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Zeinab Ghassabi - One of the best experts on this subject based on the ideXlab platform.

  • the fovea bmo Axis Angle and macular thickness vertical asymmetry across the temporal raphe
    Journal of Glaucoma, 2018
    Co-Authors: Zeinab Ghassabi, Andrew Nguyen, Navid Amini, Sharon Henry, Joseph Caprioli, Kouros Nourimahdavi
    Abstract:

    PURPOSE To test the hypothesis that the fovea-Bruch's membrane opening (FoBMO) Axis Angle influences the thickness symmetry of the macular ganglion cell/inner plexiform layer (GCIPL) across the temporal horizontal meridian in normal subjects. DESIGN Cross-sectional diagnostic study at a tertiary academic center. METHODS One hundred sixteen eyes of 60 normal subjects aged 40 to 85 years underwent spectral domain optical coherence tomography(SD-OCT) imaging. The FoBMO Angle was estimated on en face infrared SD-OCT images. Posterior Pole algorithm images acquired with Spectralis SD-OCT were used to define vertical asymmetry as follows. The average thickness difference between the 3 most temporal superpixels above and below the horizontal meridian, the second row of superpixels from the horizontal meridian, and 3 central superpixels above and below the horizontal meridian were calculated. Factors influencing GCIPL thickness asymmetry were explored and changes in thickness asymmetry as a function of FoBMO Angle were investigated. RESULTS No demographic or clinical factors affected temporal GCIPL asymmetry (P>0.05 for all). A more (negatively) tilted FoBMO Angle was associated with relatively thinner inferior compared with superior GCIPL thickness in superpixels immediately adjacent to the temporal raphe (P<0.001). The second row of temporal superpixels from the horizontal meridian (P=0.349) or central superpixels (P=0.292) did not show this tendency. CONCLUSIONS Vertical GCIPL symmetry across the horizontal meridian is influenced by the FoBMO Angle. SD-OCT algorithms using vertical asymmetry as a diagnostic index should be adjusted for the FoBMO Angle.

  • The Fovea-BMO Axis Angle and Macular Thickness Vertical Asymmetry Across The Temporal Raphe.
    Journal of glaucoma, 2018
    Co-Authors: Zeinab Ghassabi, Andrew Nguyen, Navid Amini, Sharon Henry, Joseph Caprioli, Kouros Nouri-mahdavi
    Abstract:

    PURPOSE To test the hypothesis that the fovea-Bruch's membrane opening (FoBMO) Axis Angle influences the thickness symmetry of the macular ganglion cell/inner plexiform layer (GCIPL) across the temporal horizontal meridian in normal subjects. DESIGN Cross-sectional diagnostic study at a tertiary academic center. METHODS One hundred sixteen eyes of 60 normal subjects aged 40 to 85 years underwent spectral domain optical coherence tomography(SD-OCT) imaging. The FoBMO Angle was estimated on en face infrared SD-OCT images. Posterior Pole algorithm images acquired with Spectralis SD-OCT were used to define vertical asymmetry as follows. The average thickness difference between the 3 most temporal superpixels above and below the horizontal meridian, the second row of superpixels from the horizontal meridian, and 3 central superpixels above and below the horizontal meridian were calculated. Factors influencing GCIPL thickness asymmetry were explored and changes in thickness asymmetry as a function of FoBMO Angle were investigated. RESULTS No demographic or clinical factors affected temporal GCIPL asymmetry (P>0.05 for all). A more (negatively) tilted FoBMO Angle was associated with relatively thinner inferior compared with superior GCIPL thickness in superpixels immediately adjacent to the temporal raphe (P

Jing-fung Lin - One of the best experts on this subject based on the ideXlab platform.

