Nonablative skin resurfacing for skin rejuvenation

INTRODUCTION — Over time, chronic sun exposure and chronologic aging contribute to changes in the skin, such as dyschromia, rhytides (wrinkles), telangiectasias, textural alterations, and skin laxity (table 1). Although ablative laser resurfacing and surgical procedures are effective for improving features of cutaneous aging, concerns regarding potential adverse effects and required recovery times have spurred on the development of alternative procedures with minimal to no downtime.

Nonablative lasers and light sources are therapeutic options for skin rejuvenation that demonstrate low risks for serious adverse effects and nonexistent or abbreviated recovery periods. Certain nonablative procedures are highly effective for the treatment of the dyschromia (eg, intense pulsed light [IPL] and fractional lasers) and vascular changes (eg, vascular lasers and IPL) seen in photoaged skin.

Significant improvements in rhytides and skin laxity require the induction of dermal remodeling, increasingly achievable with nonablative technology. Infrared lasers, radiofrequency devices, and fractional lasers are typically used for these indications. Picosecond lasers are a relatively newer technology introduced for nonablative skin rejuvenation. Since the degree of improvement achieved with nonablative technology is often modest, patients with mild to moderate rhytides or skin laxity are better candidates for nonablative procedures than individuals with more severe manifestations of these features.

The modalities of nonablative skin resurfacing utilized for skin rejuvenation, including vascular lasers, IPL, infrared lasers and light sources, radiofrequency, photodynamic therapy, and nonablative fractional lasers, will be reviewed here. The basic principles of laser and light therapy for cutaneous lesions and ablative laser skin resurfacing are discussed separately. (See "Principles of laser and intense pulsed light for cutaneous lesions" and "Ablative laser resurfacing for skin rejuvenation".)

BACKGROUND — Restoration of healthy skin is dependent upon the ability to remove or improve features characteristic of photodamage (cutaneous damage induced by ultraviolet light) and chronologic aging, such as irregular skin pigmentation, telangiectasias, and cutaneous erythema. Chronic exposure to ultraviolet light also promotes damage to the dermis, which manifests clinically as rhytides and skin laxity and histologically as disorganized collagen fibrils and abnormal elastotic material [1]. Because collagen and elastin are the major structural components of the skin, treatments that successfully restore these dermal constituents are beneficial for the reversal of these features. (See "Photoaging".)

Nonablative skin resurfacing techniques arose from the desire to achieve clinically significant cosmetic improvements in aging skin with procedures that had lower risks and shorter recovery times than ablative laser or surgical treatments [2]. Ablative resurfacing with continuous wave carbon dioxide (CO₂) lasers, which was introduced in the 1980s, was associated with a high rate of side effects including scarring [2]. (See "Ablative laser resurfacing for skin rejuvenation", section on 'Overview'.)

Although subsequent advances in ablative laser technology led to the availability of short-pulse, high peak-power CO₂ lasers; rapidly scanned, focused-beam CO₂ lasers; and normal-mode erbium:yttrium aluminum garnet (Er:YAG) lasers, all of which were less prone to severe adverse effects than continuous wave CO₂ lasers, recovery periods remained relatively long (several days to three weeks) and a small but significant complication risk persisted.

Most nonablative skin resurfacing modalities (eg, vascular lasers, intense pulsed light [IPL], infrared lasers and light sources, and radiofrequency and ultrasound devices) function through the utilization of light or energy to selectively heat and alter components of the dermis without inducing significant epidermal damage or tissue ablation. This results in the ability to improve signs of cutaneous aging with minimal collateral damage, which in turn manifests as rapid recovery times, relatively insignificant post-treatment erythema, and a low risk for complications.

However, these favorable characteristics of nonablative modalities have been tempered by the generally lower degree of improvement in rhytides attained after nonablative treatments when treatment outcomes are compared with the results achieved with ablative laser resurfacing. In addition, multiple treatment sessions were often required to achieve results that are less significant than those achieved with a single session with an ablative laser. Continued advancements in nonablative protocols have progressively increased efficacy with decreased treatment sessions. (See "Ablative laser resurfacing for skin rejuvenation".)

Fractional resurfacing, which was developed in the early 21^st century, is a unique form of laser therapy that represents a midpoint between traditional nonablative skin resurfacing and ablative skin resurfacing with respect to clinical efficacy and side effects. Fractional lasers deliver microscopic columns of light to the epidermis and dermis in regularly spaced arrays, thereby treating only a select fraction of the skin (figure 1). Rapid healing occurs after treatment due to the retention of reservoirs of viable tissue within treated areas. Fractional nonablative lasers are more effective than vascular lasers and IPL for rhytides [2]. In addition, post-treatment recovery periods are shorter than those that follow treatment with traditional ablative or fractional ablative lasers. (See "Principles of laser and intense pulsed light for cutaneous lesions", section on 'Fractionated lasers' and "Ablative laser resurfacing for skin rejuvenation", section on 'Traditional ablative lasers' and "Ablative laser resurfacing for skin rejuvenation", section on 'Ablative fractional lasers'.)

