1. All Articles

    25-48 of 16462 « 1 2 3 4 5 ... 684 685 686 »
    1. Corneal Stromal Demarcation Line Determined With Anterior Segment Optical Coherence Tomography Following a Very High Intensity Corneal Collagen Cross-Linking Protocol

      Corneal Stromal Demarcation Line Determined With Anterior Segment Optical Coherence Tomography Following a Very High Intensity Corneal Collagen Cross-Linking Protocol

      Purpose: To evaluate corneal stromal demarcation line depth after very high intensity (18 mW/cm2) ultraviolet-A irradiation for a 5-minute corneal collagen cross-linking (CXL) protocol with the use of anterior segment optical coherence tomography. Methods: This prospective interventional study enrolled 14 patients (18 eyes) with progressive keratoconus who underwent CXL with an ultraviolet-A irradiation intensity of 18 mW/cm2 for 5 minutes. One month postoperatively, corneal stromal demarcation line depth was measured with the use of anterior segment optical coherence tomography by 2 independent observers. The rate of reepithelialization and endothelial cell density at a 3-month follow-up period were also ...

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    2. Evaluation of Microvascular Anastomosis Using Real-Time, Ultra-High-Resolution, Fourier Domain Doppler Optical Coherence Tomography

      Evaluation of Microvascular Anastomosis Using Real-Time, Ultra-High-Resolution, Fourier Domain Doppler Optical Coherence Tomography

      Background: Evolution in microsurgical techniques and tools has paved the way for supermicrosurgical anastomoses, with vessel diameters often approaching below 0.8 mm in the clinical realm and even smaller (0.2 to 0.3 mm) in murine models. Several imaging and monitoring devices have been introduced for postoperative monitoring, but intraoperative guidance, assessment, and predictability have remained limited to binocular optical microscopy and the surgeon’s experience. The authors present a high-resolution, real-time, three-dimensional imaging modality for intraoperative evaluation of luminal narrowing, thrombus formation, and flow alterations. Methods: An imaging modality that provides immediate, in-depth, high-resolution, three-dimensional structure view ...

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    3. Multimodal Imaging In Type 2 Idiopathic Macular Telangiectasia

      Multimodal Imaging In Type 2 Idiopathic Macular Telangiectasia

      Background: Macular telangiectasia Type 2 is a bilateral, progressive potentially blinding retinal disease characterized by both vascular and neurodegenerative signs that have been documented using different imaging techniques. The correlation between macular telangiectasia Type 2 signs from various imaging modalities is unknown. Our aim was to investigate the relationship of various macular telangiectasia Type 2 signs using fundus fluorescein angiography, optical coherence tomography and dual-wavelength autofluorescence images. Methods: Participants were selected from the macular telangiectasia Type 2 Natural History Observation Study, based on a confirmed diagnosis and the availability of images. Signs in fundus fluorescein angiography, dual-wavelength autofluorescence, and optical ...

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    4. Preoperative OCTs for multifocal patients

      Preoperative OCTs for multifocal patients

      W hen implanting a multifocal IOL (MFIOL), it is vital the patient be a good candidate, so a careful preoperative examination is necessary. This may include optical coherence tomography (OCT) to check for any macular pathology or retina problems. Carl Regillo, MD, Mid Atlantic Retina, Philadelphia; Jeffrey Heier, MD, Ophthalmic Consultants of Boston; and Pravin Dugel, MD, Retinal Consultants of Arizona, Phoenix, spoke about important things to know about a preop examination.

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      Mentions: Optos
    5. Detecting corneal bulging with swept-source OCT

      Detecting corneal bulging with swept-source OCT

      C orneal ectasia after LASIK ranks in seriousness to endophthalmitis after cataract surgery. While the severity of each problem differs, these continue to be a significant issue when they occur after their relative surgeries. Ectasia continues to mystify, to some extent. Forme fruste keratoconus, numerous LASIK procedures, and even high myopia are just some of the risk factors for the disease, but nothing predicts with 100% accuracy who will get ectasia. Refractive surgery itself has been known to potentially cause forward protrusion of the posterior cornea, suggesting that minor bulging of the eye happens in some cases. Given the wide ...

