Author: Assoc. Prof. Marius Rademaker, Hamilton, New Zealand, 2008.
Most acne patients notice an improvement in their acne over the summer, although unfortunately it doesn’t last long. Ultraviolet (UV) light (phototherapy) has long been used in the management of acne, as has superficial radiotherapy. However, the well-established long-term side effects of radiotherapy, and the concerns around the skin cancer risks of ultraviolet light/sun beds, have limited their use. UVB (short wavelength UV) has only short term efficacy. UVA (longer wavelength UV) may increase comedone production.
The last few years however, have seen an increased interest in the use of light and laser therapy for acne. There are two main mechanisms that laser/light treatments may help acne:
To date, many studies have shown early promise, with improvements in the 50-75% range. However, most of the trials have been fairly small, of short duration and with relatively short follow-up periods. Few have had the opportunity to assess long term outcomes and, very importantly, long term complications/side-effects.
It is difficult to know where lasers/lights will eventually fit in the overall management of acne vulgaris. For some individuals, they are likely to be beneficial, although very few comparative studies have been made with conventional medical treatment. The best device, dose and frequency of treatments are as yet undetermined.
It is known that the bacteria present in some acne lesions, C. acnes, produce chemicals called porphyrins during their growth and proliferation in the skin pore (follicular unit). These porphyrins may contribute to how non-inflamed acne lesions become inflamed.
It is thought that the two main porphyrins involved are protoporphyrin IX (PpIX) and coproporphyrin III. Both of these chemicals absorb light at 415 nm (the Soret band), which corresponds to the blue range of the visible light spectrum, and to 630 nm, which corresponds to red light.
Photo-excitation of these porphyrins, from exposure to an appropriate light source, will form singlet oxygen (free radicals) within the bacteria, which then selectively destroy them, thereby hopefully improving the clinical signs of the acne. The sebaceous gland is also a target. Differing topical photosensitising agents have been applied to the acne-prone skin to try to specifically damage sebaceous tissues while leaving the epidermis alone, and in an attempt to minimise the side effects of treatment.
There are a number of light and lasers being investigated. These include:
There are a number of units that produce ‘Blue’ light. These tend to be high-intensity, narrow-band blue light source in the 405nm-420nm range.
Several studies have shown some benefit:
At 532 and 532/1064 nm, several green light lasers have been studied.
These are generally low-fluence pulsed dye lasers (PDL) at 585-595nm.
Intense Pulsed Light (IPL) devices use light and heat, known as LHE technology, to trigger the destruction of the P. acnes bacteria.
Several longer wavelength laser systems have been used to treat inflammatory acne vulgaris by destroying the sebaceous glands including near-infrared lasers, 1320nm CoolTouch®, 1450nm SmoothBeam®, 1540nm erbium glass Aramis® and radiofrequency devices.
ICG, a fluorescent dye used for imaging purposes, acts as a sensitizing agent to help target the sebaceous glands. The combined use of ICG with diode lasers showed a reduction in inflammatory acne vulgaris lesions
A monopolar radiofrequency (RF) with ThermaCool® device has been trialled:
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