NONABLATIVE SYSTEMS

Overview — A wide variety of nonablative lasers, light sources, and other devices have been utilized to rejuvenate skin. The classes of technologies employed for this purpose include the following:

●Vascular lasers

●Infrared lasers and infrared broadband light sources

●Intense pulsed light (IPL)

●Radiofrequency devices

●Ultrasound devices

●Photodynamic therapy

●Nonablative fractional lasers

The value of nonablative modalities to treat features of cutaneous aging varies. Light from vascular lasers, although highly absorbed by hemoglobin and useful for reducing telangiectasias and erythema, has relatively shallow penetration into the dermis and demonstrates limited ability to induce the dermal collagen remodeling necessary to improve rhytides or skin laxity (figure 2B). IPL devices, noncoherent light sources that emit wavelengths of light that are strongly absorbed by melanin and hemoglobin, are highly effective for treating dyschromia and vascular changes in aging skin, but may be less valuable for inducing clinically significant effects on collagen in the dermis. (See "Laser and light therapy for cutaneous vascular lesions", section on 'Yellow and green light lasers' and "Principles of laser and intense pulsed light for cutaneous lesions", section on 'Intense pulsed light'.)

Certain lasers and light sources that emit light in the infrared range are much better suited for rhytides since the longer wavelengths penetrate more deeply into the dermis [3,4]. Energy emitted from radiofrequency devices can also be utilized to target the dermis, resulting in improvements in rhytides and skin laxity. (See 'Preoperative counseling and treatment selection' below.)

The light sources utilized for nonablative skin resurfacing are reviewed in greater detail below.

Vascular lasers — Vascular lasers emit wavelengths of light that are highly absorbed by their target chromophore, hemoglobin (figure 2A). These lasers, including the 585 nm and 595 nm pulsed dye lasers (PDLs) and the 532 nm potassium titanyl phosphate (KTP) laser, are efficacious for the treatment of the telangiectasias and erythema [5,6]. Long-pulsed PDLs used with a compression handpiece have also been effective for the treatment of lentigines [7-10]. (See "Laser and light therapy for cutaneous vascular lesions", section on 'Yellow and green light lasers'.)

After clinical and histologic benefits in collagen remodeling were observed after PDL treatment of erythematous hypertrophic scars, striae distensae, and acne scars, studies were employed to determine the efficacy of these lasers for rhytides [2]. Although small, uncontrolled studies demonstrated clinical and histopathologic improvements in facial rhytides following treatments with 585 nm PDLs [11-13] and long-pulsed 595 nm PDLs [14], the efficacy of PDL for this indication is limited and modest in comparison to other treatments. Thus, vascular lasers are typically not used for the treatment of rhytides.

Intense pulsed light — The broad range of wavelengths emitted from IPL devices (500 to 1200 nm) account for the ability of these devices to effectively target both melanin and hemoglobin in the skin (figure 2A) [15]. This correlates with the utility of IPL for improving the dyspigmentation and vascularity that often characterize photoaged skin (picture 1) [16,17]. (See "Laser and light therapy for cutaneous hyperpigmentation", section on 'Intense pulsed light' and "Laser and light therapy for cutaneous vascular lesions", section on 'Intense pulsed light'.)

Although histologic evaluation has demonstrated IPL-induced dermal remodeling that is characterized by increases in extracellular matrix proteins and neocollagenesis [18], studies conflict on the clinical efficacy of this modality for rhytides. Small, split-face randomized trials comparing treatment with IPL alone to IPL in combination with other rejuvenating procedures have documented variable amounts of improvement in fine rhytides after IPL monotherapy [19,20]. In addition, partial improvement after IPL has been detected in several uncontrolled studies [21-23].

However, other randomized trials have not found IPL to be effective for rhytides [5,16]. As an example, in a randomized split-face trial in which 32 women with mild to moderate rhytides received three once-monthly treatments with filtered IPL (530 to 750 nm, 7.5 to 8.5 J/cm², 2.5 ms pulses, 10 ms interpulse delay) to one side of the face and no treatment to the other side, greater improvements in telangiectasias, pigmentation, and skin texture were detected in sites treated with IPL, but there was not a significant difference in the effect on rhytides [16]. Variability in the treatment methods across studies (eg, fluence, pulse durations, and filtered wavelengths) may account for the inconsistent findings on the efficacy of IPL for this indication. Of note, the trials above that found that IPL was not effective for rhytides filtered out the longer, more deeply penetrating wavelengths of IPL (750 to 1200 nm), a factor that is likely to have compromised treatment efficacy [5,16].

