Low-fluence and low-density CO2 laser: histological analysis of collagen fiber changes in skin and its clinical repercussions in photorejuvenation.

This study refers to clinical and histologic analysis of effects on photorejuvenation after one single treatment of fractional CO2 laser with low fluence and low density. To analyze histologically the quantitative variation of collagen fibers type I and III, elastic fibers, and epidermal thickness on D84, besides clinical evaluation of amount, length, thickness, and depth of periocular wrinkles during the same period. This is an open, prospective, interventional study. There were 40 healthy female with age between 35 and 65 years. Twenty-six participants were randomly selected for D0 and D84 biopsy. A single session of fractional CO2 laser was done in the hole face, using a 800-µm tip, 5% density, and 10 mJ fluence with a single pass. On D0, D42, and D84, a clinical comparative analysis of amount, length, depth, and thickness of periocular wrinkles has been done. On histological analysis, a comparative quantitative evaluation of collagen fibers type I and III, elastic fibers, and epidermal thickness has been done on D0 and D84. The results of this study denoted a significant clinical improvement of amount (- 32.17%; p < 0.0001), thickness (- 33%; p < 0.0001), lenght (- 35.84%; p < 0.0001), and depth of periocular wrinkles (- 32.46%; p < 0.0001). A significant increase in the amount of collagen fibers type III was observed on D84 (+ 60.67%; p = 0.0013). Collagen fibers type I and elastic fibers did not have the same result, with a nonsignificant increase (+ 8.31%; p = 0.3820) and a decrease (- 12.4%; p = 0.0585) respectively. Epidermal thickness has a tendency to significant variation (p = 0.05553). The results demonstrate that fractional CO2 laser with low fluence and low density is a safe and efficient option for photorejuvenation of the face.

Laser-assisted MAL-PDT associated with acoustic pressure wave ultrasound with short incubation time for field cancerization treatment: A left-right comparison.

BACKGROUND: Laser-assisted MAL-PDT has been reported to increase the effectiveness of conventional PDT. Nonetheless, clinical effects of this association when reducing MAL incubation time is poorly discussed. Furthermore, the association of acoustic pressure wave ultrasound with laser-assisted MAL-PDT with short incubation time for field cancerization had not been reported before. OBJECTIVES: To compare clinical effects of ablative fractional laser-assisted MAL-PDT associated with acoustic pressure wave ultrasound (IMPACT US) with 1-hour incubation time and conventional MAL-PDT for skin field cancerization on the forearms, as well as the impact on safety and tolerability. METHODS: Fifteen patients with 638 AK (grade I-III) with field cancerized-skin on the forearms were enrolled in this left-right trial. Two protocols were randomly chosen. One side was treated with conventional MAL-PDT, whereas the other with laser-assisted MAL-PDT associated with acoustic pressure wave ultrasound with 1-hour incubation time. Actinic keratoses were quantitively measured, and the other signs of sun-damaged skin, like pigmentation and texture, in field cancerized skin were qualitatively evaluated before and after six months. Side effects were assessed subjectively during the procedure and one week after. RESULTS: All patients completed the study. At six months after treatment, both protocols reduced the number of AK (72%; CO2 + PDT, and 65%; MAL-PDT). The difference between these two protocols was not statistically significant (p = 0.77). The improvement of pigmentation and texture of field cancerized skin was more significant on the side treated with laser-assisted MAL-PDT associated with acoustic pressure wave ultrasound. Both protocols were well tolerated and without significant difference in adverse events. CONCLUSION: Laser-assisted MAL-PDT using CO2 laser and acoustic pressure wave ultrasound with short incubation time of 1 h was as effective as conventional MAL-PDT for field-cancerized skin with actinic keratosis in forearms with better cosmetic outcome.