Abstract
Purpose :
Camera-based imaging photoplethysmography (PPG) provides facial blood pulsation intensity (BPI) maps, also known as facial angiosomes. Optical coherence tomography (OCT) provides non-invasive measurements of choroidal thickness (CT), indicative of choroidal blood volume. This study was designed to determine if BPI measurements of central forehead skin are correlated with the CT measurements in eyes with AMD and normal eyes.
Methods :
The subject eyes were scanned by swept-source OCT angiography (SS-OCTA) using the 12x12 mm scan pattern. Mean CT (MCT) was automatically obtained using a validated algorithm and averaged from both OD and OS for each subject. The BPI maps of the central forehead (cfrBPI) and the vertical centroid of the facial BPI maps, representative of terminal branches from the ophthalmic artery, were obtained by camera-based imaging PPG.
Results :
Fifty-six patients were enrolled. The MCT measurements were significantly negatively correlated with cfrBPI measurements (r=-0.46, P<0.001). However, this correlation was reversed when compared to the vertical centroid of facial BPI maps (r=0.48, P<0.001).
Conclusions :
Central forehead blood pulsations were increased in eyes with thinner choroids, demonstrating that the blood flow to the choroid and the skin of the central forehead have an inverse relationship, which suggests a decrease in ophthalmic artery blood flow to the eye may correspond to an increase in blood flow to the forehead. One possible explanation is that less blood diverted to the eye results in greater blood flow to the forehead. Another possible explanation is that decreased blood flow to the eye corresponds to an overall decrease in blood flow in the ophthalmic artery and the increased cfrBPI results from collateral perfusion from the external carotid artery. Camera-based PPG may serve as a cost-efficient tool to indicate choroidal blood perfusion for assessment of ocular conditions.
This abstract was presented at the 2023 ARVO Annual Meeting, held in New Orleans, LA, April 23-27, 2023.