Levels of ‘safe’ visible light may need modification

MAUI, HAWAII — The long-standing notion that visible light — such as lasers and fluorescent lamps, according to a 2015 report  as well as computer screens and cell phones — of 400 nm to 700 nm in wavelength has no significant biologic effect on the skin may not be accurate, a speaker here at Maui Derm for Dermatologists 2020 said.

“Data show that this is no longer true,” Henry W. Lim, MD, department of dermatology, Henry Ford Hospital, Detroit, said. Lim stated he based his conclusion in part on several studies he coauthored.

In the first study, two electromagnetic radiation sources were used to irradiate the lower back of 20 volunteers with skin types IV to VI in two different ways: the first was UVA1 and the second was visible light. Results indicated that the pigmentation resulting from visible light was darker and more sustained than the UVA1 source.

In the second study, 10 volunteers with Fitzpatrick skin phototypes IV to VI were irradiated on their back with visible light coming from a pure visible light source. A second round of tests used a visible light source with less than 0.5% UVA1. Reciprocity was observed in the pure visible light sites in tests conducted immediately, 24 hours, 7 days and 14 days post-irradiation.

There are a limited number of ways patients can block against the harmful effects of visible light, according to Lim.

“Organic sunscreens do not protect against visible light,” Lim said. “Tinted sunscreens could be beneficial on downregulating some of the effect of visible light. Other means of protection are being studied.” – by Janel Miller

References:

Lim HW. Hot topic: Controversies in photoprotection. Presented at: Maui Derm for Dermatologists; Jan. 25-29, 2020; Maui, Hawaii.

Tsibadze A, et al. Georgian Med News. 2015;(246):46-53.

Disclosures: Lim reports serving as an investigator for six companies including Estee Lauder and Ferndale; serving as a consultant for four companies including ISDIN and Pierre Fabre; and speaking at educational sessions for Eli Lilly and Pierre Fabre.