Picosecond Alexandrite Laser With Diffractive Lens Array Combined With Long‐Pulse Alexandrite Laser for the Treatment of Facial Photoaging in Chinese Women: A Retrospective Study

ABSTRACT

Background and objectives

Facial photoaging is a type of facial skin aging induced mainly by exogenous factors (ultraviolet radiation) and often manifests itself in the form of hyperpigmentation, telangiectasia, roughness, increase in fine lines/wrinkles, and enlarged pores. Recently, picosecond lasers have become an emerging option for the treatment of facial photoaging, and long‐pulse alexandrite lasers (LPAL) have demonstrated promising potential in the treatment of photoaging‐related symptoms. This study aimed to evaluate the efficacy and safety of picosecond alexandrite laser (PSAL) with diffractive lens array (DLA) combined with LPAL for facial photoaging.

Methods

This is a retrospective study of 20 Chinese female patients with facial photoaging who received PSAL with DLA combined with LPAL during a 1‐year period. All patients were treated every 4 weeks for a total of three treatments. Objective indicators of facial photoaging and patient satisfaction were evaluated before each treatment, and pain scores and adverse effects were recorded after each treatment.

Results

Compared with baseline, patients showed significant differences in all facial photoaging indices (p < 0.01). After receiving three treatments, there was a 20.1% decrease in the pigmentation index, a 23.9% decrease in the erythema index, a 34.5% decrease in the texture index, a 28.4% decrease in the fine lines index, a 56% decrease in the pore index, a 9.3% elevation and a 17.1% decrease in elasticity R2 and F4, respectively, and a 55% decrease in sebum content. The mean satisfaction score for the three treatments was 4.67 (3.33, 5.00), and the mean visual analogue scale (VAS) pain score was 7.00. No serious adverse effects such as post‐inflammatory hyperpigmentation (PIH), hypopigmentation, or blistering were observed at the treatment site during the treatment period.

Conclusion

PSAL with DLA combined with LPAL for the treatment of facial photoaging with significant efficacy, high patient satisfaction, and minimal adverse effects.

1. Introduction

Skin aging is a cosmetic skin disease caused by a combination of endogenous and exogenous factors. Endogenous factors are mainly cellular aging, genetic mutations, and declining hormone levels, while exogenous factors are mainly ultraviolet radiation [1]. Facial skin aging induced by exogenous factors, that is, facial photoaging, is mostly manifested clinically as hyperpigmentation, telangiectasia, roughness, increased fine lines/wrinkles, and enlarged pores [2]. The treatments for photoaging are diverse, such as topical retinoids, chemical peels, radiofrequency, and lasers. Adverse effects of the above treatments mainly include erythema, itching, edema, dryness, burning, and post‐inflammatory hyperpigmentation (PIH) [3, 4, 5, 6]. Therefore, it is the goal of cosmetic dermatologists to find facial rejuvenation therapies that have short downtime, low incidence of adverse effects, and high efficacy. As technology advances and researchers study facial photoaging, new laser therapies for facial rejuvenation are showing their advantages.

Picosecond lasers are novel lasers with pulse duration typically on the order of 10⁻¹² s, one‐thousandth of that of Q‐switched lasers, which, when applied to the target chromophore, produces a greater degree of photomechanical effect rather than photothermal effect. The FOCUS lens, a novel diffractive lens array (DLA), when used in conjunction with picosecond lasers, diffracts the resulting laser beam into high fluence laser micro‐beams encircled by a low fluence background and generates laser‐induced optical breakdown (LIOB) in the epidermis and dermis, which is thought to stimulate collagen and elastin production and substantially reduce the incidence of adverse reactions. Currently, picosecond alexandrite lasers (PSAL) with DLA are used in the treatment of scars, melasma, benign pigmented lesions, and photoaging [7, 8, 9].

Several studies have shown that PSAL with DLA have a high degree of efficacy and safety when used alone in the treatment of facial photoaging [10, 11], but there is a lack of research to confirm the potential synergistic benefits of combining them with other lasers. By virtue of its 755 nm wavelength and long pulse, the long‐pulse alexandrite laser (LPAL) can be absorbed by the hemoglobin and melanin of the skin and subcutaneous tissues, and at the same time it can safely and adequately heat the above target chromophores. It has already shown good therapeutic effects in vascular lesions, hair removal, and pigmented lesions, and good potential in the treatment of telangiectasia, lentigines, and other photoaging‐related symptoms [12]. Therefore, we designed this retrospective cohort study to evaluate the efficacy and safety of PSAL with DLA combined with LPAL for the treatment of facial photoaging in Chinese women.

