Abstract
Purpose :
To date the study of retinal blood vasodilation is limited to the vessel diameter measurement in the lateral direction, i.e., along the direction of the retina plane. This study is to employ functional OCT to verify anisotropic vasodilation in the cross-section of retinal blood vessels.
Methods :
A custom built SD-OCT system was used to acquire mouse retinal images with circular scanning to include all retinal blood vessels around optic disc. For each retina, the total OCT recording time was 30 s, including a 3 s pre-stimulation phase, a 5 s flicker light stimulation phase, and a 22 s post-stimulation phase. Traditional structural OCT and Doppler OCT images were reconstructed. Individual blood vessels were selected for quantitative analysis. Both axial and lateral profile of blood vessels were measured from OCT and Doppler OCT images recorded at different time points.
Results :
The en-face OCT clearly shows blood vessels around the optic disc (Fig. 1A). The B-scan OCT provides individual layers in the mouse retina and represents individual blood vessels (Fig. 1B). The Doppler OCT clearly differentiates blood vessels from background tissue and indicates artery and vein by different color (Fig. 1C). The axial profile of B-scan OCT shows significant vessel wall expansion after the stimulation (Fig. 1D1). The upper vessel boundary and signal peak move toward the vitreous direction whereas the lower vessel boundary remains the same location. The lateral profile shows relatively smaller change (Fig. 1D2), compared to axial profile. Both axial and lateral profiles from Doppler OCT present velocity increase after the stimulation (Fig. 1E). The blood flow area expansion is observed to be larger in axial direction compared to that in lateral direction.
Conclusions :
Functional OCT reveals anisotropic vasodilation in the cross-section of retinal blood vessels. Traditional vasodilation measurement in the lateral direction only may provide underestimated value.
This abstract was presented at the 2023 ARVO Imaging in the Eye Conference, held in New Orleans, LA, April 21-22, 2023.