ABSTRACT
Background and Objectives
Melasma is a chronic pigmented lesion on the face that is challenging to treat. Single laser treatments are usually ineffective. Recently, picosecond lasers are becoming an emerging option for the treatment of melasma. This study aimed to evaluate the efficacy and safety of fractional and non‐fractional picosecond Nd:YAG lasers (PSNL) combined with fractional picosecond KTP laser (PSKL) on melasma in female Chinese.
Methods
Forty‐eight Chinese patients with facial melasma were selected and divided into two groups. Every 4 weeks, each patient received one treatment, for a total of six treatments. Treatment was administered to 24 patients using fractional and non‐fractional PSNL in the Nd:YAG group and fractional PSKL combined with fractional and non‐fractional PSNL in the Nd:YAG+KTP group. Pain scores and adverse reactions were noted following each treatment, and the modified Melasma Area Severity Index (mMASI) and patient satisfaction were assessed 1 month following every two treatments.
Results
The mMASI scores of both groups showed a considerable decline from the baseline. Following six treatments, the Nd:YAG+KTP group's mean mMASI score was 2.29 ± 0.82, while the Nd:YAG group was 2.87 ± 0.68. This difference was statistically significant (p < 0.05). At every stage of the procedure, the Nd:YAG+KTP group experienced higher patient satisfaction than the Nd:YAG group. In comparison to the Nd:YAG group, which had a pain score of 2.75 (2.54, 3.00), the Nd:YAG+KTP group had a higher pain score of 3.00 (3.00, 3.17). During the study, no severe side effects were seen in the treated areas, including blisters, hypopigmentation, or post‐inflammatory hyperpigmentation (PIH).
Conclusion
The efficacy of fractional and non‐fractional PSNL combined with fractional PSKL in the treatment of melasma is significantly better than that of using single wavelength fractional and non‐fractional PSNL, with higher patient satisfaction and less adverse reactions.
Keywords: fractional, melasma, non‐fractional, picosecond KTP laser, picosecond Nd:YAG laser
1. Introduction
Melasma is a chronic pigmented lesion that is acquired and typically affects Asian women with Fitzpatrick skin types III–V. It is characterized by photoaging features and symmetrical brown spots or plaques on both sides of the face. These features may impact the patient's psychological well‐being and quality of life [1]. The pathogenesis of melasma is unclear. Its occurrence may be related to skin barrier damage, exposure to ultraviolet light, sex hormone disorders, and so forth [2, 3, 4]. Treatments for melasma are varied, but the course of treatment is usually long. The main therapeutic measures are laser and light therapies, systemic agents, topical agents, chemical peels, and so forth. The main adverse effects of these therapies include exacerbation of melasma, erythema, burning, and PIH [5]. With the deepening of research on melasma and the advancement of science and technology, laser therapy in cosmetic dermatology has gradually shown its advantages in the treatment of melasma.
At present, many kinds of lasers can be used to treat melasma, but none of them can become the first line of treatment. The effectiveness of using a large‐spot, low‐fluence Q‐switched Nd:YAG laser in the treatment of melasma has been proven; however, the photothermal effect of the treatment may still cause additional damage to the surrounding tissues, resulting in adverse reactions such as PIH [6].
Picosecond lasers are novel lasers with extremely short pulse duration that are now used in the treatment of benign pigmented lesions, scars, photodamage, and melasma [7]. Compared to Q‐switched Nd:YAG lasers with pulse durations typically ranging from 5 to 10 ns, picosecond Nd:YAG lasers (PSNL) operate with much shorter pulse durations, usually between 300 and 500 ps, which are approximately 10–30 times shorter. Rather than a strong photothermal effect, it produces a stronger photomechanical effect when acting on the target. Therefore, the advantages of picosecond lasers are mainly in two aspects: the ability to use lower fluence to achieve higher peak power and so more effectively destroy the target, as well as the ability to make less heat diffusion into the surrounding normal tissues and so lessen adverse reactions [8, 9].
