24 February 2009 Fundus depolarization imaging with GDx VCC scanning laser polarimeter and depolarization characteristics of normal eyes
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Proceedings Volume 7163, Ophthalmic Technologies XIX; 71630L (2009); doi: 10.1117/12.809308
Event: SPIE BiOS, 2009, San Jose, California, United States
Abstract
GDx VCC is a confocal scanning laser polarimeter (SLP) developed to assess the retinal nerve fiber layer (RNFL) of the eye based on measurement of the phase retardation in the backscattered light from the fundus. In addition to the phase retardation measurement, a depolarization measurement is readily available from the same image series. We hypothesize that the depolarized light in the GDx signal consists of backscattering from the retinal pigment epithelium (RPE) and the RPE-Bruch's membrane junction, and further, that subRPE deposits contribute to the depolarized backscattered light in proportion to their thickness. Therefore, a quantitative macular depolarization map will provide information about both spatial distribution and heterogeneity of the RPE structure and deposit thickness. Ultimately we predict that depolarization mapping will significantly increase the positive predictive power to identify early dry AMD eyes. In this paper, depolarization measurements in normal eyes and age related changes are reported. Data collection was performed at the Duke University Eye Center. A commercial GDx VCC system was modified with a central fixation target and, instead of depolarized light intensity images, normalized depolarization images were derived and saved in the database. Macular depolarization was observed to increase with age in normal eyes at a rate of 0.27%/yr.
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Qienyuan Zhou, Henry A. Leder, Barrick P.-W. Lo, Geradus C. Reed, Robert W. Knighton, Scott W. Cousins, "Fundus depolarization imaging with GDx VCC scanning laser polarimeter and depolarization characteristics of normal eyes", Proc. SPIE 7163, Ophthalmic Technologies XIX, 71630L (24 February 2009); doi: 10.1117/12.809308; http://dx.doi.org/10.1117/12.809308
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KEYWORDS
Eye

Phase measurement

Reflectivity

Voltage controlled current source

Polarimetry

Image visualization

Backscatter

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