Comparison of the safety and efficacy of low fluence Q‐switched 1064‐nm and conventional Q‐Switched 755‐nm lasers in the treatment of café‐au‐lait macules: A prospective self‐controlled trial

Abstract

Background Conventional high fluence Q‐switched (HFQS) Alexandrite 755‐nm are widely used in clinical café‐au‐lait macules (CALMs) treatment. There have been recent concerns regarding the efficacy and safety of low fluence Q‐switched (LFQS) Nd: YAG 1064‐nm lasers. Objective To evaluate the efficacy and safety of the conventional HFQS and LFQS laser in the treatment of CALMs. Methods Within 3 months, 20 patients underwent prospective self‐controlled split‐lesion treatments with HFQS once or twice depending on the recovery rate, and with LFQS six times biweekly. Then the more effective laser was selected for continued treatments. Efficacy outcomes were evaluated by a visual analog scale (VAS) biweekly during the comparative trail. Recovery process, side effects and recurrence were recorded during the trial and follow‐up visit. Patient and physician preferences for laser selection were also recorded. Results The average VAS scores of areas treated with HFQS and LFQS were 2.92 ± 0.86 and 2.93 ± 1.13, respectively (p > 0.05). The most significant efficacy change of LFQS was after the fourth laser treatment (VAS score: 1.82−2.37, p < 0.001). 11 lesions treated with LFQS and 7 with HFQS achieved an optimal treatment response (3.67 ≤ VAS ≤ 4). Three patients relapsed on one side (one on LFQS, two on HFQS) and five on both sides. Adverse effects included temporary hypopigmentation, hyperpigmentation, uneven pigmentation, and mottled hypopigmentation. Doctors thought 80% of patients were suitable for LFQS. 70% of patients preferred LFQS posttreatment. Conclusions The efficacy difference between the LFQS 1064‐nm laser and HFQS 755‐nm laser in treating CALMs in a 3‐month comparative trial was statistically insignificant. LFQS is preferred by doctors and patients and is likely to help more patients achieve treatment efficacy than the HFQS within a short time, with fewer temporary adverse reactions, and a more even pigmentation. But it can cause mottled hypopigmentation. The LFQS had obvious lesion clearance after the fourth treatment.

Low-Fluence Q-Switched Nd: YAG Laser (LF-QSNY) May Be a Better Choice for the Treatment of Early Nevus of Ota: A Prospective Self-Controlled Trial of LFQS and Picosecond Alexandrite Laser

“…Te LFQS laser had obvious lesion clearance after the frst treatment. While both research studies indicated with the increase of LF-QSNY treatment sessions, the clearance of lesions gradually accumulated [26].…”

Effect of dual‐optical pulses with temporal energy distribution on laser ablation performance in in vivo zebrafish model

“…Typically, the Q-switched laser pulses meet the stress confinement (i.e., isochoric heat deposition) in that the pulse duration is shorter than the stress relaxation time (1 μs) [8]. Because of instant heat deposition upon volumetric light absorption in a target, the Q-switched laser system has been applied in various fields, such as micromachining, scaffold fabrication, and laser-tissue resection [9][10][11]. However, a single pulse with a high peak power often causes undesirable damage to optical components and target materials [12].…”

“…Several irradiation methods have been developed to minimize thermomechanical damage by reducing the peak power of each pulse. For example, Q-switched pulses with low-pulse energies (<1 mJ) at high-repetition rates (a few hundred kHz) have been applied for laser micromachining [9,10]. The application of the multiple Q-switch pulses can minimize the excessive accumulation of thermal stress but can maintain the ablation performance during the micromachining process.…”