Choriocapillaris Flow Signal Impairment in Sorsby Fundus Dystrophy.

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Abstract

Purpose To quantify choriocapillaris flow alterations in early Sorsby Fundus Dystrophy (SFD) and to investigate the relationship of the choriocapillaris flow deficits with the choroidal and outer retinal microstructure. Methods 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 choriocapillaris flow signal deficits (FDs). Differences in choriocapillaris 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. Results SFD patients exhibited a significantly greater choriocapillaris FD density than controls (estimate [95% CI]: +20.0% [13.3; 26.7], P<0.001 for SFD patients), even when adjusted for age. Square root transformed choroidal thickness was a structural OCT surrogate of the choriocapillaris FD density (-2.1% per √ µm, P<0.001), whereas retinal-pigment-epithelium-drusen-complex thickness was not informative regarding choriocapillaris FD (P=0.061). The choriocapillaris FD density was associated with an altered microstructure of the overlying photoreceptors (outer-segments, inner-segments, and outer-nuclear-layer thinning of -0.19 µm, -0.08 µm and -0.30 µm per %FD, respectively, all P<0.001). Conclusions Patients with early SFD exhibit pronounced abnormalities of choriocapillaris flow signal on OCTA, which are not limited to areas of sub-RPE deposits seen in OCT imaging. Thus, analysis of the choriocapillaris flow may enable clinical trials at earlier disease stages in SFD.S. Karger AG, Basel.