Melasma is often characterized by photoaging, and previous studies have shown that fractional PSNL and picosecond KTP lasers (PSKL) have a high degree of efficacy and safety when used in combination or alone for the treatment of photoaging [10, 11]. Another split‐face study verified that the combination of non‐fractional PSNL and PSKL can effectively treat melasma in patients with Fitzpatrick skin types I–III [12]. However, there is still no study that has used fractional and non‐fractional PSNL combined with fractional PSKL for the treatment of melasma. Therefore, we designed this retrospective cohort study to evaluate the efficacy and safety of this therapy.
2. Material and Methods
2.1. Study Design
This retrospective study selected Chinese female patients with melasma who came to Wenzhou Hospital of Integrated Traditional Chinese and Western Medicine from January 2022 to May 2024 to receive PSNL and PSKL treatments. Every experimental subject gave their informed consent, and the study was conducted following the Declaration of Helsinki. All study methods were approved by the Institutional Review Board of Wenzhou Hospital of Integrated Traditional Chinese and Western Medicine, Affiliated Zhejiang Chinese Medical University (IRB number: 2024‐L041).
2.2. Subjects
Forty‐eight Chinese female patients (Fitzpatrick skin type III) with melasma, with a mean age of 46.65 ± 5.55 years, were included in this study and were divided into the Nd:YAG group and the Nd:YAG+KTP group. Inclusion criteria included: (1) melasma in stable stage; (2) age 18–60 years; (3) no other treatments were used during the study period; (4)mixed melasma. Exclusion criteria included: (1) use of any systemic or topical treatments for melasma within 3 months prior to or during the study period; (2) history of photosensitivity, keloid formation, or other contraindications to laser therapy; (3) inability to adhere to the study protocol.
2.3. Treatment Protocol
Nd:YAG group: treatment with PSNL (Picoway, Syneron‐Candela, USA). Parameters: wavelength 1064 nm, Zoom mode was used in the first step, with a spot diameter of 6 mm, frequency of 6 Hz, and fluence of 0.4–0.7 J/cm2, the whole face was scanned for one time; Resolve mode was used in the second step, with a spot area of 6 × 6 mm2, frequency of 3 Hz, fluence of 1.3–1.7 mJ/microbeam, melasma area was scanned one time.
Nd:YAG+KTP group: the third step was added to the treatment protocol of the Nd:YAG group, that is, combined with a PSKL (Picoway, Syneron‐Candela, USA). Parameters: wavelength 532 nm, Resolve mode, spot area of 6 × 6 mm2, frequency of 3 Hz, fluence of 0.2–0.3 mJ/microbeam, melasma area was scanned one time.
The resolve mode utilized a holographic optic that produced a 10 × 10 square pattern with 101 uniform laser beams. The endpoint of treatment in both groups was slight redness of the skin. Laser treatments were performed at 4‐week intervals for a total of six treatments.
Recombinant human epidermal growth factor (rhEGF, Shanghai Haohai Biological Technology, China) was sprayed three times daily after treatment. Patients were treated with a broad‐spectrum sunscreen (SPF 30, PA+++). Follow‐up was performed 4 weeks after the last treatment. Facial photographs of each patient were recorded before and after each treatment using a specialized facial skin detector (OBSERV+, OBSERV, NL).
2.4. Modified Melasma Area and Severity Index (mMASI)
Evaluations were performed at 8‐week intervals, and the scores were derived from photographs taken by two fixed cosmetic dermatologists who were not involved in the study of the program based on the skin detector, and ambiguous results were re‐evaluated by a third dermatologist to obtain consistent results.
Calculation method: 30% of the forehead (f), 30% of the right malar (rm), 30% of the left malar (lm), and 10% of the chin (c). Area(A) and darkness(D) scores were as follows: area: 0 = 0%, 1 = 1%–9%, 2 = 10%–29%, 3 = 30%–49%, 4 = 50%–69%, 5 = 70%–89%, and 6 = 90%–100%; darkness: 0 = absent, 1 = slight, 2 = mild, 3 = marked, and 4 = severe. mMASI total score = 0.3A(f) D(f) + 0.3A(lm) D(lm) + 0.3A(rm) D(rm) + 0.1A(c) D (c), with a total score between 0 and 24 (Table 1) [13].
