The usage of LEDs for phototherapy treatment of fine lines and wrinkles is a relatively newer approach employed in the aesthetics market for skin rejuvenation [50]. Due to the comparatively low fluency of energy that is emitted from LEDs, the methodology is sometimes referred to as Low Level Laser (or Light) Therapy (LLLT). Overall, the usage of LED as a means of treating fine lines and wrinkles is considered to be much weaker compared with other energy emitting devices, but has a much lower risk profile of negative side effects.
Mechanistically, it is speculated that the red-light energy emitted from these devices is capable of triggering, via photomodulation, a natural response by the body to the energy, thereby activating such processes as improved cellular metabolism [51], mitochondrial efficiency [52], circulation [53] and net increases in collagen synthesis [54]. This is based in part on in vitro findings on the ability of these wavelengths in the absence of heat to elicit select effects from tissue-cultured cells [55].
Relative to published work ascribing the effects of LEDs against photodamaged and aged facial skin, a clinical study on 93 patients showed significant responses for peri-ocular wrinkles and texture changes to treatment with an LED array at 590 nm [56]. Subsequent work on a larger number of patients suggests an interesting combination of using LEDs in combination with other thermal emitting devices to further enhance the skin rejuvenation effects [56]. Another variable in the usage of visible low fluency light as a biological modulator is usage of a combination of wavelengths concurrently. Russell et al. [57] reported findings on the positive improvements of facial wrinkles by treating patients with the combination of 633 nm and 830 nm. Examining the effects from the combination of 633 and 830 nm at both the clinical and biochemical level, it was reported that the treated patients saw significant improvements in their fine lines and wrinkles and that these correlated with significant changes in the levels of collagen and elastic fibers in treated skin as well as the expression patterns of several cytokines and protein levels of TIMP-1 and 2, supporting the theory that the LED treatments can elicit both molecular and structural changes in the skin [58].
This body of work highlights the potential for identifying more potent combinations of wavelengths and fluency settings that would lead to more robust effects and without the significant side effects associated with more invasive techniques.