Multimodal retinal imaging by visible light optical coherence tomography and phosphorescence lifetime ophthalmoscopy in the mouse eye
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Significance
Oxygen metabolism is important to retinal disease development, but current imaging methods face challenges in resolution, throughput, and depth sectioning to spatially map microvascular oxygen.
Aim
To develop a multimodal system capable of simultaneous phosphorescence lifetime imaging scanning laser ophthalmoscopy (PLIM-SLO) and visible light optical coherence tomography (VIS-OCT) to capture capillary-level oxygen partial pressure (pO 2 ) and structural volumes in rodents.
Approach
C57BL/6 mice were imaged by VIS-OCT with high-definition (10 kHz raster) and Doppler (100 kHz circular) protocols. Phosphorescent probe Oxyphor 2P was retro-orbitally injected to enable intravascular PLIM-SLO imaging (200 µs pixel dwell time), while a tunable lens was used to adjust the focal depth. The extracted phosphorescence lifetimes were used for pO 2 calculation. Simultaneous imaging utilized a shared imaging path and synchronized data collection.
Results
VIS-OCT images revealed detailed anatomy and Doppler shifts, while PLIM-SLO provided capillary pO 2 at multiple depths. A hemoglobin oxygen dissociation curve related retinal arterial pO 2 to systemic oxygen saturation as inhaled oxygen was varied. Registered simultaneous images were captured and pO 2 was empirically adjusted for the combined excitation.
Conclusions
Detailed anatomical structures and capillary pO 2 levels can be simultaneously imaged, providing a useful tool to study oxygen metabolism in rodent disease models.
