Central Serous Chorioretinopathy
Central serous chorioretinopathy (CSC) is an idiopathic disorder involving a focal or multifocal leak at the level of the retinal pigment epithelium (RPE), usually in conjunction with a serous pigment epithelial detachment (PED). An active leak presents with angiographic pooling of fluorescein dye into the subneurosensory retinal space. The disorder usually occurs unilaterally and asymmetrically in males between the ages of 30 and 50. The natural course of CSC is usually benign with spontaneous resolution of the neurosensory detachment within 3-4 months. However, a small but significant percentage of patients will develop recurrent or persistent detachment with widespread loss of RPE and photoreceptors. These patients are classified as having chronic CSC. Serous detachments in the posterior pole may gravitate inferiorly, resulting in discernible pigment epithelial atrophic tracts and dependent neurosensory detachment.
CSC is defined by a focal fluorescein leak at the level of the RPE with pooling of the dye into the subneurosensory retinal space. The characteristics of the focal leak will vary depending on the composition of the subretinal fluid, the morphology of the associated pigment epithelial abnormality, and possibly by convection currents induced by the warmer posterior choroid. A large active leak will rapidly pool into the subneurosensory retinal space. It is sometimes unclear why some fluorescein leaks ascend quickly, as seen in the patient above, while others slowly expand throughout the course of the angiogram.
Fluorescein Angiography in CSC
Smokestack Leak
A “smokestack” leak is associated with a focal pinpoint active RPE leak that ascends vertically in the subretinal space. Once the dye reaches the limiting point of the neurosensory detachment, its hyperfluorescence then expands laterally, constrained by the limits of the fluid compartment.
This patient has a focal “smokestack” leak (arrow) near the edge of a serous PED beneath a neurosensory retinal detachment. In the late stage of the angiogram there is a pooling of dye superiorly. Hyperfluorescence extends temporally along the same direction as the serous detachment. A “smokestack” pattern of leakage is clearly seen in the angiogram of a different patient (right image) .
Mushroom or Umbrella Leak
A “mushroom” or “umbrella” leak will rapidly pool beneath the neurosensory detachment and ascend within the subneurosensory retinal space. Presumably, this angiographic pattern occurs due to molecular weight differences between the dye and the components of the subretinal fluid and due to convection currents within this fluid compartment. The leakage will spread temporally and nasally when it reaches the upper limits of the detachment.
This patient has a focal leak from acute CSC that forms a “mushroom” or “umbrella” appearance in the late angiogram.
These are two patients who have “mushroom” RPE leaks due to acute CSC. Note that the leaks ascend in the subneurosensory retinal space until they reach the limits of the neurosensory detachments and then extend temporally and nasally to form a “mushroom” or “umbrella” appearance. The leakage of the dye into the subneurosensory retinal space will delineate the neurosensory detachment. The neurosensory detachment in CSC does not fill homogeneously with dye unlike some serous detachments due to other causes. Completely stained subneurosensory retinal spaces may be seen in inflammatory disease and choroidal neovascularization.
This patient has an “umbrella” leak seen with indocyanine green (ICG) angiography. Note the vertical ascent of the dye in the subneurosensory retinal space. The dye may outline the neurosensory detachment but does not completely fill it (middle image) . ICG dye is typically not as useful as fluorescein dye (right) in demonstrating leakage in CSC, because fluorescein dye is more permeable and more brilliantly fluorescent (25 times greater than ICG). The right photograph also shows a small serous PED (arrow), which should be differentiated from an active leak.
Inkblot Leak
An “inkblot leak” in CSC is a pinpoint area of hyperfluorescence on the fluorescein angiogram that gradually expands in a localized ovoid fashion. There is no ascent of the fluorescence in the subneurosensory retinal space. This leak usually represents a slow diffusion of the dye through an incomplete or healing defect in the RPE.
This patient with CSC has a focal “inkblot leak” near the edge of a serous PED. The leak gradually expands in the late stage of the angiogram (right) . There is some yellowish discoloration beneath the neurosensory detachment, presumably fibrin (arrow) . There are small PEDs that stain without leakage at the bottom right of the fluorescein angiograms (arrowheads).
Indocyanine Green Angiography in CSC
ICG angiography is useful in diagnosing CSC. The characteristic finding is choroidal staining or hyperpermeability, which typically appears in the mid-stage of the angiogram (middle image) . It fades in the late study (right), differentiating this leakage from that of choroidal neovascularization.
Here there is widespread choroidal leakage seen with ICG angiography (right) suggestive of choroidal hyperpermeability, a hallmark of CSC. The ICG angiogram shows choroidal abnormalities that cannot be detected with color photographs or fluorescein angiography (middle) . The fluorescein angiogram shows hyperfluorescence due to pigment epithelial atrophy overlying an intact choriocapillaris. The choroidal staining seen with ICG angiography may also be due to the presence of fibrin, which may have an affinity for the ICG molecule. In contrast, fibrin is transparent on fluorescein angiography.
Ultra-widefield ICG angiography in the early- to mid-phase reveals dilation of the choroidal vessels, which may be associated with congestion of all vortex vein ampullas (left image) or specific vortex veins, superotemporal and superonasal in this case (right image).
Ultra-widefield ICG angiography in the early- to mid-phase reveals dilation of the choroidal vessels and congestion of the vortex vein ampullas, which may be imaged best in superior gaze (top left image) and inferior gaze (top right image).
