Central serous chorioretinopathy (CSC) is a disorder characterized by serous detachment of the neurosensory retina, sometimes accompanied by retinal pigment epithelium (RPE) detachment.^1,​2 The serous detachment is caused by leakage of fluid through the RPE, which usually occurs at the macula, resulting in central vision loss.¹ Few risk factors have been associated with CSC including systemic corticosteroid use, type A personality, pregnancy, and endogenous Cushing’s syndrome with most CSC cases occurring in young males.² While the pathophysiology is not fully understood, different imaging modalities have shown that the subretinal fluid (SRF) accumulation in CSC results from hyperpermeability and congestion of the choroidal vasculature leading to SRF leakage through a dysfunctional RPE.³

Two forms of CSC can be distinguished: the acute and chronic variants.¹ Acute CSC usually presents with sudden visual loss and while spontaneous resolution is common with acute CSC, the chronic variant usually is progressive with persistence of the SRF for more than 3 months.^2,​4 The acute form is characterized by focal leaks in the RPE that are clearly visible with fluorescein angiography (FA).^2,​4 The chronic form is characterized by multifocal diffuse leakage evident with FA and indocyanine green angiography (ICGA), in addition to widespread RPE changes.¹ The persistent serous detachment in the chronic form results in progressive photoreceptor compromise, which explains the worse visual outcome with chronic CSC when compared to the acute form.⁵ Chronic CSC might also be complicated with choroidal neovascularization (CNV).¹

FA and ICGA have been the conventional imaging modalities to assess the vasculature in CSC. However, these tests remain invasive and time-consuming with potential side effects.⁶ Recently, the development of optical coherence tomography angiography (OCTA) has allowed for three-dimensional visualization of the retinal and choroidal vasculature in a fast and noninvasive manner. This technology utilizes an algorithm called “split-spectrum amplitude decorrelation angiography,” which is able to image the vasculature by using the contrast between the decorrelation of blood flow and static tissue to extract flow signals without requiring dye injection.⁷ In this chapter, we describe the OCTA findings in eyes with CSC. Additionally, we briefly review the current literature on OCTA use in CSC. Of note, the OCTA scans represented in this chapter have been acquired using the commercially available RTvue XR Avanti spectral-domain OCT (SD-OCT) device with AngioVue software (Optovue, Inc., Fremont, CA).

10.2 Acute Central Serous Chorioretinopathy

In acute CSC, OCTA shows no flow abnormalities at the level of the superficial (SCP) and deep capillary plexus (DCP; ▶ Fig. 10.1). However, before interpreting OCTA scans in any case of CSC, it is crucial to recognize that due to the detachment of the neurosensory retina, segmentation errors can arise and affect the scan interpretation. One should make sure that the segmentation lines on the co-registered B-scans correspond to the correct retinal layers before reading the scans. When flow abnormalities are seen in SCP or DCP, these can be explained by the aforementioned segmentation errors. After correcting the segmentation, normal flow patterns can be seen.

At the level of the choriocapillaris (30–60 μ below the RPE), OCTA shows flow abnormalities. First, areas of increased choroidal flow can be seen under the area of serous retinal detachment (SRD) representing an area of disease activity ( ▶ Fig. 10.1). Second, a dark area of an apparent flow reduction can be noticed corresponding to the area of the SRD. We hypothesize that this area is not a true reduction in choroidal flow but rather an artifact due to light attenuation by the overlying SRD. Alternatively, compression of the choriocapillaris by the enlarged vessels in the outer choroid can lead to focal atrophy with an actual reduction in blood flow⁸ and could explain this finding.

Recent studies have used OCTA to describe vascular changes in acute CSC. Feucht and colleagues have similarly shown that there were no vascular abnormalities seen at the level of SCP and DCP. At the choriocapillaris level, irregular blood flow patterns were described with areas of hypoperfusion surrounded by areas of hyperperfusion.⁹ Another study also found that the choriocapillaris shows an area of apparent flow reduction surrounded by an area of increased flow.¹⁰

It is important to note that the previously described OCTA changes at the level of the choriocapillaris are nonspecific given the inability of the current spectral domain OCTA devices to image the choroid accurately. This is partially due to the high reflectivity of the RPE limiting the penetration of the light beam into the choroid. Additionally, the current devices use short wavelengths, which also limit the penetration into the choroid. However, the development of swept-source OCTA utilizing higher wavelengths will allow increased light penetration and improved choroidal blood flow visualization compared to the light source used in the currently available SD-OCT devices.

10.3 Chronic Central Serous Chorioretinopathy

In chronic CSC, OCTA reveals normal retinal circulation (SCP and DCP) similar to the acute form. At the choroidal level, OCTA shows irregular flow patterns that correspond with abnormalities seen on ICGA ( ▶ Fig. 10.2). The choriocapillaris shows areas of hypoperfusion surrounded by areas of hyperperfusion. Earlier studies have demonstrated focal filling defects in the choriocapillaris with dilated arterioles and venules.³ These choriocapillary changes seem to persist even after the resolution of the SRF.

The diagnosis of CNV associated with chronic CSC can be often challenging as many clinical features are shared between CSC with and without CNV. These changes include RPE detachment, intraretinal or SRF, retinal atrophy, and diffuse irregular hyperfluorescence seen on FA or ICGA.¹¹ OCTA is useful in these cases especially when the RPE profile is irregular with associated RPE detachments to rule out possible CNV ( ▶ Fig. 10.2). OCTA has recently been shown to be sensitive and specific for the detection of CNV in different disease entities. Of note, for the scans provided in this chapter, the outer retina automatic segmentation lines were manually adjusted where the inner boundary was set to be located at the outer boundary of the outer plexiform layer and the outer boundary was set at the level of Bruch’s membrane as previously described.¹¹ This has been shown to increase the sensitivity of OCTA to detect associated CNV.¹¹ In healthy eyes, the outer retina does not have any vascular structures; therefore, OCTA is not expected to show flow signal at the outer retina level, which makes identification of CNV lesions easier at this level.

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