Light-adapted flicker-optoretinography based on raster-scan optical coherence tomography towards clinical translation

Optoretinography (ORG) is a promising non-invasive and objective technique for assessing retinal function by measuring its response to light stimulation. Optical coherence tomography (OCT) has emerged as a promising tool for implementing ORG due to its three-dimensional imaging capabilities, high sensitivity to nanometer-scale changes induced by light stimulation, and clinical availability. Although ORG has proven feasible in laboratory settings, research-grade OCT systems lack satisfactory usability and cost-effectiveness to be clinically viable. Standard clinical raster-scan OCT systems, with their limited imaging speed, fall short of the requirements for measuring rapid ORG responses. To bridge this gap, we introduce a flicker-ORG modality based on a raster-scan OCT system that resembles standard clinical OCT. This system overcomes speed limitations through an innovative two-stage scanning protocol coupled with a 600 kHz swept source, enabling repeated volume imaging and precise retinal activity measurements over a finite area. Additionally, the light-adapted ORG strategy eliminates the need for dark adaptation, allowing examinations under photopic conditions and thus improving patient compliance. We tested this new ORG method by measuring flicker-induced photoreceptor responses in five healthy subjects. The results demonstrated high repeatability and revealed dependencies of the ORG response on flicker frequency and retinal eccentricity. These findings, combined with the system's utility, cost-effectiveness, and ease of integration into existing technologies, underscore its substantial potential for clinical application.