All Articles from Masahiro Yamanari -Optical Coherence Tomography News

Articles from Masahiro Yamanari

1-24 of 49 1 2 »
1. Polarization-sensitive optical coherence tomography for estimating relative melanin content of autologous induced stem-cell derived retinal pigment epithelium
  
  Explore Nature Publishing Group May 9 2020 Ophthalmology
  
  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 aged Japanese women, one with neovascular AMD that underwent transplantation of an autologous hiPSC-RPE cell sheet and another with binocular dry AMD, were selected for this study. Entropy value was ...
  Read Full Article
  
  Comment
  
  Mentions: Masahiro Yamanari
2. Parallel detection of Jones-matrix elements in polarization-sensitive optical coherence tomography
  
  Explore OSA | OSA Publishing Apr 12 2019
  
  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 depth range are important for clinical applications, including the imaging of an anterior eye segment, a new PS-OCT method that does not have these drawbacks is desired. Here, we present ...
  Read Full Article
  
  Comment
  
  Mentions: Masahiro Yamanari Osaka University Yasushi Ikuno
3. Optical coherence tomography using polarization information
  
  Explore uspto.gov Jun 12 2018 Ophthalmology , Patents
  
  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 of the Jones matrix acquired based on the at least eigenvalue and the at least eigenvector of the expanded matrix.
  Read Full Article
  
  Comment
  
  Mentions: Masahiro Yamanari Tomey Corporation
4. Optical tomographic device capable of acquiring a plurality of tomographic images
  
  Explore uspto.gov Mar 14 2017 Patents
  
  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. A reference light generator generates at least two reference lights with different optical path lengths. An interfering light generator combines the at least two reflected lights and the at least ...
  Read Full Article
  
  Comment
  
  Mentions: Masahiro Yamanari Tomey Corporation
5. Estimation of Jones matrix, birefringence and entropy using Cloude-Pottier decomposition in polarization-sensitive optical coherence tomography
  
  Explore OSA | OSA Publishing Aug 23 2016
  
  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 the sample. In addition, we introduce entropy that shows the randomness of the polarization property. Underestimation of the entropy at a low sampling number is mitigated by asymptotic quasi maximum ...
  Read Full Article
  
  Comment
  
  Mentions: Masahiro Yamanari Tomey Corporation Tohoku University
6. Association between histological findings and polarization-sensitive optical coherence tomography analysis of a post-trabeculectomy human eye
  
  Explore Wiley Online Library Apr 13 2016 Ophthalmology
  
  Letter to the editor.
  Read Full Article
  
  Comment
  
  Mentions: Masahiro Yamanari Tohoku University
7. Fiber-based polarization-sensitive OCT for birefringence imaging of the anterior eye segment
  
  Explore opticsinfobase.org Jan 8 2015
  
  We demonstrate a prototype system of polarization-sensitive optical coherence tomography (PS-OCT) designed for clinical studies of the anterior eye segment imaging. The system can measure Jones matrices of the sample with depth-multiplexing of two orthogonal incident polarizations and polarization-sensitive detection. An optical clock is generated using a quadrature modulator and a logical circuit to double the clock frequency. Systematic artifacts in measured Jones matrices are theoretically analyzed and numerically compensated using signals at the surface of the sample. Local retardation images of filtering blebs after trabeculectomy show improved visualization of subconjunctival tissue, sclera, and scar tissue of the bleb wall ...
  Read Full Article
  
  Comment
  
  Mentions: Masahiro Yamanari Tomey Corporation
8. Scleral birefringence as measured by polarization-sensitive optical coherence tomography and ocular biometric parameters of human eyes in vivo
  
  Explore opticsinfobase.org Apr 3 2014 Ophthalmology
  
  The relationship between scleral birefringence and biometric parameters of human eyes in vivo is investigated. Scleral birefringence near the limbus of 21 healthy human eyes was measured using polarization-sensitive optical coherence tomography. Spherical equivalent refractive error, axial eye length, and intraocular pressure (IOP) were measured in all subjects. IOP and scleral birefringence of human eyes in vivo was found to have statistically significant correlations ( r = −0.63, P = 0.002). The slope of linear regression was −2.4 × 10 −2 deg/μm/mmHg. Neither spherical equivalent refractive error nor axial eye length had significant correlations with scleral birefringence. To evaluate ...
  Read Full Article
  
  Comment
  
  Mentions: Yoshiaki Yasuno Masahiro Miura Masahiro Yamanari
9. Comparison of three-dimensional optical coherence tomography and combining a rotating Scheimpflug camera with a Placido topography system for forme fruste keratoconus diagnosis
  
