1. Masahiro Yamanari

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    1. Mentioned In 54 Articles

    2. Melanin concentration and depolarization metrics measurement by polarization-sensitive optical coherence tomography

      Melanin concentration and depolarization metrics measurement by polarization-sensitive optical coherence tomography
      Imaging of melanin in the eye is important as the melanin is structurally associated with some ocular diseases, such as age-related macular degeneration. Although optical coherence tomography (OCT) cannot distinguish tissues containing the melanin from other tissues intrinsically, polarization-sensitive OCT (PS-OCT) can detect the melanin through spatial depolarization of the backscattered light from the melanin granules. Entropy is one of the depolarization metrics that can be used to detect malanin ...
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    3. Usefulness of Polarization-sensitive Optical Coherence Tomography-derived Attenuation-coefficient Images to Visualize the Internal Structure of the Filtering Bleb

      Usefulness of Polarization-sensitive Optical Coherence Tomography-derived Attenuation-coefficient Images to Visualize the Internal Structure of the Filtering Bleb
      Purpose/Aim of the study Polarization-sensitive anterior-segmental optical coherence tomography (PS-OCT) is useful to evaluate the filtering blebs after trabeculectomy. However, the attenuation phenomenon of OCT signal disturbs the visibility of intra-blebs structure and distribution of birefringence; a specific parameter of PS-OCT. This study aimed to evaluate the effectiveness of the attenuation-coefficient image of the filtering blebs. Materials and methods This study included 25 eyes 6 months after TLE. The ...
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    4. Polarization-sensitive optical coherence tomography for estimating relative melanin content of autologous induced stem-cell derived retinal pigment epithelium

      Polarization-sensitive optical coherence tomography for estimating relative melanin content of autologous induced stem-cell derived retinal pigment epithelium
      Transplantation of autologous human induced pluripotent stem cell-derived retinal pigment epithelial (hiPSC-RPE) sheets is a promising therapy for age-related macular degeneration (AMD). As melanin content is a representative feature of healthy RPE, we used polarization-sensitive optical coherence tomography (PS-OCT) to estimate the relative melanin content of RPE in diseased and non-diseased area, and in human iPSC-RPE sheets in vitro and in vivo by evaluating the randomness of polarization (entropy). Two ...
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    5. Parallel detection of Jones-matrix elements in polarization-sensitive optical coherence tomography

      Parallel detection of Jones-matrix elements in polarization-sensitive optical coherence tomography
      The polarization properties of a sample can be characterized using a Jones matrix. To measure the Jones matrix without assumptions of the sample, two different incident states of polarization are usually used. This requirement often causes certain drawbacks in polarization-sensitive optical coherence tomography (PS-OCT), e.g., a decrease in the effective A-scan rate or axial depth range, if a multiplexing scheme is used. Because both the A-scan rate and axial ...
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    6. Optical coherence tomography using polarization information

      Optical coherence tomography using polarization information
      The optical coherence tomography includes a processor, wherein the processor is configured to: vectorize the Jones matrix and then convert the vectorized Jones matrix into an expanded matrix; calculate at least an eigenvalue and at least an eigenvector of the expanded matrix by performing an eigenvalue decomposition to the expanded matrix; and estimate the polarization characteristic of the subject by using at least an eigenvalue and at least an eigenvector ...
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    7. Optical tomographic device capable of acquiring a plurality of tomographic images

      Optical tomographic device capable of acquiring a plurality of tomographic images
      Provided is an optical tomographic device for simultaneously acquiring a plurality of tomographic images at a same position in a subject without narrowing a depthwise measurement range. A measurement light generator generates at least two measurement lights with different optical path lengths, superimposes the at least two measurement lights, radiates the resultant light to a subject, and splits reflected light reflected from the subject into at least two reflected lights ...
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    8. Sample clock generator for optical tomographic imaging apparatus, and optical tomographic imaging apparatus

      Sample clock generator for optical tomographic imaging apparatus, and optical tomographic imaging apparatus
      A sample clock generator includes a first optical path and a second optical path through which input lights are guided, an optical phase shifter to shift a phase of the input light guided through the first optical path, an interference-light generating unit to combine a phase-shifted input light and the input light guided through the second optical path to thereby generate an interference light for sample clock, a splitting unit ...
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    9. Estimation of Jones matrix, birefringence and entropy using Cloude-Pottier decomposition in polarization-sensitive optical coherence tomography

