Biomedical optical imaging of acne pathology: from single-modality methods to multimodal integration

Acne vulgaris is a prevalent inflammatory skin disorder, and the objective, timely, and accurate assessment of its severity is critical for guiding standardized treatment. Conventional evaluation methods are often subjective and time-consuming, limiting clinical efficiency. Optical imaging technologies, characterized by non-invasiveness and high resolution, enable the rapid visualization of key pathological features at the microstructural level, including follicular hyperkeratinization, sebaceous hyperactivity, bacterial colonization, and inflammation. Single-modality imaging techniques, such as OCT, RCM, dermoscopy, LSCI, UV fluorescence imaging, and HSI, can delineate various acne-related changes but face limitations in complex clinical settings. In contrast, multimodal imaging integrates complementary techniques to offer a more comprehensive pathological profile, demonstrating significant potential in clinical applications. Future advancements should prioritize enhanced resolution, sensitivity, and integration with artificial intelligence to improve the precision and reliability of acne severity assessment. This review summarizes the photobiological properties of key acne-related biomarkers and their potential to be harnessed through optical imaging for improved diagnosis and management.