Identification of Primary RPE Atrophy in Neovascular Age-Related Macular Degeneration Using Polarization-Sensitive Optical Coherence Tomography

Abstract

Purpose: : Anti-angiogenic therapy is an effective therapy in neovascular age-related macular (nAMD), visual function usually improves following resolution of fluid. The visual prognosis however, is limited depending on the level of concomitant RPE disease. It is the aim of this study to identify the status of the retinal pigment epithelium (RPE) pathology in patients with nAMD before and during anti-VEGF therapy using polarization sensitive spectral domain optical coherence tomography (PS-SD-OCT).

Methods: : 50 eyes of 50 patients with all angiographic types of choroidal neovascularisation (CNV) were examined in a prospective interventional case series. A PS-SD-OCT capable of measuring the degree of polarization uniformity (DOPU) in retinal tissue was used in comparison to conventional SD-OCT (Spectralis, Cirrus) to identify RPE selectively. RPE integrity maps were generated from PS-SD-OCT datasets. PS-images were correlated with autofluorescence and fluorescein angiography images.

Results: : Unlike the regular appearance of the RPE in healthy eyes, PS-SD-OCT identified irregular patterns of elevated RPE and particularly focal areas of RPE absence before treatment in >90% of cases in nAMD. The majority of patients showed more than 4 areas with RPE loss which were usually located centrally and at the margins of coexisting pigment epithelial detachments (PED), RPE defects were located and delineated over a 3-month follow-up period. Based on PS-SD-OCT image series, characteristic patterns of the RPE could be demarcated and displayed as topographic en face maps demonstrating a realistic three-dimensional morphology of the RPE. Absence of RPE in PS-SD-OCT was found to correlate with atrophy of the overlying retina and was responsible for lack in visual improvement during treatment.

Conclusions: : Advanced RPE atrophy is found in the majority of patients with exudative AMD. Despite successful resolution of edema with anti-VEGF therapy, RPE disease persists and may progress and is a limiting factor for visual prognosis. PS-SD-OCT allows for the first time to identify the level of RPE disease qualitatively and quantitatively.

Keywords: age-related macular degeneration • retinal pigment epithelium • imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)