Pretreating sun exposure with LED therapy

May 1, 2008

LED therapy prior to sun exposure could provide UVB protection equivalent to SPF 15 sunscreen, an expert says.

Key Points

Limitations of traditional sunscreens include effects of water or perspiration, spectral limitations, user allergies and compliance, says Daniel Barolet, M.D., the study's lead author, clinical adjunct professor of dermatology, McGill University School of Medicine, Montréal, and chief scientific officer, Opusmed.

If dermatologists can use non-thermal high-power LED treatments to increase skin's resistance to UV-induced damage, he says, "One day, we may avoid having to apply a sunscreen or sunblock" before sun exposure.

For example, instead of exposing themselves to tanning parlor UV rays to establish a base tan, "which is harmful to the skin long-term, PLE patients could use prophylactic LED treatments. These involve a visible red light using specific parameters and have no known side effects to date," he says.

LED interest

Dr. Barolet says his interest in LEDs and similar technologies dates back more than 15 years. He began working with LEDs in earnest in the late 1990s, because "They're easier to modulate technically and were better able to treat large areas than the small spot sizes available with lasers," he says.

More recently, in vitro research into the use of LED treatment prior to sun exposure inspired him to test this modality in vivo, Dr. Barolet says.

These studies showed that, "If several treatments with near-infrared light are performed before UVB exposure, a state of cellular resistance against sun damage could be induced and potentially act as a good sunscreen," he says.

"We decided to test this method in vivo, using a well-established minimal erythema dose (MED) method used for sunscreen SPF determination," he says.

Preliminary experiments

Indeed, Dr. Barolet says, a preliminary 2006 experiment involving three healthy subjects showed that treatment with noncoherent, nonthermal light in the red spectrum (delivered by the LumiPhase-R device; Opusmed, Montréal) was "clearly effective, achieving a significant response in the reduction of the erythema induced by UVB."

In early 2007, Dr. Barolet and his colleague, Annie Boucher, Ph.D., repeated this trial with 15 subjects (13 completed the study). Using the above device, they divided patients into four groups and treated each patient's side (right thigh) with the LumiPhase-R, prior to UVB insults. The left thigh was used as a control.

Each group received a given LumiPhase-R treatment regimen as follows: five sessions spaced over one week; five sessions a week for two week; two sessions a week for three weeks; and five times a week for two weeks (this group consisted of two PLE patients).

Following this treatment - called LED Photoprophylaxis - and one day prior to UVB exposure, investigators established each patient's individual UVB MED, defined as the minimum UVB light dose producing redness in the next 24 hours.

"Once MED baseline was identified," Dr. Barolet says, "we exposed both anterior thighs to UVB following a standard MED protocol, and compared the LED-treated side versus control."