LLLT for Acne

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Acne vulgaris is a relatively common skin disorder, with a reported prevalence of up to 90% among adolescents. Some studies have reported a comedone prevalence nearing 100% for both male and female sexes during adolescence (Stathakis et al., 1997). Although typical acne is neither a serious nor a contagious condition, it can greatly impact the emotional and social aspects of an individual’s life.

The pathogenesis of acne is not completely understood, but the current consensus is that it involves four major events: follicular hyperconification, increased sebum production, colonization of Propionibacterium acnes (P. acnes), and inflammation (Lee et al., 2007b). P. acnes plays a major role in the development of acne by acting on triglycerides and releasing cytokines, which results in inflammatory reactions, and alters infundibular keratinization (Lee et al., 2007b).

Current therapeutic options for acne vulgaris include topical antibiotics (e.g., clindamycin and erythromycin), topical retinoids (e.g., tretinoin and adapalene), benzoyl peroxide, alpha hydroxy acids (AHA), salicylic acid, and azelaic acid. In severe cases, administration of antibiotics (e.g., tetracycline, doxycycline online), oral retinoids, and certain hormonal treatments is recommended (Aziz-Jalali et al., 2012).

Most medications work by counteracting microcomedone formation, sebum production, P. acnes, and inflammation (Aziz-Jalali et al., 2012). Despite the many treatment options currently available, several patients still show an inadequate response to the treatment, while others suffer from actual adverse effects.

Phototherapy offers an alternative mode of treatment for acne vulgaris with a suitable profile of side-effects (Rotunda et al., 2004). Sunlight exposure has often been reported to have a significant impact on the treatment of acne, with a high efficacy of up to 70%. More recently, techniques utilizing broad-spectrum visible light (LLLT) are currently being employed for the treatment of acne (Cunliffe and Goulden, 2000). One mechanism of action of phototherapy is via the excitation of porphyrins generated by P. acnes as part of its normal metabolism.
These porphyrins act as endogenous photosensitizers, absorbing light (specifically blue light, and to a lesser extent, red light) and stimulating photochemical reactions that generate reactive free radicals and singlet oxygen species, which are toxic for P. acnes (Figure 2) (Lee et al., 2007b; Ross, 2005). Red light has been demonstrated to have a greater penetration depth when compared to that of blue light (Aziz-Jalali et al., 2012). Infrared (IR) light has been proposed to destroy sebaceous glands, and thus, reduce acne lesions (Lloyd and Mirkov, 2002). Red light is believed to stimulate cytokine release from various cells including macrophages, and reduce inflammation (Rotunda et al., 2004; Sadick, 2008).

The sebaceous gland is colonized by bacteria, which can be killed by blue light due to the endogenous porphyrins they produce, acting as photosensitizers and forming reactive oxygen species. Red light can reduce inflammation and stimulate healing with minimal scarring.

Several studies have demonstrated the efficacy of red to near infrared light (NIR) (spectral range 630 nm to 1000 nm, and non-thermal power less than 200 mW) for the treatment of acne vulgaris. Red light may be used alone or in combination with other modalities (in particular, blue light) (Cunliffe and Goulden, 2000; Goldberg and Russell, 2006; Lee et al., 2007b; Posten et al., 2005; Sadick, 2008).

One study demonstrated a significant reduction in active acne lesions after 12 sessions of treatment, using 630 nm red spectrum LLLT with a fluence of 12 J/cm2, twice a week for 12 sessions in conjunction with 2% topical clindamycin (Aziz-Jalali et al., 2012). However, the study showed no significant effects when an 890 nm laser was used (Aziz-Jalali et al., 2012).

It was proposed that, the enhanced effects of mixed light were due to synergy between the anti-bacterial and anti-inflammatory effects of blue light and red light respectively (Lee et al., 2007b; Papageorgiou et al., 2000) (Figure 2). In several studies, improvements in inflammatory lesions were reported to be greater than the improvements in comedones (Lee et al., 2007b; Papageorgiou et al., 2000).

Acne Scarring

Additionally, fractional laser therapy can be used to treat post-acne scars with the best results obtained for the treatment of macular, superficial and medium-depth scars. Deep scars and ice-pick scars show only marginal improvement with the use of fractional laser treatment, although, severe scarring can be treated in combination with other modalities such as chemical peels, surgical dermabrasion, derma-roller, and trichloroacetic acid chemical peel (CROSS) techniques.
Additionally, fractional laser treatment provides a suitable means for the treatment of scars in individuals with darker skin tones, and has also shown remarkable pore improvement (Goel et al., 2011). As with any therapeutic modality, proper counseling and evaluation should be conducted to minimize the probability of adverse effects.