16 Central Serous Chorioretinopathy
Central serous chorioretinopathy (CSC) is a complex chorioretinal disorder characterized by a circumscribed serous (exudative) retinal detachment that is usually confined to the posterior pole. The pathogenesis is incompletely understood but is generally thought to be due to alterations of the choroidal vasculature, resulting in a breakdown of the retinal pigment epithelium (RPE) barrier and subsequent leakage of fluid into the subretinal space. 1 , 2 , 3 While previously thought to be idiopathic, several systemic associations including elevated endogenous or exogenous corticosteroids, 4 , 5 , 6 pregnancy, 7 gastric Helicobacter pylori infection, 8 , 9 and Type A personality traits 10 have been described.
CSC most commonly affects otherwise healthy individuals between the ages of 30 and 50 years, with a male-to-female ratio of approximately 6:1. 11 , 12 , 13 , 14 The condition is most commonly reported in Asian and Caucasian populations. 12 While most cases are self-limited with recovery of visual function, others may be chronic or recurrent, leading to progressive visual decline from persistent serous macular detachment.
Insights from indocyanine green angiography (ICGA) and spectral-domain optical coherence tomography (OCT) have improved our understanding of this condition, but the precise pathophysiology remains elusive. Therapies for CSC are evolving, including modified photodynamic therapy (PDT) protocols, anti–vascular endothelial growth factor (anti-VEGF) therapy, and steroid hormone antagonists, but evidence from randomized, controlled trials remains limited.
16.2 Clinical Features
Common symptoms of CSC include a relative scotoma and distorted central vision. Visual acuity is usually reduced to between 20/30 and 20/60 and can be partially corrected with a low-plus lens, as the anteriorly displaced neurosensory retina results in a hyperopic shift. Some patients, particularly those with severe or recurrent disease, have visual acuities as low as 20/200. With the onset of macular subretinal fluid collection, patients describe symptoms of metamorphopsia, micropsia, persistent afterimages, altered color vision, and a central dimness in vision.
16.2.1 Typical Central Serous Chorioretinopathy
Typical CSC is the most common presentation, characterized by a solitary, round or oval-shaped neurosensory detachment of limited size located in the macula (Fig. 16-1). The subretinal fluid is clear and well demarcated. The finding of turbid subretinal fluid or subretinal blood is unusual in CSC and suggests another diagnosis. In some cases, the neurosensory detachment can be very shallow and a hint to its presence will be the loss of the foveal reflex. Once suspected, the retinal elevation can be confirmed with OCT. Using a macular contact lens with a narrow slit beam directed at an angle, viewing the macula under red-free conditions, and using indirect ophthalmoscopy are helpful clinical examination techniques that may be employed when OCT is unavailable.
Small serous retinal pigment epithelial detachments (PEDs) are observed commonly in association with the neurosensory detachment. These serous PEDs are smooth, well-circumscribed, orange-colored elevations with a slightly darker, distinct rim. They may be under or adjacent to the neurosensory elevation.
16.2.2 Chronic Central Serous Chorioretinopathy
Chronic CSC is characterized by widespread RPE alterations in the posterior pole secondary to chronic subretinal fluid. This variant of CSC has been referred to as decompensated RPE. 12 Patients may have chronic disease resulting from one persistent episode of CSC or after multiple recurrences following initial resolution.
Patients with chronic CSC generally have a more pronounced loss of visual acuity than those with typical CSC. 12 The following findings may, infrequently, be seen in patients with chronic CSC: retinal capillary telangiectasia or nonperfusion, cystoid macular edema, choriocapillaris atrophy, and secondary choroidal neovascularization (CNV). 15 Because of the extensive pigmentary alterations and chronically reduced visual acuity, these patients are sometimes misdiagnosed as having an inherited macular dystrophy or age-related macular degeneration.
16.2.3 Bullous Central Serous Chorioretinopathy
A third form of the disease is described by the presence of a large amount of subretinal fluid in the macula that extends into the inferior periphery. 16 The “bullous” appearance of the retinal detachment accounts for the name of this variant. Affected eyes may also have multiple, large PEDs. Bullous CSC is rare in the United States but appears to be more common in Japan. 17 It has also been reported in organ transplant patients and others treated with high doses of corticosteroids. 6
16.2.4 Miscellaneous Fundus Findings
Eyes with CSC of any variant occasionally have fibrin or lipid deposited under the retina. 18 It appears as gray-white translucent dots or sheets on the undersurface of the detached retina. The fibrin is often located near the leakage site and occurs more commonly in eyes with PED and in patients who are pregnant or diabetic. Subretinal lipid has a yellow, hard-edged, waxy appearance. It is commonly found at the border of neurosensory detachments but also may be deposited in clumps in an apparently random distribution. Eyes with either type of subretinal deposits have been misdiagnosed as having retinitis, choroidal tumors, or CNV because of the presence of exudate. 12
16.3 Imaging Modalities
16.3.1 Fluorescein Angiography
In acute cases of typical CSC, fluorescein angiography (FA) demonstrates at least one hyperfluorescent leak at the level of the RPE. Most commonly, the leakage of dye takes the form of an expanding dot (Fig. 16-1). In a minority of cases (10–20%), the dye rises up under the neurosensory detachment as a “smokestack” leak (Fig. 16-2). This pattern is thought to be related to the increased concentration of protein in the fluid accumulating in the detachment. 19 The new fluid entering into the detachment has less protein and, consequently, a lower specific gravity. The newly entering fluid rises up and then spreads out when it reaches the dome of the detachment.
