Blue Light

The target of light therapy for acne vulgaris relies partly on the characteristics of Propionibacterium acnes , in that porphyrins produced by the bacteria absorb light in the visible spectrum. The most abundant of these is coproporphyrin III, which has peak absorption at 415 nm, and the singlet oxygen species produced by photoexcitation can eliminate P acnes bacteria. High-intensity blue light devices, with narrow band spectrum of 407 to 420 nm, are available for in office use. In an open-label clinical trial with a blue light device, 30 patients were treated twice weekly for a total of 5 weeks. Improvement was seen after 1 week, and at the end of treatment total acne lesions were reduced by 64%. Blue light is most effective for inflammatory acne lesions, with a reduction of papules and pustules of 69% and 73%, respectively. Other studies with the high-intensity blue light have demonstrated similar efficacy in the reduction of inflammatory acne lesions, and reported improvement rates range from 59% to 76%.

Blue Light and Red Light

Combining blue light, which is effective against P acnes , with red light can also significantly improve acne vulgaris. Red light has an antiinflammatory effect by modulating cytokine response, and is able to penetrate deeper into the skin than blue light. Various red and blue light sources have been used successfully to treat acne vulgaris. One published report of fluorescent lamps with 660 nm red light and 415 nm blue light were used by subjects with mild to moderate daily for 12 weeks, and inflammatory lesions were reduced by 75% at the end of the study, as well as a 50% reduction in noninflammatory lesions. Another study included subjects with severe acne, who improved more significantly than the subjects affected mildly to moderately. A total of 24 subjects were treated with twice weekly alternating sessions of 20 minutes with 415 nm blue light and 20 minutes of 533 nm red light for a total of 8 sessions. After the 4-week treatment period, subjects were followed to 12 weeks and an overall reduction of more than 80% of both inflammatory and noninflammatory lesions.

Intense Pulsed Light

The intense pulsed light (IPL) is a nonlaser device that uses flash lamps and capacitor banks to generate pulsed polychromatic, noncoherent, high-intensity light. The electrical energy is passed through xenon gas to produce light in the emission spectrum of 500 to 1200 nm. Filters can focus the wavelength to the desired spectrum. Several mechanisms of action for IPL devices on acne have been mentioned in the literature. One mechanism involves a photodynamic effect where the absorption of ultraviolet (UV) and visible light by porphyrins in P acnes bacteria causes production of highly reactive free radical oxygen that subsequently kill the bacteria. Another mechanism involved is the thermolysis of blood vessels supplying the sebaceous glands. This reduces the production of sebum. Also, a photosensitizer can be applied to the skin that then accumulates in sebaceous glands, and after activated by light, can destroy the sebaceous glands. Studies have shown that IPL causes an upregulation of the transforming growth factor-β1/Smad3 signaling pathway in patients with inflammatory acne. ClearTouch (Radiancy, Inc, Orabgeburg, NY) was the first IPL system reported to be useful in the treatment of acne vulgaris. There are a few clinical studies on IPL devices in the treatment of acne, but they are difficult to compare because they used different devices, filters, and energy parameters. Adverse effects of IPL include pain, swelling, erythema, blistering, and crusting.

Elman and colleagues completed a study on 19 patients with mild to moderate acne who underwent biweekly treatments of IPL for 4 weeks. Each pulse used an average energy density of 3.5 J/cm ² , a pulse width of 35 ms, and a wavelength between 430 and 1100 nm. After the eighth treatment, noninflammatory lesions cleared 63% and inflammatory lesions cleared 50%. Acne clearance for noninflammatory and inflammatory lesions was 79% and 74%, respectively, 1 month after the last treatment and had further improvement in acne clearance at 2 months. In 2010, Kawana and colleagues performed a study on 25 Japanese patients, mainly of skin phototypes III or IV, with moderate to severe acne. They were treated with IPL 5 times at wavelengths of 400 to 700 nm and 870 to 1200 nm. After the first exposure, numbers of noninflammatory and inflammatory acne lesions decreased to 36.6% and 43.0%, respectively, of their pretreatment values. After 5 treatments, they decreased to 12.9% and 11.7%, respectively, of their pretreatment values. Transient erythema with or without burning/stinging was noted in 80% of the subjects.

