Comparative efficacy of filtered blue light(emitted from sunlight) and topical erythromycin solution in acne treatment.(a randomized controlled clinical trial)
Acne vulgaris is one of the commonest skin conditions .The visible light has attracted attention as a new and safe option.As some studies show; more than 80% response to 420 nm- phototherapy yields a significant reduction in inflammatory acne lesions after only eight treatments .
Patients & Methods :
We have evaluated the use of blue light and topical erythromycin on 32 acne patients. In one group the right sided lesions were treated with solution twice daily and the left ones were treated with irradiation of sunlight by a filter for 15 minutes once daily for 8 weeks and in another treatment group the lesions in sides of the face were treated on reverse manner.
The difference between the treatment and control sides was not significant at Week 4, and 8 (p>.05). After 12 weeks of starting the program; a mean improvement of 20 % in lesion counts was achieved by the blue light phototherapy.
In our study; a mean improvement of 46% in acne score which was achieved by the blue light , was not significantly different to that achieved by topical erythromycin (58% ). Based on this study, blue light is somewhat effective in treating acne.
Further studies are needed to clarify the role of phototherapy as a monotherapy or an adjuvant in management of acne vulgaris. we found that visible light phototherapy improved partially acne lesions and may be an appealing noninvasive alternative for the treatment of acne,
Key words: acne, blue light, phototherapy.
Background & targets:
The mainstay of treatment of acne is the use of topical or systemic antibiotics. The rapid increase in the incidence of antibiotic resistance in the causative bacterium, Propionibacterium acnes, is causing great concern and there is a pressing need for effective, non-antibiotic treatments.Available topical anti-acne treatments are slow and frequently irritating, so,the need for alternative therapies remains important(1).
The effects of blue light phototherapy on inflammatory acne lesions were recently investigated. Some studies show more than an 80% response to 420 nm acne phototherapy with a significant reduction of 59-67% of inflammatory acne lesions after only eight treatments of 8-15 minutes(2). In vitro, P. acnes has been inactivated by relative small doses (5 kJ m22) of broad band near-UV radiation; this phenomenon was found to be oxygen dependent(3). The sensitivity was highest for the lowest wavelength used (320 nm), decreasing continuously towards longer wavelengths but had a secondary maximum in the blue region at 415 nm. The latter corresponds to the absorption maximum of the porphyrins produced by P. acnes, which are very likely to act as chromophores . Acne often improves after exposure to sunlight artificially produced solar radiation. Blue light works by killing the acne-causing bacteria Propionibacterium acnes (P.acnes), and is being used to treat inflammatory acne vulgaris that has not responded to other acne therapies(4). P. acnes produces porphyrins which absorb light energy at the near ultraviolet (UV) and blue light spectrum. Irradiation of P. acnes colonies with blue visible light leads to photoexcitation of bacterial porphyrins, singlet oxygen production and eventually bacterial destruction (3). In vivo it has been shown that acne may be treated successfully with blue visible light phototherapy. Red light may have anti-inflammatory properties by influencing the release of cytokines from macrophages or other cells but its exact mode of action in the treatment of acne vulgaris is not yet fully understood (4). Recently it has also been shown that irradiation of P. acnes with UVA and blue light, by affecting trans- membrane proton influx, induces intracellular pH alterations and bacterial damage(5).
Macrophages exposed to 660 nm low-level wavelengths release cytokines which stimulate fibroblast proliferation and the production of growth factors, thus influencing the inflammatory process, healing and wound repair(6). In vitro investigation revealed that irradiation from this light source reduced the number of P .acnes ,probably by combining antibacterial and anti-inflammatory action,which is nearly similar to topical antibiotic agents and a partially effective means of treating acne vulgaris of mild to moderate severity.
Our main objective is to compare the efficacy of filtered blue natural light in reducing acne severity score to topical standard solution of erythromycin in mild to moderate acne patients.