Typical CSC will show an expanding dot or, less commonly, a “smokestack” leak on FA. The chronic variant will show widespread transmission defects and may often show multiple, subtle leakage sites.
16.3.2 Indocyanine Green Angiography
ICGA in eyes with CSC has demonstrated changes that appear to represent areas of possible decreased choroidal perfusion and overlapping or adjacent areas of choroidal vascular hyperpermeability. 20 , 21 , 22 Delayed choroidal filling has been reported in 63 to 100% of patients with CSC in certain series. 20 , 23 Dilated choroidal vasculature is observed in early phases, followed by multifocal, often bilateral choroidal vascular hyperpermeability in the mid to late phases of the angiographic evaluation. The later phases of ICGA show dispersion of leaked dye into hyperfluorescent patches. 22 Because the dye has cleared significantly from the circulation at this point, the large choroidal vessels in the region of the leak stand out as hypofluorescent channels. Interestingly, the areas of abnormal hyperfluorescence on ICGA are typically larger or more widespread than the abnormalities identified by FA (Fig. 16-3).
16.3.3 Fundus Autofluorescence
Fundus autofluorescence (FAF) is an increasingly important imaging modality in the assessment of patients with CSC. In acute cases, the presence of subretinal fluid results in hyperautofluorescence in the area of neurosensory detachment. This hyperautofluorescence may persist even with resolution of subretinal fluid and, in this setting, is thought to be secondary to accumulation of damaged photoreceptor outer segments and/or unmasking of background RPE fluorescence in the presence of photoreceptor loss. 24 , 25 Ultimately, in chronic cases, progressive degeneration and atrophy of the RPE is later manifested as hypoautofluorescence (Fig. 16-4). 24 , 25 , 26 Thus, the pattern of autofluorescence adds information regarding chronicity of disease, and in patients with chronic-recurrent CSC, a mixed autofluorescence pattern may exist.
Patterns of autofluorescence may also provide prognostic information. In one study, specific patterns of hypoautofluorescence, namely, granular or confluent patterns, were associated with poor visual outcomes on multiple regression analysis. 25 Furthermore, an additional study revealed FAF patterns correlated with best-corrected visual acuity and microperimetry results in patients with resolved CSC. 27
Newer, ultra-widefield FAF allows for complete imaging of peripheral, gravitational tracts that may occur in patients with chronic CSC and, along with ultra-widefield ICGA, may help identify peripheral disease activity. 26
16.3.4 Optical Coherence Tomography
OCT allows for fast, detailed, noninvasive assessment of patients with CSC (Fig. 16-5). Neurosensory detachments and PEDs (Fig. 16-6), and progression/resolution of fluid over time (Fig. 16-7), are demonstrated readily on OCT. Cystoid macular edema and ellipsoid layer disruption, features described in patients with chronic CSC associated with poor visual outcome, are also detected readily with OCT.
Enhanced depth imaging (EDI) OCT reveals increased choroidal thickness in patients with CSC, consistent with choroidal changes noted on FA and ICGA. 28 Maruko et al demonstrated that, in patients with unilateral CSC, choroidal thickness as measured by EDI-OCT was significantly greater in the affected eye as compared to the unaffected fellow eye (414?± 109 vs. 350 ± 116 µm, respectively; p < 0.001). 29 Lending support to the idea that choroidal changes are present bilaterally in patients with CSC, Kim et al found choroidal thickness was increased in affected eyes (445.58 ± 100.25 µm) and unaffected fellow eyes (378.35 ± 117.44 µm) compared to healthy controls (266.80 ± 55.45 µm; p < 0.001 in both groups). 30 Choroidal thickness may be more pronounced in patients with chronic CSC. In a recent study, Hamzah et al reported mean EDI-OCT choroidal thickness to be 336.6 ± 91.6 µm in acute CSC and 388.0 ± 103.4 µm in chronic CSC. 31
Similar to FA, OCT is helpful in differentiating CSC from other diagnoses, such as age-related macular degeneration. Newer OCT technology may provide information that was previously only available from FA or ICGA. In a recent study, en face swept-source OCT was able to identify RPE loss, enlarged choroidal vessels, and focal choroidal dilation in patients with chronic CSC. 32