Sunscreen Remanence on the Skin: A Noninvasive Real-Time In Vivo Spectral Analysis Assessing the Quenching of Specular Ultraviolet A Light Reflectance
 August 2015   
in “
 Journal of Cosmetic Dermatology 
”
 
      TLDR  Sunscreens with UVA blockers effectively reduce skin fluorescence for several hours.   
  The study assessed the remanence of sunscreens on the skin using the Visiopor® and Visioscan® devices to measure the quenching effect on follicular fluorescence caused by UVA blockers. Results showed that all tested suncare products with UVA blockers effectively reduced porphyrin-related follicular fluorescence on facial skin, with the effect lasting for several hours. Variations in fluorescence recovery were attributed to the quantity of sunscreen applied and the formulation's components.