INTRODUCTION: Photo aging predominantly occurs in the face, neck and hands due to UVA and UVB irradiation. It is associated with skin cancer and histological studies indicate thinning of the epidermis and elastosis occurs. Dynamic Optical coherence tomography (D-OCT) is a non-invasive imaging tool able to visualize the epidermis and upper dermis and its blood vessels as well as to evaluate epidermal thickness (ET) and blood flow.
OBJECTIVE: To investigate ET and blood vessel depth using D-OCT in human subjects correlated to UV exposure.
METHODS: We evaluated data from 249 healthy adults, that had D-OCT-scans conducted at four different regions (forehead, neck, arm and hand) and correlated ET and blood vessel depth with occupational UV exposure (total standard erythema dose, Total SED), season and demographic data.
RESULTS: Regional differences in ET and blood vessel depth were found (p values < 0.001). Multiple linear regressions showed a seasonal effect on both ET (- 0.113 to - 0.288 µm/day, p values < 0.001) and blood vessel depth (0.168-0.347 µm/day, p values < 0.001-0.007) during August-December. Significant age-related decrease of ET was seen in forehead, arm and hand (0.207-0.328 µm/year, p values = 0.002-0.18) and blood vessel depth in forehead (0.064-0.553 µm/year, p values = 0.01-0.61). Males had thicker epidermis (3.92-10.93 µm, p values = 0.002-0.15).
CONCLUSION: Changing seasons are a major predictor of both ET and blood vessel depth, showing strongest effect in non-exposed areas, suggesting a systemic effect, possibly due to seasonal vitamin D fluctuation. Sex, age and occupational UV exposure affect ET. This study demonstrated the feasibility of D-OCT to evaluate epidermal thickness and blood vessel depth.