Light-based therapy for acne vulgaris

Abstract

Acne is a disorder of the pilosebaceous unit often complicated by scarring. Five studies were performed to test the hypothesis that acne is common among Chinese and that the use of laser and light source is safe and effective for the treatment of acne and acne scars in Asians. The self-reported prevalence of acne in Hong Kong was assessed using a questionnaire among a randomised sample of 522 persons aged 15-25 years. The prevalence was 91.3% with a point prevalence of 52.2%, and acne scars and pigmentation were reported by 52.6%.

The existing topical and oral anti-acne medications are limited by their efficacy, adverse effects and patient compliance. Light can target the pilosebaceous unit and reduce the growth of Propionibacterium acnes, for which lasers or light sources have been explored as therapeutic options. The aim of this study was to determine whether lower fluence and shorter cooling of the 1450-nm diode laser would improve acne while minimising post-laser hyperpigmentation in Asians. A total of 26 Chinese subjects received four treatments of three passes with this laser at a fluence of 8 J/cm2 with dynamic cooling of 25 ms. A 40% reduction (p<0.03) in mean lesion count was observed 6 months after treatment with a significant improvement in sebum production and a hyperpigmentation rate of 3.8%.

A split-face, controlled study was performed to evaluate the effectiveness of intense pulsed light (IPL) alone or in combination with short-contact 16% methyl aminolevulinate photodynamic therapy (PDT) in 30 Chinese subjects with acne. Among the PDT-treated group, 25% withdrew due to treatment discomfort. No significant differences in the reduction of inflammatory lesions were observed between the intervention groups and the control group. A delayed effect with reductions in non-inflammatory lesions was observed in the PDT-treated (38%; p=0.05) and IPL-treated (43%; p=0.01) groups 12 weeks after treatment.

Liposome was used to deliver 5-aminolevulinic acid (5-ALA) into the pilosebaceous unit to lower the concentration of 5-ALA by 40-fold during PDT. The study aimed to investigate the tolerability and efficacy of PDT with IPL using 0.5% liposomal 5-ALA for inflammatory acne. A mean reduction of 65% in the inflammatory lesion count was observed after 6 months (p=0.043) in 12 Chinese subjects. No dropout or significant side effects were observed.

The treatment of acne scars has often been complicated by Asian skin phototypes regarding the risk of post-inflammatory hyperpigmentation. Fractionated radiofrequency induces deep dermal heating with less epidermal disruption. The aim of this study was to examine the efficacy and safety of combined bipolar radiofrequency and fractional diode 915 nm laser followed by fractional radiofrequency in 24 Chinese subjects with acne scars. The mean grade improved by 29% (p<0.001), and 52% subjects were rated as having at least a moderate global improvement at 3 months. Subjective improvement was moderate to significant in 36.8%. Hyperpigmentation occurred after 6.5% of the treatments.

In conclusion, the studies indicated that laser and light source can be used effectively and safely for the treatment of acne and acne scars commonly found in Asians.