AUTHOR=Tornow Ralf-Peter , Odstrcilik Jan , Kolar Radim TITLE=A multi-color video-ophthalmoscopes allows to measure the spectral distribution of light absorption of blood in the human retina JOURNAL=Frontiers in Medicine VOLUME=Volume 10 - 2023 YEAR=2023 URL=https://www.frontiersin.org/journals/medicine/articles/10.3389/fmed.2023.1125154 DOI=10.3389/fmed.2023.1125154 ISSN=2296-858X ABSTRACT=Based on our previously developed mono-color video-ophthalmoscope a multi-color video-ophthalmoscope was developed. Using narrow band transmission filters, this instrument allows to measure the pulsatile cardiac cycle induced blood volume changes in the human retina for any wavelength in the sensitivity range of the used CMOS-camera. In this key-experiment, video sequences (8 s, 25 fps, 200 frames) of the optic nerve head (ONH) were acquire for seven wavelength between 475 nm and 677 nm. After image registration of all frames of each video sequence (to compensate for eye movements) and trend correction (to compensate for slow intensity changes), the amplitude of the cardiac cycle induced light intensity changes (pulsatile absorption amplitude PAA) can be calculated for all seven wavelength. The spectral distribution of PAA() follows the distribution of the light absorption of blood. The measured values correspond to the absorption of a thin blood layer of about 0.5 µm thickness.