In-vivo Blood Flow Imaging in Human Retina with Adaptive Optics

Orateur : Serge MEIMON (Dépt Optique et Techniques Associées, ONERA, Paris)

The eye is the only optically accessible organ of the human body, in which a deep vascular network can be observed directly, non-invasively, at high resolution. Indeed, adaptive optics (AO) ophthalmoscopy, first demonstrated in 1997, enables micron scale resolution in retinal vessels. Two kinds of AO-ophthalmoscopes have been developed since 1997 : Full-field – or Flood Illumination – Ophthalmoscopes (FIO), where a camera is conjugated with the retina ; and Scanning Laser Ophthalmoscopes (SLO), analogous to confocal microscopes. These two categories of systems have complementary assets and flaws, but we deemed the full-field technique more adapted to the fine observation of the vascular network. The ECUROeil testbed, located inside 15-20 national ophthalmology hospital was used to acquire 200Hz videos of blood circulation, in large arteries (250µm) down to capillaries. Angiography maps computed from these videos reveal for example how the blood streams from small vessels converge in a larger vein without mixing immediately. Comparison between these videos and numerical or in-vitro blood circulation models could shine a new light on blood circulation in the retina, especially in diseased eyes where blood flow regulation failure is at the core of the pathology (typically in diabetic retinopathy).

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