Confocal laser scanning and advanced image processing in ophthalmology

A confocal scanning laser ophthalmoscope (AngioScan(TM)) has been used to acquire confocal image series of the initial filling of Indocyanine Green (ICG) dye in eyes of normal subjects. Acquisition of the images was automatically triggered by detecting the fluorescence signal from the ICG reaching the ocular vasculature. The proprietary detection scheme of the AngioScan allowed to capture both the fundus reflectance image and the ICG fluorescence image simultaneously at any time. The authors sampled image pairs for about four seconds alter the automatic image trigger with frame rates of up to 30 image pairs per second. The images then were processed into a color-coded map depicting the time resolved filling pattern of the eye. In addition, the authors obtained 32 confocal image pairs at different focal planes. Processing the series of fundus reflectance images resulted in a map of retinal surface topography, while the simultaneous fluorescence images were used to calculate the depth of the sub retinal vessels.