Line-field confocal optical coherence tomography coupled with artificial intelligence algorithms to identify quantitative biomarkers of facial skin ageing.

Quantitative biomarkers of facial skin ageing were studied from one hundred healthy Caucasian female volunteers, aged 20-70 years, using in vivo 3D Line-field Confocal Optical Coherence Tomography (LC-OCT) imaging coupled with Artificial Intelligence (AI)-based quantification algorithms. Layer metrics, i.e. stratum corneum thickness (SC), viable epidermal thickness and Dermal-Epidermal Junction (DEJ) undulation, as well as cellular metrics were measured for the temple, cheekbone and mandible. For all three investigated facial areas, minimal age-related variations were observed in the thickness of the SC and viable epidermis layers. A flatter and more homogeneous epidermis (decrease in the standard deviation of the number of layers means), a less dense cellular network with fewer cells per layer (decrease in cell surface density), and larger and more heterogeneous nuclei within each layer (increase in nuclei volume and their standard deviation) were found with significant variations with age. The higher atypia scores further reflected the heterogeneity of nuclei throughout the viable epidermis. The 3D visualisation of fine structures in the skin at the micrometric resolution and the 1200 µm × 500 µm field of view achieved with LC-OCT imaging enabled to compute relevant quantitative biomarkers for a better understanding of skin biology and the ageing process in vivo.

"You look sleepy " The impact of sleep restriction on skin parameters and facial appearance of 24 women.

BACKGROUND: Total sleep deprivation has a visible impact on subjective facial appearance. However, there is a lack of knowledge on how moderate sleep restriction objectively impairs skin quality and facial aspect. METHODS: Twenty-four healthy good-sleeping women, aged 30-55, volunteered for this study on the impact of sleep restriction (SR) on their facial skin. SR was limited to 3 h per night for 2 consecutive nights. We assessed the following parameters at the same time of day, before and after SR: sebumetry (Sebumeter SM 815), hydration (Corneometer CM 825), trans-epidermal water loss (Tewameter TM 210), biomechanical properties (Cutometer MPA 580), pH (PH-meter 900), desquamation quantification (D-Squameter and microscopy), and image analysis (ColorFace - Newtone Technologies). We also obtained skin samples (swab) for malondialdehyde quantification (MDA). RESULTS: We observed that some skin parameters are significantly associated with SR in both the morning and afternoon, including: lower hydration (p < 0.001), increased trans-epidermal water loss (PIE) (p < 0.001), and decreased extensibility (Uf; p = 0.015) and viscosity (Uv; p < 0.001) of the skin. The average pH increased from 4.8 (±0.2) to 4.9 ± 0.4; p < 0.001. For face photography, brightness and saturation also significantly decreased with SR in mornings and afternoons (p < 0.001 for all tests). Finally, we observed a significant decrease in isolated corneocytes after desquamation associated with SR (p < 0.001 for all tests). SR was also associated with significantly increased MDA levels (p < 0.001 for all tests). CONCLUSIONS: Two nights of SR significantly altered the skin and facial appearances in our test group of typically good-sleeping women.