PEER-REVIEW | DERMATOLOGY | 4-week period. Follow-up visits were at 1 month and 3


months, respectively. A statistically significant decrease in mean acne counts from baseline was observed11


. Many


studies for the treatment of mild to moderate acne show the efficacy of blue light, or combination of both blue and red light12-13


.


Immunological mechanisms


Potassium titanyl phosphate laser In one study, 38 subjects were divided into two groups; one group was treated once weekly and the other twice weekly. One half of face was treated with 532 nm KTP and the other half was left untreated. They were evaluated at the beginning of the study, and then again 1 and 4 weeks after the last session with the Michaëlsson acne severity grading score (MASS). A significant improvement was seen in the second group who were treated twice weekly14


Microbiological factors


. The 532 nm KTP laser could penetrate and activate


porphyrins to target P. acnes. It targets sebaceous glands with non-specific collateral thermal injury. It is well tolerated, safe and effective, with positive results up to 4 weeks post-treatment14-15


.


Pulse dye laser The efficacy of pulse dye lasers (PDLs) was demonstrated in a randomised, controlled, single-blind, split-face clinical trial of 40 patients with facial acne. They received one or two non-purpuric PDL sessions to half of the face (fluence of 3 J/cm2


). Serial blinded clinical assessments


from baseline to 12 weeks between treated and untreated sides of the face showed no significant difference16


.


PDL 585 nm laser targets oxyhaemoglobin selectively and induces photo-thermolysis of the inflammatory dilated vessels. Porphyrins are activated to produce phototoxic effects by the delivery of coherent yellow light16


. In another study, 80


patients were randomly divided in a 1:2 ratio and received only clindamycin 1%-benzoyl peroxide 5% hydrating gel C/BPO alone or in combination with PDL treatment (wavelength 585 nm, pulse duration 0.35 ms, energy fluence 3 J/cm2


, spot


size 7 mm), and were evaluated at baseline and at 2 and 4 weeks after initial treatment. Findings did not support the benefit of PDL treatment in acne vulgaris17


Hypertrophic scars


depends on its local anti-inflammatory effects. A randomised pilot study comparing a non-ablative, fractional 1550 nm laser versus a 595 nm PDL for facial erythema in 12 patients showed significant improvement results in both modalities for the treatment of acne erythema19


. Figure 1


PATHOGENESIS OF ACNE VULGARIS


Skin factors


Infrared lasers Low-level laser (light) therapy (LLLT) is a fast-growing technology in treating acne. During LLLT, adenosine triphosphate, nitric oxide release, electron transport, reactive oxygen species increase, blood flow, diverse signaling pathways, and stem cells are activated, allowing increased tissue repair and healing20


. Water is the


Hormonal factors


dominant chromosphere in the sebaceous gland, which is the target for infrared lasers. Selectively, it produces a dermal injury zone where sebaceous glands are located and therefore arrest the over production of sebum8


.


1450 nm diode laser The 1450 nm diode laser affects the pilosebaceous apparatus through peak thermal heating of the upper- to mid-dermis to a depth of 500 m and causes thermal coagulation21


. An infrared 1450 nm diode laser


accompanying a dynamic cooling device reduces sebaceous gland activity and inflammation of acne lesions safely and effectively with fluences as high as 14 J/ cm2


.22


baseline was sustained on 20 patients 12 months after the final laser session. Therefore, the 1450 nm diode laser could provide a long-term remission in acne and sebum production23


. In contrast, in a split-face trial on 38 participants, one


side of the face was randomly selected while the other side served as a within-patient control. A Candela 1450 nm Smoothbeam laser (Wayland, MA) was used with a double-pass technique, 6 mm spot size, 210 ms pulse duration and fluence of 8 or 9 J/cm2


. Three


POST-ACNE SCARS


Scars involving excess tissue


Keloids Bridge


Papular scars


Figure 2


CLASSIFICATION OF POST-ACNE SCARS


. Also, Seaton et al18 suggest that PDL


does not have an effect on P. acnes colonisation or sebum production. However, they revealed that the potent stimulator of neocollagenesis and a potent inhibitor of inflammation is the upregulation of transforming growth factor- (TGF-). So, its efficacy


26  July/August 2014 | prime-journal.com


treatments were performed 1 month apart. On average, within participants, the lesion count and acne grade reduced on both sides of the face by the same amount. Also, both remained similar 12 months after the last treatment24


Atrophic scars


Deep dermal scarring


Superficial macular


Icepick scar


Rolling scar


Boxcar scar


.


1540 nm erbium glass laser In a study by Boineau D et al,


they point to the efficacy of the 1540 nm erbium glass laser in treating acne25


. In 2011, Isarría and colleagues


treated 20 patients with acne and scarring. Each one achieved good results with four sessions with a 1-month interval between sessions. Active acne improved in 85% of cases, and a very large improvement was witnessed in


A study showed 76.1% lesion reduction from


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