In vivo optical imaging of physiological responses to photostimulation in human photoreceptors

TL;DR

This study demonstrates non-invasive in vivo optical imaging of human photoreceptor responses to light stimuli using phase-sensitive OCT, revealing potential for new diagnostic and research applications in ophthalmology and neurology.

Contribution

It is the first to non-invasively detect optical path length changes in human photoreceptors in vivo, advancing understanding of visual phototransduction.

Findings

Detected spatially and temporally resolved changes in photoreceptor outer segments.

Showed optical path length changes correlate with photoreceptor activity.

Provided a new method for non-invasive retinal diagnostics.

Abstract

Non-invasive functional imaging of molecular and cellular processes of vision is expected to have immense impact on research and clinical diagnostics. Although suitable intrinsic optical signals (IOS) have been observed ex vivo and in immobilized animals in vivo, it was so far not possible to obtain convincing IOS of photoreceptor activity in humans in vivo. Here, we observed spatially and temporally clearly resolved changes in the optical path length of the photoreceptor outer segment as response to an optical stimulus in living human. To obtain these changes, we evaluated phase data of a parallelized and computationally aberration-corrected optical coherence tomography (OCT) system. The non-invasive detection of optical path length changes shows the neuronal photoreceptor activity of single cones in living human retina, and, more importantly, it provides a new diagnostic option in ophthalmology and neurology and could give new insights into visual phototransduction in humans.