In Vivo Histological Study Evaluating Non-Ablative Fractional 1940-nm Laser.

Area of Science:

• Dermatology
• Laser Medicine
• Histopathology

Background:

• Non-ablative fractional lasers (NAFL) are increasingly preferred over ablative treatments due to reduced downtime and fewer side effects.
• NAFL devices operating between 1320-nm and 1927-nm have demonstrated safety and efficacy in skin resurfacing.
• The 1940-nm wavelength represents a newer option within NAFL technology for skin rejuvenation.

Purpose of the Study:

• To histologically evaluate the healing process of microthermal treatment zones (MTZs) induced by 1940-nm NAFL in human abdominal skin.
• To assess the depth, width, and duration of MTZ formation and resolution following 1940-nm NAFL treatment.
• To determine the safety profile and clinical healing response of 1940-nm NAFL skin resurfacing.

Main Methods:

• Three subjects underwent 1940-nm NAFL treatment on abdominal test areas at varying energy settings (5-20 mJ/MTZ) and 20% coverage.
• Skin biopsies were collected immediately post-treatment and at 1, 3, 7 days, and 6 weeks.
• Hematoxylin and eosin stained slides underwent blinded analysis to measure MTZ dimensions and evaluate inflammatory and healing responses.

Main Results:

• Histology revealed mild early inflammation, necrosis, and coagulation zones immediately post-treatment, with dimensions correlating to laser energy.
• Long-term observations (7 days to 6 weeks) showed signs of healing, including dermal mucin, fibrosis, and absence of necrosis.
• MTZs persisted beyond 6 weeks, with an estimated duration of 100 days. Mild, transient erythema and edema were the only clinical responses, resolving within 24 hours. No serious adverse events were reported.

Conclusions:

• 1940-nm NAFL treatments are safe for creating fractional coagulation and necrosis zones in abdominal skin.
• The depth and coverage of injury induced by 1940-nm NAFL suggest its efficacy for skin resurfacing, comparable to other NAFL devices.