Chapter 16

Core Messages

■Central serous chorioretinopathy (CSC) typically affects young and middle-aged males and is characterized by serous retinal detachment at the macula secondary to increased permeability of choroidal vessels and a barrier defect in the retinal pigment epithelium (RPE)

■Spectral-domain optical coherence tomography (OCT) offers a new approach to diagnose, prognosticate, and monitor the clinical course of the disease and its response to therapy

■Morphologic alterations in the RPE, detached retina, and subretinal space around the fluorescein­ leakage sites can be observed in acute CSC

■Three-dimensional (3D) OCT imaging delineates the microstructural changes that occur within the photoreceptor layers and demonstrates the spatial relationship between the laterally spreading or scattering microstructures and the fovea in the eyes with CSC.

■Primarily, the outer segment layer is altered in CSC

■Visual prognosis in patients with CSC can be linked to retinal morphological changes by OCT

■Presence of correlation between foveal thickness and visual acuity has been observed

■Topographic changes in CSC can be very elegantly­ visualized and documented with 3D-reconstru­ ction.

16.1  Introduction

Central serous chorioretinopathy (CSC) [1–4] that typically affects middle-aged males is characterized by serous retinal detachment at the macula secondary to increased permeability of the choroidal vessels and a barrier defect in the retinal pigment epithelium (RPE) [5, 6]. Ultrastructural studies in animal models of CSC have shown defects in RPE, which might favor a breakdown in the outer bloodretinal barrier [7].

Presenting symptoms include central visual loss, a sudden decrease in vision that can be corrected with an increased hyperopic correction, metamorphopsia, central scotoma, and decreased color saturation. The symptoms are usually self-limiting, but can recur in the same or the opposite eye. The association of the disease with type A

personality, systemic hypertension, and cortiocosteroid intake is well known.

Although eyes with CSC usually have a good visual prognosis, prolonged and recurrent macular detachment may lead to degenerative changes and poor visual outcome [8, 9].

Acute CSC: The acute form is classically unilateral and characterized by one or more focal leaks at the level of RPE on fluorescein angiography. The neurosensory detachment contains clear subretinal fluid, but may be cloudy or have subretinal fibrin in some cases. This form is self-limiting and does not lead to gross visual deficit after resolution.

Chronic CSC: The chronic form is believed to be due to diffuse RPE disease and is usually bilateral. It presents with diffuse RPE atrophic changes, varying degrees of subretinal fluid, RPE alterations, and RPE tracks. It is characterized by

proliferating RPE cells at the leakage site (Figs. 16.2a, b and 16.3). Fibrinous exudates in the subretinal space and sagging/dipping of the posterior layer of the neurosensory retina above the leakage sites may also be noted (Fig. 16.4). An RPE defect at the edge of or within the PED may be evident through which fluid might pass from the sub-RPE to the subretinal area. The posterior surface of the detached retina is smooth or granulated. The smooth posterior detached retina becomes granulated in the presence of residual subretinal fluid (Figs. 16.5 and 16.6). Persistent PED may also be observed despite SRF resolution.

Summary for the Clinician

■Among the leakage sites, spectral-domain OCT shows RPE abnormalities in the majority of cases. Pigment epithelial detachment and protruding or irregular RPE layer can also be observed.

■Fibrinous exudates in the subretinal space and sagging/dipping of the posterior layer of the neurosensory retina above the leakage sites may also be noted.

■The posterior surface of the detached retina may be smooth or granulated.

■Persistent PED may also be observed despite SRF resolution.

En face OCT has been found to detect alterations of RPE in the form of PED or a small bulge of RPE in the eyes with CSC. Most alterations of RPE are associated with choroidal abnormalities [19]. OCT-ophthalmoscope has also been found to detect morphologic changes easily and noninvasively at the point of dye leakage in the eyes with CSC. Transverse images (C-scan) clearly showed serous retinal detachment and irregular lesions in RPE. These

findings agree with the location of lesions in areas of fluorescein dye leakage on fluorescein angiography. Longitudinal images (B-scan) of irregular RPE lesions in transverse images show PED and small protrusion of the RPE layer and rough RPE layer [20]. 3D single-layer RPE map has been found to reveal abnormal pattern in the asymptomatic eyes of patients with unilateral CSC [21].

