Clinical and Morphologic Characteristics of Perivenular Fernlike Leakage on Ultrawide-field Fluorescein Angiography

Purpose: To analyze the spectrum of the perivenular fernlike leakage on ultrawide-field fluorescein angiography (UWFA) and discuss its potential implications in the current understanding of the retinal venous outflow. Design: Retrospective, observational case series. Participants: Eyes presenting with fernlike patterns of dye leakage on UWFA were included in this study. Methods: Analysis of the clinical characteristics and multimodal imaging findings using UWFA and wideangle swept-source OCT-angiography (SS-OCTA). Main Outcome Measures: The disease spectrum, anatomic origin, and clinical implications of this fernlike leakage. Results: Multimodal retinal images from 40 eyes of 29 patients with fernlike leakage on UWFA were studied. The underlying etiologies included a wide range of inflammatory disorders, including pars planitis (18 eyes) and central retinal vein occlusion (2 eyes). On UWFA, the fernlike leakage originated from the retinal capillaries and venules directly adjacent to the veins and spared the periarterial zone. This perivenular fernlike leakage involved the far periphery in all cases and progressed more diffusely and centripetally in cases with more severe intraocular inflammation. On wide-angle SS-OCTA, the impairment of deep capillary plexus (DCP) flow signals precisely colocalized with the perivenular fernlike leakages identified on UWFA. Conclusions: The fernlike leakage on UWFA refers to the distinctive perivenular dye leakage that originates from the retinal capillaries and venules. Multimodal imaging correlation suggests that the predominant impairment is at the level of the DCP. The axial symmetry of the fernlike leakage with the veins and sparing of the periarterial zone may support the dominant venous role of the DCP.