Abstract

During clinical application of the fluorescence lifetime laser scanner ophthalmoscope, a stepped slope of ocular autofluorescence was found. Fitting of fluorescence results in wrong lifetimes if the left border of the fitting interval is set at the time channel of first appearance of fluorescence. A better fit was reached at least for the fluorescence decay if the left border of the fitting interval is set near the maximum of detected fluorescence. Analysing the appearance of the stepped slope, its origination was found by the different appearance time of fluorescence from the crystalline lens and from the fundus fluorescence. The extension of the exponential model function by a parameter tci results in an optimal fit of both the slope and of the fluorescence decay. This new parameter describes differences in the appearance time of fluorescence originating from different layers. Taking into account the refractive index between layers, the geometrical distance between them can be determined. In this way, functional information (lifetimes) and geometrical information (distances) can be determined by the same measurement. To reach geometrical resolution comparable with OCT, pulses and time resolution are required in the order of 30 fs.

© 2009 OSA/SPIE