  Different features of skin are associated with various medical conditions and
provide opportunities to evaluate and monitor body health. This study created a
strategy to assess choroidal thinning through the video analysis of facial
skin. Videos capturing the entire facial skin were collected from 48
participants with age-related macular degeneration (AMD) and 12 healthy
individuals. These facial videos were analyzed using video-based
trans-angiosomes imaging photoplethysmography (TaiPPG) to generate facial
imaging biomarkers that were correlated with choroidal thickness (CT)
measurements. The CT of all patients was determined using swept-source optical
coherence tomography (SS-OCT). The results revealed the relationship between
relative blood pulsation amplitude (BPA) in three typical facial angiosomes
(cheek, side-forehead and mid-forehead) and the average macular CT (r = 0.48, p
< 0.001; r = -0.56, p < 0.001; r = -0.40, p < 0.01). When considering a
diagnostic threshold of 200{\mu}m, the newly developed facial video analysis
tool effectively distinguished between cases of choroidal thinning and normal
cases, yielding areas under the curve of 0.75, 0.79 and 0.69. These findings
shed light on the connection between choroidal blood flow and facial skin
hemodynamics, which suggests the potential for predicting vascular diseases
through widely accessible skin imaging data.
