INTRODUCTION
The electromagnetic spectrum is a range of wavelengths that includes radio waves, infrared light, visible light, ultraviolet (UV) light, x-rays, and gamma rays.1 Visible light is the segment that can be seen by the human eye, corresponding to 400 to 700 nanometer (nm) wavelengths.1
Kharazi et al10 conducted a split-face, RCT comparing blue light therapy alone vs blue and red-light combination therapy in 33 patients with mild-moderate acne. Both hemifaces were treated with blue light (415 nm, 48 J/cm2) and one was also treated with red light (633 nm, 96 J/cm2). Treatment was twice weekly for 4 weeks, with a follow-up 12 weeks post-therapy. They found a statistically significant reduction in acne lesions in the combination group as early as 2 weeks (31.39% vs 25.56%) through the trial endpoint (70.00% vs 51.20%). They hypothesized that a synergistic effect is observed because red light penetrates deeper than blue light.
Blue light, also known as high-energy visible (HEV) light, has the shortest wavelength of visible light (400 to 500 nm).1 While the effects of UV-A (315 to 400 nm) and UV-B (280 to 315 nm) have been extensively studied, blue light exposure is less understood. The main molecular mediator is reactive oxygen species (ROS), which activate numerous molecular cascades where pathways are not completely understood.2-4
There are 3 sources of light exposure: direct, diffusion, and reflection. Direct exposure occurs primarily via solar radiation.5 Artificial sources also exist, including light-emitting diode (LED) technology, like computers, televisions, and cell phones.5 Diffusion is also related to solar radiation.6 Light constantly scatters from hitting particles of a smaller wavelength than its own waves.6 Light also reflects off surfaces. This occurs when a wave (incident ray) contacts a surface that cannot absorb its energy, causing the wave to bounce off (reflected ray).7
Benefits
Acne
Antoniou et al8 conducted a split-face, randomized, controlled trial (RCT) evaluating chromophore gel-assisted blue light therapy (KLOX BioPhotonic System) efficacy for the treatment of moderate-severe acne vulgaris in 98 participants (Main trial). Prior to this, most studies examined mild-moderate acne response. Treatment was twice weekly for 6 weeks with a topical photoconverter chromophore gel and a blue light-emitting (415/446 nm, 33-45 J/cm2, 5 minutes), multi-LED device (KLOX THERATM lamp) with follow-up 6 weeks post-treatment. At week 12, a reduction of greater than or equal to 2 grades on the Investigator's Global Assessment (IGA) scale was observed in 51.7%, versus 18% in control hemifaces (P <0.0001). Inflammatory acne counts dropped by greater than 40% in 81.6%, versus 46% in control hemifaces (P<0.0001).
An extension trial9 was conducted with the same equipment/protocols. They evaluated protocol efficacy on the untreated hemiface and assessed the duration of a sustained response in the main trial treated hemiface for 12 additional weeks.9 Main trial participants were enrolled. Those with baseline IGA of 3 had success (IGA decrease greater than or equal to 1 grade) rates of 81.8% and 90%, at 6 and 12 weeks, respectively. Those with a baseline IGA of 4 saw 100% success at both timepoints. After 24 weeks, only 15.5% returned to baseline, suggesting long-term benefits.
Kharazi et al10 conducted a split-face, RCT comparing blue light therapy alone vs blue and red-light combination therapy in 33 patients with mild-moderate acne. Both hemifaces were treated with blue light (415 nm, 48 J/cm2) and one was also treated with red light (633 nm, 96 J/cm2). Treatment was twice weekly for 4 weeks, with a follow-up 12 weeks post-therapy. They found a statistically significant reduction in acne lesions in the combination group as early as 2 weeks (31.39% vs 25.56%) through the trial endpoint (70.00% vs 51.20%). They hypothesized that a synergistic effect is observed because red light penetrates deeper than blue light.
