High speed volumetric fluorescein angiography in mouse retina by oblique scanning laser ophthalmoscopy (oSLO) (Conference Presentation)

Despite the recent development of advanced ophthalmic imaging techniques, volumetric fluorescence angiography (vFA) over a large field of view is still lacking. Fundus photography techniques have significant limitations due to the lack of 3D imaging capability. Scanning laser ophthalmoscopy (SLO) and confocal SLO (cSLO) use confocal gating to remove diffused light, resulting in crisper image quality. However, the volumetric imaging of SLO requires to compile z stacks, which can be challenging and time-consuming. Adaptive optics SLO (AOSLO) allows diffraction-limited resolution in both axial and lateral resolution. This technique is limited however, by its small field of view (FOV) and also the necessity of z stacks for volumetric imaging. To fill the technical void of vFA over a large field of view (FOV), we developed a novel retinal imaging modality called oblique scanning laser ophthalmoscopy (oSLO) for in vivo volumetric fluorescence retinal imaging. By using oblique illumination and detection, oSLO essentially allows “OCT-like” cross-sectional images contributed solely by the fluorescent contrast, without the need for z stacking. We will demonstrate 3D vFA over a 30˚x30˚ FOV in vivo in mouse retina. We will further report a high-speed oSLO in imaging capillary hemodynamics. The new capability allows the calculation of capillary hematocrit and blood speed in 3D, which can be potentially valuable in diabetic retinopathy and macular degeneration.