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Oxidative Stress and Intense Pulsed Light Therapy

Molecular study suggests that we keep an open mind about the long-term safety of IPL therapy.

The intense pulsed light (IPL) source, with an emission spectrum in the 500-nm to 1200-nm range, has been used for nearly 10 years to treat telangiectasias, pigmented lesions, and photoaging. Because the pulse duration is short, and because the amount of light delivered during treatment is relatively modest, IPL is considered to produce little tissue damage. Investigators studied the truth of this assumption by comparing the effects of IPL, UVA, and UVB irradiation in nine healthy adult volunteers.

Separate skin sites on each volunteer were exposed to a single dose of solar radiation (corresponding to 80 mJ/cm² UVB radiation), a single dose of 40 J/cm² UVA radiation, or a single dose of 9 J/cm² IPL radiation; a fourth control site was unexposed. Biopsy samples were taken from the exposed areas and evaluated for the presence of thymine dimers (as an index of DNA damage) and lipid peroxides (as a marker of oxidative stress). The skin samples exposed to IPL did not differ significantly from control skin in the extent of thymine dimer formation. However, the level of lipid peroxides in IPL-exposed skin was six times as high as in nonirradiated skin and twice as high as in skin exposed to UVA light.

Comment: The implication of this study is that IPL treatment may not be without consequences. Although IPL irradiation did not affect thymine dimer production because the light source does not emit in the UV range, it did produce considerable amounts of lipid peroxides, an indicator of oxidative stress. Oxidative stress has been associated with a number of deleterious effects; beyond premature aging of the skin, it has been shown to promote skin cancer in experimental animal models. Although these molecular studies do not necessarily mean that long-term adverse effects will ensue, the results point to our ignorance of IPL’s lasting effects. Many highly effective therapies have had adverse effects that were not fully identified until years after regulatory approval. Until IPL has been in active use for a while longer, continuing follow-up of patients remains important.

— Craig A. Elmets, MD

Published in Journal Watch Dermatology April 13, 2007

Citation(s):

Sorg O et al. Effect of intense pulsed-light exposure on lipid peroxides and thymine dimers in human skin in vivo. Arch Dermatol 2007 Mar; 143:363-6.

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