Abstract
Purpose :
This study is to investigate stimulus-evoked intrinsic optical signal (IOS) changes in photoreceptor outer segment (OS) and inner segment (IS), and thus to demonstrate the potential of functional IOS imaging of phototransduction and metabolic integrity of retinal photoreceptor.
Methods :
A custom-designed optical coherence tomography (OCT) was used for in vivo imaging of transient IOS changes in the retina of wild-type mice (C57BL/6J). A near-infrared superluminescent diode (SLD) was used as the light source for OCT imaging, and a visible light-emitting diode (LED) was employed for retinal stimulation. Depth-resolved IOSs were calculated at individual retina layers, based on the time-lapse OCT sequence. IOS changes at OS and IS ellipsoid (ISe) were segmented for quantitative analysis.
Results :
Individual retina layers, including OS and ISe, were observed in OCT image (Fig. 1A). Rapid IOS response was consistently observed in OS almost right away after the onset of the retinal stimulation (Fig. 1B). However, robust IOS change at ISe had a ~2 s time delay, compared to that observed at OS (Fig. 1C). As shown in Fig. 1, the rapid OS-IOS reached the peak value before the slow IS-IOS. The time courses of these OS-IOS and IS-IOS were dependent on the stimulus strength.
Conclusions :
Functional OCT revealed rapid IOS at OS, and relatively slow IOS at ISe. We anticipate that the OS-IOS and IS-IOS can work as objective, noninvasive biomarkers for functional assessment phototransduction property and metabolic integrity at photoreceptor OS and IS segments respectively.
This is a 2020 Imaging in the Eye Conference abstract.