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Tilman Schmoll, Erich Götzinger, Angelika Unterhuber, Amardeep S. Singh, Michael Pircher, Christoph K. Hitzenberger, Rainer A. Leitgeb; Ultra-high Speed Polarization Sensitive OCT In The Human Retina Using A Single Spectrometer. Invest. Ophthalmol. Vis. Sci. 2011;52(14):1324.
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© ARVO (1962-2015); The Authors (2016-present)
To use polarization sensitive optical coherence tomography (PSOCT) for imaging the human retina with ultra-high speed and high lateral resolution, while gaining depth resolved information on its polarization properties.
We present a PSOCT system that is capable of retrieving, with a single camera, both retardation and optical axis orientation images. The method is based on a differentiation between orthogonal polarization channels through spatial modulation introduced by an electro-optic modulator. In post processing, the spatial spectra are bandpass filtered, in order to extract the orthogonal polarization components. Those components are therefore recorded virtually in parallel allowing for high quality reconstruction of retardation and optics axis orientation. The presented setup enables recording PSOCT 3D volumes of the human retina at line rates of up to 160.000 A-scans per second, while maintaining good sensitivity. At this speed motion artifacts, by involuntary eye motion are reduced to a minimum. Combining the ultra-high speed acquisition with the high-transverse and axial resolution of OCT, enables resolving microscopic retinal structures, such as the cone photoreceptor mosaic or individual nerve fiber bundles.
As a proof of principle, we acquired high-speed motion artifact free 3D PSOCT volumes of the fovea and optic disc. These images reveal comprehensively the retardation introduced by the retinal nerve fiber layer (RNFL) and the Henle’s fiber, as well as the depolarizing effect of the RPE. We then focused the ultra-high speed PSOCT system on individual nerve fiber bundles around the fovea, and revealed them within the intensity volumes.
To the best of our knowledge, we presented the fastest polarization sensitive OCT measurements in the human retina, and in general. The capability of our high-speed system, to resolve microscopic retinal features, such as individual nerve fiber bundles, gives us motivation for further investigations concerning the polarization contrast of such microscopic features.
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