Hyperpigmentation and pigmentary disorders are major consequences of sun exposure. The role of all UV rays up to the longest UVAs is now well established. In addition, Visible Light (VL) also contributes to the development, aggravation, or relapses of pigmentary problems such as dyschromia, melasma or post-inflammatory hyperpigmentation.
In the VL wavelengths’ domain, the shortest wavelengths are the most efficient in inducing pigmentation1,2, especially HEV (High Energy Visible Light 400-450nm) and Blue light (400-500nm) contributing for 47 and 71 % in VL-induced pigmentation. This pigmentation is mostly observed in individuals Fitzpatrick Phototype III and above. Within these populations, the level of induced-pigmentation was compared after four exposures to 144J/cm² of VL. In three groups, European FPTIII, African descent FPTVI and Asian descent FPTIII individuals, significant differences were observed; the highly pigmented, FSPVI as well as Asian FSPIII subjects having a higher response to VL compared to Europeans FSPIII.
To provide VL photoprotection, the efficient solutions relies on the use of pigments. Robust in vivo method can determine a VL-PF (Visible Light Protection Factor) which can be expressed as a percentage i.e. pVL-PF ranging from 0 to 100% performance3. Using a similar methodology, 30 different formulas were assessed. We propose a new framework to calculate pVL-PF together with statistical indicators allowing to rank formulas’ efficacy. In parallel the VL transmittance profile of the formulas showed a very high correlation with in vivo performance. These data provide methodologies to quantify VL photoprotection.
In conclusion, photoprotection should take into account all UV rays, but also VL, especially for populations with a high susceptibility to develop pigmentary disorders.
1 Duteil et al. Pigment Cell Melanoma Res. 2014 27:822-6.
2 Marionnet et al. J Eur Acad Dermatol Venereol. 2023 37 Suppl 4:3-11.
3 Duteil et al. . J Eur Acad Dermatol Venereol. 2022 36:922-926.