1. Articles from Tetsuro Oshika

    1-24 of 24
    1. Influence of pterygium size on corneal higher-order aberration evaluated using anterior-segment optical coherence tomography

      Influence of pterygium size on corneal higher-order aberration evaluated using anterior-segment optical coherence tomography

      Background The prospective observation study aimed to evaluate changes in corneal higher-order aberrations induced by advancement of pterygium using an anterior-segment optical coherence tomography (AS-OCT) and Zernike aberration analysis. Methods The corneal topography of 284 eyes with primary pterygia originating from the nasal region was measured using an AS-OCT (SS-1000, Tomey). With anterior corneal elevation data, Zernike polynomial coefficients were calculated in diameters of 1.0, 3.0, and 5.0 mm, and the coma, spherical, coma-like, spherical-like, and total higher-order aberrations were obtained. Pterygium size was also measured as a ratio of positions of the pterygium end with respect ...

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    2. Comparison of intensity, phase retardation, and local birefringence images for filtering blebs using polarization-sensitive optical coherence tomography

      Comparison of intensity, phase retardation, and local birefringence images for filtering blebs using polarization-sensitive optical coherence tomography

      Polarization-sensitive optical coherence tomography (PS-OCT) allows the recording of depth-resolved polarimetric measurements. It has been reported that phase retardation and local birefringence images can noninvasively detect fibrotic area in blebs after glaucoma surgery. Evaluation of scar fibrosis in blebs is important not only for predicting bleb function, but also for planning revision trabeculectomy. Herein, we characterize the intensity, phase retardation, and local birefringence images of blebs using PS-OCT. A total of 85 blebs from 85 patients who had undergone trabeculectomy were examined. Both phase retardation and local birefringence images detected fibrotic changes in blebs after glaucoma surgery. Phase retardation images ...

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    3. Changes In Metamorphopsia And Optical Coherence Tomography Findings After Successful Retinal Detachment Surgery

      Changes In Metamorphopsia And Optical Coherence Tomography Findings After Successful Retinal Detachment Surgery

      Purpose: To investigate changes in metamorphopsia after rhegmatogenous retinal detachment surgery and to evaluate the relationship between metamorphopsia and retinal microstructures assessed with optical coherence tomography . Methods: The study included 47 eyes of 47 patients undergoing retinal detachment surgery. We examined the severity of metamorphopsia using M-CHARTS, best-corrected visual acuity, and optical coherence tomography images. All data were recorded before and 3, 6, and 12 months after surgery, except for M-CHARTS which were recorded only postoperatively. Results: Metamorphopsia scores at 3, 6, and 12 months postoperatively were 0.46 ± 0.51, 0.41 ± 0.44, and 0.28 ± 0.37 ...

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    4. Quantitative Evaluation of Phase Retardation in Filtering Blebs Using Polarization-Sensitive Optical Coherence Tomography

      Quantitative Evaluation of Phase Retardation in Filtering Blebs Using Polarization-Sensitive Optical Coherence Tomography

      Purpose : Polarization-sensitive optical coherence tomography (PS-OCT) can detect and evaluate scar fibrosis of the filtering blebs after glaucoma surgery. Although the change in phase retardation reportedly reflects bleb function, quantitative assessment of phase retardation in ocular tissues has not been conducted. We aimed to establish quantitative methods to investigate changes in phase retardation in the blebs after surgery using PS-OCT. Methods : Twenty-two blebs of 22 patients who had undergone glaucoma filtration surgery were consecutively examined for 4 months. Phase retardation was measured by PS-OCT and quantitatively analyzed to evaluate its relationship with bleb function based on intraocular pressure and medication ...

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    5. Objective Evaluation of Functionality of Filtering Bleb Based on Polarization-Sensitive Optical Coherence Tomography

      Objective Evaluation of Functionality of Filtering Bleb Based on Polarization-Sensitive Optical Coherence Tomography

      Purpose : The fibrosis score is a new diagnostic score that we have developed to evaluate the function of bleb structures after glaucoma filtration surgery using polarization-sensitive optical coherence tomography (PS-OCT). This study aims to assess the efficacy of the fibrosis score in discriminating nonfunctional from the functional blebs. Methods : A total of 20 patients who had undergone glaucoma filtration surgery were imaged at different time periods after surgery using PS-OCT. Birefringence tomography of blebs was obtained from PS-OCT, and the fibrosis score was computed for each patient. The fibrosis score is defined as the area of occupation of high birefringence ...

