Abstract
Purpose:
Fluorescence Lifetime Imaging Ophthalmoscopy (FLIO) is a technique that allows non-invasive in vivo measurements of fluorescence lifetimes of natural fluorophores in the retina after excitation with picosecond laser pulses. It is a powerful tool to distinguish between different natural fluorophores. However, very little is known about the influence of the different retinal layers on overall fluorescence lifetimes in the retina. To address this knowledge gap we examined different mouse strains for their retinal fluorescence characteristics.
Methods:
Fluorescence lifetimes (Tau 1, Tau 2, Tau mean) were measured in short and long wave channels (SWC: 498 - 560 nm, LWC: 560 - 720 nm) in pigmented (C57BL/6) and non-pigmented mice (BALBc) and in a mouse model of retinal degeneration (RDS; C3A.Cg-Pde6b+ Prph2Rd2/J ) using a Fluorescence Lifetime Imaging Ophthalmoscope (FLIO). The system is based on a Heidelberg Engineering Spectralis® system. Group means were calculated and statistical analysis was performed using students t-test.
Results:
In the short wave length channel BALBc mice showed significant longer mean fluorescence lifetimes (Tm) compared to C57BL/6 and RDS mice (p= 0.0023 and p=0.0005, respectively). Between C57BL/6 and RDS mice, the lifetimes Tm of retinal fluorescence of C57BL/6 were significant longer than those of RDS (p=0.03). In the long wave length channel BALBc mice showed also highly significant longer fluorescence lifetimes compared to C57BL/6 and RDS mice (both p<0.0001). However, the difference between Tm of C57BL/6 and RDS mice was not significant in that channel (p=0.3).
Conclusions:
The melanin content in the retinal pigment epithelium appears to strongly influence mean fluorescence lifetimes in the murine fundus. In addition, the outer retinal layers seem to play a role in fluorescence lifetimes. The FLIO technique is a promising new technique for measurement of fluorescence lifetimes in the murine retina in vivo.
Keywords: 551 imaging/image analysis: non-clinical •
690 retina: neurochemistry •
552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)