  Explore BJO Online Oct 2 2013 Ophthalmology
  
  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 and posterior keratometric parameters (steep K, flat K, average K), elevation, topographic parameters, regular and irregular astigmatism (spherical, asymmetry, regular and higher-order astigmatism) and five pachymetric parameters (minimum, minimum–median ...
  Read Full Article
  
  Comment
  
  Mentions: Yoshiaki Yasuno Masahiro Yamanari University of Tsukuba
10. Comparison of three-dimensional optical coherence tomography and combining a rotating Scheimpflug camera with a Placido topography system for forme fruste keratoconus diagnosis
  
  Explore BJO Online Sep 30 2013 Ophthalmology
  
  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 and posterior keratometric parameters (steep K, flat K, average K), elevation, topographic parameters, regular and irregular astigmatism (spherical, asymmetry, regular and higher-order astigmatism) and five pachymetric parameters (minimum, minimum–median ...
  Read Full Article
  
  Comment
  
  Mentions: Yoshiaki Yasuno Masahiro Yamanari University of Tsukuba
11. Keratoconus diagnosis using anterior segment polarization-sensitive optical coherence tomography
  
  Explore iovs.org Jan 25 2013 Ophthalmology
  
  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)-OCT. Average of en face phase retardation of the posterior surface of the cornea, curvature, videokeratographic parameters, regular and irregular astigmatism, pachymetry map, and elevation were measured. The AROC of ...
  Read Full Article
  
  Comment
  
  Mentions: Yoshiaki Yasuno Masahiro Yamanari University of Tsukuba
12. Optical Rheology of Porcine Sclera by Birefringence Imaging
  
  Explore PLoS ONE Sep 6 2012
  
  Purpose To investigate a relationship between birefringence and elasticity of porcine sclera ex vivo using polarization-sensitive optical coherence tomography (PS-OCT). Methods Elastic parameters and birefringence of 19 porcine eyes were measured. Four pieces of scleral strips which were parallel to the limbus, with a width of 4 mm, were dissected from the optic nerve head to the temporal side of each porcine eye. Birefringence of the sclera was measured with a prototype PS-OCT. The strain and force were measured with a uniaxial material tester as the sample was stretched with a speed of 1.8 mm/min after preconditioning. A ...
  Read Full Article
  
  Comment
  
  Mentions: Shuichi Makita Yoshiaki Yasuno Masahiro Miura
13. Passive component based multifunctional Jones matrix swept source optical coherence tomography for Doppler and polarization imaging
  
  Explore opticsinfobase.org May 25 2012 Ophthalmology
  
  We present a fiber based multifunctional Jones matrix swept source optical coherence tomography (SS-OCT) system for Doppler and polarization imaging. Jones matrix measurement without using active components such as electro-optic modulators is realized by incident polarization multiplexing based on independent delay of two orthogonal polarization states and polarization diversity detection. In addition to polarization sensitivity, this system measures Doppler flow without extra hardware for phase stabilized SS-OCT detection. An eighth-wave plate was measured to demonstrate the polarization detection accuracy. The optic nerve head of a retina was measured in vivo. Detailed vasculature and birefringent structures were investigated simultaneously.
  Read Full Article
  
  Comment
  
  Mentions: Yoshiaki Yasuno Masahiro Yamanari University of Tsukuba
14. Office based multi-functional anterior eye segment optical coherence tomography
  
  Explore Linking to Scitation Content Mar 9 2012 Ophthalmology
  
  An office based Doppler and polarization sensitive swept-source optical coherence tomography (Doppler-PS-SS-OCT) was developed for diagnosis and evaluation of abnormalities of anterior eye segment in clinic. A healthy eye was measured in vivo by the Doppler PS-OCT. The results showed that the Doppler PS-OCT may have potential to identify blood vessels and discriminate fibrous tissues in abnormalities, such as scarring in bleb, and scleral inflammation.
  Read Full Article
  
  Comment
  
  Mentions: Shuichi Makita Yoshiaki Yasuno Masahiro Miura
15. Automated detection of chorio-scleral interface using polarization-sensitive optical coherence tomography
  