The use of a topical photosensitizer in conjunction with IPL (photodynamic therapy) may enhance the level of improvement in features of photoaging attained with IPL devices [19,24]. (See 'Photodynamic therapy' below.)

Infrared lasers and light devices — Although the depth of penetration of visible light into the skin rises with increasing laser wavelength (figure 2B), this principle does not consistently apply to light in the infrared range (figure 3). Strong absorption of infrared light by water can significantly limit the depth of penetration, as occurs with the ablative 2940 nm Er:YAG and 10,600 nm CO₂ lasers (figure 2A-B). (See "Ablative laser resurfacing for skin rejuvenation", section on 'Mechanism of action'.)

In contrast, infrared devices with wavelengths between 1000 and 1800 nm penetrate deeply and exert nonablative effects in the reticular dermis. These devices exert these effects by eliminating shorter wavelengths that absorb strongly in melanosomes and hemoglobin, yet including infrared wavelengths that are less strongly absorbed by sebaceous glands than by water and collagen (figure 2A). As light emitted from these devices is absorbed by water and collagen fibrils in the dermis, the dermis is heated, leading to collagen contraction, new collagen formation, and improvements in rhytides and skin laxity. Since infrared wavelengths are poorly absorbed by hemoglobin and melanin, these devices are not useful for the treatment of pigmentary or vascular changes (figure 2A). Technology to cool the skin surface, such as a cryogen spray, is essential to prevent heat-related damage to the epidermis during treatment with infrared devices.

The first infrared device utilized for nonablative skin resurfacing was a 1320 nm neodymium:yttrium aluminum garnet (Nd:YAG) laser [3,4]. This was followed by the development of a 1450 nm diode laser and a 1540 nm erbium:glass laser. In a randomized split-face trial in which nine patients were given three treatments with a 1450 nm diode laser and cryogen spray on one side of the face (23.3 to 28.6 J/cm²) and the cryogen spray alone on the contralateral side, periorbital or perioral wrinkle scores were significantly reduced from baseline on the laser-treated side, but not on the control side [25]. Moreover, in another split-face randomized trial and several uncontrolled studies, treatment with nonablative infrared lasers has yielded mild to moderate clinical improvements in rhytides and findings of increased dermal thickness and neocollagenesis on histopathologic examination [3,4,25-28].

In addition to the infrared lasers, an infrared broadband device that emits wavelengths spanning 1100 to 1800 nm has demonstrated efficacy for skin tightening (picture 2) [29-31]. In an uncontrolled study of 25 patients with laxity of the brow, cheek, neck, and/or lower face, one to three treatments (20 to 30 J/cm²) resulted in eyebrow lifting in 18 of 24 patients, and improvement of cheek or neck flaccidity in 18 of 22 patients. Changes consistent with skin contraction were noted immediately after treatment in most patients. Other studies of this device have also documented beneficial effects on skin laxity [32,33].

Unlike treatment with nonablative infrared lasers, which is typically painful and requires topical anesthesia, treatment with the infrared broadband device is associated with minimal discomfort [34]. Altering the method of delivery of broadband infrared light may reduce patient discomfort even further and may allow for more aggressive treatment. In a small, uncontrolled study, a treatment protocol in which the handpiece of an 1100 to 1800 nm broadband infrared device was kept in continuous motion allowed for painless treatment and facilitated the use of higher fluences and more passes. Treatment was also effective; all 22 women had improvement in skin laxity (mean percent improvement in laxity score of 14±11 percent) [35]. Further study is necessary to determine the efficacy of the mobile protocol in comparison to other treatment methods.

Picosecond lasers — Picosecond infrared lasers are a newer form of laser technology that may be useful for skin rejuvenation [36-40]. These lasers emit wavelengths at ultra-short pulse durations in the picosecond range and are employed for pigment reduction and for rejuvenation, with improvement in skin texture.

Picosecond lasers for skin rejuvenation are available in a variety of wavelengths, including lasers that emit wavelengths of 755 nm; 532, 680, and 1064 nm; and 532, 785, and 1064 nm. Diffraction lens beam splitters have been added to create a fractionated delivery of picosecond lasers, which may reduce risk for complications.

Radiofrequency — Nonablative radiofrequency devices target the dermis and are effective for the treatment of rhytides and skin laxity [41]. These devices generate electrical current or unipolar incoherent electromagnetic radiation that is utilized to heat the dermis. The depth of heating varies with the type of delivery. Treatment results in collagen contraction that manifests as immediate skin tightening as well as the induction of subsequent collagen remodeling.

