1. 1-24 of 439 1 2 3 4 ... 17 18 19 »
    1. Assessment of the anterior segment of patients with primary congenital glaucoma using handheld optical coherence tomography

      Assessment of the anterior segment of patients with primary congenital glaucoma using handheld optical coherence tomography

      Purpose To investigate the potential of handheld optical coherence tomography (HH-OCT) in assessing the anterior segment of the eye in patients with primary congenital glaucoma. Design A prospective, case-controlled observational study. Participants Twenty-two patients with primary congenital glaucoma (PCG, 9 females and 13 males; mean age 4.36 ± 3.4 years) and age-, gender- and ethnicity-matched healthy participants. Methods Anterior OCT was performed in all participants using a high-resolution HH SD-OCT device (Envisu 2300, Leica Microsystems, Germany) without anaesthesia or sedation. Results Anterior HH-OCT in PCG visualised Haab’s striae in 14.3%, uneven internal cornea in 9.5% and ...

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    2. Focus Tracking System for Femtosecond Laser Machining using Low Coherence Interferometry

      Focus Tracking System for Femtosecond Laser Machining using Low Coherence Interferometry

      We designed a real time, single-laser focus tracking system using low coherence properties of the machining femtosecond laser itself in order to monitor and correct the sample position relative to the focal plane. Using a Michelson Interferometer, the system collects data arising from part of the beam backscattered at the ablation spot. The data is analyzed by a custom software for position correction (employing an XYZ automated translation stage). With the focus tracking enabled we were able to etch channels with a stable cross-section profile on a bovine tooth with relief amplitude tens of times greater than the Rayleigh length ...

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      Mentions: Marcus P. Raele
    3. Investigating spontaneous retinal venous pulsation using Doppler optical coherence tomography

      Investigating spontaneous retinal venous pulsation using Doppler optical coherence tomography

      We demonstrate the advantages of optical coherence tomography (OCT) imaging for investigation of spontaneous retinal venous pulsation (SRVP). The pulsatile changes in venous vessel caliber are analyzed qualitatively and quantitatively using conventional intensity-based OCT as well as the functional extension Doppler OCT (DOCT). Single-channel and double-channel line scanning protocols of our multi-channel OCT prototype are employed to investigate venous pulsatile caliber oscillations as well as venous flow pulsatility in the eyes of healthy volunteers. A comparison to recordings of scanning laser ophthalmoscopy (SLO) – a standard en-face imaging modality for evaluation of SRVP – is provided, emphasizing the advantages of tomographic image ...

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    4. Quantitative reconstruction of time-varying 3D cell forces with traction force optical coherence microscopy

      Quantitative reconstruction of time-varying 3D cell forces with traction force optical coherence microscopy

      Cellular traction forces (CTFs) play an integral role in both physiological processes and disease, and are a topic of interest in mechanobiology. Traction force microscopy (TFM) is a family of methods used to quantify CTFs in a variety of settings. State-of-the-art 3D TFM methods typically rely on confocal fluorescence microscopy, which can impose limitations on acquisition speed, volumetric coverage, and temporal sampling or coverage. In this report, we present the first quantitative implementation of a new TFM technique: traction force optical coherence microscopy (TF-OCM). TF-OCM leverages the capabilities of optical coherence microscopy and computational adaptive optics (CAO) to enable the ...

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    5. 3-Dimensional characterization of cortical bone microdamage following placement of orthodontic microimplants using Optical Coherence Tomography

      3-Dimensional characterization of cortical bone microdamage following placement of orthodontic microimplants using Optical Coherence Tomography

      Microimplants are being used extensively in clinical practice to achieve absolute anchorage. Success of microimplant mainly depend on its primary stability onto the cortical bone surface and the associated Microdamage of the cortical bone during insertion procedure leads to many a microimplants to fail and dislodge from the cortical bone leading to its failure. Even though, previous studies showed occurrence of microdamage in the cortical bone, they were mainly 2-dimension studies or studies that were invasive to the host. In the present study, we used a non-invasive, non-ionizing imaging technique- Optical Coherence Tomography (OCT), to image and analyze the presence ...

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    6. Automatic Choroid Layer Segmentation from Optical Coherence Tomography Images Using Deep Learning

      Automatic Choroid Layer Segmentation from Optical Coherence Tomography Images Using Deep Learning

      The choroid layer is a vascular layer in human retina and its main function is to provide oxygen and support to the retina. Various studies have shown that the thickness of the choroid layer is correlated with the diagnosis of several ophthalmic diseases. For example, diabetic macular edema (DME) is a leading cause of vision loss in patients with diabetes. Despite contemporary advances, automatic segmentation of the choroid layer remains a challenging task due to low contrast, inhomogeneous intensity, inconsistent texture and ambiguous boundaries between the choroid and sclera in Optical Coherence Tomography (OCT) images. The majority of currently implemented ...

