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M. Miura, A. E. Elsner, T. Iwasaki, M. Yamanari, T. Yatagai, Y. Yasuno; Imaging Polarimetry in Age Related Macular Degeneration. Invest. Ophthalmol. Vis. Sci. 2007;48(13):2857.
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© ARVO (1962-2015); The Authors (2016-present)
To compare scanning laser polarimetry (GDx-N) images with polarization-sensitive Fourier-domain optical coherence tomography (PS-FD-OCT) images to evaluate the polarization properties of the deep retinal lesions in age-related macular degeneration.
We prospectively examined 5 eyes of 5 patients with age related macular degeneration. To obtain the en face polarimetry images, images of 256 x 256 pixels were digitized using a GDx-N with scanning polarized light at 780 nm. A polarization modulation amplitude image was computed from the modulation of the light returning to the crossed detector in GDx-N. To obtain the depth-resolved polarimetry images, a fiber-based PS-FD-OCT system was developed. The light source is a superluminescent diode with a central wavelength of 840 nm. Two synchronized line-CCD cameras allow high-speed measurement of birefringence of retina (line rate 27.7 kHz). Fiber birefringence of the OCT system and corneal birefringence were canceled. Phase retardation and the orientation of the birefringence were measured with a Jones matrix based algorithm.
In the scanning laser polarimetry image, polarization scramble was observed at the area with exudative lesions. In the old lesions with fibrous change, polarization changes were more conspicuous than in new lesions with less fibrous change. The bow-tie appearance, which is due to the interaction of corneal and retinal birefringence, was disrupted to varying degrees. The finding of the PS-FD-OCT images corresponded well with the scanning laser polarimetry images. In PS-FD-OCT images, phase retardation was changed in exudative lesions. These polarization changes were more prominent in the old lesions with more fibrous tissue than lesions with less fibrous tissue. In some cases, polarization scrambling was observed at the retinal pigment epithelial layer.
A combination of scanning laser polarimetry and PS-FD-OCT is an effective tool to understand the polarization properties in age related macular degeneration. Both methods indicate that polarization imaging may develop into a useful, non-invasive tool for detection of active exudation that may require treatment.
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