Broad-spectrum sunscreens protecting from UV-radiation are useful in the management of melasma, but they failed to prevent relapses.
The impact of the visible light on pigmentation is now demonstrated. However, using sunscreens effective against the entire visible light spectrum is almost impossible to use in daily practice. We recently demonstrated that short wavelengths of the visible spectrum (415 nm) can induce a prolonged hyperpigmentation in healthy volunteers while longer wavelengths (630 nm) do not affect pigmentation.
F Boukari, E Jourdan, E Fontas, H Montaudié, E Castela, JP Lacour, T Passeron
Prevention of Melasma Relapses With Sunscreen Combining Protection Against UV and Short Wavelengths of Visible Light: A Prospective Randomized Comparative Trial
J Am Acad Dermatol 2015 Jan 01;72(1)189-190.e1