Proposal of New Parameters for Non-Ablative Fractional Er:Glass 1,550 nm Laser for Hypertrophic Scars: A Histological and Clinical Analysis

Introduction: Hypertrophic scars (HS) can be highly limiting, both functionally and aesthetically.Lasers serve as a middle ground between conservative treatments (such as silicone and injectables) and surgical revision.Objectives: To evaluate improvements in HS and associated histopathological changes following treatment with non-ablative fractional laser (NAFL) Er: 1,550 nm glass.Methods: Eight hypertrophic scars were treated with three monthly sessions of low fluence and high-density NAFL, applied to one-half of each scar.Clinical and symptomatic improvements, along with histopathological changes, were compared between the treated and control sides.Results: Partial symptomatic improvement was noted.A statistically significant reduction in the proportional area of collagen fibers was observed in hematoxylin-eosin staining (p=0.009) and Masson's trichrome staining (p=0.001) on the treated side compared to the control.No significant differences were found in the proportional area of elastic fibers or epidermal thickness.Conclusion: The histological changes suggest that low fluence and high-density NAFL is an effective treatment for HS.We recommend increasing the number of sessions or combining it with other techniques to achieve faster and more optimal results.