INTRODUCTION
Wrinkles and fine lines develop following structural epidermal and predominately dermal skin changes. This involves an evolution on the ultrastructural level, upon which collagen I production is downregulated, disorganized, and/or crosslinked collagen fibrils appear and elastin-rich materials accumulate.1-4 This process leads to an aged appearance, and can have both physical and emotional impacts on patient well-being.5 A variety of ablative and non-ablative laser-based techniques have been shown to induce epidermal resurfacing and promote collagen synthesis,6,7 resulting in skin rejuvenation. While ablative approaches improve skin roughness, adequately address facial rhytides, and bring immediate and marked outcomes, their use is limited to very superficial dermal layers8 and is associated with a high risk of complications (ie, erythema and pigmentary changes) and lengthy recovery periods.9 The non-ablative skin rejuvenation techniques have proven effective in improving skin texture and fine wrinkles, and have gained popularity due to minimal wounding, significantly shorter recovery times, and decreased morbidity.10 However, they require a series of treatment sessions, and their efficacy is typically lower.11,12 Treatment efficacy has been improved and downtime further reduced upon introduction of light fractionation options, which allow for sustained thermal injury within microscopic columns, spaced at regular intervals along the tissue surface. The cells of the intervening columns then readily repopulate the thermally damaged layers, which form the basis for improved efficacy.13 Introduction of Q-switched (QS) submicrosecond-long laser pulses enabled selective photothermolysis via preferential absorption by pigmented structures whose profiles vary with the penetrating potential of the applied wavelengths.14 Due to the rapid and selective nature of this process, collateral damage to the adjacent normal tissue is avoided. More specifically, the widely used QS Nd:YAG (1064 nm) laser has been shown to effectively clear dark-inked tattoos15,16 and rhytids17 and has been associated with a lower incidence of hypopigmentation when compared to other wavelengths.16 Due to its safety and effectiveness, the technology used at low fluences and high Hz has become popular in skin toning procedures in dark skinned populations.18 This prospective, split-face study aimed to assess whether sequential delivery of non-ablative fractional laser (NAFL) and QS laser treatments yield a synergistic effect on skin rejuvenation outcomes in 17 Fitzpatrick skin type II-V-treated patients, in comparison to NAFL treatment alone.