  • Measurement of linear birefringence using a rotating-wave-plate Stokes polarimeter
    Optik, 2010
    Co-Authors: Jing-fung Lin
    Abstract:

    Abstract In this study, a compact polarimeter is developed to measure the linear birefringence property of optical materials. The principal Axis Angle and the retardance are obtained by a simple signal-processing algorithm, which is derived via Stokes parameters extractions when using an incident light linearly polarized at 45°. There exists an absolute error of 0.0296° on average in the principal Axis Angle measurement and a relative error of 2.54% in the retardance measurement of a quarter-wave-plate sample with its principal Axis ranging from −40° to 40°. The standard deviations for the principal Axis Angle and retardance measurements are determined to be 0.015° and 0.018°, respectively, while one standard deviation to the average value of the principal Axis Angle and retardance, respectively, are just 0.066% and 0.020% with high repeatability, and corresponding dynamic ranges of −45° to 45° and −180° to 180°, respectively. Consequently, the developed polarimeter has a potential in linear birefringence measurement, especially in the retardance measurement.

  • The optical linear birefringence measurement using a Zeeman laser
    Optics Communications, 2007
    Co-Authors: Jing-fung Lin, Te-tan Liao, Sen Yung Lee
    Abstract:

    In the paper we present a new optical system that uses a transverse Zeeman dual-frequency laser in conjunction with plane polariscope for simultaneously measuring both the principal Axis Angle and the retardance of the optical linearly birefringent materials. The Zeeman laser produces a standard heterodyne signal as a polarizer is set in front of a photodetector. Owing to the use of a Zeeman laser and design of optical configuration, the measurement system has the advantages of compact structure, low non-linearity, high stability, and good portability. By using the amplitudes of a reference signal and of two measuring signals, a simply derived algorithm can obtain the principal Axis Angle and the retardance directly and easily. The dynamic range of the principal Axis Angle measurement is limited in the range from 0° to 90° and that of the retardance measurement is extended to be 180° successfully. According to the measurement results, the average absolute errors of the principal Axis Angle and the retardance measurements for a quarter-wave plate with its principal Axis Angle set at 90° are determined to be 1.47° and 2.85%, respectively. The absolute error of the retardance measurement is within the uncertainty range of 5% or more for commercial quarter-wave plates.

  • The new circular heterodyne interferometer with electro-optic modulation for measurement of the optical linear birefringence
    Optics Communications, 2006
    Co-Authors: Jing-fung Lin
    Abstract:

    Abstract We present a new circular heterodyne interferometer with electro-optic modulation for measurement of the optical linear birefringence. It enables the measurement of not only the phase retardation but also the principal Angle. The measurement procedure is carried out in two steps. In the first step of measurements, we use the electro-optic modulated circular heterodyne interferometer and the phase-lock technique to precisely measure the principal Axis Angle. After rotating the analyzer in the setup, the phase retardation is determined also by the phase-lock technique. The compact configuration requires only a photodetector and two simple phase-lock extractions to determine the principal Axis Angle and the phase retardation. The validity of the proposed design is demonstrated by measurement of the principal Axis Angle and phase retardation of a quarter-wave plate sample. The root-mean-square resolutions for the principal Axis Angle and phase retardation are found to be 0.0396° and 0.0796°, respectively, with corresponding dynamic ranges of 0–180° and 0–180°.

  • measurements of phase retardation and principal Axis Angle using an electro optic modulated mach zehnder interferometer
    Optics and Lasers in Engineering, 2005
    Co-Authors: Sen Yung Lee, Jing-fung Lin
    Abstract:

    Abstract This paper presents an electro-optic modulated circular heterodyne modified Mach–Zehnder interferometer and a convenient two-phase signal-processing algorithm for the measurement of variations in the magnitude of phase retardation and the Angle of principal Axis in optical materials. The developed method solves the problems of normalized intensity jump and limited phase retardation measurement range associated with the circular heterodyne interferometer proposed previously. The present method uses a saw-tooth wave signal to drive an electro-optic (EO) modulator, and employs a lock-in amplifier to demodulate the principal Axis Angle and the phase retardation. Specifically, this paper considers two main sources of measurement errors, namely the misorientation of the EO modulator and the reflection phase retardation of the beam splitter. Furthermore, the study develops calibration procedures and identifies a means to minimize measurement errors induced by the reflection phase retardation of the beam splitter.