TABLE 1.
Modified melasma area and severity index (mMASI).
| Location of melasma | Scoring | Calculation for total score |
|---|---|---|
| Forehead (f) | 0.3 × A × D | 0.3A(f)D(f) + 0.3A(lm)D(lm) + 0.3A(rm)D(rm) + 0.1A(c) D (c) |
| Left malar (lm) | 0.3 × A × D | |
| Right malar (rm) | 0.3 × A × D | |
| Chin (c) | 0.1 × A × D |
2.5. Improvement Rate Calculation and Assessment of the Degree of Clinical Improvement
Improvement rate = (baseline mMASI score—mMASI score 1 month after the last treatment)/baseline mMASI score × 100%. In this study, the rate of decrease in mMASI score before and after treatment (improvement rate) was used as an important evaluation index of the degree of clinical improvement and was categorized into four grades: very significant improvement >90%, significant improvement 60%–90%, moderate improvement 30%–59%, and mild improvement <30%.
2.6. Patient Satisfaction Evaluation
Satisfaction with the treatment was recorded for all patients at 8‐week intervals. Satisfaction was evaluated on a five‐point scale, with five points for very satisfied, four points for satisfied, three points for fair, two points for dissatisfied, and one point for very dissatisfied.
2.7. Safety Assessment and Pain Assessment
The patients’ pain level, immediate skin reaction, the presence of PIH, hypopigmentation, blisters, scarring, and other adverse reactions were observed and recorded during the study. The pain level was assessed by numerical visual analogue scale (VAS), and the score was between 0 and 10.
2.8. Statistical Analysis
Statistical analysis was performed using SPSS 25.0 software. For quantitative variables satisfying normal distribution, expressed as mean ± standard deviation (SD), two independent samples t‐test was used for between‐group comparisons; for quantitative variables not satisfying normal distribution, expressed as median (P25, P75), Mann‐Whitney U‐test was used for between‐group comparisons. For categorical variables, expressed as the number of cases (%), the Chi‐square test was used for between‐group comparisons. For ranked data, between‐group comparisons were made using the rank‐sum test. p < 0.05 indicates a statistically significant difference.
3. Results
3.1. Demographic Data
A total of 48 Chinese female patients (46.65 ± 5.55 years old) with melasma, all with Fitzpatrick skin type III, were enrolled. The mean age of the Nd:YAG group was 46.33 ± 5.59 years, and the mean course of the disease was 5.75 ± 2.89 years; the mean age of the Nd:YAG+KTP group was 46.96 ± 5.61 years, and the mean course of the disease was 5.67 ± 2.48 years. There was no statistical difference (p > 0.05) in the demographic data of patients in both groups (Table 2). All patients cooperated throughout to complete the treatment and were followed up at the end of the treatment.
TABLE 2.
Modified melasma area and severity index (mMASI).
| Nd:YAG | Nd:YAG + KTP | p value | |
|---|---|---|---|
| No. of subjects | 24 | 24 | |
| Age (years) | 46.33 ± 5.59 | 46.96 ± 5.61 | 0.701 |
| Course of disease (years) | 5.75 ± 2.89 | 5.67 ± 2.48 | 0.915 |
3.2. mMASI
At the time of enrollment, the mean mMASI score was 5.07 ± 0.99 in the Nd:YAG group and 4.84 ± 0.73 in the Nd:YAG+KTP group, with no statistically significant difference in scores (p = 0.367). From baseline (before the 1st treatment) to 4 weeks after the sixth treatment, there was a significant decrease in mMASI scores in both groups (p < 0.05) (Table 3). Before the fifth treatment and 4 weeks after the sixth treatment, the mean mMASI scores of the Nd:YAG+KTP group were significantly lower than those of the Nd:YAG group, and the difference was statistically significant (Figure 1).
