Abstract
Purpose :
This study is to test the feasibility of concurrent optical imaging of retinal neural activity and vascular hemodynamics. It is well established that major retinal diseases, such as age-related macular degeneration (AMD), glaucoma, and diabetic retinopathy (DR), involve distortions of retinal neural physiology and the blood vascular system. However, details of distortions in retinal neurovascular coupling (i.e., coherent interaction between retinal neural physiology and blood vascular system) associated with these major eye diseases are not well understood due to the limitation of existing techniques. We report here a multi-modal optical coherence tomography (OCT) to allow for concurrent imaging of retinal neural activity and vascular hemodynamics.
Methods :
A custom-designed OCT was constructed for in vivo imaging of mouse retinas. The OCT employed a near infrared (center wavelength: 843 nm) for dynamic retinal imaging. A visible light (505 nm) pulsed stimulation (10Hz) was used for retinal stimulation. Each experiment consisted of three OCT acquisition phases, including pre-stimulation (5 s), stimulation (15 s) and post-stimulation (40 s). Based on the same OCT data sets, stimulus-evoked intrinsic optical signal (IOS) was calculated to map retinal photoreceptor responses; while dynamic OCT angiography was reconstructed to detect transient hemodynamic changes in individual retinal layers.
Results :
Rapid IOS changes occurred almost immediately (< 10 ms), and typically reached peak value within 1 s after the stimulation onset. Both positive and negative IOSs were observed in adjacent retinal locations. In contrast, dynamic OCT angiography gradually disclosed blood flow changes, and typically reached peak value after 10 s of the stimulation onset.
Conclusions :
Multi-modal OCT enabled concurrent IOS imaging of retinal neural activity and angiographic monitoring of vascular hemodynamics. Further development of the multi-modal OCT may provide a new imaging methodology to study how retinal structure, metabolic and neural functions are affected by AMD, glaucoma, DR, etc., promising noninvasive biomarkers for early disease detection and treatment evaluation.
This is an abstract that was submitted for the 2016 ARVO Annual Meeting, held in Seattle, Wash., May 1-5, 2016.