Comparison Study of Intense Pulsed Light Versus a Long-Pulse Pulsed Dye Laser in the Treatment of Facial Skin Rejuvenation

Kono, Taro MD*; Groff, William Frederick DO†; Sakurai, Hiroyuki MD*; Takeuchi, Masaki MD*; Yamaki, Takashi MD*; Soejima, Kazutaka MD*; Nozaki, Motohiro MD*

From the *Department of Plastic and Reconstructive Surgery, Tokyo Women's Medical University, Tokyo, Japan; and the †Division of Cosmetic Dermatology, La Jolla Cosmetic Surgery Centre, La Jolla, CA.
Received November 29, 2006 and accepted for publication, after revision, December 22, 2006.
Reprints: Taro Kono, MD, Department of Plastic and Reconstructive Surgery, Tokyo Women's Medical University, 8-1 Kawada-cho, Shinjuku-ku, Tokyo 162-8666, Japan.

Abstract:

Currently, various nonablative skin resurfacing techniques are being used to rejuvenate facial skin, including lasers and intense pulsed light (IPL). There are few direct comparison studies between IPLs and lasers. The objective of our study is to compare the effectiveness of intense pulsed light versus a long-pulse pulsed dye laser (LPDL) in the treatment of facial skin rejuvenation. Ten Asian patients with Fitzpatrick skin types III–IV were enrolled in this study. One half of the face was treated with IPL (6 treatment sessions) and the other side was treated by LPDL (3 treatment sessions). An LPDL with a wavelength of 595 nm and spot size of 7 mm was used. Utilizing the compression method, lentigines were treated using a PDL with a fluence between 9–12 J/cm2 and a pulse duration of 1.5 ms. Wrinkles were treated with fluences between 10 to 12 J/cm2 and a pulse duration of 20 ms, using a pulse-stacking technique. An IPL with a type B handpiece was used. Lentigines and wrinkles were treated with fluences between 27 to 40 J/cm2 and a pulse duration of 20 ms. The improvement of lentigines was 62.3% and 81.1% for IPL and LPDL respectively. There was no significant difference between IPL and LPDL in wrinkle reduction. There was no scarring or pigmentary change seen with either device. Both IPL and LPDL are effective for facial skin rejuvenation in Asians, but LPDL treatment is significantly better than IPL treatment in the treatment of lentigines. The use of the compression technique may allow this LPDL to be used effectively for facial rejuvenation and with fewer treatment sessions, when compared with the IPL.

blative laser resurfacing is considered to be the most effective option for skin rejuvenation. However, this technique is associated with several potential adverse effects. These include prolonged transient erythema, pigmentary changes, infection, and scarring, especially in Asians.1 Nonablative skin resurfacing has become quite popular due to its effectiveness and low incidence of side effects. As a result, many IPL systems have been introduced for photorejuvenation. Although nonablative techniques are associated with limited downtime, 5 to 8 treatments sessions are typically required and the degree of improvement appears to be limited.2,3

PDL and LPDL have been used to treat facial wrinkles.4–8 PDL and LPDL are well absorbed by oxyhemoglobin, but also by melanin. It is well known that compression removes blood from skin by collapsing blood vessel walls. In previous research, we attached a glass contact window to the tip of the treatment handpiece of the LPDL to displace blood and avoid vascular injuries. We reported that using the compression handpiece with the LPDL is safer and more effective than the Q-switched ruby laser in the treatment of lentigines.9 These studies provide further evidence that the LPDL could be the treatment of choice for skin rejuvenation, especially with the benefits of minimal downtime and fewer treatment sessions required.

