Abstract
Purpose: :
To demonstrate the performance of a new imaging technology combining a state–of–the–art spectral domain optical coherence tomography (OCT) system with a polarization sensitive detection unit to obtain depth–resolved polarization sensitive images of the human retina in three dimensions.
Methods: :
A new polarization sensitive spectral domain OCT system was developed (center wavelength 840 nm, bandwidth 50 nm, depth resolution in tissue: 4–5 µm). Polarization sensitive information is achieved by a two–channel polarization sensitive detection unit consisting of a polarizing beam splitter and two spectrometers operating in parallel at 20000 A–lines/s each. A phase sensitive recording provides three parameters simultaneously: reflectivity, retardation, and optic axis orientation. Recording time for a full 3D data set was 3 seconds. Imaging was performed in the macula and nerve head region of healthy subjects.
Results: :
Several polarization changing structures were identified and imaged. Birefringent structures observed comprise the retinal nerve fiber layer, Henle's fiber layer, the rim of the scleral canal, and the lamina cribrosa. The retinal pigment epithelium shows a pronounced depolarizing effect.
Conclusions: :
Polarization sensitive OCT provides an additional contrast mechanism yielding more information than conventional intensity based OCT. The spectral domain implementation of polarization sensitive OCT provides 3D images of human retinal structures with short acquisition time.
Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • retina • optic disc