Abstract
Purpose :
Fluorescence lifetime imaging ophthalmoscopy (FLIO) is a novel method to investigate and monitor changes in the retina. Using FLIO, we have studied different patterns of macular pigment (MP) in several disease entities in a clinic-based, cross-sectional study design. Additionally, we have analyzed the ex vivo fluorescence characteristics of carotenoids.
Methods :
The study included 31 eyes of 25 young healthy subjects, two eyes from a patient with albinism, 36 eyes of 18 patients with macular telangiectasia type 2 (MacTel), 24 eyes of 12 patients with retinitis pigmentosa, and one eye from a patient with a macular hole. All patients underwent Heidelberg Engineering FLIO and MP measurements (two-wavelength autofluorescence method). Foveal autofluorescence (FAF) lifetimes from a 30° retinal field were detected in short (498-560 nm, SSC) and long (560-720 nm, LSC) spectral channels. Mean fluorescence lifetimes (τm) were calculated from the recorded FAF lifetimes. Additionally, autofluorescence lifetimes of lutein (L) and zeaxanthin (Z) were measured using a cuvette, with known dilutions in both free and protein-associated states.
Results :
We found a strong inverse correlation between MP and FAF lifetimes measured with FLIO (SSC: r = -0.608; p<0.001). Different distribution patterns can be assigned to specific disease-related changes. A patient with albinism, who lacks MP, was found to be missing short FAF lifetimes. Lutein (L) and zeaxanthin (Z) in solution show very short autofluorescence lifetimes (L: 47 ps, Z: 45 ps; SSC), but when combined with their specific binding proteins, the decay times shift to longer means (L: 92 ps, Z: 58 ps; SSC).
Conclusions :
This study expands upon the previous characterization of the impact of MP on short FAF lifetimes, describes ex vivo autofluorescence lifetimes of macular carotenoids, and furthermore describes several patterns of fluorescence lifetimes that can be associated with certain diseases.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.