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Comparing the Effects of Chemical Optical Clearing Agents and Mechanical Compression on the Optical Attenuation of
Camila Ramos Silva1, Tania Mateus Yoshimura1, Jailda Nonato Dos Santos Oliveira2
1Nuclear and Energy Research Institute- IPEN/CNEN, São Paulo, Brazil.
Abstract:
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.
Insights
Optical Clearing Agents (OCAs) significantly reduce skin optical attenuation, outperforming mechanical compression. PEG-400/oleic acid demonstrated the highest efficacy, enhancing light delivery for deep-tissue diagnostics and therapies.
Area of Science:
- Biomedical Optics
- Optical Engineering
- Dermatology
Background:
- Light scattering in biological tissues impedes deep-tissue optical diagnostics and therapies.
- Optical Clearing Agents (OCAs) and Mechanical Compression (MC) are methods to reduce skin optical attenuation.
- The comparative effectiveness of OCAs and MC under standardized conditions is not well-established.
Purpose of the Study:
- To quantitatively compare the efficacy of various OCAs and MC in reducing skin optical attenuation.
- To evaluate the impact of different OCA formulations and enhancers on optical properties.
- To determine the optimal strategy for enhancing light penetration in deep tissues.
Main Methods:
- Spectral-domain Optical Coherence Tomography (OCT) at 840 nm was used to measure optical attenuation in porcine skin.
- Various OCAs (mineral oil, PEG-400, fructose, tartrazine) with enhancers (oleic acid, 1,2-propanediol) were tested.
- Load-dependent Mechanical Compression (1.6–47 kPa) was applied and compared with OCA treatments.
Main Results:
- PEG-400/oleic acid (80/20%) achieved the highest reduction in optical attenuation coefficient (OAC) by 23.8% ± 1.7% within 15 minutes.
- Fructose-based and tartrazine formulations also significantly reduced OAC (16.8% and 20.4%, respectively).
- Mechanical Compression showed no significant reduction in skin optical attenuation.
Conclusions:
- Optical Clearing Agents offer a more potent and stable reduction in skin optical attenuation compared to Mechanical Compression.
- OCA formulations, particularly PEG-400 with oleic acid, are superior for optimizing light delivery in deep-tissue applications.
- This study provides quantitative data to guide the selection of agents for improved optical diagnostics and therapies.
