In vivo sun protection factor and UVA protection factor determination using (hybrid) diffuse reflectance spectroscopy...

Area of Science:

• Photomedicine
• Spectroscopy
• Dermatology

Background:

• Current sun protection factor (SPF) determination relies on invasive ultraviolet (UV) light irradiation of volunteers.
• Non-invasive hybrid diffuse reflectance spectroscopy (HDRS) shows promise for correlating with conventional SPF testing.
• A need exists for efficient and reliable in vivo methods for evaluating sunscreen efficacy.

Purpose of the Study:

• To present a novel, compact, and adjustable diffuse reflectance spectroscopy (DRS) test system for in vivo SPF and UVA-PF measurements.
• To validate the performance of the new DRS system against established in vivo SPF testing methods.

Main Methods:

• Development of a compact DRS test system utilizing a multi-lambda-LED light source and an 84-channel imaging spectrograph.
• In vivo measurements on 10 volunteers per 11 sunscreen products, calculating transmission spectra from reflectance data.
• Fitting pre-exposure in vitro spectra to in vivo spectra for SPF and UVA-PF value determination.

Main Results:

• The novel DRS system achieved high correlation coefficients: R² = 0.86 for SPF and R² = 0.92 for UVA-PF.
• The results demonstrate valid and reproducible measurements compared to certified in vivo SPF testing.
• The multi-lambda-LED device proved suitable for in vivo SPF and UVA-PF assessment.

Conclusions:

• The presented compact DRS system offers a reliable and non-invasive alternative for in vivo sunscreen efficacy testing.
• This HDRS-based approach provides accurate SPF and UVA-PF values, supporting its use in product development and quality control.