2. Material and Methods

2.1. Study Design

This retrospective cohort study was conducted on Chinese female patients with facial photoaging who received PSAL with DLA combined with LPAL from September 2023 to September 2024. Every patient 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‐L062).

2.2. Subjects

Twenty Chinese female patients (Fitzpatrick skin types II–III) with facial photoaging and a mean age of 32.50 ± 4.19 years were included in this study.

2.2.1. Inclusion Criteria

(1) Facial photoaging manifestations and active request for improvement; and (2) age 25–50 years.

2.2.2. Exclusion Criteria

(1) Photosensitivity of facial skin; (2) recent history of sun exposure; and (3) administration of photosensitizing drugs or topical retinoids in the last 1 month.

2.3. Treatment Protocol

No surface anesthetics were used in all patients. In the first step, treatment was performed with an LPAL (Elite+, Cynosure, USA). Treatment parameters: wavelength 755 nm, spot size 12 mm, pulse duration 30 ms, fluence 15 J/cm², frequency 2 Hz, one scan of the entire face, about 300 pulses. Epidermal cooling is provided with a cold air device (Cryo 6, Zimmer, Germany) with 1–2 levels of wind power. In the second step, treatment was performed with a PSAL (Picosure, Cynosure, USA) in combination with a DLA (Focus, Cynosure, USA). Treatment parameters: wavelength 755 nm, spot size 6 mm, pulse duration 750 ps, fluence 0.71 J/cm², frequency 10 Hz, one scan of the entire face, about 1500 pulses. Mild‐to‐moderate erythema over the whole face was observed after the treatment, which was regarded as the endpoint of the treatment, and then the patients were instructed to apply cold compresses over the face with ice packs for 20 min. During the study period, the patients were asked to pay attention to moisturizing and to use a broad‐spectrum sunscreen with SPF 50, PA+++. Each treatment was separated by 4 weeks, for a total of three treatments, and the patients were followed up for 4 weeks at the end of the treatment program.

2.4. Evaluation of Objective Indicators of Facial Photoaging

Before each treatment and 4 weeks after the last treatment, patients were instructed to rest for 20 min in a relatively constant environment (temperature 20°C–26°C, humidity 40%−60%, avoiding direct sunlight) after cleansing their faces, and then a facial skin test was performed to evaluate the indicators of photoaging.

Skin image analyzer (Antera 3D, Miravex, Ireland) was used to evaluate the skin pigmentation index, texture index, erythema index, fine line index, and pore index of all patients. The evaluation areas of pigmentation index and texture index were forehead, cheeks, and periorbital region. The evaluation areas of the erythema index and pore index were forehead and cheeks. The evaluation areas of fine line index were lateral canthus. A circular detection area with a diameter of 35 mm on both sides was used for the forehead region, a square detection area with a side length of 40 mm was used for both cheeks, a circular periorbital stripe‐like detection area with a diameter of 12 mm was used for the periorbital region, and a circular detection area with a diameter of 25 mm was used for the lateral canthus. Keeping the image acquisition window perpendicular to the skin surface, close to the skin and avoiding pressure, observing the image displayed on the software, adjusting the exposure to 98%, and acquiring the image after it was clear, the average score of the above indexes was obtained. The higher the score, the higher the degree of photoaging.

Skin elasticity and sebum content were assessed in all patients using a skin tester (MPA580, Courage+Khazaka, Germany). The skin elasticity index was assessed using a cutometer probe, which was placed vertically on the median forehead, bilateral zygomatic prominence, and bilateral masseter eminence, respectively. Measurement mode: indentation 0.2 mm, repetitions 10, target pressure 450 mbar, on time 1 s, off time 1 s, multi‐point testing to derive average values. The values of R2 and F4 were used to assess skin elasticity, and R2 denotes the ratio of the amplitude of the suction to the ability to recover to the initial position. The higher the recovery ratio, the better the skin elasticity and the lower the degree of photoaging. F4 represents the area under the curve of 10 repeated measurements enveloped by the envelope function, which is shown as the logarithmic mean of the maximum and minimum amplitudes. The stronger the skin elasticity, the smaller the area (the greater the recovery). The sebumeter probe was used to assess the sebum content, with the same test points as before. The probe is placed vertically on the test point for 30 s and the average value is taken from multiple points. The higher the value, the higher the sebum production and the higher the degree of photoaging.

