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Yoshiaki Yasuno – 1st expert on this subject based on the ideXlab platform

  • Birefringence measurement of cornea and anterior segment by office based polarization sensitive optical coherence tomography
    Biomedical Optics Express, 2011
    Co-Authors: Masahiro Yamanari, Shinichi Fukuda, Yuichi Kaji, Takahiro Kiuchi, Masahiro Miura, Tetsuro Oshika, Yoshiaki Yasuno


    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 abnormal Birefringence in the cornea was likely to be an indication of cross-linking of collagen fibrils. The measurement of rabbit showed abnormal Birefringence in the scarring eyes. Wide regions of strong Birefringence were observed in the eyes of trabeculectomy patients who had high intraocular pressure. Visualization of scarring in bleb by PS-OCT may be useful for the planning of secondary surgery. PS-OCT showed promising for the study and diagnosis diseases related to abnormal fibrous tissues of the cornea and anterior eye segment.

Johannes F De Boer – 2nd expert on this subject based on the ideXlab platform

  • thickness and Birefringence of healthy retinal nerve fiber layer tissue measured with polarization sensitive optical coherence tomography
    Investigative Ophthalmology & Visual Science, 2004
    Co-Authors: Barry Cense, Teresa C Chen, Hyle B Park, Mark C Pierce, Johannes F De Boer


    PURPOSE: Thinning of the retinal nerve fiber layer and changes in retinal nerve fiber layer (RNFL) Birefringence may both precede clinically detectable glaucomatous vision loss. Early detection of RNFL changes may enable treatment to prevent permanent loss of vision. Polarization-sensitive optical coherence tomography (PS-OCT) can provide objective information on RNFL thickness and Birefringence. METHODS: PS-OCT scans around the optic nerve head (ONH) of two healthy young volunteers were made using 10 concentric circles of increasing radius. Both the mean RNFL thickness and mean retinal nerve fiber Birefringence for each of 48 sectors on a circle were determined with data analysis. RESULTS: Both the RNFL thickness and Birefringence varied as a function of sector around the ONH. The RNFL became thinner with increasing distance from the ONH. In contrast, the Birefringence did not vary significantly as a function of radius. CONCLUSIONS: Birefringence of healthy RNFL is constant as a function of scan radius but varies as a function of position around the ONH, with higher thickness values occurring superior and inferior to the ONH. Measured double-pass phase retardation per unit depth around the ONH ranged between 0.10 and 0.35 deg/microm, equivalent to Birefringences of 1.2 x 10(-4) and 4.1 x 10(-4) respectively, measured at a wavelength of 840 nm. Consequently, when a spatially constant Birefringence around the ONH is assumed, the conversion of scanning laser polarimetry (SLP) phase-retardation measurements to RNFL thickness may yield incorrect values. The data do not invalidate the clinical value of a phase-retardation measurement, but affect the conversion of phase retardation to RNFL thickness.

Matthew E. Reid – 3rd expert on this subject based on the ideXlab platform

  • Origin of Birefringence in Wood at Terahertz Frequencies
    IEEE Transactions on Terahertz Science and Technology, 2012
    Co-Authors: Tara M. Todoruk, Ian D. Hartley, Matthew E. Reid


    In the wood products industry, terahertz (THz) radiation is showing promise for new types of sensing and imaging applications, which depend on the ability of THz radiation to probe the gross fiber structure of wood. The sensitivity to this gross fiber structure is a result of the strong Birefringence of wood at THz frequencies. Wood is a complex structure, and the large Birefringence observed may be due to either intrinsic or form Birefringence. In this paper, the origin of Birefringence in wood at THz frequencies is examined in detail. Although the source of Birefringence varies according to species, the trend shows contributions from both types of Birefringence. This has implications for application development in the wood products industry, where the possibility of probing both the gross physical structure of wood and wood products, and the intrinsic properties of wood such as crystallinity and microfibril angle, simultaneously may allow for nondestructive noncontact strength testing of wood and composite wood products.