardized ophthalmic examination, including measurements of best-corrected visual acuity (BCVA), refractive error, axial length, corneal curvature and presence of cataracts. Optic disc and macular cube scans were acquired using the Cirrus HD-OCT (software version 6.0, Carl Zeiss Meditec, Dublin, CA, USA). Signal strength of the optical coherence tomography (OCT) scan was recorded for each study eye. Multivariable linear regression analyses were performed to ...

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    22. Comparison of Bleb Morphology Between Trabeculectomy and Deep Sclerectomy Using a Clinical Grading Scale and Anterior Segment Optical Coherence Tomography.

      Comparison of Bleb Morphology Between Trabeculectomy and Deep Sclerectomy Using a Clinical Grading Scale and Anterior Segment Optical Coherence Tomography.

      Importance This study highlights the role of the filtration bleb for IOP management following Trabeculectomy (TRAB) and deep sclerectomy (DS) in Glaucoma. Background This study serves to analyse the bleb morphology and IOP using the Indiana bleb appearance grading scale (IBAGS) and the anterior-segment optical coherence tomography (AS-OCT) postoperatively and at 3 months. Design Retrospective study by a single surgeon. Participants 28 patients with open-angle glaucoma were recruited into the study, 14 in each of the TRAB (fornix) and DS groups. Methods The surgical intervention was dependent on the irido-corneal angle configuration on gonioscopy. Main Outcome Measures Pre-operatively we collected ...

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    23. Multimodal imaging of suspicious choroidal neoplasms in a primary eye-care clinic

      Multimodal imaging of suspicious choroidal neoplasms in a primary eye-care clinic

      Small suspicious choroidal neoplasms commonly present a diagnostic challenge in primary eye-care clinics, where they are most likely to present. Differentiating benign from malignant choroidal neoplasms is essential for facilitating early diagnosis and treatment, potentially decreasing the risk of metastasis and vision loss in some cases. The purpose of this review is to describe the clinical, spectral-domain optical coherence tomography and fundus autofluorescence features of suspicious choroidal neoplasms in a case series of patients presenting to a primary eye-care clinic at the Veterans Health Administration, Cleveland, Ohio, USA.

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    1-24 of 689 1 2 3 4 ... 27 28 29 »
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