Pulsed Dye Laser

The pulsed dye laser (PDL) emits coherent yellow light in the 585 to 595 nm range. Pulse durations and energy differs for different PDL devices and settings differed for different clinical studies but short pulse duration PDL may be ideal for treating acne vulgaris, as reported using the Nlight (EUPhotonics, Swansea, Wales, UK) with a 350 μs pulse. PDL preferentially targets oxyhemoglobin resulting in selective photothermolysis of dilated blood vessels and causes cutaneous immunologic activation. For this reason, it is particularly useful in treating inflammatory acne lesions. It is also known to stimulate dermal remodeling and collagen production, which can help to treat acne scarring. PDL was originally thought to decrease P acnes and sebaceous gland activity; however, a study by Seaton and colleagues showed that this was not the case. Instead, PDL is thought to work because of an increase in transforming growth factor-β, a potent stimulator of neocollagenesis and potent inhibitor of inflammation. Transforming growth factor-β was expressed more after PDL treatments than in IPL treatments, most likely because it has a greater photothermal effect. Side effects include erythema, purpura, edema, blistering, crusting, pigmentary changes, and rarely scarring.

A study by Seaton and colleagues compared the effects of short pulse PDL with a sham treatment group in 41 adult patients with mild to moderate facial acne. A baseline treatment was given and patients were evaluated at 2, 4, 8, and 12 weeks after treatment. Acne severity was measured by the Leeds revised grading system. After 12 weeks, the total number of lesions decreased by 53% in the PDL group and by 9% in the sham group ( P = .023). Inflammatory counts decreased by 49% in the PDL group and by 10% in the sham group ( P = .024), and all treatments were well tolerated. However, in 2004 Orringer and colleagues completed a study comparing PDL with a sham treatment in a split face study of 40 adult patients with facial acne and reported no differences between the PDL-treated side and the untreated side with regard to mean papule, pustule, and comedonal counts. Harto and colleagues found a 57% decrease in inflammatory lesions and a 27% decrease in noninflammatory lesions after using a PDL treatment every 4 weeks for 3 times in 36 patients. When compared with topical treatments, studies showed that there were no differences in overall efficacy; however, remission of acne lesions was much higher for the PDL treated group. Another study compared the effects of using a combination of 595-nm PDL and a 1450-nm diode laser in 15 patients with inflammatory facial acne for 3 treatments. Mean lesion counts decreased 52%, 63%, and 84% with the first, second, and third treatments, respectively, but it is difficult to say if the combination of the 2 treatment modalities was better than each on its own. Jung and colleagues combined a laser therapy of 585/1064-nm and compared it with just a PDL treatment alone for 3 treatment sessions at 2-week intervals. The study resulted in a decrease of total inflammatory lesions for both treatments, but the findings were not significant, and noninflammatory lesion counts were significantly decreased at week 8.

Other studies compared the effects of IPL and PDL on facial acne. In a split face study, 20 patients were treated with IPL on 1 side of the face and PDL on the other side. Both treatments were performed 4 times at 2-week intervals. Acne lesions decreased in both treatments, but inflammatory lesions showed an earlier improvement on the IPL-treated side than the PDL-treated side. However, 8 weeks after the completion of treatment, there was a rebound increase of acne observed on the IPL-treated sides. PDL showed gradual improvements, which were sustained at 8 weeks after treatment completion. Noninflammatory lesions also decreased after both treatments with the PDL-treated sides having better improvement overall. Ultimately, PDL- and IPL-treated acne effectively but PDL showed a more sustained effect. Sami and colleagues performed a study on 45 patients with moderate to severe acne that were randomly divided into 3 equal groups. Group 1 was treated with a PDL, group 2 was treated with IPL, and group 3 was treated with a blue–red combination LED. Results showed that the PDL was more effective and took a lesser number of treatments to reach a greater than 90% improvement than the other 2 groups. IPL was more effective than the blue–red LED treatment.

Potassium Titanyl Phosphate Laser

The potassium titanyl phosphate (KTP) laser has typically been used for vascular lesions, but has recently been used for the treatment of acne. It emits pulsed green light at 532 nm. The exact mechanism of action is unclear, but is thought to cause selective photothermolysis of blood vessels and a photodynamic effect on P acnes and/or sebaceous glands. Baugh and colleagues performed a study on 26 subjects with moderate facial acne where one-half of the face was treated with 4 laser exposures with continuous contact cooling. Their results showed a mean 35% and 20% reduction at the 1- and 4-week posttreatment stages, respectively. Yilmaz and colleagues studied 38 patients who underwent a once weekly or twice weekly treatment of KTP to one-half of the face. Improvements were found for both treatment groups and there was no difference found between once and twice weekly applications.

Infrared Lasers

The infrared lasers were developed originally for facial rejuvenation. They target water, which happens to be the dominant chromosphere in the sebaceous gland, thus creating a thermal injury that decreases the amount of sebum produced. When combined with surface cooling, these lasers effectively heat the upper dermis while keeping the epidermis cool. Fluences as high as 14 J/cm ² can be used with a cooling device.

