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    1. Advances of optical coherence tomography in myopia and pathologic myopia

      Advances of optical coherence tomography in myopia and pathologic myopia

      The natural course of high-axial myopia is variable and the development of pathologic myopia is not fully understood. Advancements in optical coherence tomography (OCT) technology have revealed peculiar intraocular structures in highly myopic eyes and unprecedented pathologies that cause visual impairment. New OCT findings include posterior precortical vitreous pocket and precursor stages of posterior vitreous detachment; peripapillary intrachoroidal cavitation; morphological patterns of scleral inner curvature and dome-shaped macula. Swept source OCT is capable of imaging deeper layers in the posterior pole for investigation of optic nerve pits, stretched and thinned lamina cribrosa, elongated dural attachment at posterior scleral canal, and ...

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    2. Optical coherence tomography angiography in paracentral acute middle maculopathy secondary to central retinal vein occlusion

      Optical coherence tomography angiography in paracentral acute middle maculopathy secondary to central retinal vein occlusion

      Purpose To report the clinical course and the optical coherence tomography angiography (OCTA) findings of patients presenting with paracentral acute middle maculopathy (PAMM) and central retinal vein occlusion (CRVO). Methods Retrospective case series. Clincal records and multimodal imaging findings of patients presenting with PAMM and CRVO were reviewed. Results Three eyes of three patients (2 males; mean age: 66 years) were included in the study. Mean follow-up was 9 months and images using OCTA (AngioVue OCT angiography system, Optovue, Inc., Fremont, CA, USA) were available at the last follow-up visit. During follow-up, best corrected visual acuity (BCVA) of case 1 ...

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    3. Quantifying the influence of Bessel beams on image quality in optical coherence tomography

      Quantifying the influence of Bessel beams on image quality in optical coherence tomography

      Light scattered by turbid tissue is known to degrade optical coherence tomography (OCT) image contrast progressively with depth. Bessel beams have been proposed as an alternative to Gaussian beams to image deeper into turbid tissue. However, studies of turbid tissue comparing the image quality for different beam types are lacking. We present such a study, using numerically simulated beams and experimental OCT images formed by Bessel or Gaussian beams illuminating phantoms with optical properties spanning a range typical of soft tissue. We demonstrate that, for a given scattering parameter, the higher the scattering anisotropy the lower the OCT contrast, regardless ...

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    4. Contrast-enhanced optical coherence tomography with picomolar sensitivity for functional in vivo imaging

      Contrast-enhanced optical coherence tomography with picomolar sensitivity for functional in vivo imaging

      Optical Coherence Tomography (OCT) enables real-time imaging of living tissues at cell-scale resolution over millimeters in three dimensions. Despite these advantages, functional biological studies with OCT have been limited by a lack of exogenous contrast agents that can be distinguished from tissue. Here we report an approach to functional OCT imaging that implements custom algorithms to spectrally identify unique contrast agents: large gold nanorods (LGNRs). LGNRs exhibit 110-fold greater spectral signal per particle than conventional GNRs, which enables detection of individual LGNRs in water and concentrations as low as 250 pM in the circulation of living mice. This translates to ...

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    5. Predicting macular hole closure with ocriplasmin based on spectral domain optical coherence tomography

      Predicting macular hole closure with ocriplasmin based on spectral domain optical coherence tomography

      Purpose To assess the preoperative features of patients with idiopathic macular hole (IMH) and vitreomacular adhesion (VMA) treated with ocriplasmin (OCP) that can predict successful closure. Method Data were prospectively collected on all patients with IMH treated with OCP in three British ophthalmic centres. Several preoperative variables were recorded including the IMH base diameter (BD), minimum linear diameter (MLD), and VMA width measured on spectral domain optical coherence tomography. Several other IMH indices were derived including a ‘width factor’, defined as the BD minus the MLD in μm. The occurrence of VMA release and hole closure were used as the ...

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    6. In vivo cross-sectional imaging of the phonating larynx using long-range Doppler optical coherence tomography

      In vivo cross-sectional imaging of the phonating larynx using long-range Doppler optical coherence tomography

      Diagnosis and treatment of vocal fold lesions has been a long-evolving science for the otolaryngologist. Contemporary practice requires biopsy of a glottal lesion in the operating room under general anesthesia for diagnosis. Current in-office technology is limited to visualizing the surface of the vocal folds with fiber-optic or rigid endoscopy and using stroboscopic or high-speed video to infer information about submucosal processes. Previous efforts using optical coherence tomography (OCT) have been limited by small working distances and imaging ranges. Here we report the first full field, high-speed, and long-range OCT images of awake patients’ vocal folds as well as cross-sectional ...