Materials and methods:
This was a prospective, experimental ,forwarded ,comparative clinical trial. 38 Patients with mild to moderate acne of either sex and age ranging from 14 to 50 years (( Fitzpatrick skin phototypes II IV)) attended the out-patient clinics at educational centers (Noor,Alzahra and Shahid Beheshti), and were recruited into the trial. They have been satisfied to enter the study with full insight. None of the patients should suffer from severe acne that is an indication of systemic treatment .One of the main drugs causing photosesitivity is Accutane. The patients should not use this drug or any similar ones,such as: thiazides,tetracyclines,benzodiazepines. Other exclusion criteria :pregnancy, use of any acne treatment other than that issued, or any intake of oral antibiotics, oral contraceptives, immigration, un cooperativeness and unwillingness to continue the treatment.
All patients were otherwise healthy. First,after the patients were recruited, a full medical and dermatological history was taken and a physical examination performed. each patient"s acne was assessed by a spot count of both inflamed and non-inflamed lesions.
ASI score (acne severity index) is estimated by such formula:
0.25 x comedone number + 1 x papule number + 2 x pustule number= ASI score.
In one group of patients, after gentlely washing the face with *TCC soap( from the same manufacturer company,) the right-sided lesions were treated with topical erythromycin 4% in 70% ethanol solution twice daily and the left sided ones were treated with irradiation of sunlight by a filter of blue light (415 nm) made by SAAIRAN Optics Governmental Company in touching position on the face.The portable light-weighted filter was touching the face for 15 minutes once daily at mid-day time ,while another part of the face was covered with a dense black cloth. The tested light was blue (405-420 nm) visible narrow band light with maximal conductivity of 40% of the filter and the band width of about 30 nm.
In another treatment group the lesions in opposite sides of the face were treated on a reverse manner,so, a split-face comparison was performed. The type of treatment for each facial side was selected randomly.
Inflammatory and non-inflammatory acne lesions were counted at baseline and after each visit up to 4 weeks after cessation of the treatment period and the results were registered .The investigator assessed the global severity of acne at baseline and each study visit using acne severity index for grading .The patients were followed up to 12 weeks.
Six patients discontinued their treatment study because of undesirable results and experience of deterioration and discomfort, though none of the patients showed any harmful direct side effects from filtered blue light phototherapy such as burns, pigmented macules , keratoses etc. One patient dropped out after two sessions of irradiation and the other three dropped out after four to five sessions because of unsatisfactory results as claimed by the patients themselves.Meanwhile,2 patients refused from continuing the trial ,as they did not like to use erythromycin due to undesirable smell and stinging sensation . So our study was completed by 32 remaining patients.
Exacerbation of acne was noted in three patients (3/32) at the side treated by Blue light filter and in two patients (2/32)at the side treated by erythromycin at 1-month follow up.The exacerbation was determined as an increase more than 10% in ASI score compared to the baseline value.
Criteria of improvement:
Reduction up to 25% in ASI is regarded as poor improvement,
25-75% good improvement and
above 75% regarded as marked improvement in our trial
In Table 1 demographic Data between treatment groups were shown .It indicates no significant differences in age range and baseline ASI scores between them(p>0.05)
Data were tested by t-test for changes in mean ASI score between two groups and by ANOVA Variance analysis in each group in different time points. The percent improvement in lesion counts of the irradiated side was not significant compared to the control side (p>.05). Mean ASI changes in treatment group(irradiated) and control group(erythromycin) at baseline and 4-week, 8-week and 12 weeks were summarized in table 2 .
By Anova analysis no significant differences were found between the groups at the baseline up to the end of study. There were not significant differences between the blue light and the erythromycin groups at all time points (P >0.05).Meanwhile, gender (P=0.471), could not be used as predictive factor of therapeutic effectiveness. Except for erythema and stinging, which were more common in irradiated side than erythromycin side, 25% vs. 9% (p<0.05),the other side effects such as drying effect and exacerbation of lesions were not significantly different in both sides(p>0.05). Adverse reactions are summarized in Table 3 . VAS decreased from 3.9 to 1.9 on the erythromycin side and from 3.9 to 2.4 on the light irradiated side, and the difference between them was not significant at Week 4 (p=0.45) (table 4).
About 50% of patients were highly satisfied with the treatment by erythromycin and only 39% with irradiation of light .
The recurrence as defined by increase of more than 20% in acne score after its reduction at the end of follow up was seen in 8 patients in blue light group and in 10 patients in erythromycin group and the result was not statistically significant (Mann-Whitney Test),(p=0.41) (shown by table 5 ).