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    7. One-Year Outcome Predictors of Strabismus Surgery from Anterior Segment Optical Coherence Tomography with Multiple B-Scan Averaging

      One-Year Outcome Predictors of Strabismus Surgery from Anterior Segment Optical Coherence Tomography with Multiple B-Scan Averaging

      Strabismologists are eager to identify preoperative or intraoperative strabismus surgery outcome predictors because of the variable effects in each patient. Conjunctival closure position recession after rectus muscle recession is effective for correcting large angle strabismus. The elasticity of the conjunctiva and Tenon’s capsule is important for strabismus surgery management. In this longitudinal study, we evaluated the prognosis of conjunctiva and Tenon’s capsule thickness (CTT) near the limbus 1 year after strabismus surgery with a limbal conjunctival incision using swept-source anterior segment optical coherence tomography with multiple B-scan averaging. Also, we identified preoperative and/or intraoperative parameters associated with ...

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    8. Diagnostic algorithm utilising multimodal imaging including optical coherence tomography angiography for the detection of myopic choroidal neovascularisation

      Diagnostic algorithm utilising multimodal imaging including optical coherence tomography angiography for the detection of myopic choroidal neovascularisation

      Purpose To develop a diagnostic algorithm in patients with pathologic myopia who present with typical symptoms or signs of myopic choroidal neovascularisation (mCNV). Methods Retrospective study. Patients with high myopia and suspected mCNV underwent fluorescein angiography (FFA), structural spectral-domain optical coherence tomography (SD-OCT) and optical coherence tomography angiography (OCTA). Active mCNV on one imaging modality plus clinical features were considered as the benchmark reference for the other two tests. Sensitivity was calculated for each modality individually and in combination. Morphological features were noted on SD-OCT and OCTA. Results Twenty-seven eyes of 26 patients were analysed. Sensitivity of SD-OCT or FFA ...

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    9. Quantitative assessment of outer retinal folds on enface optical coherence tomography after vitrectomy for rhegmatogenous retinal detachment

      Quantitative assessment of outer retinal folds on enface optical coherence tomography after vitrectomy for rhegmatogenous retinal detachment

      We aimed to investigate the possible causes of metamorphopsia for rhegmatogenous retinal detachment (RRD) based on findings of enface optical coherence tomography (OCT). The study was a retrospective, consecutive case series of 33 eyes with macula-off RRD. Metamorphopsia was measured by M-CHARTS and enface OCT images covering a macular area of 6 × 6 mm square obtained at 1, 3, and 6 months postoperatively. Within the outer retinal slabs of enface OCT, multiple lines that looked like folds were delineated in all eyes at month 1, and we succeeded in extracting images of folds by subtracting retinal vessels. We calculated their ...

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      Mentions: Hiroshi Ishikawa
    10. Quantitative nontumorous and tumorous human brain tissue assessment using microstructural co- and cross-polarized optical coherence tomography

      Quantitative nontumorous and tumorous human brain tissue assessment using microstructural co- and cross-polarized optical coherence tomography

      Optical coherence tomography (OCT) is a promising method for detecting cancer margins during tumor resection. This study focused on differentiating tumorous from nontumorous tissues in human brain tissues using cross-polarization OCT (CP OCT). The study was performed on fresh ex vivo human brain tissues from 30 patients with high- and low-grade gliomas. Different tissue types that neurosurgeons should clearly distinguish during surgery, such as the cortex, white matter, necrosis and tumorous tissue, were separately analyzed. Based on volumetric CP OCT data, tumorous and normal brain tissue were differentiated using two optical coefficients — attenuation and forward cross-scattering. Compared with white matter ...

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    11. Retinal Microvasculature and Visual Acuity after Intravitreal Aflibercept in Diabetic Macular Edema: An Optical Coherence Tomography Angiography Study

      Retinal Microvasculature and Visual Acuity after Intravitreal Aflibercept in Diabetic Macular Edema: An Optical Coherence Tomography Angiography Study

      We investigated changes in retinal vascular area and the foveal avascular zone (FAZ) after intravitreal aflibercept in diabetic macular edema (DME) and the association of these changes with visual outcomes. The retinal vascular area in the superficial capillary plexus (SCP) and the deep capillary plexus (DCP) and the FAZ area were measured using optical coherence tomography angiography (OCTA) in 23 eyes of 23 patients with DME, before and after intravitreal aflibercept. Overall, there was no significant change in retinal vascular area or FAZ. Better BCVA after treatment was significantly associated with larger retinal vascular area in the SCP and the ...