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    6. Correlation between depth and area of retinal nerve fiber layer defect as measured by spectral domain optical coherence tomography

      Correlation between depth and area of retinal nerve fiber layer defect as measured by spectral domain optical coherence tomography

      Background To evaluate the correlation between the depth and area of retinal nerve fiber layer (RNFL) defect, as measured on an RNFL map of spectral-domain optical coherence tomography (SD-OCT). Methods The RNFL of 472 glaucoma subjects and of 217 healthy subjects was imaged by an SD-OCT. RNFL defect depth and area on the RNFL map were expressed as an RNFL defect depth percentage index (RDPI) and an RNFL defect area index (RDAI), respectively, according to the following two formulas: 100×[1–{summation of thicknesses of RNFL defects/summation of thicknesses of upper 95th percentile range of age-matched healthy subjects in ...

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    7. Anterior and Posterior Ocular Biometry in Healthy Chinese Subjects: Data Based on AS-OCT and SS-OCT

      Anterior and Posterior Ocular Biometry in Healthy Chinese Subjects: Data Based on AS-OCT and SS-OCT

      Background To measure the anterior and posterior ocular biometric characteristics concurrently and to determine the relationship between the iris and choroid in healthy Chinese subjects. Methods A total of 148 subjects (270 eyes) were enrolled in this cross-section study. The anterior and posterior ocular biometric characteristics were measured simultaneously by anterior segment optical coherence tomography (AS-OCT) and swept-source optical coherence tomography (SS-OCT). Results Compared with male eyes, female eyes had narrower anterior biometric parameters that presented with smaller anterior segment parameters [including anterior chamber depth (ACD), width (ACW), area (ACA), and volume (ACV); (all p<0.001)], narrower anterior chamber ...

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    8. Optical Coherence Tomography Opens a New Era in the Afferent Visual System Evaluation

      Optical Coherence Tomography Opens a New Era in the Afferent Visual System Evaluation

      For decades, thinning of the retinal nerve fiber layer in optic neuropathy could only be observed ophthalmoscopically or using red-free fundus photography. These days are over. Subsequently, different techniques to image the optic nerve and the retina have been developed. Optical coherence tomography (OCT) has gained the most attention and has opened a new area of revolutionary diagnostic possibilities. OCT is a noncontact diagnostic imaging technique that provides detailed, cross-sectional images of the retina and the optic disc in vivo. It was first used in 1991 to visualize the eye.[ 1 ] Image capture is noninvasive, painless, and fast. The technology ...

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    9. Ultrahigh-speed optical coherence tomography utilizing all-optical 40 MHz swept-source

      Ultrahigh-speed optical coherence tomography utilizing all-optical 40 MHz swept-source

      We present an ultrahigh-speed optical coherence tomography (OCT) based on an all-optical swept-source with an A-scan rate of 40 MHz. The inertia-free swept-source, which has its output power of 41.2 mW and tuning range of 40 nm and high scan linearity in wavenumber with Pearson’s correlation coefficients r of 0.9996, consists of a supercontinuum laser, an optical band-pass filter, a linearly chirped fiber Bragg grating, an erbium-doped fiber amplifier, and two buffer stages. With sensitivity of 87 dB, high-speed OCT imaging of biological tissue in vivo is also demonstrated.

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    10. Applications of Optical Coherence Tomography in Pediatric Clinical Neuroscience

      Applications of Optical Coherence Tomography in Pediatric Clinical Neuroscience

      For nearly two centuries, the ophthalmoscope has permitted examination of the retina and optic nerve—the only axons directly visualized by the physician. The retinal ganglion cells project their axons, which travel along the innermost retina to form the optic nerve, marking the beginning of the anterior visual pathway. Both the structure and function of the visual pathway are essential components of the neurologic examination as it can be involved in numerous acquired, congenital and genetic central nervous system conditions. The development of optical coherence tomography now permits the pediatric neuroscientist to visualize and quantify the optic nerve and retinal ...

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    11. Measuring the optical characteristics of medulloblastoma with optical coherence tomography

      Measuring the optical characteristics of medulloblastoma with optical coherence tomography

      Medulloblastoma is the most common malignant pediatric brain tumor. Standard treatment consists of surgical resection, followed by radiation and high-dose chemotherapy. Despite these efforts, recurrence is common, leading to reduced patient survival. Even with successful treatment, there are often severe long-term neurologic impacts on the developing nervous system. We present two quantitative techniques that use a high-resolution optical imaging modality: optical coherence tomography (OCT) to measure refractive index, and the optical attenuation coefficient. To the best of our knowledge, this study is the first to demonstrate OCT analysis of medulloblastoma. Refractive index and optical attenuation coefficient were able to differentiate ...