1450 nm

Friedman and colleagues first reported the use of the 1450-nm diode laser in 19 patients with inflammatory facial acne. Patients underwent 1, 2, and 3 treatments at 4- to 6-week intervals and lesion counts decreased 37%, 58%, and 83%, respectively. Adverse effects were limited to transient erythema and edema. Although the pain was tolerable in this study, the 1450-nm diode laser has been known to cause considerable pain and a topical anesthetic is often recommended for use. The laser can even be used with minimal side effects in Fitzpatrick skin phototypes IV to VI. Long-term reductions in acne lesion counts can be maintained for up to 12 months after treatment. One study of 38 patients reported no difference in lesion counts when performing a split face study treating 1 side of the face with the 1450-nm diode laser and the other side as a control. Both sides showed a decrease in lesion counts raising the possibility of a systemic effect of the laser. A lower energy, double pass treatment with a larger 12 mm-diameter spot size has also shown to be effective for patients that complain of considerable pain.

1540 nm

Angel and colleagues performed a long-term study that used a 1540-nm erbium:glass laser with a cooling device in 25 patients with facial acne. The parameters for the laser were 3 ms, 4 pulses, 10 J/cm ² and 2 Hz for a cumulative fluence of 40 J/cm ² . Four treatments were performed at 4-week intervals. Treatment reductions in acne lesions were 71% at 6 months, 79% at 1 year, and 73% at 2 years, and there were no side effects. Patients reported a decrease in oiliness of their skin and biopsies showed progressive rarefaction and miniaturization of sebaceous glands and pilosebaceous follicles. Another study used the 1540-nm erbium:glass laser to treat 15 patients with moderate to severe acne 4 times at 2-week intervals. At 6 months, there was a 68% improvement in patient assessments and a 78% improvement in investigator assessments. Another treatment was given 6 months after the initial course and at 9 months there was an 80% clearance compared with a 72% clearance for those who were not retreated. This study suggests the importance of maintenance therapy to prolong the lesion-free time period.

1550 nm

One study used a 1550-nm (30–40 mJ) fractional erbium glass laser to treat 24 patients with 4 sessions at 2-week intervals. Patients were evaluated every 3 months for 1 year. They found a significant decrease ( P < .0001) in the mean number of lesions at the end of the study. They also found a significant decrease in the size of the sebaceous glands using an image analyzer computer system. This finding most likely contributes to the extended lesion free period.

1064 and 1320 nm

The Nd:YAG laser is another infrared laser that is typically used at a wavelength of 1064 nm for acne treatments; however, the 1320-nm laser has also been used. Orringer and colleagues used the CoolTouch II 1320 nm (ICN Pharmaceuticals, Inc, Costa Mesa, CA) to conduct a split face study on 46 patients with facial acne. Three nonablative treatments were given to patients on one-half of the face. Their findings suggest that this treatment regimen may improve comedonal acne. A study used fractional 1320-nm ND:YAG laser to treat 35 patients with moderate to severe acne using 6 treatment sessions at 2-week intervals. Their results were significant and showed a 57% decrease in inflammatory lesions and a reduction of noninflammatory lesions by 35%. Chun and colleagues report a case using the 1064-nm Nd:YAG laser on a 14-year-old girl with moderate to severe pustular and cystic acne. After using a topical anesthesia, they applied a topical carbon lotion to the face. They then used a Q-switched frequency-doubled Nd:YAG laser first in a quasi-long pulsed mode (a 300-μs pulse width at 1.1–1.5 J/cm ² ) followed immediately by a Q-switched mode (5-nsec pulse width, 1.5–2.0 J/cm ² ) using a 7-mm hand piece for both modes. Six treatments were given, 2 weeks apart. Significant improvement was noted by the fourth treatment and by the sixth treatment there was a greater than 90% improvement in inflammatory lesions. Results remained up to 8 weeks after treatment. The procedure was well-tolerated. Another study used the dual mode (quasi-long pulse and Q-switched mode) 1064-nm Nd:YAG laser with a topically applied carbon suspension in 22 subjects. They received 3 laser treatments at 2-week intervals. Results were significant showing a 59% decrease in inflammatory lesions and a 52% decrease of noninflammatory lesions on the laser treated side; however, there was a 5% increase in acne lesions on the untreated side. Mild transient erythema was the only side effect observed, but it resolved after a few hours. Multiples studies have noted a significant decrease in the sebum level in patients after treatments with the Nd:YAG laser.