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    6. Repeatability of Corneal Phase Retardation Measurements by Polarization-Sensitive Optical Coherence Tomography

      Repeatability of Corneal Phase Retardation Measurements by Polarization-Sensitive Optical Coherence Tomography

      Purpose. Polarization-sensitive optical coherence tomography (PS-OCT) can evaluate internal tissue structures of the cornea, such as collagen fibers, by phase retardation measurement. In this study, we assessed the repeatability of corneal phase retardation measurements using anterior segment PS-OCT. Methods. A total of 173 eyes of 173 patients were measured using PS-OCT. In total, 58 eyes of young subjects with normal corneas, 28 eyes of old subjects with normal corneas, 26 eyes with corneal dystrophy or degeneration, 37 eyes with corneal transplantation, and 24 eyes with keratoconus were evaluated. The 3-mm diameter average of en face phase retardation of the posterior ...

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    7. Noninvasive Evaluation of Phase Retardation in Blebs after Glaucoma Surgery Using Anterior Segment Polarization-Sensitive Optical Coherence Tomography

      Noninvasive Evaluation of Phase Retardation in Blebs after Glaucoma Surgery Using Anterior Segment Polarization-Sensitive Optical Coherence Tomography

      Purpose: Evaluation of bleb morphology using anterior segment optical coherence tomography (OCT) can offer important information regarding bleb function after glaucoma surgery. However, analysis of tissue properties, such as scar fibrosis of blebs, is difficult with conventional OCT. The birefringence of the blebs as susceptible measure of fibrosis scar was evaluated using polarization-sensitive OCT (PS-OCT) and its relation with bleb function was assessed. Methods: One hundred and fifty-three blebs of 122 patients that had undergone trabeculectomy or an Ex-Press tube shunt were examined. Also, in 14 blebs of 12 patients, consecutive measurements were performed for 2 months after surgery. The ...

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    8. Bayesian maximum likelihood estimator of phase retardation for quantitative polarization-sensitive optical coherence tomography

      Bayesian maximum likelihood estimator of phase retardation for quantitative polarization-sensitive optical coherence tomography

      This paper presents the theory and numerical implementation of a maximum likelihood estimator for local phase retardation (i.e., birefringence) measured using Jones-matrix-based polarization sensitive optical coherence tomography. Previous studies have shown conventional mean estimations of phase retardation and birefringence are significantly biased in the presence of system noise. Our estimator design is based on a Bayes’ rule that relates the distributions of the measured birefringence under a particular true birefringence and the true birefringence under a particular measured birefringence. We used a Monte-Carlo method to calculate the likelihood function that describes the relationship between the distributions and numerically implement ...

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    9. 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

      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 ...

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    10. Metamorphopsia and Optical Coherence Tomography Findings After Rhegmatogenous Retinal Detachment Surgery

      Metamorphopsia and Optical Coherence Tomography Findings After Rhegmatogenous Retinal Detachment Surgery

      Purpose To investigate the relationship between metamorphopsia and macular morphologic changes after successful repair of rhegmatogenous retinal detachment (RD). Design Prospective, interventional, consecutive study. Methods The study included 129 eyes of 129 patients who had undergone successful retinal reattachment surgery. The severity of metamorphopsia was recorded using M-CHARTS and foveal microstructure was assessed with spectral-domain optical coherence tomography (OCT) at 6-12 months postoperatively. Results The mean metamorphopsia score was 0.30 ± 0.46, and 50 of 129 patients (39%) had metamorphopsia. Metamorphopsia was more severe in eyes with macula-off rhegmatogenous RD than those with macula-on ( P < .001). Eighteen of 50 ...

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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 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 ...

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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 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 ...

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    13. 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)-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 ...

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    14. Optical Rheology of Porcine Sclera by Birefringence Imaging

      Optical Rheology of Porcine Sclera by Birefringence Imaging

      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 ...

