The optoretinogram reveals the primary steps of phototransduction in the living human eye

Photoreceptors initiate vision by converting photons to electrical activity. The onset of the phototransduction cascade is marked by the isomerization of photopigments upon light capture. We revealed that the onset of phototransduction is accompanied by a rapid (<5 ms), nanometer-scale electromechanical deformation in individual human cone photoreceptors. Characterizing this biophysical phenomenon associated with phototransduction in vivo was enabled by high-speed phase-resolved optical coherence tomography in a line-field configuration that allowed sufficient spatiotemporal resolution to visualize the nanometer/millisecond-scale light-induced shape change in photoreceptors. The deformation was explained as the optical manifestation of electrical activity, caused due to rapid charge displacement ...