TABLE 3.
mMASI score.
| Nd:YAG | Nd:YAG + KTP | t value | p value | |
|---|---|---|---|---|
| mMASI (baseline) | 5.07 ± 0.99 | 4.84 ± 0.73 | 0.911 | 0.367 |
| mMASI (3rd TX) | 4.14 ± 0.79 | 3.77 ± 0.90 | 1.507 | 0.139 |
| mMASI (5th TX) | 3.51 ± 0.80 | 2.95 ± 0.89 | 2.279 | 0.027 |
| mMASI (4 weeks after 6th TX) | 2.87 ± 0.68 * | 2.29 ± 0.82 * | 2.652 | 0.011 |
Compared with mMASI (Baseline), p < 0.05.
FIGURE 1.
mMASI score * Nd:YAG group compared with Nd:YAG+KTP group, p < 0.05.
3.3. Improvement Rate and Degree of Clinical Improvement
Four weeks after the sixth treatment, both groups showed satisfactory clinical improvement in melasma, with an average improvement rate of 52.4% in the Nd:YAG+KTP group and 41.6% in the Nd:YAG group. Moderate improvement was achieved in 11 (45.8%) and 20 (83.3%) patients in the two groups, respectively, and significant improvement was achieved in 10 (41.7%) patients in the Nd:YAG+KTP group (Figure 2). The overall clinical improvement was more significant in the Nd:YAG+KTP group, with a significant difference between the two groups (p = 0.006) (Figures 3, 4).
FIGURE 2.
Degree of clinical improvement and numbers (1) Mild improvement: <30%; (2) Moderate improvement: 30%–59%; (3) Significant improvement: 60%–90%; (4) Very significant improvement: >90%.
FIGURE 3.
Melasma in a 47‐year‐old woman with a disease duration of 5.5 years in the Nd:YAG+KTP group. (A) baseline, mMASI score = 5.1; (B) Week 8, mMASI score = 3.9, patient satisfaction score = 5; (C) Week 16, mMASI score = 2.8, patient satisfaction score = 4; (D) Week 24, mMASI score = 1.8, patient satisfaction score = 5. The overall improvement rate was 64.7%, with an average pain score of 2.83 throughout the treatment course.
FIGURE 4.
Melasma in a 60‐year‐old woman with a disease duration of 5 years in the Nd:YAG group. (A) baseline, mMASI score = 4.9; (B) Week 8, mMASI score = 4.1, patient satisfaction score = 4; (C) Week 16, mMASI score = 3.4, patient satisfaction score = 4; (D) Week 24, mMASI score = 2.4, patient satisfaction score = 4. Improvement rate of 51%, with an average pain score of 2 throughout the treatment course.
3.4. Patient Satisfaction
Before the third and fifth treatments and 4 weeks after the sixth treatment, patient satisfaction was relatively higher in the Nd:YAG+KTP group than in the Nd:YAG group, with significant differences between the two groups at all stages (p < 0.05) (Table 4).
TABLE 4.
Patient satisfaction.
| Nd:YAG | Nd:YAG + KTP | p value | |
|---|---|---|---|
| 3rd TX | 4 (3, 4) | 4 (4, 5) | 0.011 |
| 5th TX | 3 (3, 4) | 4 (3, 4.75) | 0.001 |
| 4 weeks after 6th TX | 4 (3, 4) | 4 (3.25, 5) | 0.027 |
Note: 5 = very satisfied, 4 = satisfied, 3 = fair, 2 = dissatisfied, 1 = dissatisfied.
3.5. Adverse Reactions and VAS Pain Scores
The erythema that appears immediately after treatment is often taken as an indication that the desired treatment endpoint has been reached; this erythema is transient and is not considered a serious adverse reaction. No serious adverse reactions such as PIH, hypopigmentation, scarring, or blistering occurred in all patients during the study. Only one patient in the Nd:YAG+KTP group experienced mild itching or persistent erythema symptoms after treatment, respectively, which resolved within 48 h with instructions to protect against sunlight and intensify moisturization. Patients experienced mild pain during treatment, and the VAS pain scores were relatively higher in the Nd:YAG+KTP group than in the Nd:YAG group, at 3.00 (3.00,3.17) and 2.75 (2.54,3.00), respectively, with a statistically significant difference between the two groups (p = 0.003), but both were still in the lower pain level (Table 5).