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    15. Birefringence measurement of cornea and anterior segment by office-based polarization-sensitive optical coherence tomography

      Birefringence measurement of cornea and anterior segment by office-based polarization-sensitive optical coherence tomography
      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 ...
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    16. Repeatability and reproducibility of anterior chamber volume measurements using 3-dimensional corneal and anterior segment optical coherence tomography

      Repeatability and reproducibility of anterior chamber volume measurements using 3-dimensional corneal and anterior segment optical coherence tomography
      Purpose: To evaluate the repeatability and reproducibility of anterior chamber volume (ACV) measurements using swept-source 3-dimensional corneal and anterior segment optical coherence tomography (CAS-OCT) and dual Scheimpflug imaging.Setting: Department of Ophthalmology, Institute of Clinical Medicine, University of Tsukuba, Ibaraki, Japan.Design: Nonrandomized clinical trial.Methods: Measurements were taken in normal eyes (subject group) and in eyes with primary angle closure (PAC) (patient group). In the subject group, the entire ACV and the central 8.0 mm diameter ACV were measured using CAS-OCT and dual Scheimpflug imaging. In the patient group, the entire ACV and 8.0 mm ACV were ...
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    17. Wound Architecture of Clear Corneal Incision With or Without Stromal Hydration Observed With 3-Dimensional Optical Coherence Tomography

      Wound Architecture of Clear Corneal Incision With or Without Stromal Hydration Observed With 3-Dimensional Optical Coherence Tomography
      Purpose To evaluate wound architectures of a clear corneal incision and the duration of stromal edema caused by intentional hydration in cataract surgery using 3-dimensional (3-D) cornea and anterior segment optical coherence tomography (OCT). Design Prospective, randomized study. Methods On 30 eyes of 23 patients, cataract surgery was performed through a clear corneal incision created with a 2.4-mm blade. After confirming the water tightness of the clear corneal incision at the end of surgery, 15 randomly selected eyes received stromal hydration, and the remaining 15 eyes did not. Using the 3-D cornea and anterior segment optical coherence tomography, wound ...
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    18. Visibility of trabecular meshwork by standard and polarization-sensitive optical coherence tomography

      Visibility of trabecular meshwork by standard and polarization-sensitive optical coherence tomography
      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 ...
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    19. Repeatability and reproducibility of anterior ocular biometric measurements with 2-dimensional and 3-dimensional optical coherence tomography

      Repeatability and reproducibility of anterior ocular biometric measurements with 2-dimensional and 3-dimensional optical coherence tomography
      Purpose To evaluate the repeatability and reproducibility of central corneal thickness (CCT), anterior chamber depth (ACD), and anterior chamber width (ACW) measurements using 3-dimensional (3-D) corneal and anterior segment optical coherence tomography (CAS-OCT) and 2-dimensional (2-D) anterior segment OCT (AS-OCT). Setting Department of Ophthalmology, Institute of Clinical Medicine, University of Tsukuba, Ibaraki, Japan. Design Nonrandomized clinical trial. Methods The CCT, ACD, and ACW were measured in normal eyes using a prototype 3-D swept-source CAS-OCT device and a 2-D time-domain AS-OCT device (Visante). The coefficient of repeatability and reproducibility and the intraclass correlation coefficient (ICC) were calculated to evaluate the repeatability ...
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    20. Investigation of multifocal choroiditis with panuveitis by three-dimensional high-penetration optical coherence tomography

      A single case of multifocal choroiditis with panuveitis (MFCPU) was investigated by a three-dimensional (3-D) high-penetration optical coherence tomography. The HP-OCT is based on a swept-source OCT technology, uses a probe beam with a center wavelength of 1060 nm, and possesses a depth resolution of 10.4 [mu] min tissue. Two eyes of an MFCPU patient were involved in this study. The eyes were also examined by color fundus photograph, fluorescein angiography (FA), and indocyanine green angiography (ICGA). Findings in these four modalities are comparatively discussed. The OCT scans revealed the following characteristic properties of the lesion sites. Thinning of ...
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    21. Anterior Ocular Biometry Using 3-Dimensional Optical Coherence Tomography

