Erythematous scars (reddened scars caused by a dilation of superficial blood vessels in the skin, or erythema), and hypertrophic scars (scars with excessive deposits of collagen that cause a raised-scar appearance) are seen frequently in the first year after injury. Vascularspecific lasers and light devices, especially the 595-nm pulsed dye laser (PDL), are already well established for such applications. PDL is often combined with fractional laser therapy—either in the same treatment session or in alternating sessions.
Hypertrophic burn and traumatic scars are best improved by ablative fractional lasers. Ablative lasers, when compared to other lasers, have a significantly greater potential depth of thermal injury. One such laser modified for the treatment of scars reaches 4.0 mm in depth. Furthermore, tissue ablation appears to induce a modest immediate photomechanical release of tension in some restrictive scars. An appropriate degree of surrounding thermal coagulation appears to facilitate the subsequent remodeling response. To determine the appropriate laser pulse energy settings (treatment depth), scar pliability and thickness is estimated by the physician through palpation or physical exam by touch.
Pigment-related abnormalities of scars (hypopigmentation, or a lack of coloring; hyperpigmentation, or darkening; and depigmentation, a loss of pigment) can also be improved with fractional therapy. Flat or atrophic scars from burns and trauma also respond well to fractional laser therapy. Atrophic scars are dermal depressions that occur due to collagen destruction during an injury. The goal of laser treatment for atrophic scars is to stimulate collagen production within the atrophic areas. Neocollagenosis, or collagen production, is most stimulated by fractional laser therapy, making it the best choice for flat or thin scars.