3D OCT imaging delineates the microstructural changes that occur within the photoreceptor layers and demonstrates the spatial relationship between the laterally spreading or scattering microstructures and the fovea in the eyes with CSC. Visualization of the 3D relationship between the external limiting membrane and each photoreceptor layer before and after macular reattachment facilitates understanding of the anatomic and vision changes that result from CSC [22].

Visual prognosis in patients with CSC can be linked to retinal morphological changes by OCT [23–25]. Pathologic changes in the foveal photoreceptor layer show a line corresponding to back reflection from the external limiting membrane visible in images from eyes with all stages of CSC. Back reflection from the photoreceptor inner and outer segment junction (IS/OS) is absent before, but is present after reattachment. Primarily, the outer segment layer is altered in CSC. Punctate areas of intense reflectivity are observed more frequently in the outer segment layer of the detached retinas in cases of chronic or recurrent versus acute CSC. Eyes with large defects in the subfoveal IS/OS have poor visual acuity when compared with eyes with small or no defects which have good visual acuity [22].

Photoreceptor-segment morphologic changes at the detached retina show elongation of the photoreceptor outer segments and decreased thickness of the outer nuclear layer [26]. The outer nuclear layer thickness is positively correlated with the best-corrected visual acuity (BCVA) in resolved CSC. Discontinuity of the IS/OS line

is prevalent in eyes with thinner outer nuclear layer and lower BCVA [27].

In patients with acute phase of CSC, the detached neurosensory retina is thickened and visual acuity is kept well before and after resolution of subretinal fluid [28]. However, in cases with chronic CSC prolonged for several years, the persistent macular detachment may cause degenerative changes in RPE and the neurosensory retina, which results in a poor visual outcome (Fig. 16.7) [23, 29]. Foveal thickness can be a factor predictive of visual outcome in patients with persistent CSC. Presence of correlation between foveal thickness and visual acuity

has been observed [23]. Even simple measurements of foveal thickness on OCT images can provide objective information for the management of CSC. Final visual acuity correlates with initial and final foveal thickness. Damage of the neurosensory retina may reflect in foveal thickness at final examination and visual outcome [30]. Both foveal thickness and visual acuity have been observed to be proportional to the duration of symptoms, which lead to foveal attenuation and atrophy, which may result from prolonged absence of contact between photoreceptors and retinal pigment epithelial cells [31].Visual recovery after macular reattachment may be predicted by

preserved undamaged outer photoreceptor layer and higher visual acuity at presentation [25]. Prolonged and recurrent retinal detachment at the macula causes an apoptotic mechanism which is involved in the process of degeneration of photoreceptor death [32, 33]. This process may cause thinning of foveal thickness after the resolution of subretinal fluid.

Accumulation of abnormal production of outer segment of the neurosensory retina is related to clinical manifestations in OCT as a granulated profile on the outer surface of the detached retina, and in fundus camera or scanning laser ophthalmoscope as an autofluorescence in the eyes with CSC [34–37].

Choroidal neovascularization may also occur in patients with CSC (Fig. 16.8).

Summary for the Clinician

■3D OCT imaging delineates the microstructural changes that occur within the photoreceptor layers in the eyes with CSC.

■Visualization of the 3D relationship between the external limiting membrane and each photoreceptor layer before and after macular reattachment facilitates understanding of the anatomic and vision changes that result from CSC.

Effect of therapy can also be observed on spectraldomain OCT [38]. Furthermore, resolution of serous retinal detachment and quantitative macular thickness can be documented very well (Figs. 16.9a, b).

The spectral-domain OCT can create 3D area scans by combining B-scans. As it is possible to acquire highdensity volumetric data of the macula, the OCT data can be processed to provide comprehensive structural information. With 3D image reconstruction, the 3D area scans can be manipulated and viewed from multiple angles. The unprecedented visualization provided by this technology enables determination of specific alterations in the retinal anatomy characteristics. Topographic changes in CSC can be very elegantly visualized­ and documented with 3D reconstruction (Fig. 16.10).

The X, Y, and Z planes for slicing are defined as follows: X plane is the horizontal B-scan as it is acquired. The anatomical features shown in the X plane are real, as the

eye movement is negligible.

Y plane is the vertical reconstructed B-scan. The eye movement in the reconstructed B-scan is quite noticeable.

Z plane is a reconstructed en face image. It is also called the coronal scan.

The relationship among the X, Y, and Z planes can be observed exquisitely [39].