Depth-resolved optical probing of retinal physiology with functional ultrahigh resolution optical coherence tomography

Abstract

Non-contact, depth-resolved, optical probing of retinal response to visual stimulation with a <10µm spatial resolution, achieved by using functional ultrahigh-resolution optical coherence tomography (fUHROCT), is demonstrated in isolated rabbit retinas. The method takes advantage of the fact that physiological changes in dark-adapted retinas caused by light stimulation can result in local variation of the tissue reflectivity. fUHROCT scans were acquired from isolated retinas synchronously with electrical recordings before, during, and after light stimulation. Pronounced stimulus related changes in the retinal reflectivity profile were observed in the inner / outer segments of the photoreceptor layer and the plexiform layers. Control experiments (e.g., dark adaptation vs. light stimulation), pharmacological inhibition of photoreceptor function, and synaptic transmission to the inner retina confirmed that the origin of the observed optical changes is the altered physiological state of the retina evoked by the light stimulus. The conducted experiments demonstrated that fUHROCT allows for simultaneous, noninvasive probing of both retinal morphology and function, which could significantly improve the early diagnosis of various ophthalmic pathologies and could lead to better understanding of pathogenesis.

In the past year, advances in UHROCT technology have allowed conducting in-vivo fUHROCT measurements in animal models and human patients, thus bringing the fUHROCT technique closer to clinical trials and commercial development.