Fractional Ablative Carbondioxide Laser Resurfacing for Acne Scars-A single Centered Study

Materials and Methods: Forty participants (Fitzpatrick skin types III–IV) ranging from the age group of 25-45 who had moderate to severe acne scars were included in the study.CO2 Fractional laser was used, Unit: eCO2 Lutronic Korea; FDA approved, in 3 sessions at one month interval and 4th and 5th sessions at the interval of 2 months. Comparison was done on a monthly basis for the improvement of scars at one monthly interval and any other symptoms like pain, recovery time for wound healing and complications of laser like hyperpigmentation were noted by asking the patient to fill up a questionaire.

Acne is a common skin condition especially in adult age group 1 . Its course varies according to its severity, mishandling and management. 2 Acne scars are quite common and lead to disfigurement and psychosocial problems. 3,4 A recent, comprehensive and functional scheme was proposed, whereby scars are classified as rolling, ice-pick, shallow boxcar, and deep boxcar. Various procedures like chemical peeling, derma abrasion, laser resurfacing, punch excision, elevation and scar revision may have to be sorted to improve the appearance with variable results and outcomes. 4,5 Ablative therapies with CO 2 fractional laser has been effectively used for the treatment of acne scars. High-energy, short duration exposure to 10,600 nm CO 2 laser light vaporizes intra and extracellular water, causing tissue ablation, rapid enough to limit dermal injury and reduce the likelihood of additional scarring. 6 Ablative laser therapies with CO 2 fractional laser and erbiumdoped yttrium aluminumgarnet (Er:YAG) lasers are well accepted treatments for post acne scars. 7 Use of these lasers in Asian patients was discouraged due to delayed recovery time, edema, prolonged erythema, post-inflammatory pigmentations and scarring. 8,9 In this study, we examined the efficacy and safety of ablative CO 2 fractional laser, (10,600nm) in 40 patients with mild to moderate acne scars.

MATERIALS AND METHODS
The study was conducted in Nepal skin hospital, Bijulibazar from March 2012 to September 2013. Permission from the ethical committee was obtained. A series of forty participants (Fitzpatrickskin types III-IV) ranged 25-45 years-old who had moderate to severe acne scars have been included. Participants with the following criteria were excluded from the study: active infections, history of keloid scar formation, known allergies to lidocaine, recent accutane use, smoking, pregnancy or cosmetic procedures in the treatment area within last 2 months.
The treatment areas were cleansed (debris , including dirt, makeup and powder) by using a mild cleanser and 70% isopropyl alcohol. Lidocaine 2.5% and prilocaine 2.5% cream (Lidocaine-p cream) were applied under close dressing on the entire face. After 40 minutes of application, the anesthetic cream was gently removed with clean gauze. CO 2 Fractional laser was used, Unit: eCO 2 Lutronic Korea; FDA approved, in 3 sessions at one month interval and 4th and 5th sessions at the interval of 2 months. Photographic documentation using identical camera settings, lighting, and patient positioning were obtained at baseline, before each treatment session, and 3 months after the final treatment session. We compared improvement rate of scars after every sessions at 1 month interval. Adverse effects and recovery times were recorded in each session and visit. We had two questionnaire sheets, one of them filled by the participants and the other one by another dermatologist who evaluated the photographs. We requested them to fill the questionnaire sheets about the scale of clinical improvement as fair (<30%), good (30%-60%) and excellent (>60%).
Immediately, after each treatment session, they also were asked to rate the pain associated with treatment on a 10-point pain scale (0 = very light to 10 = very severe). Finally, data were analyzed and the results were confirmed. The baseline features such as the texture, score, scars were noted using a skin analyser. In addition to it, two dermatologists independently compared the digital photos for clinical evaluation of the acne scars and graded according to table 1.

Statistical Analysis
Data were presented as Kendall test for comparison of the three sessions. SPSS software version18 was used. In the comparison of the different sessions for each participant, we estimated a P-value at most <0.05, consequently, we confirmed the significant difference of statistical analysis in this clinical trial.

RESULTS
A total of 40 patients were included in the study as 40 patients completed the treatment session. Among them 29 (72.5%) were female and 11 (27.5%) were male patients, completed the treatment sessions. They have a mean age of 21 years.
At the end of the session participants experienced a reduction in the size of the scars. After the first laser session, they presented 10-25%, at the second session 20-45% and at the third session 30-60 percent reduction in the size of the scars as shown in bar diagram 1. All participants felt an ascending improvement rate during and after the course of treatment. The fractional CO 2 laser showed significant reductions in the scars compared to baseline according to the dermatologist opinion.    mean pain score was 2.2 (a score of 2.5 is easily tolerated). All of them had an improvement in their acne scarring but of variable grade. Two of the patients showed almost clearance of scarring (grade 4) , while a large number (13 patients) showed mild to moderate healing of acne scars grade 2 and 16 patients showed marked improvement (grade 3) and 9 patients showed minimal improvement. An average improvement of 70% was observed. Among the studied population, 10-20% achieved near total clearance of scarring after 1st sitting, whereas 30-70% required 3 sessions to reach near total clearance of scarring. (Table 2) Side effects (14 patients) included mild pain or burning during laser treatment, post-treatment crusting, scaling and transient pigmentation ( fig.2). Twelve of sixteen patients showed mild erythema which was transient and recovered at its own. Two of these had hyperpigmentation. It is interesting that, the initial edema and erythema improved after 2-3 days, but there was remarkable superficial crusting which remained for 4-7 days so they could return to work after 4days after applying sunscreen and moisturizing lotion. There were no pigmentation changes, infections and other immediate adverse effects.
No long-term side effects were observed after 6 months of follow-ups and improvement continued after the last session.

DISCUSSION
This study demonstrated the efficacy of fractional CO 2 laser treatments for moderate to severe acne scarring. Final results in participants and dermatologist evaluation was 20%-70% and 30%-70%, respectively.The fractional CO 2 laser is useful in the treatment of scars, wrinkles, nevus, sun damaged skin and etc 5,6 .
Theoretically, the mechanisms of action of laser resurfacing include tissue ablation, immediate collagen shrinkage, and dermal collagen remodeling. Columns of microscopic ablated epidermis anddermis after treatment with Fractional CO 2 laser may result in macroscopic epidermal regenerationas evidenced by clinical improvement of scar andskin texture. 7 No evidence of clinical infection occurred during the study period. The participants returned back to work after 4 days. Considering the recovery time, adverse effects and outcome, Fractional CO 2 laser can be an alternative treatment technique for acne scar. There are many options for the treatment of acne scarring including chemical peeling, dermabrasion, punch techniques, fat transplantation, other tissue augmenting agents, needling, subcision and combined therapy. Various modalities have been used to treat the patent's scar, but with limited efficacy and problematic side effects have restricted their applications.
For acne scars CO 2 fractional lasers has been used worldwide with 50-70% improvement in scars individual scars which vary widely in type and depth different treatment approaches are recommended. Hence the treatment is to be individualized according to the patients need. 11

CONCLUSIONS
Fractional Co 2 laser ablation provides a safe and effective treatment of moderate to severe facial acne. It has very less side effects and patient tolerate very well. Hence, fractional CO 2 laser ablation should be the recommendation to the patient with facial scar.