Purpose: To investigate a depolarizing layer that is visible in polarization-sensitive optical coherence tomography (PS-OCT) images of the retina. To identify this layer and characterize its depolarizing effect quantitatively.
Methods: Ten healthy human subjects (mean age, 31 +/- 8 years) and two patients with RPE diseases participated in the study. The macular region of one eye of each subject was investigated with a phase-resolved PS-OCT system. The instrument measured backscattered intensity (standard OCT), phase retardation, and (cumulative) birefringent axis orientation, simultaneously. For a quantification of the depolarizing layer, plots of the distributions of retardation and axis orientation within and above this layer were analyzed.
Results: A polarization-scrambling layer (PSL) was observed at the posterior boundary of the retina in PS-OCT images of all volunteers. It was identified in PS-OCT images by determining random retardation and axis orientation in a transverse direction. Measurements in patients with neurosensory retinal detachment, retinal pigment epithelium (RPE) detachment, and RPE atrophy suggest that the PSL is the RPE. The statistical analysis provided objective discrimination of the RPE from the other retinal structures.
Conclusions: PS-OCT represents a powerful tool for increasing image contrast in ocular tissues. The observed polarization-scrambling nature of the RPE may be used in diseased eyes to locate the RPE or remains of the RPE definitively in OCT images.