Volumetric fluorescence imaging in a human eye model by oblique scanning laser ophthalmoscope (oSLO): a feasibility study

Abstract Fluorescence retinal imaging, such as fluorescein angiography, indocyanine green angiography, and autofluorescence imaging, are valuable tools in ophthalmology and vision science. However, these clinical imaging modalities provide en face view of the retina, with limited capability to discriminate retinal layers over a large field-of-view (FOV). We recently developed a novel retinal imaging method, oblique scanning laser ophthalmoscopy (oSLO), to provide volumetric retinal fluorescence imaging without any depth sectioning. OSLO breaks the coaxial alignment of the excitation and detection, to produce a cross-sectional view on retina using the natural ocular optics. In this paper, we demonstrated oSLO in a realistic human eye model and showed the feasibility for future in vivo human retinal imaging. A new optical design was implemented to significantly simplify our previous oSLO systems. We overcame the limitation by the small numerical aperture (NA) of the human eye, by integrating a pair of cylindrical lens in the remote focusing system. We experimentally showed that the current setup can achieve a FOV of ～3×6×0.8 mm3, and the transverse and axial resolutions of 7 and 41 μm, respectively. The capability of volumetric fluorescence imaging over a large FOV in the human retina could lead to new clinical imaging paradigms for retinal diseases.