Retinal blood delivery and oxygen handling are complementary functional observables. We seek a rapid proof of concept combining flow-related speckle contrast with relative oxygenation changes in healthy volunteers. Linking these signals will test whether flow responses are accompanied by reproducible changes in oxygenation-sensitive absorption. A single camera will provide spatially matched measurements of vascular dynamics and spectral reflectance, creating a simple route to investigate retinal perfusion–oxygenation coupling. Arterial and venous signals will be analysed separately to compare flow-related and spectral variations at rest and during physiological challenges. This provides a concrete physiological test of whether combining the observables adds information beyond either measurement alone. Our recent demonstration [1] processed human retinal images at 1,000 frames/s (8.29 Gpixel/s). Kim et al. [2] established wavelength-swept speckle imaging with spectral absorbance measurements. Brief challenges, such as flicker stimulation [3], can provide an initial test of responsiveness. Ametek Phantom streaming cameras and Superlum laser sources swept continuously over 820–870 nm, provide the essential hardware. Sweeps will yield wavelength-resolved contrast and reflectance measurements. Repeated undilated recordings will establish feasibility and repeatability ; sweep-induced decorrelation, source intensity and eye motion will be assessed before interpreting spectral changes as relative oxygenation.
[1] Auray Z et al. High-speed laser speckle contrast imaging of the human retina. arXiv:2610.34605 (2026).
[2] Kim JW et al. Multi-spectral laser speckle contrast images using a wavelength-swept laser. J Biomed Opt. 2019 ;24:076001. doi:10.1117/1.JBO.24.7.076001.
[3] O’Shea S et al. Low-rank modal endpoints from beat-resolved retinal arterial Doppler holography velocity waveforms characterize the response to flicker provocation. arXiv:2608.15677 (2026).