  Explore Linking to Scitation Content Feb 9 2012 Ophthalmology
  
  A polarization sensitive optical coherence tomography based automated algorithm for segmentation of the chorio-scleral interface is presented. The algorithm employs a two-step segmentation approach. At first, local birefringence based segmentation with low precision is performed to roughly distinguish the choroid and sclera. Successively, a depth oriented slope fitting to phase retardation is applied in both the choroid and sclera. The interface is determined as the cross-point of the two phase retardation slope lines. The algorithm shows potential for functional, objective, and volumetric choroid thickness measurement
  Read Full Article
  
  Comment
  
  Mentions: Yoshiaki Yasuno Masahiro Yamanari University of Tsukuba
16. Automated phase retardation oriented segmentation of chorio-scleral interface by polarization sensitive optical coherence tomography
  
  Explore opticsinfobase.org Jan 30 2012 Ophthalmology
  
  An automated chorio-scleral interface (CSI) detection algorithm based on polarization sensitive optical coherence tomography (PS-OCT) is presented. This algorithm employs a two-step scheme based on the phase retardation variation detected by PS-OCT. In the first step, a rough CSI segmentation is implemented to distinguish the choroid and sclera by using depth-oriented second derivative of the phase retardation. Second, the CSI is further finely defined as the intersection of lines fitted to the phase retardation in the choroid and sclera. This algorithm challenges the current back-scattering intensity based CSI segmentation approaches that are not fully based on anatomical and morphological evidence ...
  Read Full Article
  
  Comment
  
  Mentions: Yoshiaki Yasuno Masahiro Yamanari University of Tsukuba
17. Dual-beam-scan Doppler optical coherence angiography for birefringence-artifact-free vasculature imaging
  
  Explore opticsinfobase.org Jan 23 2012 Ophthalmology
  
  Dual-beam-scan Doppler optical coherence angiography (DB-OCA) enables high-speed, high-sensitivity blood flow imaging. However, birefringence of biological tissues is an obstacle to vasculature imaging. Here, the influence of polarization and birefringence on DB-OCA imaging was analyzed. A DB-OCA system without birefringence artifact has been developed by introducing a Faraday rotator. The performance was confirmed in vitro using chicken muscle and in vivo using the human eye. Birefringence artifacts due to birefringent tissues were suppressed. Micro-vasculatures in the lamina cribrosa and nerve fiber layer of human eyes were visualized in vivo. High-speed and high-sensitivity micro-vasculature imaging involving birefringent tissues is available with ...
  Read Full Article
  
  Comment
  
  Mentions: Shuichi Makita Yoshiaki Yasuno Masahiro Yamanari
18. In vivo evaluation of human skin anisotropy by polarization-sensitive optical coherence tomography
  
  Explore opticsinfobase.org Aug 16 2011 Dermatology
  
  We performed an in vivo three-dimensional analysis of anisotropic changes in the dermal birefringence of mechanically deformed human skin using polarization-sensitive optical coherence tomography (PS-OCT). The papillary-dermal birefringence of the forehead increased significantly when the skin was shrunk parallel to the body axis, and decreased significantly when the skin was shrunk perpendicular to the body axis. En-face images of the papillary-dermal birefringence revealed variations among individual subjects, and that both shrinking parallel to and stretching in perpendicular to the body axis promoted the formation of macro rope-like birefringent domains. We found that PS-OCT is useful for understanding anisotropic properties of ...
  Read Full Article
  
  Comment
  
  Mentions: Yoshiaki Yasuno Masahiro Yamanari University of Tsukuba
19. Monte-Carlo-based phase retardation estimator for polarization sensitive optical coherence tomography
  
  Explore opticsinfobase.org Aug 10 2011
  
  A Monte-Carlo-based phase retardation estimator is developed to correct the systematic error in phase retardation measurement by polarization sensitive optical coherence tomography (PS-OCT). Recent research has revealed that the phase retardation measured by PS-OCT has a distribution that is neither symmetric nor centered at the true value. Hence, a standard mean estimator gives us erroneous estimations of phase retardation, and it degrades the performance of PS-OCT for quantitative assessment. In this paper, the noise property in phase retardation is investigated in detail by Monte-Carlo simulation and experiments. A distribution transform function is designed to eliminate the systematic error by using ...
  Read Full Article
  
  Comment
  
  Mentions: Shuichi Makita Yoshiaki Yasuno Masahiro Yamanari
20. Birefringence measurement of cornea and anterior segment by office-based polarization-sensitive optical coherence tomography
  
