Focal Choroidal Excavation and Central Serous Chorioretinopathy Following Choroidal Neovascularization: A Longitudinal Case Study

Abstract

Purpose:

This report describes the development of focal choroidal excavation (FCE) and recurrent central serous chorioretinopathy (CSCR) following the treatment of choroidal neovascularization (CNV) years earlier.

Methods:

A case report is presented.

Results:

A 30-year-old man previously treated for an active CNV returned several years later with subacute metamorphopsia. Optical coherence tomography and angiography demonstrated no recurrence of the CNV but instead found an FCE and associated CSCR in its place.

Conclusion:

Longitudinal follow-up with multimodal imaging demonstrated FCE with recurrent CSCR as possible sequelae of treated CNV.

Introduction

First described in 2006 by Jampol and colleagues ¹ using time-domain optical coherence tomography (OCT) and further characterized by Margolis et al ² in 2011, focal choroidal excavations (FCEs) are localized areas of choroidal and retinal pigment epithelium (RPE) concavity in the absence of a posterior staphyloma or scleral ectasia. Wakabayashi and colleagues ³ have further defined FCEs as conforming or nonconforming types. In the former, the ellipsoid layer and RPE are continuous within the excavation, whereas in the latter the photoreceptor tips are discontinuous from the underlying RPE, creating an optically empty intervening space between the outer retina and RPE.

The pathogenesis of FCEs remains unclear. Associations with choroidal inflammation and choroidal neovascularization (CNV) have been reported, and features consistent with the pachychoroid ^{4 -7} spectrum have been discussed. However, because most descriptions provide limited longitudinal follow-up, causality cannot be established. Here we describe a patient who presented with an idiopathic CNV and years later developed an FCE and recurrent central serous chorioretinopathy (CSCR).

Methods

Case Presentation

A 30-year-old Asian man first presented to us in 2010 with a 5-day history of a right central scotoma. He denied any previous history of trauma, surgical or laser procedures, or systemic illness. Refractive correction was –0.25 diopters OD and –0.5 diopters OS, and visual acuity (VA) was 6/7.5→6/6 OD and 6/4.8 OS. There were no signs of intraocular inflammation, and on dilated fundus examination subretinal hemorrhages and pigmentary changes were noted over the right macula. Optical coherence tomography (Topcon 3D-OCT 1000, Topcon Medical Systems) demonstrated a hyperreflective lesion anterior to the RPE that extended into the outer retina with disruption of the ellipsoid zone, associated subretinal fluid (SRF), and overlying intraretinal fluid (Figure 1). Fundus fluorescein angiography (FFA) and indocyanine green angiography (ICGA) (Topcon 50DX fundus camera, Topcon Medical Systems) confirmed the presence of juxtafoveal classic CNV (Figure 2). The patient was treated with intravitreal bevacizumab. A systemic workup conducted to rule out any possible underlying autoimmune or infective etiology was unremarkable. A favorable response to intravitreal bevacizumab treatment was observed. Following a second intravitreal bevacizumab injection 4 weeks later, VA was 6/4.8 OU, and subretinal hemorrhage on fundus examination and SRF on OCT had resolved (Figure 3).

Figure 1.

Optical coherence tomography demonstrating a hyperreflective lesion anterior to the retina pigmented epithelium (RPE) with associated subretinal and intraretinal fluid. ILM, internal limiting membrane.

Figure 2.

(A) Fundus fluorescein angiography and (B) indocyanine green angiography demonstrating juxtafoveal classic choroidal neovascularization.

Figure 3.

Optical coherence tomography demonstrating resolution of subretinal fluid owing to intravitreal antivascular endothelial growth factor treatment. ILM, internal limiting membrane; RPE, retinal pigment epithelium.

At a scheduled follow-up visit 4 months later, vision in the right eye was noted to have deteriorated slightly to 6/6. Vision in the left eye remained at 6/4.8. SRF was noted on OCT, and a diagnosis of CSCR was made (Figure 4). Observation and a trial of topical nonsteroidal anti-inflammatory drug were advised but the patient did not return for follow-up.

Figure 4.

Optical coherence tomography demonstrating subretinal fluid suggestive of central serous chorioretinopathy. ILM, internal limiting membrane; RPE, retinal pigment epithelium.

Six years after his first presentation, the patient returned through the eye casualty service complaining of a month-long history of metamorphopsia. He reported that vision in the right eye had never returned to normal after his initial treatment but had acutely worsened in the last month. VA was 6/7.5 OD and 6/4.8 OS. Fundus examination was unremarkable but OCT (Cirrus HD-OCT 5000, Carl Zeiss Meditec AG) demonstrated an area of choroidal excavation (Figure 5). The overlying retinal architecture and foveal contour were well preserved, there was no associated SRF or intraretinal fluid, and an area of hyperreflectivity was noted to extend from beneath the area of concavity. The patient was managed conservatively and advised to return for a review in a few months, but he defaulted on follow-up again.

Figure 5.

Optical coherence tomography demonstrating a focal choroidal excavation.

Two years later and 8 years after his first presentation, the patient returned complaining of acute distortion in his right eye over the preceding 4 days. He described a patch within his central vision where images were dimmed. VA was 6/6 OU and fundus examination was unremarkable (Zeiss Visucam 500, Carl Zeiss Meditec AG) (Figure 6), but OCT imaging (Spectralis OCT, Heidelberg Engineering) demonstrated an area of FCE associated with SRF suggestive of CSCR (Figure 7). FFA and ICGA (Heidelberg Retinal Angiography, Heidelberg Engineering) showed multiple areas of pinpoint leakage within the macula (Figure 8). In view of his good VA, observation was advised and a resolution of symptoms and SRF was noted after 2 months. However, the patient has since had recurrent, self-limiting episodes of CSCR.