2.5. Patient Satisfaction and Pain Assessment

Satisfaction with the previous treatment was recorded for all patients before each treatment and 4 weeks after the final treatment. Satisfaction was evaluated using a 5‐point scale, with 5 points for very satisfied, 4 points for satisfied, 3 points for average, 2 points for dissatisfied, and 1 point for very dissatisfied. Satisfaction scores were averaged over the three treatments for all patients. The pain score was assessed using a numerical visual analog scale (VAS) with a score between 0 and 10, and the pain score was averaged over the three treatments for all patients.

2.6. Safety Assessment

Patients were observed and recorded for immediate post‐treatment skin reactions and the presence of PIH, hyperpigmentation, blistering, scarring, and other adverse effects.

2.7. Statistical Analysis

SPSS 26.0 software was used to analyze the data. Measurement information conforming to normal distribution was statistically described by mean ± standard deviation and a paired‐sample t‐test was used for comparison between the two groups. Non‐normally distributed measurement information was statistically described by quartiles, and Mann–Whitney U test was used for comparison between the two groups. A two‐sided p < 0.05 was considered a statistically significant difference.

3. Results

3.1. Demographic Data

A total of 20 (32.50 ± 4.19 years old) Chinese female patients with facial photoaging were enrolled, with a mean body mass index (BMI) of 20.77 ± 2.02 and Fitzpatrick skin type II–III (Table 1). All patients cooperated throughout the treatment and were followed up at the end of the treatment.

TABLE 1.

Patient demographics.

No. of subjects	20
Age (min, max)	32.50 ± 4.19 (28, 39)
BMI (min, max)	20.77 ± 2.02 (16.2, 24.5)
Fitzpatrick skin type (%)
II	4 (20)
III	16 (80)

Abbreviation: BMI, body mass index.

3.2. Objective Indicators of Facial Photoaging

Pigmentation, erythema, texture, fine lines, and pore index at baseline and 4 weeks after the final treatment obtained from the Antera 3D. Subjects showed a significant reduction (p < 0.001) in all of the above indices of facial photoaging at 4 weeks after the final treatment compared to pre‐treatment (Table 2). The pigmentation index decreased by 20.1%, the redness index by 23.9%, the texture index by 34.5% (Figure 1), the fine lines index by 28.4%, and the pore index by 56% (Figure 2).

TABLE 2.

Antera 3D photoaging indicators before and after treatment.

	Baseline	Four weeks after the final treatment	t/Z	p value
Pigmentation index	55.83 ± 8.63	44.63 ± 8.04	6.072	<0.001
Erythema index	49.01 ± 8.25	37.30 ± 5.72	9.278	<0.001
Texture index	28.09 (24.67, 30.83)	18.41 (14.67, 22.67)	4.181	<0.001
Fine lines index	20.25 (17.38, 23.63)	14.50 (10.63, 15.50)	4.602	<0.001
Pore index	0.50 ± 0.22	0.22 ± 0.12	9.856	<0.001

FIGURE 1.

Texture changes. A 36‐year‐old Chinese woman. (a–f) represents the skin texture of the patient's bilateral forehead, periorbital region, and cheeks before the first treatment, with a mean texture index of 24. (g–i) represents the patient's skin texture at 4 weeks after the last treatment, with a mean texture index of 14.83. The mean texture index decreased by 38.2% before and after the treatment.

FIGURE 2.

Pore changes. A 38‐year‐old Chinese woman. (a–d) represent the pore condition of the patient's bilateral forehead and cheeks before the first treatment, with an average pore index of 0.79. (e–h) represent the pore condition of the patient at 4 weeks after the last treatment, with an average pore index of 0.33. The average pore index before and after the treatment decreased by 58.2%.

Elasticity and sebum content data were obtained from the MPA580 skin tester at baseline and 4 weeks after the final treatment. At 4 weeks after the last treatment, the subjects showed a significant increase in the parameters of skin elasticity, R2 and F4 (p < 0.001), and a significant decrease in sebum content (p < 0.001), respectively, compared with the pre‐treatment period (Table 3). R2 was elevated by 9.3%, F4 decreased by 17.1%, and sebum content decreased by 55%.

TABLE 3.

MPA580 photoaging indicators before and after treatment.