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    7. Wide-field optical coherence tomography based microangiography for retinal imaging

      Wide-field optical coherence tomography based microangiography for retinal imaging

      Optical coherence tomography angiography (OCTA) allows for the evaluation of functional retinal vascular networks without a need for contrast dyes. For sophisticated monitoring and diagnosis of retinal diseases, OCTA capable of providing wide-field and high definition images of retinal vasculature in a single image is desirable. We report OCTA with motion tracking through an auxiliary real-time line scan ophthalmoscope that is clinically feasible to image functional retinal vasculature in patients, with a coverage of more than 60 degrees of retina while still maintaining high definition and resolution. We demonstrate six illustrative cases with unprecedented details of vascular involvement in retinal ...

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    8. Experimental Demonstration of Spectral Intensity Optical Coherence Tomography

      Experimental Demonstration of Spectral Intensity Optical Coherence Tomography

      We demonstrate experimentally spectral-domain intensity optical coherence tomography using a Mach-Zehnder interferometer with balanced detection. We show that the technique allows for a point spread function with reduced full-width at half maximum compared to conventional optical coherence tomography. The method further provides benefits similar to those of chirped-pulse interferometry in terms of dispersion cancellation but only requires a broadband incoherent source and standard detectors. The measurements are in excellent agreement with the theoretical predictions. Finally, we propose an approach that enables the elimination of potential artefacts arising from multiple interfaces

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    9. OCT-based label-free in vivo lymphangiography within human skin and areola

      OCT-based label-free in vivo lymphangiography within human skin and areola

      Due to the limitations of current imaging techniques, visualization of lymphatic capillaries within tissue in vivo has been challenging. Here, we present a label-free high resolution optical coherence tomography (OCT) based lymphangiography (OLAG) within human skin in vivo . OLAG enables rapid (~seconds) mapping of lymphatic networks, along with blood vessel networks, over 8 mm x 8 mm of human skin and 5 mm x 5 mm of human areola. Moreover, lymphatic system’s response to inflammation within human skin is monitored throughout an acne lesion development over 7 days. The demonstrated results promise OLAG as a revolutionary tool in the ...

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    10. Detection of preperimetric glaucoma using Bruch membrane opening, neural canal and posterior pole asymmetry analysis of optical coherence tomography

      Detection of preperimetric glaucoma using Bruch membrane opening, neural canal and posterior pole asymmetry analysis of optical coherence tomography

      We analysed retinal nerve fibre layer (RNFL) defects in eyes with normal circumpapillary RNFL (cpRNFL) thickness using posterior pole asymmetry analysis (PPAA) and investigated the parameters of Bruch membrane opening (BMO) and neural canals using enhanced depth imaging spectral domain optical coherence tomography (EDI-SDOCT). A total of 112 preperimetric glaucomatous eyes of 92 patients were examined to obtain cpRNFL thickness using SD-OCT. Posterior pole asymmetry analysis (PPAA) and central cross-sectional images of the optic nerve head (ONH) were obtained using EDI-SDOCT. Minimal and horizontal distances between the BMO and ONH surfaces (BMOM, BMOH) and the terminal of retinal pigment epithelium ...

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    11. Put innovation science at the heart of discovery : Nature News & Comment

      Put innovation science at the heart of discovery : Nature News & Comment

      I Innovation is being talked about everywhere. The US Senate is working on a biomedical innovation bill. Australia’s main funding agency has just announced that it will cut hundreds of climate scientists as part of its National Science and Innovation Agenda. The National Council of Science Museums in India will add Innovation Hubs at its centres. More and more organizations are using innovation in their names and brands. Innovation is a central plank of national and local policies and it consumes billions of dollars of investment worldwide. Yet the evidence base for these innovation efforts is close to nothing ...

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    12. Nanometer resolution optical coherence tomography using broad bandwidth XUV and soft x-ray radiation

      Nanometer resolution optical coherence tomography using broad bandwidth XUV and soft x-ray radiation

      Optical coherence tomography (OCT) is a non-invasive technique for cross-sectional imaging. It is particularly advantageous for applications where conventional microscopy is not able to image deeper layers of samples in a reasonable time, e.g. in fast moving, deeper lying structures. However, at infrared and optical wavelengths, which are commonly used, the axial resolution of OCT is limited to about 1  μ m, even if the bandwidth of the light covers a wide spectral range. Here, we present extreme ultraviolet coherence tomography (XCT) and thus introduce a new technique for non-invasive cross-sectional imaging of nanometer structures. XCT exploits the nanometerscale coherence ...

