Fluorescence Lifetime Imaging Ophthalmoscopy (FLIO)

Fluorescence lifetime imaging ophthalmoscopy (FLIO) is an emerging technology, which enables the time-resolved in-vivo measurement of fluorescence emitted by endogenous fluorophores within the retina. The decay time of the fluorescence is a characteristic parameter for fluorescent molecules and their environment, and therefore FLIO is a promising tool to detect and assess varying metabolic states of different areas in the retina. The system is based on a confocal scanning laser ophthalmoscope with an implemented real-time eye tracking system. The fluorophores are excited by picosecond laser pulses and the fluorescence emission is detected using time correlated single photon counting (TCSPC) technology. In this chapter the historical and technical background of FLIO technology is described first, followed by the description how the technique was integrated into a modified Spectralis system. In the subsequent sections, selected results obtained in clinical studies conducted in Bern, Salt Lake City and Jena are presented. FLIO data acquired on patients with age-related macular degeneration (AMD), diabetic retinopathy, macular dystrophies, and other diseases are discussed in regard to the additional contrast and information provided in comparison to standard intensity-based autofluorescence images.