The use of dihydroxyacetone (DHA) is a timehonored method for cosmetic "sunless tanning" by producing an orange-brown oxidation product within the stratum corneum.1 Johnson's interesting work on UV-A photoprotection by this absorption-type sunscreen is clinically important.2 Dihydroxyacetone/naphthoquinone chemically altered stratum corneum absorbs UV-A and blue visible light.3 Our study4 shows that the interaction of light scattering with light absorption can provide photoprotection more effectively than either process independently; it is interesting to speculate how epidermal scattering may enhance the effectiveness of dihydroxyacetone as a UV-A—visible sunscreen, in comparison with typical surface-layer sunscreens. We certainly appreciate this well-informed response to our article.
Kaye ET, Blank IH, Anderson RR, Arndt KA, Levin JA. Durable Protection Against Long-Wavelength UV-A Radiation and Blue Light-Reply. Arch Dermatol. 1992;128(3):409. doi:10.1001/archderm.1992.01680130131021