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    13. The design and validation of an optical coherence tomography-based classification system for focal vitreomacular traction

      The design and validation of an optical coherence tomography-based classification system for focal vitreomacular traction

      Purpose To develop and validate a classification system for focal vitreomacular traction (VMT) with and without macular hole based on spectral domain optical coherence tomography (SD-OCT), intended to aid in decision-making and prognostication. Methods A panel of retinal specialists convened to develop this system. A literature review followed by discussion on a wide range of cases formed the basis for the proposed classification. Key features on OCT were identified and analysed for their utility in clinical practice. A final classification was devised based on two sequential, independent validation exercises to improve interobserver variability. Results This classification tool pertains to idiopathic ...

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    14. Is optical coherence tomography an effective device for evaluation of tear film meniscus in patients with acne rosacea?

      Is optical coherence tomography an effective device for evaluation of tear film meniscus in patients with acne rosacea?

      Purpose To investigate the tear meniscus using Fourier-domain optical coherence tomography (FD-OCT) in patients with acne rosacea and to determine the relationship between tear film break-up tests (TBUT), Schirmer test and FD-OCT values and to compare them with that of healthy controls. Methods One hundred and four patients with acne rosacea and 104 body mass index age-sex-matched healthy subjects were enrolled in this prospective case-control study. Tear meniscus height (TMH), tear meniscus depth (TMD), and tear meniscus cross-sectional area (TMA) were measured using FD-OCT (RTVue-100); TBUT, Schirmer test and dry eye questionnaire (OSDI) were evaluated. Correlation was assessed using Spearman ...

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    15. Persistent subfoveolar fluid following retinal detachment surgery: an SD-OCT guided study on the incidence, aetiological associations, and natural history

      Persistent subfoveolar fluid following retinal detachment surgery: an SD-OCT guided study on the incidence, aetiological associations, and natural history

      Purpose To investigate the incidence and natural history of persistent subfoveolar fluid (PSF) following surgery for macular off rhegmatogenous retinal detachment and the effect of PSF on photoreceptor structure and final visual acuity. Methods Retrospective study of 61 cases with post-operative optical coherence tomography (OCT) performed within 12 weeks of surgery. Based on aetiology, cases were categorized into tractional retinal tears (TRT) group or atrophic round holes and dialyses (RHD) group to investigate the incidence and duration of PSF. A Kaplan–Meier graph was plotted to compare survival time of subfoveolar fluid for both groups. Following secondary reclassification of cases ...

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    16. Ultrafast optical-ultrasonic system and miniaturized catheter for imaging and characterizing atherosclerotic plaques in vivo

      Ultrafast optical-ultrasonic system and miniaturized catheter for imaging and characterizing atherosclerotic plaques in vivo

      Atherosclerotic coronary artery disease (CAD) is the number one cause of death worldwide. The majority of CAD-induced deaths are due to the rupture of vulnerable plaques. Accurate assessment of plaques is crucial to optimize treatment and prevent death in patients with CAD. Current diagnostic techniques are often limited by either spatial resolution or penetration depth. Several studies have proved that the combined use of optical and ultrasonic imaging techniques increase diagnostic accuracy of vulnerable plaques. Here, we introduce an ultrafast optical-ultrasonic dual-modality imaging system and flexible miniaturized catheter, which enables the translation of this technology into clinical practice. This system ...

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    17. Intraoperative optical coherence tomography: past, present, and future

      Intraoperative optical coherence tomography: past, present, and future

      To provide an overview of the current state of intraoperative optical coherence tomography (OCT). Literature review of studies pertaining to intraoperative OCT examining both the technology aspects of the imaging platform and the current evidence for patient care. Over the last several years, there have been significant advances in integrative technology for intraoperative OCT. This has resulted in the development of multiple microscope-integrated systems and a rapidly expanding field of image-guided surgical care. Multiple studies have demonstrated the potential role for intraoperative OCT in facilitating surgeon understanding of the surgical environment, tissue configuration, and overall changes to anatomy. In fact ...

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    18. Intraoperative optical coherence tomography in macula involving rhegmatogenous retinal detachment repair with pars plana vitrectomy and perfluoron

      Intraoperative optical coherence tomography in macula involving rhegmatogenous retinal detachment repair with pars plana vitrectomy and perfluoron

      Purpose To investigate microanatomical relationships during surgical repair of macula involving retinal detachment with pars plana vitrectomy (PPV) and perfluoron (PFO) with a microscope-integrated intraoperative optical coherence tomography (iOCT) device. Patients and methods This consecutive case series included nine eyes of nine patients with macula involving retinal detachment operated by a single surgeon at the Cincinnati Eye Institute. All patients underwent PPV, PFO injection, endolaser, and air–fluid exchange. The macula was imaged with iOCT before PFO injection, after PFO injection, and after air–fluid exchange in all eyes. Results iOCT imaging was ergonomically easy to obtain in all eyes ...

