Lasers, lights and acne
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:
- By destroying skin bacteria Cutibacterium acnes (previously called Proprionibacterium acnes) through a photodynamic therapy (PDT) reaction
- By destroying the sebaceous glands / entire pilosebaceous unit
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.
Lasers/lights that destroy P. acnes through a photodynamic therapy (PDT) reaction
The mechanism of action
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.
Types of light / laser sources
There are a number of light and lasers being investigated. These include:
- Blue and red light sources
- Green light lasers
- Yellow light lasers
- Intense pulsed light (IPL) sources
- Radiofrequency (RF) devices
Blue light machines
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:
- 30 patients received x2/week for 5 weeks – 64% decrease acne lesions
- 35 patients x2/week for 4 weeks – 80% of patients had significant improvement
- 40 patients x2/week; 3 months following their last treatment – 43% decrease in inflammatory lesions.
- 12 patients x2/week (6 min); 2 weeks after the final treatment – 40% decrease in papules, 65% decrease in pustules, 62% decrease in comedones
- Multicenter study of blue light system vs. topical 1% clindamycin – blue light therapy was more effective than the topical clindamycin in decrease inflammatory acne lesions.
Green light lasers
At 532 and 532/1064 nm, several green light lasers have been studied.
- 11 patients in a split-face prospective, randomized clinical trial. 4 treatments at 7-9J/cm2 utilizing a 4mm spot size and pulse duration of 20msec with parallel contact cooling. 6-10 passes over the half-treated face.
At 1 month:
- Acne lesion counts decreased 35.9% vs. 11.8%.
- Sebum excretion rate (SER) decreased 28.1% vs. 6.4% control
Yellow light sources
These are generally low-fluence pulsed dye lasers (PDL) at 585-595nm.
- 41 patients, double blind, randomized clinical trial. Acne severity decrease from a score of 3.8 to 1.9 in the PDL group vs. 3.6 to 3.5 in the placebo.
- 40 individuals receiving 1-2 treatments with the PDL. No significant differences.
Intense Pulsed Light
Intense Pulsed Light (IPL) devices use light and heat, known as LHE technology, to trigger the destruction of the P. acnes bacteria.
- 19 patients – 85% had a >50% improvement in their acne vulgaris lesions following x2/week therapy for 4 weeks.
- 14 patients received 5 treatments every 2-4 weeks. 2-3 passes at 10J/cm2. At 6/12, clearance rates of 72% for noninflammatory lesions and 73% for inflammatory lesions.
Lasers that destroy sebaceous glands
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.
1450nm SmoothBeam® laser
- 27 patients. Acne on back, 4 treatments at 3-week intervals. The average fluence used was 18J/cm2
- At 6/12 – a 98% reduction in inflammatory lesions after 4 treatments.
- At follow-up – 100% lesion clearance was seen in all but one patient.
- 19 patients with facial acne.
- 37% reduction after 1 treatment, 58% after 2 treatments and 83% after 3 treatments.
- Side effects included transient erythema and oedema. Topical anaesthetics were used to minimize the discomfort.
Indocyanine green (ICG) + diode laser (810nm-900nm)
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
- 22 patients with acne of the face or back. The targeted areas were stained with the ICG for 5-15 minutes and then irradiated with a diode laser. Multiple treatments were required.
A monopolar radiofrequency (RF) with ThermaCool® device has been trialled:
- 22 patients were treated twice with the average fluence of 72J/cm2.
- At 1-8 months – excellent responses were seen in 82%, modest responses in 9%, and no response in 9%
- Patients were administered topical anaesthesia because treatment with this device can cause a great deal of discomfort
- Results are not permanent.