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      Mentions: Osaka University
    12. The Bull’s Eye Pattern of the Tear Film in Humans during Visual Fixation on En-Face Optical Coherence Tomography

      The Bull’s Eye Pattern of the Tear Film in Humans during Visual Fixation on En-Face Optical Coherence Tomography

      The aim of the study was to define and characterize the optical behavior of the tear film during visual fixation in humans on en-face optical coherence tomography (OCT). We included 20 healthy participants, 60% female, aged from 25 to 42 years (33.05 ± 4.97 [mean ± SD]) and ten patients with severe dry eye, 50% female, aged from 26 to 42 years (33.7 ± 5.31). To perform high-resolution tear film imaging, participants were asked to gaze at the internal fixation point in the spectral-domain anterior segment OCT device, and meanwhile scanning session was executed at the following time-points after ...

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    13. Imaging of meibomian glands: from bench to bedside and back

      Imaging of meibomian glands: from bench to bedside and back

      In this issue of Eye, Randon et al. [ 1 ] present the interesting findings of an in vivo confocal microscopy (IVCM) cross-sectional study in which they describe different patterns of presumed meibomian glands (MGs) abnormalities and propose a new IVCM–meibomian gland dysfunction (MGD) classification. This research represents an interesting effort toward a personalized diagnostic and therapeutic approach to MGD patients. In the last years, we have seen an imaging revolution in the study of MGD. Technological evolution provided us new non- (or nearly non-) invasive tools, including infrared (IR) meibography [ 2 ], IVCM, and optical coherence tomography meibography (OCT-M) [ 3 , 4 ...

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    14. Unsupervised feature extraction of anterior chamber OCT images for ordering and classification

      Unsupervised feature extraction of anterior chamber OCT images for ordering and classification

      We propose an image processing method for ordering anterior chamber optical coherence tomography (OCT) images in a fully unsupervised manner. The method consists of three steps: Firstly we preprocess the images (filtering the noise, aligning and normalizing the resolution); secondly, a distance measure between images is computed for every pair of images; thirdly we apply a machine learning algorithm that exploits the distance measure to order the images in a two-dimensional plane. The method is applied to a large (~1000) database of anterior chamber OCT images of healthy subjects and patients with angle-closure and the resulting unsupervised ordering and classification ...

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    15. Elucidation of microstructural changes in leaves during senescence using spectral domain optical coherence tomography

      Elucidation of microstructural changes in leaves during senescence using spectral domain optical coherence tomography

      Leaf senescence provides a unique window to explore the age-dependent programmed degradation at organ label in plants. Here, spectral domain optical coherence tomography (SD-OCT) has been used to study in vivo senescing leaf microstructural changes in the deciduous plant Acer serrulatum Hayata . Hayata leaves show autumn phenology and change color from green to yellow and finally red. SD-OCT image analysis shows distinctive features among different layers of the leaves; merging of upper epidermis and palisade layers form thicker layers in red leaves compared to green leaves. Moreover, A-scan analysis showed a significant (p < 0.001) decrease in the attenuation coefficient ...

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      Mentions: Wen-Chuan Kuo
    16. SLIME: robust, high-speed 3D microvascular mapping

      SLIME: robust, high-speed 3D microvascular mapping

      Three dimensional (3D) microvascular imaging of cubic millimeter to centimeter size volumes often requires much time and expensive instruments. By combining optical clearing with a novel scatter-based optical coherence tomography (OCT) contrast agent, we have greatly extended OCT imaging depth in excised tissues while maintaining a simple and low cost approach that does not require in-depth OCT knowledge. The new method enables fast 3D microvascular mapping in large tissue volumes, providing a promising tool for investigating organ level microvascular abnormalities in large cohorts.

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    17. Biomarkers of optical coherence tomography in evaluating the treatment outcomes of neovascular age-related macular degeneration: a real-world study

      Biomarkers of optical coherence tomography in evaluating the treatment outcomes of neovascular age-related macular degeneration: a real-world study

      This study evaluated the characteristic changes in optical coherence tomography (OCT) biomarkers in neovascular age-related macular degeneration (nAMD) treated with anti-vascular endothelial growth factor drugs and their relationship with visual outcomes at 1-year follow-up in a real-world setting. We retrospectively reviewed the medical records of 126 eyes with nAMD treated with either intravitreal ranibizumab or aflibercept, including ophthalmologic examinations and spectral-domain OCT at baseline and months 3, 6, and 12 after first injection. Treatment response of intraretinal cysts (IRCs), subretinal fluid (SRF), and pigment epithelial detachment (PED), and the correlation between best-corrected visual acuity (BCVA) changes and these OCT biomarkers ...

