Evaluating the Influence of the Lens Autofluorescence on Adaptive Optics Fluorescence Lifetime Imaging Ophthalmoscopy

PurposeTo assess the impact of lens autofluorescence on adaptive optics fluorescence lifetime imaging ophthalmoscopy (AOFLIO). MethodsEighteen subjects (n = 18) aged 23 to 68 years with normal chorioretinal health and phakic lenses were imaged using a research-grade AOFLIO instrument. Retinal autofluorescence was excited with a pulsed diode laser ({lambda} = 473 nm) and detected in two spectral channels (500-560 nm and 560-720 nm). AOFLIO images were acquired at locations from the foveal center to 10{degrees} of the nasal retina. Autofluorescence decay was modeled using bi-exponential and tri-exponential functions, with and without accounting for the early arrival of the lens signal. The contribution of lens autofluorescence was evaluated in relation to age and retinal location. ResultsThe tri-exponential model that accounted for the early arrival of lens autofluorescence demonstrated superior conformity to the measured autofluorescence decay. The amplitude coefficient of lens contribution was 3 - 4%. However, this component accounted for 19.4 - 29.0% of photon-weighted signals and resulted in a 22.8 - 42.9% overestimation of the mean retinal fluorescence lifetime when uncorrected. Len effect was more pronounced in the short spectral channel. The time shift parameter of lens signal was associated with axial length and age (p = 0.023) and negatively correlated with axial length (p = 0.036). ConclusionsAOFLIO substantially suppresses lens autofluorescence; however, residual lens signal persists and can disproportionately bias retinal autofluorescence lifetime estimates. Accurate correction of the lens component are essential for reliable AOFLIO measurements. Translational RelevanceMinimizing the impact of lens autofluorescence in AOFLIO ensures accurate assessments of metabolic status in the retina and retinal pigment epithelium.