1. Articles from Kentaro Nakamura

    1-6 of 6
    1. Relationship Between Optical Coherence Tomography Parameter and Visual Function in Eyes With Epiretinal Membrane

      Relationship Between Optical Coherence Tomography Parameter and Visual Function in Eyes With Epiretinal Membrane

      Purpose: To investigate the associations between visual function and the optical coherence tomography (OCT) parameters in eyes with idiopathic epiretinal membrane (ERM). Methods: Thirty-nine consecutive eyes with ERM were enrolled. In addition to OCT parameters, such as central retinal thickness (CRT), the area of gap between the ERM and the retinal surface (SUKIMA) was newly defined and calculated from the vertical and horizontal OCT images (SUKIMAv and SUKIMAh). The average of SUKIMAv and SUKIMAh (SUKIMAave) was used for the statistical analysis. The vertical and horizontal metamorphopsia scores (MV, MH) and the average of MV and MH (Mave) were also used ...

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    2. High-speed optical correlation-domain reflectometry without using acousto-optic modulator

      High-speed optical correlation-domain reflectometry without using acousto-optic modulator

      To achieve a distributed reflectivity measurement along an optical fiber, we develop a simplified cost-effective configuration of optical correlation- (or coherence-) domain reflectometry based on a synthesized optical coherence function by sinusoidal modulation. By excluding conventional optical heterodyne detection (practically, without using an acoustooptic modulator) and by exploiting the foot of the Fresnel reflection spectrum, the electrical bandwidth required for signal processing is lowered down to several megahertz. We evaluate the basic system performance and demonstrate its high-speed operation (10 ms for one scan) by tracking a moving reflection point in real time.

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    3. Measurement of elastic wave propagation velocity near tissue surface by optical coherence tomographyand laser Doppler velocimetry

      Measurement of elastic wave propagation velocity near tissue surface by optical coherence tomographyand laser Doppler velocimetry

      We demonstrate a new technique for measuring the velocity of elastic waves propagating near a tissue surface by swept-source optical coherence tomography (OCT). We establish a theory for estimating the elastic wave velocity from the OCT images taken with a slow mechanical scanning, which is experimentally verified using agar and tissue samples. The elastic wave velocity measured by this technique agrees well with previous results and that measured with a laser Doppler velocimeter. We also carry out some trial measurements of the elastic wave velocities of several tissue samples by this method.

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    4. Endoscopic optical coherence elastography using acoustic radiation force and bending vibration of optical Fiber

      Endoscopic optical coherence elastography using acoustic radiation force and bending vibration of optical Fiber
      We investigate endoscopic optical coherence elastography with micro-scale resolution using acoustic radiation force. The endoscopic optical scanner has vibration of an optical fiber for scanning the measurement light from an optical coherence tomography (OCT) system to sample tissue. The optical fiber with the length of mechanical resonance condition is vibrated in the bending mode using a cylindrical piezoelectric actuator driven by the phase-shifted voltages, and the output light from the optical fiber end is collimated by a small lens. The prototype of the scanner probe is 1 mm in diameter and 20 mm in length. Stress in the tissue is ...
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    5. Liquid lens using acoustic radiation force

      Liquid lens using acoustic radiation force
      A liquid lens is proposed that uses acoustic radiation force with no mechanical moving parts. It consists of a cylindrical acrylic cell filled with two immiscible liquids (degassed water and silicone oil) and a concave ultrasound transducer. The focal point of the transducer is located on the oil??water interface, which functions as a lens. The acoustic radiation force is generated when there is a difference in the acoustic energy densities of different media. An acoustic standing wave was generated in the axial direction of the lens and the variation of the shape of the oil??water interface was observed ...
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    6. High-speed imaging with endoscopic optical coherence tomography using bending vibration of optical fiber

      In this report, we propose an endoscopic scanner head for optical coherence tomography (OCT) using bending vibration of an optical fiber. The optical fiber is attached to the center of a cylindrical piezoelectric actuator with four outer electrodes, and the voltages with the phase shift of /2 are applied to the electrodes to excite a circular vibration of the fiber end. The output light from the fiber end is collimated by a lens, and deflected by 90 degrees using a cone mirror. The collimated light is scanned along the circumference of the endoscope due to the vibration of the optical ...

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    1-6 of 6
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  2. Topics in the News

    1. (3 articles) Tokyo Institute of Technology
    2. (1 articles) Columbia University
    3. (1 articles) University of Rochester
    4. (1 articles) Stanford University
    5. (1 articles) Johns Hopkins University
    6. (1 articles) National University of Singapore
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    Liquid lens using acoustic radiation force Endoscopic optical coherence elastography using acoustic radiation force and bending vibration of optical Fiber Measurement of elastic wave propagation velocity near tissue surface by optical coherence tomographyand laser Doppler velocimetry High-speed optical correlation-domain reflectometry without using acousto-optic modulator Relationship Between Optical Coherence Tomography Parameter and Visual Function in Eyes With Epiretinal Membrane Optical coherence tomography findings in patients with transfusion-dependent β-thalassemia Higher-order regression three-dimensional motion-compensation method for real-time optical coherence tomography volumetric imaging of the cornea Optical coherence tomography image based eye disease detection using deep convolutional neural network Optical Coherence Tomography Biomarkers in Predicting Treatment Outcomes of Diabetic Macular Edema After Dexamethasone Implants Macular and Optic Disc Parameters in Children with Amblyopic and Nonamblyopic Eyes under Optical Coherence Tomography Fundus Images Optical coherence tomography assessment of the enamel surface after debonding the ceramic brackets using three different techniques Schizophrenia in Translation: Why the Eye?