High-speed volumetric fluorescein angiography (vFA) by oblique scanning laser ophthalmoscopy in mouse retina

Oblique scanning laser ophthalmoscopy (oSLO) is a recently developed technique to provide three-dimensional volumetric fluorescence imaging in retina over a large field of view, without the need for depth sectioning. Here in the paper, we present high-speed volumetric fluorescein angiography (vFA) in mouse retina in vivo by oSLO. By simply using a low-cost industrial CMOS camera, we improved the imaging speed by ~10 times comparing to our previous results, achieving vFA at 2 volumes per second. Enabled by high-speed vFA, we visualized hemodynamics at single capillary level in 3D and provided methods to quantify capillary hematocrit, absolute capillary blood flow speed, and detection of capillary flow stagnancy and stalling. The quantitative metrics for capillary hemodynamics at 3D retinal capillary network can offer valuable insight in vision science and retinal pathologies.