Abstract
Purpose :
Retinal blood flow plays a central part in the development of major retinal diseases, yet current instruments are technologically limited either spatially or temporally to measure this quantity. We developed a prototype non-invasive instrument in the Quinze-Vingt ophthalmology hospital in Paris based on laser Doppler holography that allows for retinal blood flow imaging over a wide-field of view.
Methods :
The retina is illuminated with 1.2 mW of constant laser radiation at 785 nm and the backscattered light is combined with a reference wave to record interferograms at a 39 kHz framerate. Power Doppler images with angiographic contrast are calculated from a short-time Fourier transform analysis of the reconstructed holograms.
Results :
Power Doppler images have a contrast related to blood perfusion: experiments performed on healthy volunteers showed vascular structures such as retinal vessels as well as part of the choroidal vasculature. The temporal resolution of the power Doppler images is 13 ms; blood flow can be observed through cardiac cycles over 512x512 pixels covering a field of view of approximately 2.5x2.5 mm on the retina; the spatial resolution is 20-30 µm.
Conclusions :
Laser Doppler holography revealed retinal blood flow in humans with a high temporal resolution. The information obtained with this instrument could prove useful both in ophthalmology and in cardiology.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.