Spectral-Domain and Polarization-Sensitive Optical Coherence Tomography Findings in Pigmented Choroidal Lesions

Abstract

Purpose: : To characterize changes of the retinal pigment epithelium and associated structures in eyes with benign chorioretinal lesions and suspected choroidal melanomas with conventional spectral-domain and polarization-sensitive optical coherence tomography (OCT).

Methods: : 15 eyes of 15 patients with pigmented chorioretinal lesions were imaged using conventional spectral-domain OCT (Cirrus HD-OCT, Carl-Zeiss Meditec, Inc. and Spectralis OCT, Heidelberg Engineering, Inc) with high-resolution single-line scans as well as volumetric scan modes. Spectral domain polarization-sensitive OCT was used to additionally investigate retardation, birefringent axis orientation and degree of polarization uniformity (DOPU) characteristics of the respective lesions.

Results: : We were able to image all pigmented lesions in the full lateral extension. Irregularities of the retinal pigment epithelium such as drusen could be identified in detail. Subretinal fluid and thickening of the choriocapillary layer could be shown. Additionally, the polarization scrambling characteristics of pigmented structures (e.g. RPE, lesion) could be visualized in DOPU images that can be used to clearly demarcate the lesions and the RPE from other retinal tissue. Enlargement of lesions could therefore be monitored in close detail.

Conclusions: : Both SD- and PS-OCT modalities contribute to a detailed monitoring of patients with pigmented choroidal lesions. Although commercial SD-OCT systems do currently not allow for a full penetration of the choroid, small changes of associated retinal pigment epithelium and thickening of the choroid can be closely followed. PS-OCT provides additional contrast between pigmented and non pigmented tissue, which therefore represents a unique imaging modality to characterize these structures.

Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • choroid • tumors