Comparing the Effects of Chemical Optical Clearing Agents and Mechanical Compression on the Optical Attenuation of Porcine Skin.

Light scattering remains a primary challenge for deep-tissue optical diagnostics and therapies. While Optical Clearing Agents (OCAs) are used to reduce skin attenuation, Mechanical Compression (MC) is also applied in clinical settings despite its inconclusive results. Their relative effectiveness under standardized conditions remains poorly characterized. This study quantitatively compares various OCA formulations, including mineral oil, PEG-400, fructose, and tartrazine, with enhancers such as oleic acid and 1,2-propanediol, under load-dependent MC (1.6-47 kPa). Using spectral-domain OCT at 840 nm on porcine skin, we found that PEG-400/oleic acid (80/20%) achieved the highest efficiency, reducing the optical attenuation coefficient (OAC) by 23.8% ± 1.7% within 15 min. Fructose-based and aqueous tartrazine formulations also showed significant reductions (16.8% and 20.4%). Conversely, our results show that MC does not effectively reduce skin optical attenuation. These findings demonstrate that OCAs provide a more potent, stable reduction in OAC, offering a superior strategy for optimizing light delivery.