Atypical Chronic Central Serous Chorioretinopathy Mimicking Vogt-Koyanagi-Harada Disease: Full Therapeutic Response to Half-Fluence Photodynamic Therapy

Central serous chorioretinopathy (CSCR) is characterized by neurosensory macular detachment. However, in rare instances, the neurosensory detachment may be very extensive, causing bullous exudative retinal detachment. This rare variant of the disease is defined as atypical (bullous) CSCR. Characteristic fundoscopic features are multifocal exudative lesions in the posterior pole and inferior retinal detachment with shifting subretinal fluid.¹

Due to the unusual presentation, this form may be incorrectly diagnosed as rhegmatogenous retinal detachment, Harada disease, uveal effusion, multifocal choroiditis, metastatic carcinoma, or lymphoma.² Inappropriate use of systemic corticosteroids and other immunosuppressive agents may cause exacerbation of the symptoms and lead to development of subretinal fibrosis and scarring.

The pathogenesis of CSCR is not well documented. A breakdown in the permeability of the choriocapillaris has been implicated as the possible pathogenetic mechanism, leading to a focal loss of RPE-Bruch’s membrane attachment and allowing passage of the choroidal fluid into the subretinal space.³ Bullous retinal detachment is an extremely rare atypical variant of chronic CSCR which has been reported in a limited number of case presentations and case series.^1,4

Corticosteroid therapy is one of the many systemic factors implicated in the pathogenesis of the bullous variant of CSCR.⁴ In our case, due to the presence of trace amount of vitreous cells, the patient was initially misdiagnosed with VKH disease and received intravenous high-dose corticosteroids. The use of steroids may aggravate the clinical findings of CSCR. Then, because the patient’s findings did not improve and her vision worsened, steroid-resistant VKH was suspected and her treatment was changed to other immunosuppressive and biologic agents.⁵

In atypical CSCR cases, providing an earlier definitive diagnosis may be a clinical challenge. Atypical bullous CSCR is most commonly misdiagnosed as the acute phase of VKH due to the exudative retinal detachment.⁶ Subretinal fibrin reaction and presence of generalized RPE irregularities in the absence of vitreous cells and lack of optic disc hyperemia and edema are signs in favor of CSCR. An absence of optic disc staining on FA and ICGA is a finding that further facilitates the diagnosis of CSCR. On OCT, RPE bulge may be seen in CSCR, whereas RPE folds, fluctuations of the internal limiting membrane, and subretinal septa are seen only VKH.⁷ Subretinal fibrin reaction is frequently encountered in eyes with bullous CSCR.⁸

Therapeutic options for atypical CSCR include laser photocoagulation, PDT, and oral mineralocorticoid receptor antagonists.⁹ The main mechanism of action of PDT is angio-occlusion leading to constriction of choroidal vessels and choroidal vascular remodelling.¹⁰ Therefore, it may be the most appropriate treatment approach, being effective on the direct pathogenesis. In our case, we used a combination of half-fluence PDT and eplerenone therapy, which provided very rapid and complete resolution of subretinal fluid without complications.

In conclusion, the use of multimodal imaging may enable early definitive differential diagnosis of atypical CSCR from other chorioretinal diseases. Otherwise, inappropriate use of corticosteroids and other immunosuppressive agents may worsen the clinical findings and lead to poor visual prognosis. Hf-PDT in combination with oral eplerenone may be a successful treatment option for atypical CSCR that prevents subretinal fibrosis and scar formation.