Pilot Study of Choroidal Synphlebia

To describe the multimodal imaging characteristics and clinical associations of choroidal synphlebia, a newly recognized configuration of the choroidal venous system.

This retrospective study analyzed patients imaged with the DREAM swept-source OCT system (Intalight, San Jose, CA), capable of deep choroidal penetration. Choroidal synphlebia was defined as a confluent vascular structure ≥750 µ m in smallest lateral or vertical dimension. The multimodal imaging characteristics were evaluated.

Nineteen eyes of 16 patients (mean age 63.2 years; eight male) were identified. Associated diagnoses included central serous chorioretinopathy in 16 eyes, neovascular age-related macular degeneration in 2, and myopia in 1. Three patients had bilateral involvement. Two morphologic patterns were observed: (1) broad confluence of large choroidal veins forming a lobulated venous lake and (2) a caput medusa-type arrangement with smaller tributaries converging radially into a dilated central channel. The lesions often occurred near presumed choroidal watershed zones. Macular neovascularization was present in seven eyes. In several central serous chorioretinopathy cases, subretinal fluid was resistant to photodynamic therapy but responsive to faricimab.

Choroidal synphlebia represents a distinct choroidal venous phenotype characterized by fusion or coalescence of major veins with a lack of visible vessels in the overlying Sattler's layer and inner choroid. Alterations in the capacitance, resistance, and pressure distribution in the venous drainage system appear to be affected by synphlebia lesions. Recognition of synphlebia may provide insight into choroidal hemodynamics and may help explain atypical or treatment-resistant central serous chorioretinopathy and neovascular presentations.