Aim: To describe the RPE/Bruch’s membrane complex micro-rips image of central serous chorioretinopathy (CSC) by OCT.
Methods: The novel OCT images were observed in patients with CSC. CSC diagnosis was based on findings from both clinical examination and multimodal images. Although the patients had been conducted many ophthalmologic examinations, such as fundus fluorescein angiography (FFA) and indocyanine green angiography (ICG), visual field, ultrasonography, pattern visual evoked potential (PVEP), we did not assess them and evaluate the results of SD-OCT and en-face OCT examination only.
Results: On the images of SD-OCT and en-face OCT, the fluid was blowout passing through RPE /Bruch’s membrane complex into sub-interdigitation zone space from choroid, it’s like a whale blow to be called “blowout sign” with the hyperreflection. RPE/Bruch’s membrane complex micro-rips, especially Bruch’s membrane micro-rips, Double-layer sign (DLS), pigment epithelial detachment ( PED ) and hyperreflective dots (HRDs) were observed.
Conclusion: The blowout sign can be found in patients with CSC, micro-RPE rips with Bruch’s membrane micro-rips, but it is random and not every patient can be seen. The liquid erupts into the sub-interdigitation zone space from choroid associated with hyperpermeable choroidal vessels and increased tissue hydrostatic pressure.
Keywords: Central Serous Chorioretinopathy; Micro-RPE Rips; Bruch’s Membrane Micro-Rips; OCT; Sub-Interdigitation Zone Space
Central serous chorioretinopathy (CSC) is a common disorder characterized by serous retinal detachment with or without serous pigment epithelial detachment (PED). It is an idiopathic ocular disease . The pathogenesis of CSC remains poorly understood. However, some advancements have led to further understanding of the disease, choroidal abnormalities are believed to be the primary underlying pathophysiology. These abnormalities can include choroidal thickening and hyperpermeability, together with increased hydrostatic pressure, which has been hypothesized to induce detachment of the retinal pigment epithelium (RPE). These points of RPE detachment can remain isolated, but breakdown of the outer blood-retina barrier can also cause leakage of fluid into the subretinal space, resulting in active CSC .
In the present study, the novel image change with CSC was observed by SD-OCT and en-face OCT (Spectralis is OCT, Heidelberg Engineering, Heidelberg, Germany. Cirrus HD-OCT 5000, Germany), the fluid is blowout passing through RPE/ Bruch’s membrane complex into sub-interdigitation zone space from choroid and micro-RPE rips and Bruch’s membrane micro-rips were observed.
The eight eyes of eight male patients with CSC were retrospectively evaluated. All patients underwent a comprehensive eye examination. Ages range was from 35 to 50 years. CSC diagnosis was based on findings from both clinical examination and multimodal images. The findings included the presence of serous macular detachment, thick choroid with congested choroidal vasculature, color fundus photography (CFP), SD-OCT and en-face OCT, fundus fluorescein angiography (FFA) and indocyanine green angiography (ICGA) and so on. The patients were defined acute CSC as that occurring within 6 months of
symptom onset and chronic CSC as that occurring more than 6
months after symptom onset .
Patients were diagnosed in our hospital and all patients
provided informed consent. This study adhered to the tenets of
the Declaration of Helsinki. In this study, we assessed the results of
SD-OCT and en-face OCT examination only. Although the patients
had been conducted many ophthalmologic examinations, such
as FFA, ICGA, visual field, ultrasonography, pattern visual evoked
potential (PVEP), we did not assess them.
The unusual images were observed with acute or chronic
CSC by B-scan images of SD-OCT and en-face OCT. Both acute
and chronic CSC, the fluid spout passing through RPE /Bruch’s
membrane complex into sub-interdigitation zone space from
choroid with a hyperreflection, it’s like the whale blows to be
called as “blowout sign” in this paper. Blowout sign occurs in subinterdigitation
zone space associated with PED and double-layer
sign (DLS) that describes the shallow and irregular elevation of
the retinal pigment epithelium from the underlying intact Bruch’s
membrane visualized on OCT. On SD-OCT, the eyes with CSC had
thickened choroids as well as an increase in the diameter of
choroidal vessels, particularly of the larger veins in Haller’s layer.
