Development of a laser speckle contrast imaging analysis pipeline reveals a triphasic retinal blood flow waveform

Laser speckle contrast imaging (LSCI) is an under-utilized retinal imaging modality capable of non-invasively generating contrast-free, widefield maps of retinal blood flow from which multiple metrics of retinal hemodynamic function can be derived using relatively simple flood illumination instrumentation. Technical and computational advancements have improved spatiotemporal resolution and data extraction to the extent that three-peak blood flow waveforms, currently unaccounted for in LSCI nomenclature, are consistently revealed in the murine retina. Herein, we utilize a custom LSCI instrument and newly developed analysis pipeline to demonstrate the prevalence of the triphasic blood flow waveform, map timing of its first and third peaks to systole and diastole, respectively, via corroboration with arterial cannulation, and measure basal hemodynamic values for global, arterial, and venous retinal blood flow.