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Scanning laser polarimetry
Last reviewed: 11.04.2020
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[How Scanning Laser Polarimetry Works
The advantage of GDx (Laser Dia gnostic Technologies, San Diego, CA) - in the property of the interaction of polarized light with a tissue having the ability to birefringence, which makes it possible to measure the thickness of the START. This method is based on the principle of the appearance of changes in polarized light in the case of a birefringence of SNV, known as retardation. This deceleration linearly depends on the thickness and optical properties of the START. Polarized light from a near-infrared diode source at 780 nm is focused at one point of the retina. Polarized light penetrates through the START and is partially reflected from its deep layers back. The polarization state of the reflected light is analyzed using digital technologies. The stationary compensator device neutralizes the mean birefringence of the anterior segment. Data on the retardation of 65,536 individual retinal segments (256 by 256 pixels) occupying 15 ° are obtained from a circular line concentric to the disk, 1.5 by 2.5 times its diameter. Each pixel is quantitatively illustrated with yellow or white for a large deceleration and dark blue for a small deceleration.
Restrictions
The cornea and the lens are structures with significant birefringence, which introduces changes in retardation and leads to inaccurate measurements of the thickness of the START. In addition, the amount of retardation (retardation) displays a more relative rather than an absolute indicator of the thickness of the strategic offensive arms. The imposition of non-retinal (corneal and lenticular) birefringence on the measurement of the SNB thickness with scanning laser polarimetry is an obstacle to the wide application of this study. The user needs to determine the size of the ellipse.