Hyperreflective dots (HRDs) were observed.
In acute CSC, well-defined serous retinal detachment with
or without serous PED is typically confined to the macula. In
chronic CSC, the retinal detachment is usually shallow and broad,
with attenuation of outer retinal layers related to chronic serous
detachment (Figures 1, 2). In chronic CSC, en-face OCT showed
micro-RPE rips with Bruch’s membrane micro-rips. SD-OCT
showed Bruch’s membrane micro-rips opening towards RPE with
the fibrin in PED and there is a hyporeflective line underlying
Bruch’s membrane (Figure 3).
Central serous chorioretinopathy is characterized by a serous
detachment of the neurosensory retina. Although the precise
pathophysiology of CSC is unclear, a congested and hyperpermeable
choriocapillaris and thickened choroid (pachychoroid) may
be the primary source of serous fluid leakage. Additionally, it is
hypothesized that due to secondary retinal pigment epithelium
alterations, the outer blood-retinal barrier is dysfunctional, which
subsequently leads to fluid passage into the subretinal space. CSC
typically affects young adult men [4, 5].
In CSC, the macula is detached because of fluid leakage at
the level of the retinal pigment epithelium. The fluid appears
to originate from choroidal vascular hyperpermeability, but
the etiology for the fluid is controversial. Choroidal venous
overload provides a unifying concept and theory for an improved
understanding of the pathophysiology and classification of a
group of diseases to a greater extent than previous proposals .
Mechanisms of subretinal fluid (SRF) accumulation in CSC
are still uncertain. Several theories have been proposed to
explain fluid entry from the choroid toward the subretinal space:
dilated and hyperpermeable choroidal vessels, changes in RPE
cell polarity altering hydroionic pumping direction, multifocal
rupture of the RPE barrier or active reverse flow by unknown
triggering mechanisms . Results of the current study indicate
that the composition of SRF in CSC may be associated with
choroidal blood composition. CSC is part of the spectrum of
pachychoroid diseases that include CSC, pachychoroid pigment
epitheliopathy, pachychoroid neovasculopathy, and polypoidal
choroidal vasculopathy .
Subretinal space is well known, it is a gap between external
limiting membrane and RPE. RPE is separated from the
photoreceptor outer segments by the subretinal space . The
observation of this study is that SRF of CSC accumulate in the
sub-interdigitation zone space on SD-OCT. As the disease duration
increases, HRDs appear in SRF and increase in number with
duration, indicative of chronicity of SRF. The origin of these HRDs
is not clear, but they could be photoreceptor outer segments
shedding, activated microglia and macrophages, or concentrated
fibrin or lipid compounds [10, 11].
The double-layer sign describes the shallow and irregular
elevation of the retinal pigment epithelium from the underlying
intact Bruch’s membrane visualized on SD-OCT. Sato et al. initially
described DLS in as a tomographic feature of the branching
vascular networking polypoidal vasculopathy. However, DLS was
also first described in eyes with chronic CSC indicating that DLS
per se may not be disease specific and that there may be other
features in the DLS that may help differentiate the variants within
the pachychoroid spectrum. A hyporeflective gap within the DLS
favored the diagnosis of chronic CSC . In this study, DLS was
observed in acute and chronic CSC respectively, not only chronic
CSC but also acute CSC. In the eyes with DLS, the space between
the undulated RPE line and the straight Bruch’s membrane line
appeared hyporeflective on SD-OCT. Yang et al. were the first to
study DLS as an important OCT feature of both acute and chronic
CSC and the DLS in chronic CSC was more prevalent .