Radiofrequency can be administered via monopolar, bipolar, tripolar, and unipolar devices. Similar to nonablative infrared light sources, interventions to cool the skin surface and prevent heat-related damage to the epidermis (eg, cooling module, capacitive coupling gel) are utilized with these devices.

Radiofrequency microneedling involves the administration of radiofrequency via needle electrodes, which are inserted into the skin at targeted depths. This mode of delivery has increased efficacy and decreased the number of treatments required to treat rhytids, acne scars, and laxity [42].

Monopolar — Monopolar radiofrequency devices transmit current through the skin; tissue resistance to the current flow results in a uniform volumetric heating effect in the dermis. A grounding pad is required.

While early reports of monopolar radiofrequency for skin tightening demonstrated inconsistent results [43], subsequent technologic advances (eg, increase in tip size) and technique modifications (eg, increase in the number of passes with lower energy settings) have augmented the consistency and extent of improvement and have made treatment discomfort tolerable [44-46]. The ultrastructural changes in collagen fibers detected in skin treated with five lower energy passes were similar to those observed after a single, more painful pass [45].

The clinical efficacy of multiple low energy passes with a monopolar radiofrequency device was evident in an uncontrolled prospective study in which 66 patients with moderate facial laxity were treated with up to five passes on the lower face and neck [46]. Six months after treatment, improvement in facial skin laxity was detected in 92 percent of patients. Among the study participants, 28 percent achieved 50 to 75 percent (very good) improvement, 33 percent achieved 26 to 50 percent (good) improvement, 31 percent achieved less than 25 percent (minimal) improvement, and 8 percent had no improvement. Although high rates of improvement were reported in preceding studies that utilized higher energies and fewer passes [47,48], the degree of clinical improvement that occurred was less extensive than seen in the protocol with multiple low energy passes [46].

Monopolar radiofrequency technology has greatly advanced, offering multiple frequencies and handpiece sizes to treat large surface areas. The clinical efficacy has improved, and applications to the body have yielded improvements in the appearance of cellulite and skin laxity [49].

Bipolar — Bipolar radiofrequency devices transmit current between two electrodes on the handpiece tip. Bipolar systems allow for better control of energy distribution but may penetrate the skin less deeply [50,51].

Combination devices that consist of bipolar radiofrequency plus diode lasers [52-54], IPL [55,56], or broadband infrared light provide a synergistic effect in which the light energy emitted from the optical device selectively heats the target tissue, thereby lowering its resistance to radiofrequency (also referred to as electro-optical synergy technology or selective radiophotothermolysis) [53,56]. Because less optical and radiofrequency energy is required to achieve the desired results, the risk for side effects associated with optical modalities (eg, dyspigmentation and scarring) and radiofrequency devices (eg, pain, blistering, burns) may be lower [52,53,57]. Uncontrolled studies have demonstrated efficacy of these combination devices for rhytides and abnormalities in skin texture [52,53,55,58,59]. For bipolar radiofrequency combined with IPL, improvements in skin erythema, telangiectasia, and hyperpigmentation have also been detected [55].

In line with the positive effects on photoaging demonstrated with dual devices, treatment regimens that include three or more nonablative modalities have been administered in attempts to concurrently improve multiple aspects of photoaging. As an example, one to five treatments with both a radiofrequency/diode laser device and a radiofrequency/IPL device effectively improved multiple signs of aging, including rhytides, skin laxity, and other features of photodamage in an uncontrolled study of 28 patients [60]. In a separate small, split-face randomized trial, four treatment sessions with radiofrequency, IPL, infrared light, and a diode laser also led to improvement in multiple features of aging [61].

Tripolar — Tripolar delivery of radiofrequency allows for more efficient tissue heating with little to no discomfort via mobile delivery [62]. The current flows between three electrodes in the handpiece tip. The advantage of this modality is faster heating to target temperatures. Typical target skin surface temperatures of >40°C may be attained within one to two minutes with this approach, decreasing treatment times and potentially improving clinical outcomes. More research is required to assess this modality.

Unipolar — Unipolar delivery of radiofrequency energy as electromagnetic radiation is estimated to penetrate more deeply into targeted tissue than other methods of radiofrequency delivery (up to 20 mm for unipolar versus 2 to 8 mm for bipolar) [63]. However, the relevance of this feature on clinical outcome is uncertain.

The efficacy of unipolar radiofrequency electromagnetic radiation was compared with bipolar radiofrequency current in a randomized split-face trial of 10 patients [63].