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    18. Characterizing Branching Vascular Network Morphology in Polypoidal Choroidal Vasculopathy by Optical Coherence Tomography Angiography

      Characterizing Branching Vascular Network Morphology in Polypoidal Choroidal Vasculopathy by Optical Coherence Tomography Angiography

      This study analyze the morphological characteristics of branching vascular networks (BVN) in polypoidal choroidal vasculopathy (PCV) using optical coherence tomography angiography (OCTA), and correlate imaging characteristics with clinical presentations. We presented a retrospective observational case series for fifty cases of PCV confirmed by indocyanine green angiography. Macular OCTA were done by the AngioVue. The PCV cases were classified by distinct morphologic patterns of BVN by two retina specialists and clinical features were analyzed. The sensitivity of polyp detection by OCTA was 86% after manual segmentation and that of BVN was 90%. Three distinct morphologic patterns of BVN were identified. (1 ...

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    19. Retinal Microvascular Change in Hypertension as measured by Optical Coherence Tomography Angiography

      Retinal Microvascular Change in Hypertension as measured by Optical Coherence Tomography Angiography

      Many studies have reported the effect of hypertension on microcirculation of the retina. Advance of optical coherence tomography angiography (OCTA) allows us more detailed observations of microcirculation of the retina. Therefore, we compared OCTA parameters between chronic hypertension (disease duration of at least 10 yrs; Group A, 45 eyes), relieved hypertensive retinopathy (grade IV HTNR < 1 yr prior; Group B, 40 eyes), and normal controls [Group C (50 eyes) ≥ 50 yrs old and Group D (50 eyes) < 50 yrs old]. A 3 × 3 mm macular scan was performed in each group by OCTA. In vessel density of 3 mm full ...

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    20. Postdoc position, Intravital nanoscopy for investigating the blood-brain barrier (m/f/d)

      Postdoc position, Intravital nanoscopy for investigating the blood-brain barrier (m/f/d)

      The University Medical Center Schleswig-Holstein is one of the largest university hospitals in Europe with more than 80 clinics and institutes. We provide top research at the interface of medicine, science and technology and maintain research co-operations with universities all over the world. The project is funded by the Deutsche Forschungsgemeinschaft ( DFG ) within the call ‘Neuartige, experimentelle Lichtmikroskopie für die Forschung’ ( http://www.dfg.de/service/presse/pressemitteilungen/2018/pressemitteilung nr 59/index.html). It aims to adapt STED nanoscopy to the in vivo imaging of vascular processes in the neurosciences. New microscopic techniques such as advanced scanning patterns ...

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    21. Proprietary data formats block health research

      Proprietary data formats block health research

      The UK Biobank database contains health data from more than half a million people. It is an invaluable resource for understanding diseases and developing predictive machine-learning algorithms (see also Nature 562 , 163–164; 2018 ). In our experience, however, proprietary data formats by manufacturers of medical equipment are obstructing the sharing of clinical data. In ophthalmology, for example, the Eye and Vision consortium has collected data for more than 100,000 individuals from the UK Biobank data set — one of the largest annotated data sets available. Unfortunately, a key data modality — from optical coherence tomography (OCT) — is inaccessible. It is present ...

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    22. Real-time high-resolution mid-infrared optical coherence tomography

      Real-time high-resolution mid-infrared optical coherence tomography

      The potential for improving the penetration depth of optical coherence tomography systems by using light sources with longer wavelengths has been known since the inception of the technique in the early 1990s. Nevertheless, the development of mid-infrared optical coherence tomography has long been challenged by the maturity and fidelity of optical components in this spectral region, resulting in slow acquisition, low sensitivity, and poor axial resolution. In this work, a mid-infrared spectral-domain optical coherence tomography system operating at a central wavelength of 4 µm and an axial resolution of 8.6 µm is demonstrated. The system produces two-dimensional cross-sectional images ...

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    23. Spectral contrast optical coherence tomography angiography enables single-scan vessel imaging

      Spectral contrast optical coherence tomography angiography enables single-scan vessel imaging

      Optical coherence tomography angiography relies on motion for contrast and requires at least two data acquisitions per pointwise scanning location. We present a method termed spectral contrast optical coherence tomography angiography using visible light that relies on the spectral signatures of blood for angiography from a single scan using endogenous contrast. We demonstrate the molecular sensitivity of this method, which enables lymphatic vessel, blood, and tissue discrimination. Optical coherence tomography (OCT) is a noninvasive optical imaging modality that provides micron-scale resolution of three-dimensional (3D) tissue morphology 1 . In addition to providing structural information, enhanced processing of an OCT signal can ...

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    1-24 of 439 1 2 3 4 ... 17 18 19 »
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