  Explore opticsinfobase.org Jul 27 2011 Ophthalmology
  
  We present a case series of cornea and anterior segment disorders investigated by an office-based polarization-sensitive optical coherence tomography (PS-OCT). Blebs of glaucoma patients treated by trabeculectomy, and corneas of keratoconus and keratoplasty patients were measured by PS-OCT. Birefringence formations in trabeculectomy bleb were measured in 1 control eye and 3 eyes of trabeculectomy model rabbits. Polarization insensitive scattering OCT and the depth-resolved birefringence were measured simultaneously by PS-OCT. Abnormal birefringence was observed in keratoconus cases with advanced thinning and with a rupture of Descemet’s membrane. The graft-host interface of the keratoplasty case showed abnormal birefringence. The appearance of ...
  Read Full Article
  
  Comment
  
  Mentions: Yoshiaki Yasuno Masahiro Miura Masahiro Yamanari
21. Complex Conjugate Resolved Retinal Imaging by One-micrometer Spectral Domain Optical Coherence Tomography Using an Electro-optical Phase Modulator
  
  Explore opticsinfobase.org Jun 25 2011 Ophthalmology
  
  Full-range spectral domain optical coherence tomography (SD-OCT) with a 1-μm band light source is shown here. The phase of the reference beam is continuously stepped while the probing beam scans the sample laterally (B-scan). The two dimensional spectral interferogram obtained is processed by a Fourier transform method to obtain a complex spectrum leading to a full-range OCT image. A detailed mathematical explanation of the complex conjugate resolving method utilized is provided. The system’s measurement speed was 7.96 kHz, the measured axial resolution was 9.6 μm in air and the maximum sensitivity 99.4 dB. To demonstrate the ...
  Read Full Article
  
  Comment
  
  Mentions: Shuichi Makita Yoshiaki Yasuno Masahiro Yamanari
22. Comprehensive in vivo micro-vascular imaging of the human eye by dual-beam-scan Doppler optical coherence angiography
  
  Explore opticsinfobase.org Jan 11 2011 Ophthalmology
  
  Comprehensive angiography provides insight into the diagnosis of vascular-related diseases. However, complex microvascular networks of unstable in vivo organs such as the eye require micron-scale resolution in three dimensions and a high sampling rate to access a wide area as maintaining the high resolution. Here, we introduce dual-beam-scan Doppler optical coherence angiography (OCA) as a label-free comprehensive ophthalmic angiography that satisfies theses requirements. In addition to high resolution and high imaging speed, high sensitivity to motion for detecting tiny blood flow of microvessels is achieved by detecting two time-delayed signals with scanning of two probing beams separated on a sample ...
  Read Full Article
  
  Comment
  
  Mentions: Shuichi Makita Yoshiaki Yasuno Masahiro Miura
23. Visibility of trabecular meshwork by standard and polarization-sensitive optical coherence tomography
  
  Explore SPIE Digital Library Dec 23 2010 Ophthalmology
  
  Polarization-sensitive optical coherence tomography (PS-OCT) is known to be advantageous because of its additional tissue-specific contrast of the anterior eye. So far, this advantage has been shown only qualitatively. We evaluate the improved visibility afforded by 3-D PS corneal and anterior eye segment OCT (PS-CAS-OCT) in visualizing the trabecular meshwork (TM) based on statistical evidences. A total of 31 normal subjects participated in this study. The anterior eye segments of both the eyes of the subjects are scanned using a custom-made PS-CAS-OCT and the standard-scattering OCT (S-OCT) and polarization-sensitive phase-retardation OCT (P-OCT) images are obtained. Three graders grade the visibility ...
  Read Full Article
  
  Comment
  
  Mentions: Shuichi Makita Yoshiaki Yasuno Carl Zeiss Meditec
24. Full-range polarization-sensitive swept-source optical coherence tomography by simultaneous transversal and spectral modulation
  
  Explore opticsinfobase.org Jun 15 2010 Ophthalmology , Tunable Sources
  
  Polarization-sensitive swept-source optical coherence tomography (PS-SS-OCT) is used to measure three-dimensional phase-retardation images of birefringent biological tissue in vivo. PS-SS-OCT with continuous source polarization modulation is used to multiplex the incident states of polarization in the signal frequency of each A-scan. Although it offers the advantage of measurement speed that is as high as that of standard SS-OCT, its disadvantage is low axial measurement range. To overcome this drawback, we employed the B-M-mode scan (BM-scan) method, which removes complex conjugate ambiguity by applying phase modulation along the transversal scanning direction. Since polarization modulation and BM-scan are applied in different scanning ...
  Read Full Article
  
  Comment
  
  Mentions: Shuichi Makita Yoshiaki Yasuno Masahiro Yamanari
1-24 of 49 1 2 »