Retromode Imaging of Alterations of Retinal Pigment Epithelium on Central Serous Chorioretinopathy

Abstract

 

Purpose:

 

To propose a simple, noninvasive retro-mode imaging by scanning laser ophthalmoscope (SLO) as a novel imaging modality in detecting alteration of retinal pigment epithelium (RPE) in central serous chorioretinopathy (CSC) and to compare the findings with those obtained by angiography and spectral domain optical coherence tomography (SD OCT).

 

Methods:

 

In this prospective observational cross-sectional study, 46 eyes of 40 patients with various phases of CSC were enrolled. All patients underwent SD OCT, fluorescein angiography (FA), indocyanine green angiography (IA), and noninvasive darkfield retro-mode imaging of SLO (F-10, Nidek, Japan). We investigated the retro-mode images to evaluate the RPE status by comparing with SD OCT, FA and IA.

 

Results:

 

Patients had various phases of CSC; acute CSC (11 eyes), chronic CSC (20 eyes), atypical CSC (5 eyes) and regressed CSC (10 eyes). In FA, typical leaking patterns in 34 eyes (73.9%) and nonspecific hyperfluorescence patterns in 12 eyes (26.1%) were seen. In IA, choroidal vascular hyperpermeability were observed on the corresponding FA area in 37 eyes (80.4%). In SD OCT, subretinal fluid (SRF) in 23 eyes (50%), pigment epithelial detachment (PED) in 25 eyes (54.3%), bulges of RPE in 12 eyes (26.1%) and RPE irregularity in 29 eyes (63%) were observed on the corresponding area of angiographic images.The retro-mode imaging revealed SRF and RPE alterations such as PED, RPE bulging, RPE irregularity. The correspondence of the retromode findings with SD OCT findings reached 96.4% in SRF, 94.4% in PED, 91.0% in RPE bulging and 92.2% in RPE irregularity. The retro-mode imaging was much more sensitive in detecting subretinal and RPE abnormalities than FA and IA. Retro-mode images represented SRF as highly reflective smooth round contour, PED as relatively smooth round contour, and bulges or irregular RPE as irregular pattern of mixed hyperreflective and hyporeflective changes with rough surface. Exudation or vertex of SRF is regarded as a highly reflective focus.

 

Conclusions:

 

We propose that simple, noninvasive retro-mode imaging by SLO provides the more comprehensive topographic information of RPE alterations in CSC than SD OCT, which are barely detected in angiography.

 

Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound) • retinal pigment epithelium