Kohli SC, et al. - The contributions of visible light (VL) and ultraviolet (UV)A on pigmentation and erythema were assessed during this trial. In addition, this study aspired to optimize the parameters for in-vivo testing. A synergistic association was disclosed between VL and UVA1. The findings stressed on the need for developing means of photoprotection against VL.

Methods

• This trial comprised of 10 candidates with Fitzpatrick skin phototype IV-VI.
• They were irradiated on their back with VL using two light sources: One containing pure VL and one containing VL with less than 0.5% UVA1 (VL+UVA1).
• 4 different irradiances were administered to determine the reciprocity behaviour.
• Analyses were carried out, with the inclusion of photography, investigator's global assessment, colorimetry, and spectroscopy, immediately, 24 hours, 7 days and 14 days post-irradiation.

Results

• There was pigmentation with both light sources.
• Nevertheless, greater pigment intensity was reported with VL+UVA1 than pure VL.
• Reciprocity was noted in pure VL sites, but not VL+UVA1.
• The spectral output change exhibited greater impact on pigment intensity than irradiance.
• There was clinical erythema on the VL+UVA1 side, but not on the pure VL side.
• The proposition put forth was protocol for testing photoprotection product efficacy against VL induced effects.