	Baseline	Four weeks after the final treatment	t/Z	p value
Elasticity
R2 (%)	77.44 ± 4.77	84.62 ± 4.24	−8.771	<0.001
F4 (mm*s)	2.05 ± 0.31	1.70 ± 0.39	5.334	<0.001
Sebum content (µg/cm2)	29.74 ± 16.72	13.37 ± 8.21	5.818	<0.001

3.3. Patient Satisfaction and Pain Score

All subjects in this study had a mean satisfaction score of 4.67 (3.33, 5.00) and a mean VAS pain score of 7.00 (4.92, 8.00) for the three treatments.

3.4. Adverse Reactions

All subjects experienced mild to moderate facial erythema with mild edema immediately after treatment, which is considered a normal endpoint response to this laser therapy. This erythema with edema was transient, and the facial erythema with edema resolved spontaneously within 24 h in all the subjects in this study. The major adverse reactions seen in this study included pruritus and sensitization. Two of the subjects experienced itching on the face after each procedure, which resolved spontaneously after 3 days. Another subject experienced skin sensitivity for 2 weeks after the first treatment, and was instructed to intensify hydration and moisturization, and did not experience skin sensitivity after subsequent treatments. All subjects in this study had no serious adverse reactions such as PIH, hypopigmentation, scarring, or blistering throughout.

4. Discussion

The main cause of facial photoaging is prolonged exposure to ultraviolet radiation. Clinical features include dilated capillaries, hyperpigmentation, enlarged pores, irregular texture, increased fine lines/wrinkles, skin laxity, and sebaceous gland hyperplasia [2, 13]. Therefore, the treatment of facial photoaging should address all of these symptoms. Originally used primarily for tattoo removal, with the development and application of DLA, the indications for PSAL have included, but are not limited to, hyperpigmentation, atrophic scars, wrinkles, and enlarged pores, and have demonstrated the potential for additive or synergistic benefits when combined with other treatments [14]. LPAL were initially used mainly for hair removal, and when used for hair removal for cosmetic purposes, good efficacy, and safety can be achieved, while enlarged pores due to increased facial hair can often be treated with hair removal lasers. Not only that, LAPL can also treat the symptoms of photoaging such as capillary dilatation, freckles, lentigines, melasma, and so on [12, 15]. In this study, we applied a PSAL with DLA in combination with an LPAL for the treatment of facial photoaging in Chinese women.

The results of this study showed that 4 weeks after the final treatment, the patient's facial photoaging indicators such as facial pigmentation, erythema, texture, fine lines, pores, elasticity, and sebum content were significantly improved compared to the pre‐treatment period. The pore index and sebum content showed the most significant reduction rates of 56% and 55%, respectively, which we hypothesize is largely due to the combined use of the LPAL. Lee et al. [15] found that the main potential factors leading to increased facial pore size are increased hair follicle volume, decreased elasticity around pores, and excessive sebum. As one of the most used hair removal lasers in cosmetic dermatology, the LPAL can target melanin located in the bulb of the hair follicle and the hair shaft, heating it through the principle of selective photothermolysis and then destroying the hair follicle to achieve hair removal. The 755 nm wavelength and long pulse of the LPAL ensures the best hair follicle destruction effect and protects the surrounding tissues, reducing the occurrence of side effects [12]. In a study comparing LPAL with spot sizes of 5, 8, and 10 mm, and different fluence, the appropriate rejuvenation parameters were spot size 8 mm with fluence 36 J/cm² or spot size 10 mm with fluence 26 J/cm², with a temperature of about 60°C at 2.5 mm from the subcutaneous area. Histologically, it was observed that the laser promoted collagen formation as well as increased dermal fibroblast activity without severe damage. We suggest that the above histologic changes may lead to the restoration of elasticity around pores. The study also suggests that dermal temperature is more affected by changes in spot size than by changes in fluence. In contrast, surface temperatures were primarily affected by changes in fluence and less so by changes in spot size [16]. Compared to their study, our study used treatment parameters of spot size 12 mm and fluence 15 J/cm², which is a larger spot size and lower fluence, and may increase the dermal temperature and decrease the epidermal temperature to a certain extent to achieve a similar treatment effect. Another study states that when the pulse duration of LPAL is 30 ms, it can effectively destroy the sebaceous glands based on the principle of hair removal, resulting in a reduction in sebum output [17]. This is the same pulse duration used in our study. This suggests that the combined use of LPAL may provide targeted benefits for the treatment of enlarged pores and increased sebum production. The results of two studies using PSAL with DLA for the treatment of facial photoaging in Chinese women confirm our hypothesis. In one of these prospective studies, no significant improvement in pore size was observed at 1‐month follow‐up after six treatments on the face [18]. Another retrospective study found that the mean pore size reduction and pore index reduction rates in patients were 21.8% and 18.3%, respectively, at 3‐month follow‐up after three to four treatments [19]. Both studies had similar treatment parameters to ours, with more than twice the total number of pulses per treatment, but overall efficacy was worse than ours.