Fractional — Fractional bipolar radiofrequency devices have been developed for skin rejuvenation. Similar to fractional lasers, these devices deliver energy in a matrix array that results in heating of a select portion of the epidermis and dermis. Fractional bipolar radiofrequency devices have demonstrated efficacy for the treatment of rhytides [64-66]. However, this particular technology induces ablation, coagulation, and/or necrosis of the epidermis and is not considered a nonablative modality. The term "sublative rejuvenation" has been used to refer to this mode of treatment [65].

Microneedle radiofrequency — Microneedle-delivered radiofrequency devices have progressed significantly; they allow for the delivery of energy directly into the dermis using fine needle electrodes [67-69]. In situ temperature and impedance measurements combined with software to titrate energy delivery until a selected target temperature is attained has improved clinical safety and efficacy with this form of energy delivery. This form of energy delivery has been shown to decrease rhytides and skin laxity [67-69]. Although the epidermis is bypassed via needle delivery, the procedure is associated with side effects such as edema and ecchymosis and is, therefore, not considered a fully nonablative modality. Single treatment protocols have allowed for clinically significant outcomes in rhytids, acne scars, and laxity with minimal to no downtime and a single treatment session [68,69].

Ultrasound — High-intensity focused ultrasound has been applied to treatment of rhytides and skin laxity [70,71]. The primary mechanism is heating and tissue necrosis at the site of absorption of the acoustic energy at millisecond pulses and frequency in the megahertz domain. Although the initial indication was for brow lifting, it has since been used for facial rejuvenation, lifting, tightening, and body contouring [70,71].

Photodynamic therapy — Photodynamic therapy (PDT), which consists of the application of a topical photosensitizer (eg, 5-aminolevulinic acid [5-ALA]) followed by irradiation from a light source is effective for skin rejuvenation [72].

A variety of light sources have been utilized in PDT skin rejuvenation. Regimens with 5-ALA and IPL have been the most extensively studied, and this particular combination of treatment has been referred to as "photodynamic photorejuvenation" [24]. A randomized, split-face trial that compared five sessions of IPL alone (515 to 1200 nm, 23 to 28 J/cm², pulse duration 2.4 to 4 ms) to three sessions of PDT with 5-ALA and IPL followed by two sessions of IPL alone found greater improvements in erythema, dyspigmentation, and fine rhytides on the sides of the face treated with PDT [19].

Other light sources that have demonstrated efficacy in PDT for photodamaged skin include long-pulsed PDL [73] and blue light [74]. Red light PDT is associated with increased risk for vesiculation, crusting, and dyspigmentation, and is not considered to be nonablative therapy [75].

Fractional lasers — The fractional nonablative lasers utilized for skin rejuvenation are infrared lasers. Three major features differentiate these lasers from traditional infrared devices. First, fractional nonablative resurfacing treats a fraction of the skin surface by thermally altering microscopic columns of skin, which are known as "microthermal zones" (figure 1). The intervening areas of untreated skin serve to repopulate the columns of thermally injured tissue. Second, in contrast to standard nonablative treatments, for which thermal injury is confined to the dermis, in nonablative fractional resurfacing, the microscopic columns of thermal injury span the epidermis and superficial dermis. However, depending on the level of energy utilized, the stratum corneum can remain relatively spared, leaving epidermal barrier function intact [76]. This feature allows for the categorization of certain fractional laser treatments as nonablative therapy. Lastly, fractional nonablative resurfacing requires a recovery period [77]. Mild erythema and edema that persist for two to three days after treatment are the norm.

In general, fractional nonablative lasers achieve mild to moderate improvements in dyspigmentation and rhytides [77-80]. Multiple treatment sessions are typically required to achieve satisfactory results. In our experience, dyspigmentation tends to improve more quickly than rhytides, though we tend to achieve better results in dyspigmentation with IPL. For patients who desire improvements in skin laxity, radiofrequency devices and infrared light sources are better options.

The prototype fractional nonablative device was the 1550 nm Fraxel laser. Since then, the thulium 1927 nm device has gained prominence as an alternative [80].

Examples of published studies demonstrating the efficacy of fractional nonablative resurfacing for skin rejuvenation include:

●In the first published study of fractional photothermolysis on the skin, four treatments with an adjustable prototype nonablative fractional device (1480 to 1550 nm, 6 to 12 mJ per microscopic treatment zone [MTZ]) were administered to one side of the face [78]. Three months after treatment, improvement in wrinkles or skin texture assessed by investigators as moderate or better was present in 34 and 47 percent of patients, respectively. Post-treatment wrinkle scores were improved over baseline by 18 percent.