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    12. “How Does Breast Cancer Develop?” Pilot Grants Awarded to Multidisciplinary Teams Using the Intraductal Approach to Advance Breast Cancer Prevention

      “How Does Breast Cancer Develop?” Pilot Grants Awarded to Multidisciplinary Teams Using the Intraductal Approach to Advance Breast Cancer Prevention

      Dr. Sheldon Feldman and Dr. Fatih Balci study intraductal approaches to breast cancer. They are currently investigating the effectiveness of optical coherence tomography (OCT), which is used in cardiology to look at blood vessels from the inside using light instead of sound (as an ultrasound does) to create three-dimensional images. OCT may be able to identify early changes in the breast duct before ductal carcinoma in situ (DCIS) or cancer forms. This consortium received $17,000 to study whether it is feasible to use OCT to distinguish different types of breast cells and tissues and whether OCT can show features ...

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    13. Differential diagnosis of human bladder mucosa pathologies in vivo with cross-polarization optical coherence tomography

      Differential diagnosis of human bladder mucosa pathologies in vivo with cross-polarization optical coherence tomography

      Quantitative image analysis and parameter extraction using a specific implementation of polarization-sensitive optical coherence tomography (OCT) provides differential diagnosis of mucosal pathologies in in-vivo human bladders. We introduce a cross-polarization (CP) OCT image metric called Integral Depolarization Factor (IDF) to enable automatic diagnosis of bladder conditions (assessment the functional state of collagen fibers). IDF-based diagnostic accuracy of identification of the severe fibrosis of normal bladder mucosa is 79%; recurrence of carcinoma on the post-operative scar is 97%; and differentiation between neoplasia and acute inflammation is 75%. The promising potential of CP OCT combined with image analysis in human urology is ...

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    14. Quantitative microvascular hemoglobin mapping using visible light spectroscopic Optical Coherence Tomography

      Quantitative microvascular hemoglobin mapping using visible light spectroscopic Optical Coherence Tomography

      Quantification of chromophore concentrations in reflectance mode remains a major challenge for biomedical optics. Spectroscopic Optical Coherence Tomography (SOCT) provides depth-resolved spectroscopic information necessary for quantitative analysis of chromophores, like hemoglobin, but conventional SOCT analysis methods are applicable only to well-defined specular reflections, which may be absent in highly scattering biological tissue. Here, by fitting of the dynamic scattering signal spectrum in the OCT angiogram using a forward model of light propagation, we quantitatively determine hemoglobin concentrations directly. Importantly, this methodology enables mapping of both oxygen saturation and total hemoglobin concentration, or alternatively, oxyhemoglobin and deoxyhemoglobin concentration, simultaneously. Quantification was ...

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    15. In vivo molecular contrast OCT imaging of methylene blue

      In vivo molecular contrast OCT imaging of methylene blue

      An 830-nm spectral-domain optical coherence tomography (OCT) system with an integrated 663-nm diode pump laser has been developed to enable molecular contrast OCT imaging of methylene blue (MB), a common vital dye used clinically. The introduction of the 663-nm diode laser, which acts as the pump in this implementation of pump-probe OCT (PPOCT), represents a minor modification to an otherwise typical OCT system. A newly developed background subtraction technique completely removes all background from intensity noise at the pump modulation frequency, simplifying the interpretation of PPOCT images. These developments have enabled the first in vivo imaging of MB with PPOCT ...

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    16. Ex vivo investigations on the potential of optical coherence tomography (OCT) as a diagnostic tool for reproductive medicine in a bovine model

      Ex vivo investigations on the potential of optical coherence tomography (OCT) as a diagnostic tool for reproductive medicine in a bovine model

      Comparative visualization of ex vivo bovine testicular tissue by the Telesto TM microscopic optical coherence tomography system (left) and corresponding H&E staining (right). Routine infertility investigations in the male and female include imaging techniques such as ultrasonography and endoscopy (fertiloscopy). However, these techniques lack the resolution to localize vital sperm or to reveal detailed morphological analysis of the oviduct which is often the cause of infertility in females. Therefore we set out to evaluate the efficiency of optical coherence tomography (OCT) as a diagnostic imaging tool for micron-scale visualization of the male and female genital tract. Using the bovine ...