  • Measurements of the principal Axis and phase retardation using a new circular polariscope and the Senarmont setup
    2005
    Co-Authors: Jing-fung Lin, Sen Yung Lee, Chi Cheng Peng
    Abstract:

    Measurements of the principal Axis and phase retardation using a new circular polariscope and the Senarmont setup with electro-optic modulation is presented. In the first step of measurements, we use the electro-optic modulated circular heterodyne interferometer and the phase-lock technique to precisely measure the principal Axis Angle. After removing the first quarter-wave plate in the first setup, a Senarmont setup is designed to determine the phase retardation also using the phase-lock technique. The simple phase extraction algorithm for the principal Axis Angle and the phase retardation measurement is presented. The average absolute errors of the principal Axis Angle and the phase retardation of the λ/8-wave plate are determined to be only 0.4680 and 0.23%.© (2005) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

Kouros Nourimahdavi - One of the best experts on this subject based on the ideXlab platform.

  • the fovea bmo Axis Angle and macular thickness vertical asymmetry across the temporal raphe
    Journal of Glaucoma, 2018
    Co-Authors: Zeinab Ghassabi, Andrew Nguyen, Navid Amini, Sharon Henry, Joseph Caprioli, Kouros Nourimahdavi
    Abstract:

    PURPOSE To test the hypothesis that the fovea-Bruch's membrane opening (FoBMO) Axis Angle influences the thickness symmetry of the macular ganglion cell/inner plexiform layer (GCIPL) across the temporal horizontal meridian in normal subjects. DESIGN Cross-sectional diagnostic study at a tertiary academic center. METHODS One hundred sixteen eyes of 60 normal subjects aged 40 to 85 years underwent spectral domain optical coherence tomography(SD-OCT) imaging. The FoBMO Angle was estimated on en face infrared SD-OCT images. Posterior Pole algorithm images acquired with Spectralis SD-OCT were used to define vertical asymmetry as follows. The average thickness difference between the 3 most temporal superpixels above and below the horizontal meridian, the second row of superpixels from the horizontal meridian, and 3 central superpixels above and below the horizontal meridian were calculated. Factors influencing GCIPL thickness asymmetry were explored and changes in thickness asymmetry as a function of FoBMO Angle were investigated. RESULTS No demographic or clinical factors affected temporal GCIPL asymmetry (P>0.05 for all). A more (negatively) tilted FoBMO Angle was associated with relatively thinner inferior compared with superior GCIPL thickness in superpixels immediately adjacent to the temporal raphe (P<0.001). The second row of temporal superpixels from the horizontal meridian (P=0.349) or central superpixels (P=0.292) did not show this tendency. CONCLUSIONS Vertical GCIPL symmetry across the horizontal meridian is influenced by the FoBMO Angle. SD-OCT algorithms using vertical asymmetry as a diagnostic index should be adjusted for the FoBMO Angle.

Kouros Nouri-mahdavi - One of the best experts on this subject based on the ideXlab platform.

  • The Fovea-BMO Axis Angle and Macular Thickness Vertical Asymmetry Across The Temporal Raphe.
    Journal of glaucoma, 2018
    Co-Authors: Zeinab Ghassabi, Andrew Nguyen, Navid Amini, Sharon Henry, Joseph Caprioli, Kouros Nouri-mahdavi
    Abstract:

    PURPOSE To test the hypothesis that the fovea-Bruch's membrane opening (FoBMO) Axis Angle influences the thickness symmetry of the macular ganglion cell/inner plexiform layer (GCIPL) across the temporal horizontal meridian in normal subjects. DESIGN Cross-sectional diagnostic study at a tertiary academic center. METHODS One hundred sixteen eyes of 60 normal subjects aged 40 to 85 years underwent spectral domain optical coherence tomography(SD-OCT) imaging. The FoBMO Angle was estimated on en face infrared SD-OCT images. Posterior Pole algorithm images acquired with Spectralis SD-OCT were used to define vertical asymmetry as follows. The average thickness difference between the 3 most temporal superpixels above and below the horizontal meridian, the second row of superpixels from the horizontal meridian, and 3 central superpixels above and below the horizontal meridian were calculated. Factors influencing GCIPL thickness asymmetry were explored and changes in thickness asymmetry as a function of FoBMO Angle were investigated. RESULTS No demographic or clinical factors affected temporal GCIPL asymmetry (P>0.05 for all). A more (negatively) tilted FoBMO Angle was associated with relatively thinner inferior compared with superior GCIPL thickness in superpixels immediately adjacent to the temporal raphe (P

Joseph Caprioli - One of the best experts on this subject based on the ideXlab platform.

