The aim of the study was to quantify choriocapillaris (CC) flow alterations in early Sorsby fundus dystrophy (SFD) and to investigate the relationship of the CC flow deficits with the choroidal and outer retinal microstructure. In this prospective case-control study, 18 eyes of 11 patients with early SFD and 31 eyes of 31 controls without ocular pathology underwent multimodal imaging, including spectral-domain optical coherence tomography (OCT), followed by deep-learning-based layer segmentation. OCT angiography (OCTA) was performed to quantify CC flow signal deficits (FDs). Differences in CC FD density between SFD patients and controls were determined, and the relationships with choroidal thickness, retinal pigment epithelium-drusen complex (RPEDC) thickness and outer retinal layer thicknesses were analyzed using mixed-model analysis. 0.001). Patients with early SFD exhibit pronounced abnormalities of CC flow signal on OCTA, which are not limited to areas of sub-RPE deposits seen on OCT imaging. Thus, analysis of the CC flow may enable clinical trials at earlier disease stages in SFD.