The role of fibronectin in aqueous humor and its association with retinal and choroidal vascular parameters in branch retinal vein occlusion.

Purpose: To evaluate the relationship between fibronectin concentration in the aqueous humor and quantitative imaging parameters in patients with branch retinal vein occlusion (BRVO).

Methods: This retrospective study included 40 patients with BRVO treated for BRVO macular edema. Aqueous humor samples were collected during intravitreal injection of anti-vascular endothelial growth factor (VEGF) or steroids. Fibronectin concentration was measured using an enzyme-linked immunosorbent assay (ELISA) kit. Parameters included central macular thickness (CMT), choroidal thickness (CT), choroidal vascularity index (CVI) in optical coherence tomography (OCT), fractal dimension (FD), lacunarity (LAC), vessel density (VD), vessel length (VL), mean vessel diameter (MVD), and blood vessel tortuosity (BVT) in retinal vasculature of wide-field fluorescein angiography (wFA). Correlation analysis was performed between these parameters and fibronectin concentration, and differences in fibronectin levels were analyzed based on ischemic severity and treatment response.

Results: The fibronectin concentration in the aqueous humor was measured at 792.72 ± 237.40 ng/ml and showed no statistically significant correlation with VEGF levels (r = 0.08, p = 0.960). Fibronectin showed a significant negative correlation with retinal LAC (r = -0.461, p = 0.018) and with CVI (r = -0.340, p = 0.032). A borderline negative correlation was observed with CT (r = -0.286, p = 0.073). Fibronectin levels were significantly higher in non-ischemic BRVO patients (919.75 ± 138.26 ng/ml) compared to ischemic BRVO patients (733.04 ± 267.59 ng/ml, p = 0.033).

Conclusion: Fibronectin concentration in the aqueous humor of patients with BRVO shows significant associations with both retinal vessel homogeneity and choroidal vascular remodeling. These findings suggest that fibronectin may potentially contribute to vascular stabilization in a protective manner.