Optical Coherence Tomography (OCT) in CSC
Serous Retinal Detachment
OCT is very helpful in diagnosing and managing CSC. The left image shows a serous detachment overlying a shallow PED (arrow) . The right image shows a serous detachment with an accumulation of hyper-reflective material on the undersurface of the retina. This material may represent elongated or shed photoreceptor outer segments or fibrin.
Patients with CSC frequently demonstrate a thickened choroid or “pachychoroid,” which is visualized clearly with enhanced depth imaging OCT or swept source OCT as shown in the images above. The left image shows a serous detachment with fibrin overlying a PED. There is thickening of the choroid and large dilated choroidal vessels or “pachyvessels” beneath the area of pathology. The right image shows shallow subretinal fluid in a patient with chronic CSC. Notice the abnormally thickened choroid and grossly dilated pachyvessels.
Pigment Epithelial Detachment (PED)
Serous PEDs are a characterisitic feature of CSC. OCT imaging is very useful in detecting serous PEDs. Unlike drusenoid and vascularized PEDs seen in age-related macular degeneration, the sub-RPE space of serous PEDs is uniformly hyporeflective. The color fundus image on the left shows a serous PED with the corresponding OCT below it. The fundus autofluorescence (FAF) image on the right and corresponding OCT below it show a combined PED and serous retinal detachment. A double ring of hyperautofluorescence can be appreciated on the FAF, the larger ring (red arrows) due to the subretinal fluid and the smaller ring (yellow arrows) of the PED.
Cystoid Macular Degeneration
Cystoid macular degeneration is a recognized complication of chronic CSC and occurs in approximately 21% of cases. Cystoid macular degeneration may vary from mild (left) to massive in nature (right). Cystoid macular degeneration typically occurs in those eyes that demonstrate irreversible outer retinal damage manifested by disruptions in the external limiting membrane and ellipsoid zone on OCT. Following resolution of cystoid degenerative changes, there is predictable atrophy of the retina.
Fundus Autofluorescence (FAF) in CSC
This patient with chronic CSC shows a myriad of FAF abnormalities. The very dark areas correspond to atrophy of the RPE and photoreceptors. The granular autofluorescence represents areas of antecedent detachment, which has resolved with less severe atrophy. Hyperautofluorescent areas on the image represent cells at risk or denote areas of persistent detachment.
Image courtesy of Dr. Richard Spaide
A PED has a ring of hyperautofluorescence (left image). Acute or resolved detachments appear hyperautofluorescent (middle image). The hypoautofluorescent area in this patient corresponds to previous laser photocoagulation treatment. A chronic gravitating neurosensory detachment has an inner column of hyperautofluorescence (arrows).
This patient with chronic CSC has gravitating atrophic RPE tracts from chronic detachments. As the neurosensory detachments descend inferiorly, an atrophic and pigmentary degenerative change evolves. These changes are very characteristic of chronic CSC, but they can be produced by other causes of exudation in the central macula, such as leakage from choroidal hemangiomas and disciform disease in age-related macular degeneration.
Atrophic RPE appears hypoautofluorescent, whereas areas of with acute or resolved detachments appear hyperautofluorescent, due to the liberation of outer retinal photoreceptors in the subretinal space and unmasking of the normal RPE autofluorescence in areas of outer retinal thinning.
Images courtesy of Dr. Richard Spaide
Ultra-widefield FAF is very useful in delineating the full extent of CSC, which can sometimes be overlooked on clinical examination and standard field imaging.
Ultra-widefield FAF is also useful in detecting subtle areas of subretinal fluid in CSC (arrows), which can sometimes be missed with clinical examination and standard field imaging.
The hyperautofluorescence seen with FAF has been noted to persist for years after resolution of the subretinal fluid. Hyperautofluorescence at sites of previous detachment are predominantly due to residual outer retinal disruption and thinning, as seen on the OCT, which exaggerates and unmasks normal RPE autofluorescence.
Retinal pigment epithelial changes may appear as a reticular pattern, as shown in the above patient, in approximately 25% of CSC patients. Of these, 70% occur bilaterally and are typically asymmetric. The reticular pattern tends to be multifocal, eccentric, and peripapillary. They usually occur over areas of previous or current PEDs. It is important to recognize this reticular pattern of autofluorescence in CSC and distinguish this finding from pattern dystrophy.
CSC Simulating Age-Related Macular Degeneration (AMD)
FAF can help distinguish CSC from other entities that may appear similar on clinical examination. This patient has a zone of atrophy with fibrous metaplasia in the central macula and was initially diagnosed as having AMD. However, a gravitating tract of atrophy, coursing into the inferior fundus, is evident on autofluorescence imaging. This autofluorescent pattern is highly characteristic of prior episodes of CSC; a diagnosis that also explains the macular changes.
Asymptomatic Eye
These two patients were asymptomatic. Each had a history of acute CSC in their fellow eye. A zone of autofluorescence abnormalities was noted nasal to the disc (left images) in one of the patients. The other patient had widespread autofluorescence changes with an atrophic RPE tract from a previous inferior gravitating detachment. There was relative sparing of the fovea accounting for the asymptomatic state of these patients.
Chronic Central Serous Chorioretinopathy
Chronic CSC is defined as a detachment that persists for more than 6 months or a recurring detachment that produces widespread pigment epithelial alterations including atrophy. Chronic CSC is often associated with an incontinent or a permeable pigment epithelium in widespread areas of the fundus. Focal, recurrent leaks may complicate this form of the disease.
These patients have chronic CSC. There is widespread decompensation of the RPE and descending atrophic retinal pigment epithelial tracts that correspond to active or antecedent gravitating detachments.