      Purpose: To evaluate anterior ocular biometry by comparing the measurements of central corneal thickness (CCT) and anterior chamber depth (ACD) with 3-dimensional corneal and anterior segment optical coherence tomography (CAS-OCT) and other methods. Design: Cross-sectional study.Participants: Forty eyes of 40 normal subjects.Methods: The CCT was measured by 4 methods (CAS-OCT, Scheimpflug camera, scanning-slit topography, and ultrasonic pachymetry), and the ACD was measured by 3 methods (CAS-OCT, Scheimpflug camera, and scanning-slit topography). The anterior chamber volume (ACV) was calculated with CAS-OCT. Repeatability and reproducibility of CAS-OCT measurements were evaluated.Main Outcome Measurements: The CCT and ACD were measured and ...
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    22. Evaluation of Trabeculectomy Blebs Using 3-Dimensional Cornea and Anterior Segment Optical Coherence Tomography

      Objective: To investigate the internal structures of trabeculectomy blebs using 3-dimensional cornea and anterior segment optical coherence tomography (3-D CAS OCT).Design" Observational case series.: Participants: Thirty-eight filtering blebs in 31 patients who had undergone trabeculectomy examined retrospectively. Methods: Intrableb structures were examined using 3-D CAS OCT. The blebs were classified clinically as successful (intraocular pressure [IOP] <18 mmHg without glaucoma medication) or failed. Main Outcome Measures Bleb structures were assessed in terms of the visibility of the drainage route, scleral flap, and microcysts. The length and height of the internal fluid-filled cavity, maximum and minimum bleb wall thickness, total ...
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    23. Investigation of anterior chamber angle by swept-source polarization sensitive optical coherence tomography

      An application of swept-source polarization sensitive optical coherence tomography (PS-OCT) to anterior eye is presented. The image properties of anterior eye segments in PS-OCT images are discussed. The ability of PS-OCT to visualize trabecular meshwork is evaluated. For this evaluation, 25 normal ... [Proc. SPIE 7163, 71630O (2009)] published Wed Feb 18, 2009.
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    24. Visualization of Sub-retinal Pigment Epithelium Morphologies of Exudative Macular Diseases by High-Penetration Optical Coherence Tomography

      PURPOSE. To evaluate the clinical significance of the newly developed long-wavelength probe optical coherence tomography (LP-OCT) for the diagnosis of exudative macular diseases. METHODS. Fourteen eyes of 13 participants were prospectively enrolled in the study. There were seven type I and five type II choroidal neovascularization (CNV) cases associated with age-related macular degeneration and idiopathic neovascularization and one case of polypoidal choroidal vasculopathy (PCV). A custom-built LP-OCT based on swept-source OCT (SS-OCT) technology was used. This new OCT uses a probe beam with a wavelength of 1060 nm that provides deeper penetration into the choroid and higher image contrast to ...
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    1-24 of 24
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    1. (22 articles) University of Tsukuba
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    Repeatability and reproducibility of anterior ocular biometric measurements with 2-dimensional and 3-dimensional optical coherence tomography Visibility of trabecular meshwork by standard and polarization-sensitive optical coherence tomography Wound Architecture of Clear Corneal Incision With or Without Stromal Hydration Observed With 3-Dimensional Optical Coherence Tomography Repeatability and reproducibility of anterior chamber volume measurements using 3-dimensional corneal and anterior segment optical coherence tomography Birefringence measurement of cornea and anterior segment by office-based polarization-sensitive optical coherence tomography Bayesian maximum likelihood estimator of phase retardation for quantitative polarization-sensitive optical coherence tomography Repeatability, reproducibility and agreement of foveal avascular zone measurements using three different optical coherence tomography angiography devices Subclinical hypothyroidism is associated with lipid-rich plaques in patients with coronary artery disease as assessed by optical coherence tomography Mitigation of Speckle Noise in Optical Coherence Tomograms Mapping the phase and amplitude of ossicular chain motion using sound-synchronous optical coherence vibrography Avinger Receives CE Marking Approval for Pantheris SV, a New Image-Guided Atherectomy Device Designed to Treat Smaller Vessels Phenotyping of Mouse Models with OCT