TABLE 5.
Adverse reactions and VAS pain scores.
| Nd:YAG | Nd:YAG + KTP | ||
|---|---|---|---|
| VAS pain score | 2.75 (2.54, 3.00) | 3.00 (3.00, 3.17) | |
| Adverse reactions | Persistent erythema | Nil | 1/24 |
| Itching | Nil | 1/24 | |
4. Discussion
Melasma is usually categorized as epidermal, dermal, and mixed based on the level of the skin where the melanin is located, but there is also recent research that suggests melasma can be categorized as only epidermal and mixed. Our study addresses the mixed type of melasma [14, 15]. Melasma is not only a purely pigmented lesion, but also has photoaging features, such as decreased vascular elasticity, dilated capillaries, sunlight‐induced elastic tissue degeneration, and an increased number of mast cells [16]. Therefore, melasma treatment should target both melanin and photoaging. At present, there are various laser therapies that can be employed for the treatment of pigmentation, but the laser therapies used for the first‐line treatment of melasma remain to be explored [17, 18, 19]. Picosecond lasers were initially used primarily for tattoo removal, and as equipment upgrades and uses have been developed, indications have included, but are not limited to, benign pigmented lesions, melasma, and photoaging [7]. In this study, we compared the efficacy of fractional and non‐fractional PSNL in the treatment of melasma with the efficacy of fractional PSKL in combination with this laser.
First, we chose to combine the fractional and non‐fractional PSNL as the control group in this study, that is, the Nd:YAG group. In this group, the mean mMASI score decreased from 5.07 ± 0.99 (baseline) to 2.87 ± 0.68 at 4 weeks after sixth treatment, with a mean improvement rate of 41.6%, of which 83.3% of the patients achieved moderate improvement in melasma. A previous study showed that melasma patients had a mean improvement rate of 35.9% at follow‐up 4 months after three non‐fractional PSNL treatments [20]. At 3 months after four fractional PSNL treatments, the mean mMASI score decreased from 5.90 ± 2.86 (baseline) to 3.78 ± 3.05. The mean improvement rate was 37% [21]. In contrast, our study, which used both fractional and non‐fractional modalities, showed a higher mean improvement rate. We believe that this is mainly due to the combination of the advantages of the two modes. In the non‐fractional mode, the PSNL, by virtue of its extremely short pulse duration, causes the melanin in the dermis of the melasma area to break up more completely (photomechanical effect), and transmits less heat to the surrounding tissues, while inhibiting melanocyte activity (photomodulation) [22]. In the fractional mode, the laser microbeam generated by the PSNL penetrates into the dermis, generating laser‐induced optical breakdown (LIOB) to induce collagen synthesis, resulting in skin remodeling [23]. However, the patients in our study were treated more often, and therefore, the benefits of the increased number of treatments should not be ignored.
Based on the Nd:YAG group, we combined the fractional PSKL as the experimental group in this study, that is, the Nd:YAG+KTP group. Mean mMASI scores of the patients in this group were significantly lower than those in the Nd:YAG group at 4 weeks after sixth treatment (p = 0.011), and the mean improvement rate was 52.4%, with 41.7% of the patients achieving a significant improvement, and the overall clinical improvement was more significant in the Nd:YAG+KTP group (p = 0.006). The results demonstrate the efficacy benefits of the combined use of a 1064 and 532 nm dual‐wavelength picosecond laser for the treatment of melasma. Given that one study found that the histologic features of melasma in Chinese patients included increased melanin in both the epidermis and dermis, and that patients with increased melanin in the epidermis only may be more prevalent than those with increased melanin in both the epidermis and dermis [15]. We hypothesized that in our study, the PSKL in fractional mode could act on the epidermis to gently remove epidermal melanin, thus enhancing the treatment effect. This speculation has been confirmed in various studies. Wu et al. [24] showed that the KTP laser was better at clearing epidermal pigmentation, while the Nd:YAG laser was better at skin rejuvenation. Another prospective study of patients with facial photodamage used a similar dual‐wavelength fractional 1064 and 532 nm laser combination treatment and achieved satisfactory results. All subjects in that study received three treatments of fractional PSNL combined with fractional and non‐fractional PSKL at 4‐week intervals. At 12 weeks after the last treatment, the patients showed a mean improvement of 1.6 and 0.9 (on a five‐point scale) in the facial pigmentation index and wrinkle index, and a mean improvement of 3.3 ± 1.83 (on an eleven‐point scale) in the facial photoaging score. In this study, the non‐fractional PSKL was used primarily to remove lentigines and hyperpigmentation [11]. In our study, fractional PSKL was used because melasma is different from spot lentigines or ordinary pigmentation, its area is usually larger, and it is easy to recur and aggravate, coupled with the high absorption coefficient of melanin to the 532 nm wavelength, so the use of non‐fractional PSKL may stimulate melasma and increase the risk of side effects. Although the fractional handpiece diffracts the laser beam into 101 evenly distributed laser microbeams, so that the PSKL will not be over‐absorbed by the epidermis.
