Basic investigations for 2-dimensional time-resolved fluorescence measurements at the fundus.

The decay time is characteristic for several natural fluorophores. The determination of the decay time is independent of the fluorescence intensity. As a consequence, a short living weak fluorescence should be detectable also if it is covered by a intensive long-living fluorescence. As the decay time is influenced by the embedding matrix, information about the cellular stage might be possible. The laser scanning technique in combination with the time correlated single photon counting technique seems to be the optimal method for the discrimination of different fluorophores at the fundus according to the decay time. Fields of an equal decay time are presented as a tau mapping. An experimental set up was developed. Until now, only basic experiments were done on structured fluorescent tests, but under the conditions of the living eye. The results are promising. For the separate detection of the most important short life-time of 120 ps of A2E (excitation at 413 nm. emission 450-600 nm) as a putative precursor of lipofuscin in age-related macular degeneration [11], a light source for pulses in the range of about 50 ps is required.