Larger dimensions of DLS in pachychoroid neovasculopathy
(PCN) and polypoidal choroidal vasculopathy (PCV) is suggestive
of extensive neovascular tissue with/without leaked exudation,
which secondarily leads to significant separation of RPE from
the Bruch’s membrane leading to increased horizontal extent
along with augmented RPE elevation leading to increased vertical
extent. In contrast, the smaller extent of DLS in chronic CSC is
indicative of less significant RPE-Bruch’s membrane complex
The current understanding of the pathogenesis of CSC
emphasizes the role of the choroid. The primary role of the
choroid is further supported by the Enhanced depth imaging
optical coherence tomography (EDI-OCT) finding of a thickened
choroid in both eyes of patients with CSC . Hyperpermeable
choroidal vessels are thought to produce increased tissue
hydrostatic pressure, which promotes the formation of PED,
overwhelms the barrier function of the RPE, and leads to areas
of fluid accumulation between the retina and the RPE. The role
of the RPE in CSC pathogenesis remains poorly understood.
Some refer to the pinpoint areas of leakage seen in acute CSC as
micro-rips or blowouts. Retinal pigment epithelial detachments
(PEDs) are common in CSC and could also represent a form of
RPE decompensation in response to high choroidal hydrostatic
Gass proposed that CSC was the consequence of choroidal
vascular hyperpermeability. This hypothesis was confirmed by
recent studies, which found evidence of hyperpermeability from
the choriocapillaris on Indocyanine green (ICG) angiography.
If there is sufficient hydrostatic pressure from the choroidal
vasculature causing leakage from RPE and serous retinal
detachment . SD-OCT studies of the RPE in CSC have shown
RPE defects in the location of a fluorescein leakage in some
The precise pathophysiological event causing the exudative
neurosensory detachment in CSC is not known but it is now a
common belief that the primary pathology begins with disturbance
of the choroidal circulation. Increased choroidal leakage, local
hyperperfusion, and elevated hydrostatic pressure may lead
to serious detachment of the RPE. A mechanical disruption of
the RPE may cause the characteristic focal fluorescein leakage
whereas the chronic pressure may induce RPE atrophy .
Hyperpermeable choroidal vessels are thought to produce
increased tissue hydrostatic pressure, which promotes the
formation of PEDs, overwhelms the barrier function of the RPE,
and leads to areas of fluid accumulation between the retina and the RPE. Since areas of choroidal staining are usually contiguous with foci of RPE leakage on FA, the hypothesis of a mechanistic
relationship between the two findings is reasonable. Not all areas
of choroidal staining are associated with RPE leaks, suggesting
that in some instances the RPE may be able to withstand the
stresses posed by choroidal disease .
The phenomena of RPE micro rip or RPE blowout was explained
by Goldstein et al. The work by Ayachit et al. is appreciated for
the documentation of a rare finding. The explanations for the
finding given by them, e.g., possible presence of an RPE micro
rip or vigorous leakage from choriocapillaris is well taken and
supported by literature. An RPE micro-rip may explain the entry
of leaked ICG dye (in the PED) into subretinal space. Although
we could not identify the RPE micro-rip in either of our cases, its
presence is supported by the presence of large NSDs in both the
cases [19, 20].
In this study, the unusual images of CSC were observed by
OCT. The fluid erupts passing through RPE/Bruch’s membrane
complex into sub-interdigitation zone space from the choroid, it
is like a “whale blows” both acute and chronic CSC. It suggests
that SRF originate from choroid passing through the defective
RPE/Bruch’s membrane complex leading to the SRF formation.
Interestingly, blowout sign frequently occurs at the site of DLS or
PED indicating the existence of underlying prolonged abnormality
of RPE. The finding of Bruch’s membrane micro-rips is of
important significance, which, together with micro-RPE rips, is
important in explaining the pathogenesis of CSC. It is possible that
the abnormality of RPE lead to RPE/Bruch’s membrane complex
micro-rips then the liquid pass into the sub-interdigitation zone
space from choroid.