      Estimation of Jones matrix, birefringence and entropy using Cloude-Pottier decomposition in polarization-sensitive optical coherence tomography
      Estimation of polarimetric parameters has been a fundamental issue to assess biological tissues that have form birefringence or polarization scrambling in polarization-sensitive optical coherence tomography (PS-OCT). We present a mathematical framework to provide a maximum likelihood estimation of the target covariance matrix and its incoherent target decomposition to estimate a Jones matrix of a dominant scattering mechanism, called Cloude-Pottier decomposition, thereby deriving the phase retardation and the optic axis of ...
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    10. Scleral birefringence as measured by polarization-sensitive optical coherence tomography and ocular biometric parameters of human eyes in vivo

      Scleral birefringence as measured by polarization-sensitive optical coherence tomography and ocular biometric parameters of human eyes in vivo
      ... Ryosuke Tanaka, Takeshi Yasui, Tetsuro Oshika, Masahiro Miura, and Yoshiaki Yasuno »View Author Affiliations Masahiro Yamanari,^1,^4,^7 Satoko Nagase,^2,^4 Shinichi Fukuda,^3,^4 Kotaro Ishii,^3,^4 Ryosuke Tanaka,^5 Take...
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    11. Comparison of three-dimensional optical coherence tomography and combining a rotating Scheimpflug camera with a Placido topography system for forme fruste keratoconus diagnosis

      Comparison of three-dimensional optical coherence tomography and combining a rotating Scheimpflug camera with a Placido topography system for forme fruste keratoconus diagnosis
      Objective To evaluate the ability of parameters measured by three-dimensional (3D) corneal and anterior segment optical coherence tomography (CAS-OCT) and a rotating Scheimpflug camera combined with a Placido topography system (Scheimpflug camera with topography) to discriminate between normal eyes and forme fruste keratoconus. Methods Forty-eight eyes of 48 patients with keratoconus, 25 eyes of 25 patients with forme fruste keratoconus and 128 eyes of 128 normal subjects were evaluated. Anterior ...
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    12. Comparison of three-dimensional optical coherence tomography and combining a rotating Scheimpflug camera with a Placido topography system for forme fruste keratoconus diagnosis

      Comparison of three-dimensional optical coherence tomography and combining a rotating Scheimpflug camera with a Placido topography system for forme fruste keratoconus diagnosis
      Objective To evaluate the ability of parameters measured by three-dimensional (3D) corneal and anterior segment optical coherence tomography (CAS-OCT) and a rotating Scheimpflug camera combined with a Placido topography system (Scheimpflug camera with topography) to discriminate between normal eyes and forme fruste keratoconus. Methods Forty-eight eyes of 48 patients with keratoconus, 25 eyes of 25 patients with forme fruste keratoconus and 128 eyes of 128 normal subjects were evaluated. Anterior ...
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    13. Non-invasive assessment of corneal crosslinking changes using polarization sensitive optical coherence tomography

      Non-invasive assessment of corneal crosslinking changes using polarization sensitive optical coherence tomography
      Collagen crosslinking (CXL) has shown promising results in the prevention of the progression of keratoconus and corneal ectasia. However, techniques for in vivo and in situ assessment of the treatment are limited. In this study, ex vivo porcine eyes were treated with a chemical CXL agent (glutaraldehyde), during which polarization sensitive optical coherence tomography (PS-OCT) recordings were acquired simultaneously to assess the sensitivity of the technique to assess changes in ...
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    14. Keratoconus diagnosis using anterior segment polarization-sensitive optical coherence tomography

      Keratoconus diagnosis using anterior segment polarization-sensitive optical coherence tomography
      Purpose: To investigate the tissue properties of keratoconic corneas and normal control in vivo by using polarization-sensitive optical coherence tomography (PS-OCT) and evaluate early keratoconus by the area under the receiver-operating curve and Mahalanobis distances analysis. Methods: Thirty one eyes of 20 patients with keratoconus, seven eyes of four patients with keratoconus suspect, and 25 eyes of 25 normal subjects were investigated by PS-OCT and corneal and anterior segment (CAS ...
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  2. About Masahiro Yamanari

    Masahiro Yamanari is a Researcher in the Computational Optics Group in the Institute of Applied Physics, University of Tsukuba in Japan.