Retinal autofluorescence lifetime measurement suggest preservation of macular pigment in geographic atrophy

Abstract

Purpose : To investigate autofluorescence lifetime characteristics of the foveal center in eyes with geographic atrophy (GA) due to age-related macular degeneration (AMD) and to correlate the measurements with clinical data and optical coherence tomography (OCT) findings.

Methods : Fourty-one patients (80±6 years) with GA were imaged with a fluorescence lifetime imaging ophthalmoscope (Heidelberg Engineering, Germany). Autofluorescence lifetimes were measured in a short and a long spectral channel (498-560 nm and 560-720 nm) after excitation with a 473 nm pulsed laser. Retinal fluorescence lifetimes were analyzed within GA, the macular center and the surrounding retina, and data was correlated with best corrected visual acuity (BCVA) and OCT measurements.

Results : Mean fluorescence lifetimes within GA was 1035±52 ps (SEM) in the short and 924±36 ps in the long spectral channel compared to 411±11 ps and 506±10 ps in the unaffected retina (p<0.0001). Within the foveal center, typically short fluorescence lifetimes (SSC: 295±27 ps and LSC: 401±28 ps) were observed. There was a significant correlation between BCVA and the mean fluorescence lifetime of the central ETDRS subfield in both spectral channels (r²=0.19, p=0.004).
Ten of 41 analyzed eyes showed foveal sparing of the GA lesion within the macular center.
Short fluorescence lifetimes within the fovea of patients with central GA did not significantly differ from values from patients with foveal sparing (p=0.67 and 0.31).

Conclusions : Autofluorescence lifetimes within geographic atrophy are clearly prolonged compared to the surrounding retinal tissue. However, within the fovea, fluorescence lifetimes are short, independent on the presence or absence of GA, potentially indicating preserved distribution of the macular pigment. Only cases with extensive destruction of the retinal layer structure (including absence of the outer plexiform layer (OPL)) did not show short lifetimes within the macular center.
Thereby, short autofluorescence lifetimes within atrophy may be used to estimate damage induced by GA and may be useful to monitor disease progression and potential effects of interventional therapeutic studies.

This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.