OCT Angiography of the Choriocapillaris in Central Serous Chorioretinopathy: A Quantitative Subgroup Analysis

Abstract

Introduction: To quantify optical coherence tomography angiography (OCTA) signal changes at the level of the choriocapillaris (CC) in patients with different stages of central serous chorioretinopathy (CSC) and to explore any correlation between subretinal fluid (SRF) and retinal pigment epithelium (RPE) alterations and the OCTA CC signal.

Methods: One hundred one CSC eyes and 42 healthy control eyes were included in this retrospective study. CSC patients were allocated into four groups: acute, non-resolving, chronic atrophic and inactive CSC. CC OCTA images (AngioPlex^®, Zeiss) were automatically quantified using an image-processing algorithm. Spatial correlation analysis of OCTA signals was performed by overlapping macular edema heatmaps and fundus autofluorescence images with corresponding OCTA images.

Results: Active CSC subgroups demonstrated significantly more increased and decreased flow pixels in the CC compared with controls (p < 0.0001). No significant OCTA changes were seen within the active CSC groups or between the inactive and healthy subgroup. Spatial correlation analysis revealed a decreased OCTA signal in the SRF area and an increased signal outside the SRF area in acute CSC. Areas of RPE atrophy co-localized with areas of increased choriocapillaris OCTA signal, while areas with RPE alterations exhibited a normal signal compared with unaffected RPE.

Conclusion: The decreased OCTA signal in the area of SRF in acute CSC could be evidence of localized CC hypoperfusion or due to shadowing artifacts. The missing CC OCTA changes in altered RPE adjacent to atrophy argues against CC injury. Studies with higher resolution and optimized image acquisition are warranted to further validate our findings.

Keywords: Central serous chorioretinopathy; Choriocapillaris; OCT angiography.

Fig. 1

Patients with active central serous chorioretinopathy (CSC) demonstrate both increased and decreased OCTA signals at the level of the choriocapillaris (CC) compared with inactive CSC and control patients. Fundus autofluorescence (FAF, top row), OCTA image of the CC and flow pseudocoloration (middle rows) and OCTA segmentation (bottom row) of control patients (a), acute CCS (b), chronic non-resolving CSC (c), chronic atrophic CSC (d), and inactive CSC (e). f–i Increased CC OCTA signals are pseudocolored in red, decreased OCTA signals in green. Box and whisker plots demonstrating the number of pixels of decreased (f, g) and increased OCTA signal (h, i) in all patients and in CSC subgroups. Each dot represents one eye. Mann-Whitney t test (f, h) and ANOVA/Bonferroni multiple comparison test (g, i). **p < 0.01, ****p < 0.0001

Fig. 2

Patients with acute CSC demonstrate increased OCTA signals outside the area of subretinal fluid (SRF) and decreased OCTA signals in the area with SRF. Macular edema heatmap (a), corresponding OCTA image without (b) and with (c) pseudocoloration demonstrating areas of increased (green) and decreased flow (red), and a merged image (d) of a representative patient with acute CSC. Asterisks surround the area of increased SRF defined as > 450 µm macular thickness. e Box and whisker blot demonstrating the relative number of increased (red) and decreased flow (green) in the area with and without SRF. f Ratio of increased to decreased pixels (log) in areas with and without SRF. Each dot represents one eye (n = 15). ANOVA/Dunn post hoc test (e) and Mann-Whitney t test (f). ***p < 0.001, ****p < 0.0001

Fig. 3

RPE atrophy co-localizes with areas of increased choriocapillaris (CC) OCTA signal in patients with atrophic CSC, while areas revealing RPE alterations defined by increased fundus autofluorescence exhibit a normal OCTA signal. Fundus autofluorescence (FAF) image (a), FAF OCTA CC merge (b), naive (c), and pseudocolored OCTA image (d) of a representative patient with chronic atrophic CSC. Increased CC OCTA signals are pseudocolored in red, decreased OCTA signals in green. Blue asterisks surround the area of RPE atrophy, white asterisks surround the area with RPE changes. The yellow-dotted line marks the optic nerve head. e Box and whisker plots demonstrating the relative number of increased (red) and decreased flow (green) in the area with RPE atrophy, RPE alteration, and normal RPE. f Ratio of increased to decreased pixels (log) in areas with RPE atrophy, RPE alteration, and normal RPE. Each dot represents one patient (n = 6). ANOVA/Dunn post hoc test (d, e). ***p < 0.001