●In an uncontrolled study of 50 patients with mild to moderate cutaneous photodamage, dyspigmentation, rhytides, and skin surface irregularities on the face, neck, or chest who were given three treatments with a 1550 nm erbium-doped fiber fractionated laser, statistically significant clinical improvement was present up to nine months after treatment [77]. At nine months, at least 51 percent improvement in photodamage was achieved in 73 percent of treated areas of facial skin and 55 percent of treated areas in nonfacial sites.

An advantage of fractional nonablative resurfacing is that it may be safely applied to nonfacial sites, such as the neck, chest, limbs, hands, and feet. Treatment of these anatomic sites with other nonablative and ablative modalities has been associated with elevated risks for side effects and complications. (See "Ablative laser resurfacing for skin rejuvenation", section on 'Nonfacial sites'.)

Patient-administered fractional nonablative laser therapy may be an at-home treatment option. Two small, uncontrolled studies found that at-home treatment of periorbital wrinkles with a 1410 nm nonablative fractional laser was well tolerated and associated with clinical improvement [81].

In addition to the studies that have demonstrated the benefits of fractional nonablative laser therapy for signs of photoaging, the results of an uncontrolled study of 20 patients suggest that this treatment may improve the appearance of facial pores [82]. Two weeks after the last of six facial treatments with a 1440 nm fractional laser, assessments of facial skin with an automated imaging system revealed a significant reduction in the percentage of the skin surface with pores. Larger controlled studies with longer patient follow-up are necessary to confirm the efficacy of fractional nonablative laser therapy for this indication.

PATIENT EVALUATION AND MANAGEMENT

Preoperative counseling and treatment selection — A careful evaluation to ensure that the patient is an appropriate candidate for nonablative skin resurfacing is essential prior to proceeding with treatment. A discussion to determine the specific concerns of the patient (preferably with the use of a mirror) as well as a clinical examination to determine the type and severity of physical features should be performed. A scale created and utilized by the author during patient assessment is provided (table 1).

In general, nonablative resurfacing is appropriate for patients with features of cutaneous aging who desire rapid recovery and a low risk for complications. Since the degree of improvement attained can be modest (particularly for rhytides and skin laxity), patients should also be given clear expectations for the results of treatment. Patients who desire a greater degree of improvement than is likely to occur with nonablative techniques may achieve more satisfactory results with ablative laser resurfacing or surgical procedures. (See "Ablative laser resurfacing for skin rejuvenation".)

A basic scheme for the selection of nonablative therapies for particular indications is as follows:

●Mild to advanced erythema and/or telangiectasias – Vascular laser or IPL

●Mild to advanced dyschromia – IPL or fractional nonablative laser

●Mild to moderate rhytides – Fractional nonablative laser, infrared laser, broadband infrared light source, microneedle radiofrequency

●Mild to moderate skin laxity – Infrared laser or light source, radiofrequency devices

●Combination of features of photoaging (mild to moderate rhytides, dyschromia, vascular changes, solar elastosis, rough skin texture) – Fractional nonablative laser, IPL, radiofrequency devices, photodynamic therapy (PDT)

Nonablative skin resurfacing techniques are not favorable choices for patients with advanced rhytides or skin laxity (table 1), since satisfactory improvement is unlikely to be attained. However, these treatments are sometimes utilized for patients with such features who are adverse to more aggressive interventions and understand the therapeutic limitations of nonablative therapy.

The preferences of the patient regarding the time required to recover from a procedure also influences treatment selection. Unlike other nonablative resurfacing procedures, a recovery period of two to four days is typically necessary after fractional nonablative resurfacing [83].

Once it is determined that the patient is an appropriate candidate for nonablative skin resurfacing, informed consent for the procedure to be performed should be attained and documented. Important concepts to review include the predicted number of treatments required, expected outcomes, anticipated recovery time, adverse effects, and alternatives to treatment. Although nonablative modalities are less likely to induce dyspigmentation than ablative resurfacing techniques, dark-skinned and tanned patients should be advised of the possibility of post-treatment skin dyspigmentation. (See 'Complications' below.)

Contraindications and preoperative measures — Contraindications to therapy should be assessed prior to administering treatment. Although data on the risk for adverse effects from nonablative skin resurfacing during or following oral isotretinoin therapy are lacking, due to concern for impaired wound healing, we defer treatment when patients have received isotretinoin in the preceding six months [84]. For patients receiving fractional nonablative therapy, we extend the waiting period to one year.