It is worth stating that although the 532 nm wavelength, which is strongly selectively absorbed by epidermal melanin, was used in this study, the combination of dual wavelengths (1064 and 532 nm) and dual modalities (fractional and non‐fractional) theoretically led to an elevated probability of adverse reactions. However, in practice, no patient experienced serious adverse reactions such as PIH, hypopigmentation, blistering, and scarring, and only one patient in the Nd:YAG+KTP group, respectively, developed mild itching or persistent erythema symptoms after treatment. We hypothesize that there are several main reasons for this. First, the laser fluence used in this study was low. The laser treatment parameters used in the study by Leight‐Dunn et al. [11] were spot area 6 × 6 mm2 and fluence 1.9–2.3 mJ/microbeam (fractional PSNL), spot area 6 × 6 mm2 and fluence 0.4–0.8 mJ/microbeam (fractional PSKL), spot diameter 3 mm and fluence 0.4–1.2 J/cm2 (non‐fractional PSKL). The study used higher fluence than ours and showed prolonged swelling of the lower face in one subject and mild hyperpigmentation in one subject. Second, the use of epidermal growth factor (EGF) throughout may have reduced the incidence of adverse effects. It has been suggested that EGF may be used in the control of PIH by significantly inhibiting tyrosinase activity [25]. Lyons et al. [26] found a significant reduction in the incidence of PIH and melanin index on day thirty‐five of continuous use of an EGF‐containing cream for Q‐switched 532 nm post‐laser skin, which they believe may be related to the fact that EGF promotes tissue repair and thus reduces inflammation. In addition to this, we believe that factors such as the stringency of sun protection, the patient's skin type, and the patient's gender may have influenced the results of the study.
The limitations of our study include the retrospective cohort design, which inherently carries a risk of selection bias and limits the ability to establish causal relationships. In addition, the relatively small sample size, the inclusion of only Fitzpatrick skin type III, and the short follow‐up period further restrict the generalizability of the findings. Future prospective studies with larger, more diverse populations (in terms of skin types and gender) and longer follow‐up durations are warranted to validate and expand upon our results.
5. Conclusion
In conclusion, our results show that fractional and non‐fractional PSNL combined with PSKL can significantly improve melasma, with precise efficacy, low adverse reactions, and high patient satisfaction. Compared with the treatment of melasma with single‐wavelength fractional and non‐fractional PSNL, the efficacy is more significant, and the difference is statistically significant. At the same time, this is the first study to show that fractional and non‐fractional PSNL combined with fractional PSKL have good efficacy and safety in the treatment of melasma.
Conflicts of Interest
The authors declare no conflicts of interest.
Acknowledgments
This study was funded by the Wenzhou Key Laboratory of Laser Cosmetology (2022HZSY0042).
Funding: This study was funded by the Wenzhou Key Laboratory of Laser Cosmetology (2022HZSY0042).
Data Availability Statement
The data used to support the findings of this study are available from the corresponding author on reasonable request.
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Associated Data
This section collects any data citations, data availability statements, or supplementary materials included in this article.
Data Availability Statement
The data used to support the findings of this study are available from the corresponding author on reasonable request.