Both IPLs and lasers are used for skin rejuvenation. There are few direct comparison studies between IPLs and lasers.10–12 In this study, we compared the clinical efficacy and complication rate of the LPDL versus the IPL when treating 10 Asians patients with photodamage. One side of the face was treated with LPDL and the other side with IPL.
MATERIALS AND METHODS

Ten Asian women with photodamage were recruited. The subjects ranged from 38 to 79 years of age (average = 47.9). Five patients were Fitzpatrick skin type III while the other 5 were type IV. The ethics committee of the Tokyo Women's Medical University approved the study and all patients signed informed consent paperwork before entering the trial. After obtaining a thorough medical and surgical history on each patient, the nonablative treatments were performed.
Nonablative Treatment

A single operator (T.K.) treated all subjects. In 5 patients, left sides were treated by IPL and right sides were treated by LPDL. In the other 5 patients, left sides were treated by LPDL and right sides were treated by IPL. A LPDL (model V-beam, Candela Corporation, Wayland, MA) with a wavelength of 595 nm and a spot size of 7 mm was used. A 9-mm-diameter glass contact window was attached to the tip of the handpiece when treating lentigines. LPDL treatment fluences were 9 to 12 J/cm2 with a pulse duration of 1.5 ms. Cryogen spray cooling was not used. The clinical end point for the PDL when treating lentigines was defined as an ash-gray color change without purpura. Wrinkles were treated with fluences between 10 to 12 J/cm2 and a pulse duration of 20 ms (with skin cooling) using a pulse stacking technique (50% overlapping). Treatment intervals were 4 weeks, and a total of 3 treatment sessions were performed. Fluences were determined to be just below the threshold for epidermal damage. An IPL (model Smooth pulsed light; Palomar Corporation, Burlington, MA) with a type B handpiece (the wavelength range is between 470 nm and 1400 nm) was used. Lentigines and wrinkles were treated with fluences between 27 to 40 J/cm2 and with a pulse duration of 20 ms. IPL treatments were performed at 4-week intervals, with 6 total treatment sessions. Fluences were determined to be just below the threshold for epidermal damage (Table 1). Postoperatively, antibiotic ointment was applied to the treatment area. Subjects were advised to avoid sun exposure and scrubbing or abrasion after laser treatment. Bleaching agents such as hydroquinone were not used.

Assessment of Response

Subjects were monitored for 3 months after the last IPL and PDL treatment. The degree of lightening of the lesions was assessed by a red-green skin reflectance spectrometer (Dermaspectrometer; Cortex Technology, Hagland, Denmark).9 Melanin index (MI) measurements were taken from the lentigines before treatment (MIPre), 4 weeks after laser irradiation (MIPost), and also from the adjacent normal skin (MINormal). The degree of lightening of the lentigines was calculated as follows:

Percentage of lightening (%) = (MIPre - MIPost)/(MIPre - MINormal)

A research assistant took clinical photographs (Canon D30 with a ring flashlamp) in a standardized manner before laser treatment and at each follow-up. Two independent blinded observers reviewed the clinical photographs at 3 months after the last IPL treatment and assessed for degree of improvement in lentigines and wrinkling, as well as complications, such as scarring, hypopigmentation, and hyperpigmentation. The degree of improvement was graded as follows: 1, poor (minimal change with lightening or reduction of 0%–25%), 2, mild (slight improvement with lightening or reduction of 26%–50%), 3, moderate (though quite improved, can be differentiated from the surrounding healthy skin with lightening or reduction of 51%–75%), 4, significant (difficult to differentiate from the surrounding healthy skin with lightening or reduction of 76%–100%). The examination took place with the aid of an operating-theater light. Scarring was defined as hypertrophic, raised, or atrophic in the laser-treated area. Pigmentary changes were defined as hyper- or hypopigmentation as compared with the adjacent area of normal skin.
RESULTS

The improvement of lentigines was 62.3% and 81.1% for IPL and LPDL (Figs. 1–3) respectively. Using Student t tests, there was significant statistical difference (P < 0.05). There was no significant difference between IPL and LPDL in wrinkle reduction. The observers’ scores for the degree of improvement in wrinkles and lentigines are listed in Table 2. There was no scarring or hypo- and hyperpigmentation.

DISCUSSION

Nonablative skin resurfacing is established as a possible treatment modality for photorejuvenation, and many IPLs have been introduced for this indication.13–19 Recent studies that investigated the use of IPL to remove lentigines in Asians confirmed their effectiveness with a low risk of postinflammatory hyperpigmentation.2,3,19 Although IPL technology is associated with minimal down time, 5 to 8 treatments sessions are needed and the degree of improvement appears to be limited.

