Background and objective
Facial skin shows signs of ageing earlier than other anatomical areas. Predominantly non-thermal infrared A (IR-A) light-emitting diode (LED) photobiomodulation has proven effective in triggering intracellular photobiochemical reactions leading to new collagen synthesis and reduction of matrix metalloproteinase-1 (MMP-1). The objective of this study was to assess the effectiveness, safety, and tolerability of a sequentially combined, continuous (CW) 835±5 nm and pulsed emission (PW) 875±5 nm LED facial mask array in the treatment of facial premature ageing.
Materials and methods
Ten female subjects (47–77 years; mean 55 years) affected by photoageing were enrolled in this pilot prospective single cohort study. Facial skin was exposed to a sequentially combined 840 nm and 880 nm LED for 15 minutes twice per week for 4 weeks. Elastometry, skin colourimetry, and standardised computerised facial complexion analysis were performed to assess clinical improvements. Standardised digital photographs were taken immediately pre- and 45 days post-treatment to evaluate the internal consistency between two independent blinded observers who were asked to sort out and identify pre- and post-treatment images.
Skin texture, wrinkle count, and elasticity were remarkably improved 15 days and 45 days after eight LED facial treatments. Surface erythema showed a moderate increase after the same intervals of time. Minimal surface micro-dyspigmentation was detected by computerised digital skin complexion analysis 15 days and 45 days after eight LED treatments. Skin texture, tone, and wrinkles were considered improved by the majority of subjects. Moderate burning and warmth sensation were reported by 70% of subjects during LED exposures. Identification of pre-treatment digital images of treated subjects by two independent, blind dermatologists showed a 90% concordance.
A series of combined, sequential CW 840 nm and PW 880 nm narrowband LED irradiations, delivered through an innovative anatomically designed facial mask, has proven effective in temporarily improving premature ageing-related structural and functional skin alterations.
Premature skin ageing is more pronounced on sun-exposed body areas, particularly on facial regions, where intrinsic, environmental, and lifestyle factors are intimately associated in determining typical morphological changes, including wrinkles, telangiectasia, dryness, rough texture, yellowish colour plaque-like thickening, and pigment irregularities.
Collagen synthesis is progressively reduced, while interstitial matrix metalloproteinases (MMP; MMP-1 in particular) are up-regulated in aged skin1,2,3. It has been demonstrated that a variety of narrow band, incoherent light-emitting diodes (LEDs) can stimulate natural intracellular photobiochemical reactions, producing clinical improvements of aged skin as well as accelerating wound repair through predominantly non-thermal photobiological processes 4–9. Karu and Kolyakov identified four ‘active’ regions in the wavelength range considered important for phototherapy (600–860 nm), after analysing action spectra of red infrared (IR) (580–860 nm) monochromatic light; two were located in the red range (613–623 nm and 667–683 nm) and two in the IR range (750–772 nm and 812–846 nm) 10. Claimed photobiological effects have included fibroblasts activation, improved neovascularisation, enhanced neocollagenesis, and macrophage biostimulation, mostly induced after light absorption by cellular photoacceptors 11,12.
Continuous emission (CW) has been considered as the gold standard for the majority of low level light therapy (LLLT); however, some studies indicate that pulsed light emission (PW) may be superior to CW keeping constant all other parameters13. Different pulse frequencies have been used, but there is no universal consensus on the identification of the most effective14–21. All previously listed biological effects are quite different from those produced by molecular ‘broadband IR response’ seen after prolonged exposure to IR radiation (760 nm–1 cm). The IR spectral region is arbitrarily divided according to wavelength into three sub-regions: IR-A (760–1400 nm); IR-B (1400–3000 nm); IR-C (3000 nm–1 mm). IR constitutes 54.3% of total solar irradiance, while IR-A accounts for approximately one third of solar energy load of human skin. The depth of penetration into skin and subcutaneous tissue decreases with increasing wavelength in the IR spectrum. Broadband IR radiation typically induces molecular vibrations and rotations, causing increased tissue temperature as well as generating complex biochemical cellular effects.
Considering the different photobiological tissue response observed after narrow-band IR-A incoherent LED and broadband IR-A incoherent light, the importance of producing a selective fragmentation of IR-A to separate appropriate IR-A wavelengths able to induce positive, predominantly non-thermal, photobiochemical reactions eventually leading to clinical improvement of skin function and appearance is quite evident. This article presents the results of a pilot clinical study involving a group of 10 individuals affected by premature ageing (chrono- and photoageing) treated by a novel narrow band, sequential CW and PW light delivery system produced by a sequentially combined 840 nm CW followed by 880 nm PW LED array, innovatively distributed along the inner surface of an anatomically designed polystyrene facial mask.