En face enhanced-depth swept-source optical coherence tomography features of chronic central serous chorioretinopathy

Abstract

Objective: To characterize en face features of the retinal pigment epithelium (RPE) and choroid in eyes with chronic central serous chorioretinopathy (CSCR) using a high-speed, enhanced-depth swept-source optical coherence tomography (SS-OCT) prototype.

Design: Consecutive patients with chronic CSCR were prospectively examined with SS-OCT.

Participants: Fifteen eyes of 13 patients.

Methods: Three-dimensional 6×6 mm macular cube raster scans were obtained with SS-OCT operating at 1050 nm wavelength and 100000 A-lines/sec with 6 μm axial resolution. Segmentation of the RPE generated a reference surface; en face SS-OCT images of the RPE and choroid were extracted at varying depths every 3.5 μm (1 pixel). Abnormal features were characterized by systematic analysis of multimodal fundus imaging, including color photographs, fundus autofluorescence, fluorescein angiography, and indocyanine-green angiography (ICGA).

Main outcome measures: En face SS-OCT morphology of the RPE and individual choroidal layers.

Results: En face SS-OCT imaging at the RPE level revealed absence of signal corresponding to RPE detachment or RPE loss in 15 of 15 (100%) eyes. En face SS-OCT imaging at the choriocapillaris level showed focally enlarged vessels in 8 of 15 eyes (53%). At the level of Sattler's layer, en face SS-OCT documented focal choroidal dilation in 8 of 15 eyes (53%) and diffuse choroidal dilation in 7 of 15 eyes (47%). At the level of Haller's layer, these same features were observed in 3 of 15 eyes (20%) and 12 of 15 eyes (80%), respectively. In all affected eyes, these choroidal vascular abnormalities were seen just below areas of RPE abnormalities. In 2 eyes with secondary choroidal neovascularization (CNV), distinct en face SS-OCT features corresponded to the neovascular lesions.

Conclusions: High-speed, enhanced-depth SS-OCT at 1050 nm wavelength enables the visualization of pathologic features of the RPE and choroid in eyes with chronic CSCR not usually appreciated with standard spectral domain (SD) OCT. En face SS-OCT imaging seems to be a useful tool in the identification of CNV without the use of angiography. This in vivo documentation of the RPE and choroidal vasculature at variable depths may help elucidate the pathophysiology of disease and can contribute to the diagnosis and management of chronic CSCR.

Figure 1

Patient with chronic central serous chorioretinopathy in both eyes and a small pigment epithelium detachment (PED) close to the fovea in the right eye. Red-free image (A) and fluorescein angiography (B) show a focal change in the retinal pigment epithelium (RPE), while indocyanine-green angiography (C) shows an area of focal hyperfluorescence in the topography of the PED, and widespread hyperfluorescence suggesting increased choroidal permeability. En face swept-source optical coherence tomography (SS-OCT) image at the level of the RPE layer (D) reveals a small, focal hyporeflective area correspondent to the PED. En face SS-OCT imaging at the level of the choriocapillaris 40 μm bellow the RPE (E) is unremarkable; and at the level of large choroidal vessels 190 μm bellow the RPE (F) reveals diffuse choroidal dilation. The white area in the en face OCT image (F) shows the choroidal-scleral interface.

Figure 2

Patient with chronic central serous chorioretinopathy and serous neurosensory retinal detachment evident on red-free fundus image (A). Fluorescein angiography (B) reveals two hyperfluorescent areas; the superior one corresponding to a pigment epithelium detachment (PED) and the inferior one corresponding to dye leakage in the “ink dot sign” typical of the disease. Late-phase indocyanine-green angiography (C) shows a hyperfluorescent spot in this same topography, surrounded by multifocal choroidal hyperfluorescence. En face swept-source optical coherence tomography (SS-OCT) image 30 μm above the retinal pigment epithelium (RPE) level (D) with dark areas corresponding to subretinal or sub-RPE fluid; the large area with “smooth” borders corresponds to the serous neurosensory retinal detachment, while the two small areas with a distinct white hale corresponds to PEDs. En face SS-OCT image at the RPE level (E) revealing RPE defects at the topography of the PEDs; and 30 μm bellow the RPE level (F) with a focal dilation in the choriocapillaris at the same topography of the central lesion. Cross-sectional b-scans from the areas indicated in A, respectively, showing the PED superior to the fovea (G); the serous neurosensory retinal detachment involving the fovea (H); and the central PED within the retinal detachment (I).

Figure 5

Patient with chronic central serous chorioretinopathy and subretinal fibrosis due to secondary choroidal neovascularization (CNV), evident on red-free fundus image (A). Fluorescein angiography (B) documents widespread retinal pigment epithelium (RPE) changes around the fibrosis, which blocks the background fluorescence. Middle-phase indocyanine-green angiography (C) suggests a polypoidal-like neovascular lesion. En face swept-source optical coherence tomography (SS-OCT) image at the level of the RPE (D) reveals the neovascular network extending from the fibrosis. En face SS-OCT image 25 μm bellow the RPE (E) reveal distinct focal choroidal dilation at the level of the choriocapillaris; while diffuse choroidal dilation was observed on medium and large vessels layers as seen on a en face OCT image at 250 μm bellow the RPE level (F).

Figure 6

Patient with chronic central serous chorioretinopathy and subfoveal secondary choroidal neovascularization (CNV) evident on red-free fundus image (A). Fluorescein angiography (B) shows the hyperfluorescent active CNV, which appears as a hyperfluorescent spot in the late-phase indocyanine-green angiography (C). En face swept-source optical coherence tomography (SS-OCT) image 30 μm above the RPE (D) delineates the area of subretinal fluid, appearing in dark. En face SS-OCT image at the level of the retinal pigment epithelium (RPE)(E) shows a focal RPE loss in the center of the neovascular complex, appearing in dark, and an additional dark spot corresponding to a small pigment epithelium detachment (PED). En face SS-OCT image 40 μm bellow the RPE (F) reveals distinct area of focal choroidal dilation that extends from the choriocapillaris throughout the choroid, also evident on en face images at 120 μm (G), 160 μm (H), and 260 μm (I) bellow the RPE. Note in I that this distinct area of focal choroidal dilation seems to have anatomical connection to a large, dilated choroidal vessel. Cross-sectional b-scans from the areas indicated in A, respectively, the small PED (J); and the point of RPE rupture confirmed by the en face image on E (K). The focal choroidal dilation clearly documented on en face images is not visible on the b-scan through the fovea (L).