Comparison of the Efficacy and Safety of Delicate Pulsed Light and Q-Switched 1064 nm Nd:YAG Laser in the Treatment of Post-Acne Erythema

Acne vulgaris is a highly prevalent chronic inflammatory skin disease, affecting approximately 85% of adolescents globally, and ranking eighth among all chronic conditions in terms of global disease burden. Although traditionally perceived as a benign and self-limiting disorder, its impact on quality of life, especially when accompanied by persistent post-lesional sequelae such as post-acne erythema (PAE), is increasingly recognized. The aggravation of acne is often multifactorial, closely linked to recurrent inflammatory episodes, inadequate therapeutic interventions, and improper skincare behaviors such as manual squeezing or scratching of lesions. These factors not only exacerbate active lesions but also contribute significantly to the development and persistence of PAE.

PAE is a vascular response resulting from the dilation and proliferation of superficial dermal capillaries following inflammatory acne lesions. It presents clinically as well-demarcated erythematous macules or patches, primarily located on previously inflamed sites. Although PAE can spontaneously resolve within 2 to 6 months, in many individuals-particularly those with darker Fitzpatrick skin types-it may persist significantly longer, often overlapping with post-inflammatory hyperpigmentation (PIH). Epidemiological data suggest that the incidence of PAE and PIH in darker-skinned populations ranges from 45.5% to as high as 87.2%, highlighting the need for effective interventions. Given that acne and its sequelae predominantly involve facial skin, the psychosocial burden is substantial. Patients often experience reduced self-esteem, social withdrawal, and even symptoms of anxiety and depression, underscoring the importance of timely and effective treatment strategies.

Among current therapeutic approaches, low-energy, large-spot 1064 nm Q-switched Nd:YAG laser has garnered attention due to its favorable safety profile and ability to penetrate deeper dermal layers. Operating in the near-infrared spectrum, the 1064 nm wavelength is selectively absorbed by hemoglobin in dilated capillaries, promoting vasoconstriction and diminishing visible erythema. At low energy densities, this laser minimizes thermal injury to surrounding tissues while simultaneously stimulating neocollagenesis, thereby contributing to both vascular remodeling and dermal regeneration. This dual mechanism supports its utility in managing PAE with minimal downtime.

In contrast, Delicate Pulsed Light (DPL), an advanced form of filtered intense pulsed light (IPL), offers enhanced precision through narrower wavelength bands, typically within the 500-650 nm range. This allows for more selective targeting of hemoglobin and melanin, improving therapeutic outcomes while reducing the risk of non-specific tissue damage. In the context of PAE, DPL effectively targets superficial vascular lesions, mitigates inflammatory processes, and promotes skin healing through controlled photothermal effects and collagen stimulation. Compared to conventional IPL, DPL provides improved treatment accuracy, reduced adverse effects, and better adaptability across a range of skin phototypes.

Given the growing demand for non-invasive, effective, and safe interventions for PAE, comparative studies on commonly used energy-based devices are warranted. Therefore, in this study, we conducted a prospective, split-face, randomized controlled trial to compare the clinical efficacy and safety of low-energy 1064 nm Nd:YAG laser and DPL in the treatment of acne and PAE. This design allows for intra-individual comparison, thereby minimizing confounding variables and enhancing the validity of outcome assessments. Our primary objective was to determine whether there are significant differences in the therapeutic outcomes between these two modalities, with a particular focus on erythema resolution, patient satisfaction, and adverse event profiles.