Abstract
Purpose :
Stimulus-evoked intrinsic optical signal (IOS) changes correlated with neural activity and hemodynamic response are typically mixed together in the retina. The study was to explore optical coherence tomography angiography (OCTA) guided functional OCT data processing to differentiate neural-IOS and hemodynamic-IOS responses.
Methods :
Retinal OCT image sequence was acquired from each mouse retina activated by a flicker light stimulus. Based on the OCT image sequence, OCTA images were reconstructed. Then OCTA-guided segmentation was implemented to dissect avascular areas in each OCT image to produce blood vessel-free OCT image. Stimulus-evoked neural-IOS was calculated based on dynamic data processing of blood vessel-free OCT images; while stimulus-evoked hemodynamic-IOS was calculated based on dynamic data processing of corresponding OCTA images.
Results :
Robust neural-IOSs were observed in photoreceptor layer (PL), outer plexus layer (OPL), and inner plexus layer (IPL) (Fig1. B1). Corresponding hemodynamic-IOSs were recorded in large blood vessel, capillary, and avascular region (Fig1. B2). Rapid neural-IOS response was observed in the PL almost immediately after the onset of the retinal flicker stimulus (Fig1. C3). Neural-IOS changes at the OPL and IPL were relatively slow (Fig1. C1 and C2). The hemodynamic-IOS in the large blood vessels showed a short delay relative to stimulus onset time and reached their peak value during the stimulus (Fig1. D1); while prolonged delays were observed for the hemodynamic-IOS onset time and peak value in the capillaries (Fig1. D2).
Conclusions :
OCTA-guided OCT data processing has been demonstrated to dissect vascular (i.e., blood vessel) and avascular (i.e., neural tissue) retinal areas, enabling robust neural-IOS and hemodynamic-IOS monitoring simultaneously. Further development of the OCTA-guided functional OCT imaging can lead to a high-speed and high-resolution methodology for advanced investigation of retinal neurovascular coupling mechanism.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.