Fractional lasers have become widespread in dermatology owing to their efficacy and safety. Comparative analysis of histological features after laser rejuvenation using a 1064‐nm fractionated handpiece picosecond laser with different energy fluence levels (1.1 or 2.1 J/cm2). An open‐label, study of 28 women aged 36 to 60 years with signs of age‐related photodamage and skin changes of the face and neck was conducted using a fractional picosecond 1064 nm laser in low vs high fluence. The clinical assessment at 3 weeks showed more pronounced effect on facial skin rejuvenation with the higher fluence of 2.1 J/cm2 compared to 1.1 J/cm2. The effect and safety of laser rejuvenation using a picosecond laser has been shown with more pronounced histological effects at higher fluences.

The purpose of this research is scientific rationale for fractional photothermolysis usage to correct age-related changes of neck skin of women in different age groups. Materials and Methods. A comparative study of the results for fractional photothermolysis (FP) treatment in order to correct involutional changes in neck skin of 60 women in different age groups has been carried out (first group - 40-49 years old, second group - 50-60 years old). Skin moisture, its smoothness (relief), the width of the mouths of the pilosebaceous unit, the severity of pigmentation, the depth and width of wrinkles before the treatment, 1 week after and 1 month after the procedure have been investigated. Main results. After a week of having FP it affected all investigated functional skin parameters more in the 2nd age group than in the 1st one. Decreasing in moisture and smoothness of the skin, increasing the width and the depth of wrinkles, pores and pigmentation width have been marked. In one month there was more significant positive dynamics in parameters of smoothness, wrinkles width in the 2nd group (p < 10-8, p < 10-7) than in the 1st group (p = 0.002, p < 10-5). Hydration of the skin, the width of the mouths of the pilosebaceous unit, the depth of wrinkles and pigmentation changed more significantly among patients in group 1 (p < 10-7, p = 0.001, p < 10-5, p < 10-8). Conclusion. Skin functional parameters of patients from the first group deteriorated significantly less in comparison with the second group one week after PF procedure was carried out. 1 month after the 1st group is indicated with significant improvement in moisture, the width of the pilosebaceous unit, the depth of wrinkles and pigmentation, and the 2nd group is indicated with improvement of smoothness and width of wrinkles. The differences discovered in skin condition dynamics in different age groups should be considered when planning the aesthetic outcome of FP procedure.