We typically avoid nonablative skin resurfacing procedures in women who are pregnant or breastfeeding due to increased risk for post-treatment hyperpigmentation. The impact of nonablative treatments on pregnancy is unknown, and we avoid treatment of pregnant women. In addition, treatment with radiofrequency devices is contraindicated in patients with pacemakers, defibrillators, and facial implants in the treatment area [50]. Prophylactic antibiotic and antiviral therapy is not routinely indicated for nonablative procedures since the epidermis is not compromised.

Treatment of a small, inconspicuous area (test spot) prior to proceeding with the intended treatment is recommended in patients who are considered to be at increased risk for adverse effects, such as darkly pigmented (skin phototype IV to VI (table 2)) or tanned individuals, or patients with a history of keloidal scarring. Treatment with IPL should be avoided in tanned patients; patients may follow up for treatment when the skin returns to normal pigmentation. To reduce the risk for side effects from IPL in patients with naturally dark skin, longer pulse durations and conservative energy settings are indicated.

Scarring is a rare occurrence in patients treated with nonablative modalities. Treatment should be approached with caution in patients with histories of keloids, since scarring may be particularly disfiguring in these individuals. (See "Keloids and hypertrophic scars".)

Anesthesia — The need for anesthesia varies with the type of nonablative treatment. Anesthesia typically is not required for treatment with vascular lasers or IPL; the mild discomfort that occurs with these interventions is usually well tolerated. The application of a cold pack immediately after treatment can help to alleviate any residual mild discomfort.

In contrast, topical anesthesia is generally necessary prior to treatment with infrared lasers. A topical anesthetic agent, such as lidocaine and prilocaine cream (EMLA) or 4 to 5% lidocaine (LMX, LMX-5) is usually applied for one hour prior to the procedure. Cold packs are applied immediately after treatment to reduce residual discomfort; however, true pain should not be present after treatment. Treatment with the 1100 to 1800 nm infrared broadband light source does not require anesthesia.

Current treatment protocols for monopolar radiofrequency and the mobile delivery method of unipolar/bipolar/tripolar radiofrequency are painless and do not require anesthesia. The use of combination radiofrequency/diode and radiofrequency/IPL devices usually requires pretreatment with topical anesthetics. Discomfort is relatively mild with a skin surface-applied radiofrequency/infrared light handpiece, and anesthesia is not required. Microneedle radiofrequency devices vary from painless to painful, and local anesthetic is sometimes required.

Ultrasound devices are associated with greater discomfort. Topical anesthesia and systemic analgesics are often employed.

Topical anesthesia and cold air cooling are utilized to minimize pain during treatment with fractional nonablative devices. Some fractional nonablative devices deliver painless treatment.

Techniques — The treatment parameters and protocols differ among the nonablative technologies. General principles for treatment are as follows:

●Vascular lasers – Operated with subpurpuric fluences and pulse durations with minimally overlapping passes; multiple treatments administered every three to four weeks are typically required.

●Intense pulsed light (IPL) – Devices and techniques vary significantly; cold aqueous gel must be applied prior to treatment; one or more passes administered per treatment session; multiple treatments administered at monthly intervals.

●Infrared lasers – Operated initially at recommended moderate fluence, with gradual increase to the highest tolerated fluence with multiple passes to maximize efficacy; utilized in conjunction with cryogen spray delivered several milliseconds prior to laser pulsing to protect the epidermis; multiple treatments are given at two to four week intervals; erythema and minimal edema are the desired treatment endpoints.

●Picosecond lasers – Technique varies according to device; to create rejuvenative effects, some picosecond lasers are administered at 1064 nm with large spot size and others use a diffraction beam splitter.

●Radiofrequency devices – Technique varies according to device; a grounding pad is necessary for monopolar devices; coupling fluid or aqueous gel is applied to the treatment tip; one to three treatments given at monthly intervals; regimens with low fluences and multiple passes are increasingly utilized.

●Ultrasound devices – The device combines an imaging module to visualize tissue and a therapeutic ultrasound module that creates 1 mm³, wedge-shaped zones of thermal coagulation. Higher-frequency probes induce superficial tissue injury, and lower-frequency probes cause a deeper tissue targeting, with current protocols targeting the superficial to deep dermis. Higher-frequency probes are used on the neck, and lower-frequency probes are used for the cheeks.

Post-operative management — Unlike ablative laser resurfacing, specific post-operative measures to promote healing usually are not necessary after nonablative resurfacing treatments. The minimal erythema and edema that occur after treatment with nonfractional light sources typically resolve within several hours; only occasionally do these symptoms persist into the following day. For patients with more persistent erythema, a mild potency topical corticosteroid (group VI) can be utilized for three days (table 3). The vast majority of patients can apply makeup and return to normal activities immediately after treatment.