Figure 6.

Color fundus photographs.

Figure 7.

Optical coherence tomography demonstrating focal choroidal excavation with concurrent central serous chorioretinopathy.

Figure 8.

(A) Fundus fluorescein angiography and (B) indocyanine green angiography demonstrating leakage consistent with central serous chorioretinopathy.

Results

Aside from a case report ⁸ describing the evolution of an FCE from a combined retina and RPE hamartoma in a child and an example cited in a retrospective analysis by Ellabban et al, ⁵ most case reports and series provide limited longitudinal follow-up, thus hindering a description on the natural history of an FCE and the means of establishing a cause-and-effect relationship between an FCE and its associations. With this case report, we have detailed the evolution of an FCE and chronicled its associations.

Our patient presented with a CNV with no associated intraocular inflammation and a previous systemic workup with negative results. Early leakage on FFA led to a diagnosis of a classic CNV. Although ICGA demonstrated pachyvessels and choroidal hyperpermeability, the classic CNV leakage pattern on FFA and OCT features including the lack of a double-layer sign, were suggestive of an idiopathic or possibly punctate inner choroidopathy (PIC)–related lesion rather than pachychoroid neovasculopathy. A favorable response to antivascular endothelial growth factor therapy was noted, but the patient then developed CSCR and an associated FCE in the area (Figure 4).

Conclusions

Since its initial description and characterization, various features and mechanisms have been postulated to explain the pathogenesis of an FCE. Margolis et al ² suggested a developmental choroidal defect in which senescence and thinning of the choroid contributed to its own enlargement. Choroidal inflammation and consequent scarring have also been proposed as a possible etiology; Ellabban et al ⁵ described focal areas of hyperreflective tissue within the choroid underlying FCEs on OCT, and multiple reports have described FCEs in myriad choroidal inflammatory conditions, including PIC, multifocal choroiditis, multiple evanescent white dot syndrome, and Vogt-Koyanagi-Harada disease. ^{9 -13} With data from a retrospective analysis of multifocal choroiditis and PIC patients, Kim et al ¹¹ proposed a classification of primary and secondary FCEs in which the former represented developmental abnormalities and the latter an acquired condition.

FCE has also been described to share OCT and angiographic features of the pachychoroid spectrum. The reported incidence of FCE in patients with CSCR is 1% to 8% and is 6% in patients with polypoidal choroidal vasculopathy. ^{5 -7} OCT imaging has demonstrated dilation of adjacent choroidal vasculature with loss of choriocapillaris and Sattler’s layer within the FCE itself. ^4,5,14 Chung et al ⁴ have proposed a theory of generalized ischemia that leads to endothelial damage and fibrinoid necrosis of choroidal vessels and results in leakage of inflammatory mediators, causing focal choroidal degeneration and chronic venous congestion with subsequent mechanical atrophy of the overlying choriocapillaris. Although an enhanced depth imaging OCT was not available at the time of presentation for our patient, ICGA demonstrated dilated vessels and diffuse choroidal hyperpermeability, suggesting an underlying pachychoroid.

We hypothesize that a combination of focal RPE and Bruch’s membrane damage consequent of the initial CNV and background pachychoroid environment led to the development of an FCE with recurrent CSCR contributing to its enlargement over time. The retina and RPE are kept in direct apposition to the Bruch membrane by an active RPE pump and hydrostatic forces. A combination of choroidal hyperpermeability and RPE dysfunction predisposed to an accumulation of SRF gave rise to CSCR. As described in previous reports by Ellabban et al ⁵ and Kim and colleagues, ¹¹ choroidal scarring exacerbated by local ischemia led to a focal retraction of the choroid and RPE, resulting in a conforming FCE. The demonstration of recurrent SRF on OCT and leakage on ICGA over the area of FCE supports the suggestion of choroidal hyperpermeability exacerbated by further local hemodynamic disturbance.

With the development of a conforming FCE, our patient was largely asymptomatic but later experienced recurrent episodes of metamorphopsia coupled with an accumulation of SRF, suggestive of recalcitrant CSCR. Although FCEs are generally asymptomatic and an evolution from conforming to nonconforming types was thought to occur with a decline in retinal elasticity over time, ² it has been suggested that patients with nonconforming FCEs are more likely to experience metamorphopsia and are at greater risk of conversion from conforming to nonconforming types following an acute episode of CSCR. ^15,16 While the sclera typically remains undisturbed, ² we postulate that progressive choroidal ischemia and scarring with recurrent SRF and residual debris increased the hydrophobicity of the Bruch’s membrane-RPE complex, making it more prone to accumulation of SRF and thus setting up a vicious cycle of recurrent CSCR and a possibly enlarging FCE.

Half-dose photodynamic therapy (PDT) has been proposed as a means of effectively treating patients with combined FCE and acute CSCR. ⁶ Our patient’s episodes were largely self-limiting and good VA was preserved. Given the well-documented predilection for sight-threatening neovascularization to develop at the site of FCEs ^{17 -19} and a recent report ²⁰ describing the development of type 2 CNV following half-dose PDT treatment for CSCR with FCE, we have elected to hold off on any laser intervention.

FCEs may form following the successful treatment of a CNV. In the event of an FCE developing, patients should be counseled and observed for associated complications including CSCR and secondary CNV and polypoidal choroidal vasculopathy. In patients with CSCR, treatment with half-dose PDT should be undertaken only after careful consideration and a detailed discussion with the patient.