Photodynamic Therapy

Photodynamic therapy (PDT) combines a photosensitizer and an activating light source to treat acne vulgaris. The 2 most common sensitizing agents are 5-aminolevulinic acid (ALA) and methyl aminolevulinate (MAL), but in the United States only ALA is available at this time. The labeled use for ALA is for the treatment of actinic keratosis, and was first described in 1990. PDT with ALA can be used off label for aesthetic rejuvenation of photodamaged skin and the treatment of acne vulgaris, among other uses. The mechanism of PDT targets both the porphyrins in P acnes and the sebaceous glands. For the treatment of acne, the first reported pilot series of ALA was applied to the back with a 3-hour incubation and was then activated with a 550 to 700-nm red light. Patients were either treated with a single treatment or a series of 4 treatments and, when compared with red light alone, the ALA group showed a significant reduction in inflammatory lesions that was maintained until 20 weeks after the final treatment. Also, the multiple treatment regimens demonstrated significantly more improvement than the single treatment group. After treatment, erythema and edema were seen at 1 hour and resolved in all subjects. Also, a transient hyperpigmentation, crusting, and exfoliation were seen in subjects but resolved by the end of follow-up. Taub reported a short contact ALA-PDT treatment protocol for moderate to severe acne, in which patients were treated with 2 to 4 ALA-PDT treatments over 4 to 8 weeks with a blue visible light source. Patients had 50% to 75% improvement of inflammatory lesions after the series of treatments, and this improvement continued during the 4-month follow-up observation period. Reported side effects with ALA-PDT include mild, transient erythema and peeling. ALA-PDT may be used while patients are using topical treatment regimens without an increase in adverse effects.

In addition to blue light, ALA can be activated with other light sources such as IPL and PDL. Gold and colleagues reported a study that assessed the efficacy of IPL with ALA-PDT on 20 patients with moderate to severe inflammatory acne. The ALA remained in contact with skin for 1 hour before irradiation with the IPL device that emitted 430 to 1100 nm of radiation at 3 to 9 J/cm ² fluences. Inflammatory lesions were reduced 50% at the end of a 4-week treatment period, 69% 4 weeks after the final treatment, and 72% 12 weeks after the final treatment. There were no recurrences of treated lesions and the effects were tolerated well by all patients. Rojanamatin and Choawawanich reported a study that involved 14 patients with inflammatory facial acne treated with IPL on the left side and combination of IPL and topical ALA on the right side at 3- to 4-week intervals for 3 sessions. All patients revealed a reduction in number of acne lesions on both sides. The ALA-treated side showed a decrease of lesions by 87.7% at 12 weeks after the last treatment and the other side decreased 66.8%. The ALA-treated side had better improvement overall and sustained reduction in acne lesions. One study compared the effects of IPL alone, IPL with 16% MAL, and a control. The MAL cream was applied to one-half of the face for 30 minutes before treatment. Subjects were treated 4 times at 3-week intervals. They found no differences between the treated groups and the control group with regard to the decrease in inflammatory lesion counts. However, there were significant reductions of noninflammatory lesions in the IPL with MAL group (38%) and IPL group (43%) at 12 weeks after treatment. Four patients (25%) discontinued treatment because of significant stinging, burning, and erythema after the MAL treatment. ALA-PDT with activation by IPL was found to provide greater, longer lasting effects with more consistent improvements than with activation by radiofrequency combined with IPL or blue light.

Pulsed dye laser is another activating light source for PDT with ALA. A study by Orringer and colleagues found improvements in acne severity ratings when using ALA and PDL. The ALA was applied to the face for 60 to 90 minutes and patients received 3 PDL treatments to 1 side of the face; the other side remained untreated. The study resulted in a significant decrease in the number of inflammatory lesions. A report of complete clearance was achieved a group of 14 patients with various types of acne undergoing ALA-PDT with pulse dye laser as the activating light source. Patients received an average of 3 treatments, and were followed for 6 months with sustained improvement in the overall acne. Patients were allowed to continue topical acne products, as well as antibiotics during the study.

In addition, KTP laser can be used as the light source for PDT. The effects of ALA activated by KTP laser were studied by Sadick and colleagues. ALA was applied to one-half of the face and the entire face was exposed to KTP laser for 3 treatments. ALA was found to improve acne by 52% compared with 32% on the KTP only side.

In our practice, we combine microdermabrasion or photopneumatic therapy before ALA application to enhance penetration. This is followed by short pulse PDL and blue light to activate ALA. After a series of 3 treatments, patients have a significant improvement, including complete clearing in cases of severe acne with sustained results for 10 years or more after treatment.