Think about it: have your patients asked about the dangers of blue light? How about skin damage from cell phones or computer screens? Curtis Cole, PhD, a photobiologist and skin care researcher, posed these questions and answered a few more in his presentation at the Maui Derm Connect 2021 conference.1
“Photobiology is based on your understanding of the light spectrum, the absorbance by the biological system, the dose-response, the dose reciprocity, and any potential wavelength interactions,” explained Dr Cole.
He noted that the first step to understanding how blue light affects the skin is to examine the light sources of interest for their spectral output and intensity. Referencing data from an unpublished study of spectral scans of an iPhone, Dr Cole highlighted that different screens emit different light intensity, with a white screen and a random (Facebook) screen showing various different peaks throughout the light spectrum, but a blue screen was, to be expected, concentrated in the blue wavelength. With that base knowledge, Dr Cole pointed out that blue light exposure from the sun was 180 times higher than a cell phone on contact, despite the sun’s 91.9 million-mile distance.
However, even with this base knowledge, there are few studies and data that elucidate the effects of visible light on the skin. In one particular study of blue light-emitting diodes on in vitro keratinocytes, an 18% increase in mitochondrial free radicals was found after 3.3 J/cm2 exposure.2
“Now let’s put this into context,” said Dr Cole. “This would require about 3.6 hours of exposure to a cell phone in contact with your skin. But it’s also the same amount that you would get in about 5 minutes of exposure to sunlight.”
An additional study found that while the J/cm2 needed to cause damage varied, visible light was able to induce damage equivalent to UVA/UVB in terms of reactive oxygen species, IL-1α, and Matrix metalloproteinase 1.3
An earlier study by Zastrow et al4 in 2009 gave some additional clues as to how visible light might be compared with UV light in the increased rates of free radicals. The study found that more than half of all free radicals generated from sunlight are in the visible spectrum that is non-zero. Therefore, most of the tissue damage occurs from the visible portion of the light spectrum.
Options are available for protection against the visible light spectrum. Specifically, Dr Cole said protection from visible light requires visible protection. This means topical applications of iron oxides, which are quite effective in blocking blue light radiation. However, more experimentation with various strengths and formulations are needed.
In his take-aways conclusion, Dr Cole stated that dermatologists should recommend the same photoprotection strategies for UV light against visible light, mainly:
- Avoid direct sun exposure when possible
- Use sun protective clothing/hat/umbrella
- Use sunscreens with an SPF 30 or higher, and preferably one with iron oxides.
References
1. Cole C. Photoprotection: what’s the role of visible light? Presented at: Maui Derm Connect 2021; January 25-29, 2021; Maui, HI.
2. Bonnans M, Fouque L, Pelletier M, et al. Blue light: friend or foe? J Photochem Photobiol B. 2020;212:112026. doi:10.1016/j.jphotobiol.2020.112026.
3. Liebel F, Kaur S, Ruvolo E, Kollias N, Southall MD. Irradiation of skin with visible light induces reactive oxygen species and matrix-degrading enzymes. J Invest Dermatol. 2012;132(7):1901-1907. doi:10.1038/jid.2011.476
4. Zastrow L, Groth N, Klein F, et al. The missing link--light-induced (280-1,600 nm) free radical formation in human skin. Skin Pharmacol Physiol. 2009;22(1):31-44. doi:10.1159/000188083
