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E. Götzinger, M. Pircher, C.C. Hitzenberger; In vivo High Speed Polarization Sensitive Spectral Domain OCT of the Anterior Chamber . Invest. Ophthalmol. Vis. Sci. 2006;47(13):2952.
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© ARVO (1962-2015); The Authors (2016-present)
To demonstrate the capability of spectral domain polarization sensitive OCT (SD–PS–OCT) to measure and image the 3D– distribution of retardation and optic axis orientation of the human anterior chamber in vivo.
We developed a high–speed SD–PS–OCT system. The system uses two spectrometers, one for each polarization channel, that operate in parallel at 20000 A–lines/s each. It provides reflectivity, retardation, and cumulative optic axis orientation simultaneously. This instrument was used to obtain 3D SD–PS–OCT data sets of normal human anterior chamber in vivo. From the 3D data sets, conventional cross sectional, as well as en face sectional images of reflectivity, retardation, and optic axis orientation were derived.
The cornea is birefringent, its retardation increases in radial direction, the optic axis orientation changes linearly with azimuth angle. Since the upper layers of the iris preserve the incoming polarization state, the polarization patterns observed from this part of the iris correspond to those generated by the cornea. The signal and image quality obtained from the iris is superior to that obtained directly from the cornea. The posterior layer (pigment epithelium) of the iris depolarizes backscattered light.
Our SD–PS–OCT setup can image the birefringent properties of the anterior chamber in vivo. The polarization properties of the cornea can be derived from measurements in the iris–lens plane with better quality than from light directly backscattered from the cornea. The polarization properties of the anterior eye segment might be of great interest for diagnosis of different kind of diseases, for example keratoconus or corneal scars.
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