LPDL lasers emit yellow light, which selectively targets hemoglobin and melanin. This wavelength allows for 50% light penetration to a depth of approximately 0.4 mm in the dermis. Zelickson and Kist 5 reported the presence of increased extracellular matrix protein after periorbital treatment with a PDL. Restan et al 6 performed split-face studies on photoaging, treating half of the face with a series of LPDL treatments, while the other half was treated with cryogen coolant only. Eleven of 15 patients demonstrated improvement of the laser-treated side, while only 3 of 15 patients demonstrated improvement on the cryogen-treated side. Histologic evaluation demonstrated an increase in activated fibroblasts with positive procollagen staining on the LPDL-treated side. Tanghetti et al 8 reported multipass treatment of photodamage using PDL and reported that pigment improvement was minimal to moderate. Treatment fluences were maintained below purpuric threshold, ranging from 3 to 4 J/cm2 at a pulse duration of 0.5 ms using a 10-mm handpiece.

In this study, the pulse duration of the IPL we used was 20 ms and skin cooling was applied. In general, the optimal pulse duration for selective photothermolysis is approximately equal to or shorter than the thermal relaxation time of the intended target structure.20 In common lentigines, abnormal pigmentation exists throughout the basal cell layer of the epidermis. The pulse duration should be about equal to or shorter than the thermal relaxation time of the epidermis basal layer, which is estimated to be in the range of 1.6–2.8 ms for a basal layer thickness of 20 µm.21,22 In this study, the pulse duration of the PDL that we used to treat lentigines was 1.5 ms. This is shorter than the predicted epidermal basal layer thermal relaxation time. This is consistent with our finding of a satisfactory clinical effect with a low risk of adverse effects.

In addition, we used pressure that was applied by a glass window on the PDL handpiece. This compression displaces cutaneous blood during laser treatment. Removal of blood eliminates absorption by hemoglobin, making it possible to use the PDL for treating lentigines. The use of compression handpiece can prevent vascular injuries. Vascular injuries have a potential risk of hyperpigmentation, especially in Asians. These treatments are purpura-free and we are able to use considerably higher fluences when compared with treatment without compression. In the study by Tanghetti et al,8 fluences were maintained just below the individual's purpuric threshold for the respective wavelength and ranged from 3 to 4 J/cm2. Our clinical end point for the PDL was defined as an ash-gray color change without purpura, and the fluence ranged from 9–12 J/cm2 when treating lentigines. Fluences that we used were relatively higher than previously reported, and purpura was not observed, because of the compression technique.

In an attempt to enhance efficacy when treating vascular lesions, a pulse stacking technique has been employed.23–26 Stacking pulses of lower fluence have the advantage of heating vessels to a critical temperature. In 2004, Rohrer et al 23 used an LPDL to demonstrate that stacking pulses of subpurpuric fluences at a pulse duration of 10 ms can increase telangiectatic vessel clearance on the cheek and nasal ala, when compared with LPDL treatment utilizing single pulses of the same fluence. They also reported that pulse stacking was more likely to cause edema, but otherwise did not significantly increase the risk of side effects. Pulse stacking technique may also play a role in wrinkle reduction. It is important to point out the difference in the number of passes performed in this study with each device. We used the pulse stacking technique when treating wrinkles in this study. When treating with IPL, only 1 pass was performed.

A major reason for the popularity of IPL is its versatility and its low cost. LPDL has been accepted as the vascular laser of choice. Its applications have been expanded in the last decade to include the treatment of wrinkles, lentigines, warts, hypertrophic scars, acne, and leg veins.4–9,27–31 IPLs have become more efficient and easier to use, while applications of lasers have expanded. Both IPLs and lasers will play an important role in skin rejuvenation, and this will continue into the foreseeable future.

In conclusion, both IPL and LPDL are effective for facial skin rejuvenation in Asians. LPDL treatment is significantly better than IPL treatment in the treatment of lentigines. We also found that when using the LPDL with the compression technique for skin rejuvenation, fewer treatments were necessary than with the IPL.

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Key Words: laser surgery; intense pulsed light; pulsed dye laser; skin rejuvenation