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    17. Spectral-Domain Optical Coherence Tomography Angiography of Choroidal Neovascularization

      Spectral-Domain Optical Coherence Tomography Angiography of Choroidal Neovascularization

      Purpose To describe the characteristics as well as the sensitivity and specificity of detection of choroidal neovascularization (CNV) on optical coherence tomography angiography (OCTA) using spectral-domain optical coherence tomography. Design Observational, retrospective study. Participants Seventy-two eyes of 61 subjects (48 eyes of 43 subjects with CNV, 24 eyes of 18 subjects without CNV). Methods Patients imaged using the prototype AngioVue OCTA system (Optovue, Inc, Fremont, CA) between August 2014 and October 2014 at New England Eye Center were assessed. Patients in whom CNV was identified on OCTA were evaluated to define characteristics of CNV on OCTA: size using greatest linear ...

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    18. Imaging of retinal vasculature using adaptive optics SLO/OCT

      Imaging of retinal vasculature using adaptive optics SLO/OCT

      We use our previously developed adaptive optics (AO) scanning laser ophthalmoscope (SLO)/ optical coherence tomography (OCT) instrument to investigate its capability for imaging retinal vasculature. The system records SLO and OCT images simultaneously with a pixel to pixel correspondence which allows a direct comparison between those imaging modalities. Different field of views ranging from 0.8°x0.8° up to 4°x4° are supported by the instrument. In addition a dynamic focus scheme was developed for the AO-SLO/OCT system in order to maintain the high transverse resolution throughout imaging depth. The active axial eye tracking that is implemented in ...

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    19. Macular Thickness Profiles of Intra-retinal Layers in Myopia Evaluated by Ultra-High Resolution Optical Coherence Tomography

      Macular Thickness Profiles of Intra-retinal Layers in Myopia Evaluated by Ultra-High Resolution Optical Coherence Tomography

      Purpose To investigate the thickness and variation profiles of eight intra-retinal layers in myopia. Design Prospective cross-sectional study. Methods Young subjects with spherical equivalents ranging from +0.50 to -10.25 diopters and good corrected vision were divided into emmetropic (n=20), low myopic (n=50), and high myopic (n=30) groups. Retinal images centered on the fovea along the horizontal and vertical meridians were obtained by ultra-high resolution optical coherence tomography (OCT). Macular images were segmented into eight intra-retinal layers by an automatic segmentation algorithm to yield thickness profiles within a 6-mm diameter circle divided into central, pericentral, and ...

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    20. Fujimoto receives the OSA Frederic Ives Medal

      Fujimoto receives the OSA Frederic Ives Medal

      The Optical Society (OSA) announced on March 1 the selection of Professor James G. Fujimoto as the recipient of the Frederic Ives Medal / Quinn Prize. He is recognized for pioneering the field of optical coherence tomography (OCT) and for his research group’s and collaborator’s contributions leading to its widespread medical application and major commercial impact. The Frederic Ives Medal is the highest award of the OSA and recognizes overall distinction in optics.

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    21. Choroidal involvement in Rosai-Dorfman syndrome may be depicted and followed using enhanced depth imaging optical coherence tomography (EDI-OCT)

      Choroidal involvement in Rosai-Dorfman syndrome may be depicted and followed using enhanced depth imaging optical coherence tomography (EDI-OCT)

      Dear Editor, We read with interest the recently published case report by Vermeulen et al. [ 1 ] regarding “Rosai–Dorfman disease presenting as choroidal melanoma”. We previously published a similar presentation of a patient that underwent systemic work-up for bilateral choroidal masses [ 2 ]. Our patient initially presented with minimal visual complaints and best-corrected visual acuity of 20/20 OU. Sub-papillomacular bundle, amelanotic choroidal masses OU were discovered on dilated fundus exam. Initial work-up demonstrated focal pigment epithelial detachment OD but overall intact outer retinal layers OU on spectral domain optical coherence tomography (SD-OCT). Unlike the case report by Vermeulen et al ...

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    22. Speckle reduction in optical coherence tomography by two-step image registration

      Speckle reduction in optical coherence tomography by two-step image registration

      The image quality of optical coherence tomography can be severely influenced by speckle noise (i.e., signal-degrading speckle). Averaging multiple B-scans can effectively suppress speckle noise. Because of sample motion, images subject to averaging must be aligned exactly. We propose a two-step image registration scheme that combines global and local registrations for speckle reduction by the averaging of multiple B-scans. The method begins with a global registration to compensate for overall motion, which is estimated based on the rigid transformation model involving translation and rotation. Then each A-scan is aligned by cross-correlation using a graph-based algorithm, followed by a pixel ...

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