Retinal hemangioblastoma, clinical appearance. Dilated, tortuous retinal feeder artery and draining vein emanating from the optic nerve head (A) lead to the red- to orange-colored retinal tumor (B). An optic nerve head hemangioblastoma causes traction in the macular area (C). In the early arterial phase of fluorescein angiography, the lesion is brightly hyperfluorescent (D).