Assessment of Choroidal Vascular Alterations in Branch Retinal Vein Occlusion Using Wide-Field Indocyanine Green and Fluorescein Angiography.

Objective: To quantitatively analyze choroidal vascular characteristics in branch retinal vein occlusion (BRVO) using wide-field indocyanine green angiography (wICG) and fluorescein angiography (wFA).

Methods: Retrospective analysis of 66 eyes (33 unilateral BRVO patients, including fellow eyes) was conducted. Quantitative measures included fractal dimension (FD), lacunarity (LAC), choroidal vessel density (CVD), total vessel length (TVL), mean vessel diameter (MVD), and blood vessel tortuosity (BVT). To minimize retinal vessel influence, FD and LAC were calculated using wICG/wFA ratios (FD_r, LAC_r) and wICG-wFA differences (△FD, △LAC). Other parameters were obtained by subtracting wFA from wICG values.

Results: In BRVO-affected eyes, FD_r, △FD, CVD, and macular CVI were significantly lower than in fellow eyes (p=0.029, p=0.027, p<0.001, p=0.043). △FD correlated with choroidal thickness (CT) and Haller/Choroid thickness ratio (H/C) (r=-0.380/p=0.029, ρ=0.364/p=0.038). △FD was lower in good responders to intravitreal injection (p=0.041), and final visual acuity correlated with TVL, MVD, and BVT (β/p = 0.481/0.005, -0.386/0.027, 0.430/0.012).

Conclusions: Changes in vascular parameters in BRVO suggest choroidal remodeling driven by stromal congestion as an alternative mechanism rather than solely VEGF-driven choroidal alterations. These findings enhance understanding of choroidal dynamics and aid in predicting visual prognosis and treatment response.