Structural and Angiographic Assessment of the Nerve Fiber Layer in Age-Related Macular Degeneration and Diabetic Retinopathy

Purpose: The purpose of this study was to evaluate structural and microvascular alterations in the nerve fiber layer (NFL) in age-related macular degeneration (AMD) and diabetic retinopathy (DR). Methods: A total of 74 healthy controls, 101 patients with AMD, and 117 patients with DR were included. One eye per participant was imaged using a Solix OCTA device centered on the optic disc to measure NFL thickness and nerve fiber layer plexus (NFLP) vessel density (VD). For both parameters, we analyzed the independent associations of age, AMD, and DR; compared age-matched healthy controls with the AMD groups and with the DR groups; and evaluated correlations with age in healthy controls. Results: Multivariate analyses demonstrated that age was independently associated with both NFL thickness and NFLP VD, whereas AMD was not associated with either parameter and DR was associated only with NFLP VD. The associations of AMD and DR with these two parameters were also confirmed in age-matched analyses. Additionally, NFLP VD decreased significantly with increasing DR severity (P < 0.001). In healthy controls, age was significantly correlated with both NFL thickness (Spearman's ρ = -0.26, P = 0.026) and NFLP VD (ρ = -0.32, P = 0.006). Conclusions: NFL thickness was associated with age, but not with AMD or DR. In contrast, DR was independently associated with reduced NFLP VD, which also significantly correlated with DR severity. These findings provide evidence supporting further investigation of NFLP VD in relation to DR, while accounting for age.