Fluorescence lifetime imaging ophthalmoscopy (FLIO) of patients with neovascular age-related macular degeneration before and after treatment with intravitreal ranibizumab

Purpose

Neovascular age-related macular degeneration (AMD) is a leading cause of severe vision loss worldwide. Although intravitreal anti-vascular endothelial growth factor (anti-VEGF) injections improve outcomes, frequent treatments are burdensome and responses vary. This study investigates changes in macular fluorescence lifetime before and after anti-VEGF therapy using fluorescence lifetime imaging ophthalmoscopy (FLIO), and explores FLIO parameters as potential biomarkers for treatment response.
Methods

Twenty patients with neovascular AMD underwent FLIO imaging (excitation: 473 nm; emission: short spectral channel [SSC]: 498–560 nm; long spectral channel [LSC]: 560–720 nm) and macular OCT before and 4–6 weeks after ranibizumab injection. Fluorescence lifetime components (mean τm, short τ1, long τ2), retinal thickness (RT), and best-corrected visual acuity (BCVA, logMAR) were compared. Analysis focused on central (C), inner ring (IR), and outer ring (OR) regions of the ETDRS grid. Spearman correlation was used to assess relationships between parameter changes.
Results

Changes in FLIO parameters post-treatment varied individually without a consistent trend. However, statistically significant correlations were found between changes in BCVA (∆logMAR) and changes in τ1 in the central area (p = 0.030) as well as τ2 in the inner ring (p = 0.040) in the SSC, with greater BCVA improvement associated with shorter fluorescence lifetimes. No significant correlation was observed between RT and BCVA.
Conclusion

FLIO parameters correlated with visual acuity changes, while retinal thickness did not. This suggests that FLIO may capture treatment-induced alterations beyond structural changes, potentially reflecting metabolic processes. FLIO may therefore serve as a valuable adjunct tool for monitoring anti-VEGF therapy response in neovascular AMD.