The recovery from nonablative fractional resurfacing is variable; edema may persist for 24 hours to seven days, and post-treatment erythema typically resolves in two to four days. Additional post-treatment side effects include xerosis and pruritus, which typically appear three to four days after treatment and dissipate quickly. On average, patients require two to four days to recover from treatment [83]. Post-treatment management involves gentle cleansing of the skin and the application of a nonirritating emollient to maintain skin moisture. Some clinicians, including ourselves, utilize specialized emollients that contain ingredients that may promote healing and reduce redness.

Sun exposure may increase risk for post-treatment hyperpigmentation. Daily use of sunscreen on the treated areas is recommended for at least four weeks after nonablative skin resurfacing. Continued use of sunscreen beyond this period is advised, since it may reduce additional photodamage to the skin. (See "Photoaging".)

Complications — Rarely, blistering, transient hyperpigmentation, and pinpoint scarring have followed treatment with infrared lasers. In our experience, blistering appears to occur with increased frequency in patients with a history of flushing and rosacea, and may be prevented by premedication with H1 antihistamines administered one hour prior to treatment. In the event of vesiculation, we advise patients to apply a bland, petrolatum-based ointment (eg, Aquaphor Healing Ointment) twice daily until healed. Vesicles heal without scarring in the vast majority of cases.

Complications after nonablative fractional resurfacing are rare. Blistering that heals without scarring, prolonged erythema that eventually subsides, petechiae (particularly in thin-skinned areas), postinflammatory hyperpigmentation, and acneiform eruptions may occur [83]. Scarring is an extremely rare event that usually develops in the setting of overaggressive treatment. Hyperpigmentation due to fractional nonablative resurfacing or other nonablative modalities may improve with sun protection, topical hydroquinone, and/or superficial chemical peels.

Treatment with radiofrequency devices is associated with minimal post-operative erythema that typically resolves within hours. Infrequent complications of radiofrequency treatment include burns and scarring [50].

The potential complications of resurfacing with vascular lasers and IPL include pigmentary alteration, blistering, ulceration, and scarring. To minimize the risk for burns from IPL, gel should be applied adequately, excessive fluence settings should be avoided, and the laser should be placed in proper contact with the skin. Burns are most likely to occur in sites of bony prominences and areas of the face with little fat such as the brow or temple.

SUMMARY AND RECOMMENDATIONS

●Overview – Chronic sun exposure and chronologic aging can lead to the development of multiple changes in the appearance of skin, such as dyschromia, telangiectasias, rhytides, skin roughness, and skin laxity. A variety of skin resurfacing procedures are useful for improving these features. (See 'Background' above.)

●Role of nonablative skin resurfacing – Nonablative skin resurfacing for skin rejuvenation involves the use of devices that improve the physical characteristics of aging by heating specific targets in the skin. Unlike ablative skin resurfacing, tissue ablation does not occur and minimal or no damage is inflicted upon the epidermis. (See 'Overview' above and "Ablative laser resurfacing for skin rejuvenation".)

●Nonablative systems – Examples of nonablative treatment modalities include vascular lasers, intense pulsed light (IPL), infrared lasers, infrared light sources, radiofrequency devices, and photodynamic therapy. Vascular lasers (pulsed dye lasers and potassium titanyl phosphate [KTP] lasers) are most effective for the treatment of cutaneous erythema and telangiectasias. IPL is most beneficial for the treatment of vascular changes and dyspigmentation. (See 'Overview' above and 'Vascular lasers' above and 'Intense pulsed light' above.)

●Mechanism – Improvement in rhytides (wrinkles) and skin laxity require the induction of changes in collagen in the dermis, such as collagen contraction and remodeling. Although all nonablative skin resurfacing modalities have demonstrated some ability to alter collagen, the most effective modalities for this indication include infrared lasers, infrared light sources, radiofrequency devices, ultrasound, and nonablative fractional lasers. (See 'Infrared lasers and light devices' above and 'Radiofrequency' above and 'Fractional lasers' above.)

●Patient selection – Not all patients with aging skin are good candidates for nonablative skin resurfacing. The best candidates are individuals with dyspigmentation, vascular changes, and/or mild to moderate rhytides or skin laxity. Patients with severe rhytides or severe skin laxity are often better served by other rejuvenating procedures. (See 'Preoperative counseling and treatment selection' above.)

●Recovery period – With the exception of fractional nonablative skin resurfacing, recovery periods are not necessary after nonablative resurfacing procedures. Fractional nonablative resurfacing most frequently requires a recovery period of two to four days. (See 'Post-operative management' above.)

●Precautions – Serious adverse events are uncommon after nonablative skin resurfacing. Careful patient selection and proper treatment administration further minimize these risks. (See 'Contraindications and preoperative measures' above and 'Complications' above.)