  • the fovea bmo Axis Angle and macular thickness vertical asymmetry across the temporal raphe
    Journal of Glaucoma, 2018
    Co-Authors: Zeinab Ghassabi, Andrew Nguyen, Navid Amini, Sharon Henry, Joseph Caprioli, Kouros Nourimahdavi
    Abstract:

    PURPOSE To test the hypothesis that the fovea-Bruch's membrane opening (FoBMO) Axis Angle influences the thickness symmetry of the macular ganglion cell/inner plexiform layer (GCIPL) across the temporal horizontal meridian in normal subjects. DESIGN Cross-sectional diagnostic study at a tertiary academic center. METHODS One hundred sixteen eyes of 60 normal subjects aged 40 to 85 years underwent spectral domain optical coherence tomography(SD-OCT) imaging. The FoBMO Angle was estimated on en face infrared SD-OCT images. Posterior Pole algorithm images acquired with Spectralis SD-OCT were used to define vertical asymmetry as follows. The average thickness difference between the 3 most temporal superpixels above and below the horizontal meridian, the second row of superpixels from the horizontal meridian, and 3 central superpixels above and below the horizontal meridian were calculated. Factors influencing GCIPL thickness asymmetry were explored and changes in thickness asymmetry as a function of FoBMO Angle were investigated. RESULTS No demographic or clinical factors affected temporal GCIPL asymmetry (P>0.05 for all). A more (negatively) tilted FoBMO Angle was associated with relatively thinner inferior compared with superior GCIPL thickness in superpixels immediately adjacent to the temporal raphe (P<0.001). The second row of temporal superpixels from the horizontal meridian (P=0.349) or central superpixels (P=0.292) did not show this tendency. CONCLUSIONS Vertical GCIPL symmetry across the horizontal meridian is influenced by the FoBMO Angle. SD-OCT algorithms using vertical asymmetry as a diagnostic index should be adjusted for the FoBMO Angle.

  • The Fovea-BMO Axis Angle and Macular Thickness Vertical Asymmetry Across The Temporal Raphe.
    Journal of glaucoma, 2018
    Co-Authors: Zeinab Ghassabi, Andrew Nguyen, Navid Amini, Sharon Henry, Joseph Caprioli, Kouros Nouri-mahdavi
    Abstract:

    PURPOSE To test the hypothesis that the fovea-Bruch's membrane opening (FoBMO) Axis Angle influences the thickness symmetry of the macular ganglion cell/inner plexiform layer (GCIPL) across the temporal horizontal meridian in normal subjects. DESIGN Cross-sectional diagnostic study at a tertiary academic center. METHODS One hundred sixteen eyes of 60 normal subjects aged 40 to 85 years underwent spectral domain optical coherence tomography(SD-OCT) imaging. The FoBMO Angle was estimated on en face infrared SD-OCT images. Posterior Pole algorithm images acquired with Spectralis SD-OCT were used to define vertical asymmetry as follows. The average thickness difference between the 3 most temporal superpixels above and below the horizontal meridian, the second row of superpixels from the horizontal meridian, and 3 central superpixels above and below the horizontal meridian were calculated. Factors influencing GCIPL thickness asymmetry were explored and changes in thickness asymmetry as a function of FoBMO Angle were investigated. RESULTS No demographic or clinical factors affected temporal GCIPL asymmetry (P>0.05 for all). A more (negatively) tilted FoBMO Angle was associated with relatively thinner inferior compared with superior GCIPL thickness in superpixels immediately adjacent to the temporal raphe (P