In addition to enlarged pores and increased sebum production, this treatment has also shown promising results for fine lines and textural roughness. Fine lines, roughness, and loss of elasticity are all related to thinning of the dermis, which is caused by the loss of collagen and elastin [20, 21]. The lens used in PSAL with DLA consists of hundreds of closely spaced hexagonal lenses that concentrate 70% of the total energy into 10% of the treatment area, producing a high fluence peak. The remaining 30% of the energy is distributed over the remaining 90% of the surface area, creating a low fluence background. This unique design allows the laser to create discrete areas of plasma and cavities, or LIOBs, as it penetrates the epidermis and papillary dermis, a process that can dramatically stimulate the collagen and elastin production response with minimal damage to the surrounding tissue structure [7]. Compared with the study of Choi et al. [17] who used LPAL alone for photoaging, the average fine line index of the patients in our study decreased by 28.4%, which is more significant than the decrease rate of 8.3% in that study. After four treatments with the LPAL in another study, the patients' elasticity index R2 improved by 10% and R7 by 14.88% [22]. In contrast, the patients in our study had a 9.3% elevation in R2 and a 17.1% decrease in F4 after three treatments, with the same level of efficacy but with fewer treatments. Of course, we cannot ignore the stimulating effect of LPAL on collagen and elastin production. In a prospective study of Chinese women with photoaging, at 1‐month follow‐up after six treatments with a PSAL with DLA, 11.1% of patients had a 3‐point improvement in skin texture score, with the rest of the patients having less than a 3‐point improvement (on a 10‐point VAS scale) [18]. This is also a significant difference from our average texture index decrease of 34.5%.

The main causes of hyperpigmentation and erythema, as manifested by facial photoaging, are increased melanin and dilated capillaries, respectively [2]. The 755 nm wavelength of the alexandrite laser is absorbed not only by melanin but also by hemoglobin. We believe that very short pulses (picoseconds) and long pulses of alexandrite lasers can each have their advantages in bursting melanin and sealing blood vessels, respectively, and ultimately achieve synergistic benefits. Alavi et al. [22] studied the effect of LPAL on skin parameters and found a 15.95% decrease in melanin content and a 9.91% decrease in erythema at 4 weeks of follow‐up after four treatments. Our study, on the other hand, showed a 20.1% decrease in pigmentation index and a 23.9% decrease in erythema. The more dramatic improvement in erythema with combination therapy may be because LIOB also destroys some of the neighboring blood vessels [7]. It is important to note that when using this type of wavelength laser treatment, the laser fluence should be set precisely to prevent aggravation of pigmentation, especially in Asian skin [23].

Pruritus and sensitization were the main adverse effects in this study, and we hypothesize that it may be related to the fact that the overall baseline sebum content of the included patients was not high, but the sebum output was substantially reduced by this therapy. Therefore, patients should be instructed to intensify hydration and moisturization, and gentle cleansing after the procedure when using this combination therapy for photoaging. In addition to this, patients with high pain scores may be considered for preoperative anesthesia with compound lidocaine cream in the future.

In addition to standard lasers, our team, in summarizing studies related to facial rejuvenation, has also noted that red light‐emitting diodes (LEDs) have satisfactory therapeutic effects on facial skin aging symptoms [24]. We will consider the combined use of LED masks (for life cosmetology) and laser therapy (for medical cosmetology) to further explore the next generation of anti‐aging solutions in subsequent studies.

The limitations of this study are mainly the small number of included cases, the short follow‐up period, and the lack of a control group setting. The number of cases should be further increased in future studies as well as long‐term follow‐up studies to observe long‐term efficacy and a control group should be added to more scientifically validate our findings.

5. Conclusion

In summary, our results show that PSAL with DLA combined with LPAL can significantly improve facial photoaging in Chinese women, with precise efficacy, low adverse effects, and high patient satisfaction. At the same time, this is the first study to show that PSAL with DLA combined with LPAL has good efficacy and safety in the treatment of facial photoaging.

Conflicts of Interest

The authors declare no conflicts of interest.

Data Availability Statement

The data used to support the findings of this study are available from the corresponding author upon reasonable request.