Revealing the invisible: In vivo imaging for photoaging therapies- review of the literature

BACKGROUND: Photoaging refers to the cumulative structural and functional changes in the skin caused by chronic exposure to ultraviolet (UV) radiation, distinct from chronological (intrinsic) aging. Among available interventions, photodynamic therapy (PDT) has demonstrated not only anti-tumor efficacy but also skin rejuvenating effects. To evaluate treatment outcomes objectively, modern non-invasive imaging technologies are increasingly applied in dermatology. This review aims to summarize the use of in vivo imaging tools-Antera 3D, VISIA complexion analysis system, optical coherence tomography (OCT), and reflectance confocal microscopy (RCM)-to assess the clinical efficacy of PDT and other interventions for photoaging. METHODS: A PubMed search was conducted up to May 2024. Eligible studies included human participants, a minimum follow-up period of three months, treatment of photoaged facial or décolleté skin, and an objective assessment using one of the four imaging modalities. Seventeen studies fulfilled the inclusion criteria. RESULTS: The reviewed imaging modalities demonstrated complementary strengths. The Antera 3D and VISIA systems provide rapid and reproducible quantification of wrinkles, pigmentation, and vascular changes. OCT enables cross-sectional analysis of the epidermis and dermis, particularly collagen density and dermo-epidermal junction architecture. RCM offers near-histological resolution of epidermal and superficial dermal structures, capturing cellular and extracellular matrix changes. These modalities confirmed clinically visible improvements in photoaging after PDT and other rejuvenation procedures. CONCLUSION: PDT and other interventions can partially reverse the clinical signs of photoaging. In vivo imaging tools enhance objectivity in treatment monitoring. A multimodal imaging approach may represent the future standard for both clinical and research settings.