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    19. 0.54 μm resolution two-photon interference with dispersion cancellation for quantum optical coherence tomography

      0.54 μm resolution two-photon interference with dispersion cancellation for quantum optical coherence tomography

      Quantum information technologies harness the intrinsic nature of quantum theory to beat the limitations of the classical methods for information processing and communication. Recently, the application of quantum features to metrology has attracted much attention. Quantum optical coherence tomography (QOCT), which utilizes two-photon interference between entangled photon pairs, is a promising approach to overcome the problem with optical coherence tomography (OCT): As the resolution of OCT becomes higher, degradation of the resolution due to dispersion within the medium becomes more critical. Here we report on the realization of 0.54  μ m resolution two-photon interference, which surpasses the current record resolution ...

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    20. Optical coherence tomography-guided laser microsurgery for blood coagulation with continuous-wave laser diode

      Optical coherence tomography-guided laser microsurgery for blood coagulation with continuous-wave laser diode

      Blood coagulation is the clotting and subsequent dissolution of the clot following repair to the damaged tissue. However, inducing blood coagulation is difficult for some patients with homeostasis dysfunction or during surgery. In this study, we proposed a method to develop an integrated system that combines optical coherence tomography (OCT) and laser microsurgery for blood coagulation. Also, an algorithm for positioning of the treatment location from OCT images was developed. With OCT scanning, 2D/3D OCT images and angiography of tissue can be obtained simultaneously, enabling to noninvasively reconstruct the morphological and microvascular structures for real-time monitoring of changes in ...

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    21. ACG Clinical Guideline: Diagnosis and Management of Barrett’s Esophagus

      ACG Clinical Guideline: Diagnosis and Management of Barrett’s Esophagus

      Barrett’s esophagus (BE) is among the most common conditions encountered by the gastroenterologist. In this document, the American College of Gastroenterology updates its guidance for the best practices in caring for these patients. These guidelines continue to endorse screening of high-risk patients for BE; however, routine screening is limited to men with reflux symptoms and multiple other risk factors. Acknowledging recent data on the low risk of malignant progression in patients with nondysplastic BE, endoscopic surveillance intervals are attenuated in this population; patients with nondysplastic BE should undergo endoscopic surveillance no more frequently than every 3–5 years. Neither ...

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    22. Depth evaluation of intended vs actual intacs intrastromal ring segments using optical coherence tomography

      Depth evaluation of intended vs actual intacs intrastromal ring segments using optical coherence tomography

      Purpose Evaluation of actual vs intended intrastromal corneal ring segments (ICRS) implantation depth as measured by anterior segment optical coherence tomography (OCT) Methods Prospective study evaluating 30 Intacs segments implanted manually in 19 eyes of 15 patients suffering from keratoconus. Segment depth evaluation was performed using anterior segment OCT. Measurements were performed above and below the segment at 3 points in relation to the incision site. Statistical analysis was performed using the SAS software for ANOVA, matched t-test, and GLIMMIX procedure. Results Intacs segment depth was 153-μm shallower than intended (58 % vs 80 % ). Segment layout demonstrated the proximal and ...

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    23. Retinal vessel structure measurement using spectral-domain optical coherence tomography

      Retinal vessel structure measurement using spectral-domain optical coherence tomography

      Purpose To assess the reliability and validity of spectral-domain optical coherence tomography (SD-OCT) measurements of retinal vessel lumen diameters and wall thicknesses. Methods SD-OCT was used to characterize the circular region around the optic disc of 40 eyes (20 subjects). The inner and outer sides (vitreal and choroidal sides) of the vessel wall and the luminal diameter were measured using intensity graphs. Results Mean arterial and venous luminal diameters were 95.1±16.1 and 132.6±17.8   μm, respectively. The wall thicknesses of inner and outer sides of the artery were 23.9±4.9 and 21.2 ...

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    24. Visible light optical coherence tomography measures retinal oxygen metabolic response to systemic oxygenation

      Visible light optical coherence tomography measures retinal oxygen metabolic response to systemic oxygenation

      The lack of capability to quantify oxygen metabolism noninvasively impedes both fundamental investigation and clinical diagnosis of a wide spectrum of diseases including all the major blinding diseases such as age-related macular degeneration, diabetic retinopathy, and glaucoma. Using visible light optical coherence tomography (vis-OCT), we demonstrated accurate and robust measurement of retinal oxygen metabolic rate (rMRO 2 ) noninvasively in rat eyes. We continuously monitored the regulatory response of oxygen consumption to a progressive hypoxic challenge. We found that both oxygen delivery, and rMRO 2 increased from the highly regulated retinal circulation (RC) under hypoxia, by 0.28 ± 0.08 µL ...

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    1-24 of 241 1 2 3 4 5 6 7 8 9 10 »
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