A new in vitro method to predict in vivo photoprotection against visible light-induced pigmentation and a new visible light photoprotection factor

The pVL-PF is a new interpretation of the original VL-PF to compare more intuitively from 0% to 100% the performance of different formulations on VL-induced pigmentation. It makes it also easier to understand for dermatologists and consumers who are looking for high VL photoprotection. Interestingly, the best correlation between in vivo pigmentation and the in vitro transmittance was observed from 400 to 469 nm, which corresponds to the absorption spectrum of opsin-3. Indeed, melanocytes directly sense blue light through direct stimulation of the opsin-3 receptor. In conclusion, the in vitro method using transmittance measurement from 400 to 469 nm is a good predictive tool to evaluate sunscreen VL photoprotection efficacy and could be used to select formulations before final in vivo evaluation.