In a research ,eight 10- or 20-minute treatments over 4 weeks with a narrow band blue light was found to be effective in reducing the number of inflamed lesions in subjects with mild to moderate acne(7). Some studies show more than an 80% response to 420 nm acne phototherapy with a significant reduction of 59-67% of inflammatory acne lesions after only eight treatments of 8-15 minutes (2).
The In our trial; The improvement achieved by the topical erythromycin was superior to those of blue light , but the differences did not reach levels of statistical significance. (with 95% confidence intervals). We have concluded that: phototherapy with blue light is partially effective and safe. Despite the red light that worsens the rosacea and some kinds of skin hypersensitivity ,blue light can not do it(8).
Combination blue and red light therapy appears to have excellent potential in the treatment of mild to severe acne. Treatment appears to be both pain- and side effect-free.(9)
Optical treatments possess the potential to improve inflammatory acne on a short-term basis with the most consistent outcomes for PDT [up to 68% improvement, aminolevulinic acid (ALA), methyl-aminolevulinic acid (MAL) and red light]. IPL-assisted PDT seems to be superior to IPL alone. Only two trials compare optical vs. conventional treatments, and further studies are needed. Side-effects from optical treatments included pain, erythema, oedema, crusting, hyperpigmentation, pustular eruptions and were more intense for treatments combined with ALA or MAL. Conclusion Evidence from controlled clinical trials indicates a short-term efficacy from optical treatments for acne vulgaris with the most consistent outcomes for PDT.(10)
We really thank Dr. P.Adibi, the respected vice chancellor of research in Isfahan university of medical sciences and Mr. A. Rastegary the head of industrial interrelationship of Isfahan university of medical sciences . We are also thankful to all the valuable staff of SAAIRAN OPTICS Co. for their support in this project .
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2 -Elman M, Slatkin M, Harth Y. J .The effective treatment of acne vulgaris by a high-intensity narrow band 405-420nm light source. Cosmet Ther 2003; 5:111-7.
3- Kjeldstad B. Photoinactivation of Propionibacterium acnes by near ultraviolet
light. Z Naturforsch 1984; 39: 329-35.
4- P.Papageorgiou , A.Katsambas , A.Chu .Phototherapy with blue (415 nm) and red (660 nm) light in the treatment of acne vulgaris Br J of Dermatol 2000; 142: 973-978.
5-Breitbart H, Levinshal T, Cohen N et al. Changes in calcium transport in mammalian sperm mitochondria and plasma membranes irradiated at 633 nm (He-Ne laser). J Photochem Photobiol . 1996; 34: 117-21.
6- Iusim M, Kimchy J, Pillar T et al. Evaluation of the degree of effectiveness of Biobeam (low level narrow band light) on the treatment of skin ulcers and delayed post-operative wound healing. Orthopedics 1992; 15: 1023-6.
7- Morton CA, Scholefield RD, Whitehurst C, Birch J.An open study to determine the efficacy of blue light in the treatment of mild to moderate acne. J Dermatol Treat 2005; 16:219-23.
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9-Goldberg DJ, Russell BA. Combination blue (415 nm) and red (633 nm) LED phototherapy in the treatment of mild to severe acne vulgaris. J Cosmet Laser Ther. 2006;8(2):71-5.
10-Haedersdal M, Togsverd-Bo K, Wulf HC. Evidence-based review of lasers, light sources and photodynamic therapy in the treatment of acne vulgaris. J Eur Acad Dermatol Venereol. 2008;22(3):267-78.
Demographic Data and baseline clinical disease score:
Filtered light side
Topical erythromycin solution side
No. of patients
ASI (Acne severity index)
17.5 (( +_ SD (2.5))
18 (( +_SD (1.2))
T- test comparing the data in case and control groups indicate insignificant differences..(P>0.05)
Table 2 :
ASI changes in treatment group and control group at baseline and 4-week, 8-week and 12 weeks
Treatment group (blue filtered light)
n = 32
Lesion ,ASI median (range)
Control group(erythromycin solution)
n = 32
Lesion ,ASI median (range)
آدرس مطب : اصفهان ، خیابان فیض ، ابتدای خیابان ارباب
تلفن : 36627780 - 0313