Ablative laser resurfacing for skin rejuvenation

INTRODUCTION — Ablative laser resurfacing is used to target the cutaneous signs of photodamage that progressively increase with age and occur most prominently in individuals with fair skin. Through the ablation of the epidermis and portions of the superficial dermis as well as the induction of collagen remodeling in the deeper dermis, ablative laser resurfacing can reduce rhytides (wrinkles), dyschromia, vascular changes, and skin laxity.

The mechanism of action, efficacy, adverse effects, and administration of traditional and fractional ablative laser resurfacing for skin rejuvenation will be discussed here. The basic principles of laser therapy for cutaneous lesions and nonablative resurfacing techniques for skin rejuvenation (eg, nonablative lasers, intense pulsed light, radiofrequency devices, and photodynamic therapy) are reviewed separately. (See "Principles of laser and intense pulsed light for cutaneous lesions" and "Nonablative skin resurfacing for skin rejuvenation".)

OVERVIEW — Technology for ablative laser resurfacing has continuously evolved. The procedure was first performed in the 1980s with the continuous wave carbon dioxide (CO₂) laser. Use of this laser was complicated by an unfavorably high risk of adverse effects, and the subsequent development of pulsed CO₂ lasers and rapidly scanning continuous wave CO₂ lasers improved the safety of treatment [1]. In the 1990s the erbium:yttrium aluminum garnet (Er:YAG) laser was introduced as an alternative device for ablative laser resurfacing. Advantages of Er:YAG lasers included more precise control over the depth of cutaneous ablation and a lower incidence of adverse effects.

For a number of years, the CO₂ and Er:YAG lasers were the primary lasers used for ablative laser resurfacing for skin rejuvenation, with CO₂ lasers considered the gold standard for this indication. However, in the early 2000s, the approach to laser skin rejuvenation was dramatically altered by the development of fractional lasers, which emit numerous narrow, microscopic columns of laser light. Fractional lasers treat only a defined fraction of the skin within a targeted area, leaving intervening areas of skin unaffected (figure 1). The reservoir of undamaged skin adjacent to sites of laser injury allows for rapid reepithelialization after treatment through the migration of viable cells into wounded areas.

Aside from the repair of photodamaged skin, ablative laser resurfacing is used for a variety of other indications, such as the treatment of scars, actinic keratoses, epidermal nevi, and other cutaneous lesions and disorders. Nonablative traditional and fractional lasers also have been studied for facial rejuvenation; however, these lasers generally are less efficacious than their ablative counterparts for this indication [2].

APPROACH TO THERAPY

Patient evaluation — Selection of the appropriate patient is of critical importance in ablative laser resurfacing. The patient should be thoroughly informed of the expected treatment outcome, anticipated recovery period, and treatment risks. In most cases, treatment results in mild to moderate improvements in cutaneous signs of photoaging (picture 1).

The length of time required for healing after ablative laser resurfacing is a deterrent for some patients. The expected convalescent period after traditional carbon dioxide (CO₂) laser resurfacing is around two weeks and is followed by several weeks to several months of persistent facial erythema. Shorter recovery periods are associated with resurfacing with traditional erbium:yttrium aluminum garnet (Er:YAG) lasers and fractional lasers. Reepithelialization after traditional Er:YAG laser resurfacing is usually complete after three to eight days and postoperative erythema resolves more quickly [3-5]. Patients treated with the fractional CO₂ laser can usually return to normal activity after 5 to 10 days, depending on the intensity of treatment; less time is needed for recovery after fractional Er:YAG resurfacing.

The specific concerns of the patient and the clinical features contributing to an aged appearance should be assessed carefully by the clinician to ensure that treatment is likely to achieve the desired result. Although laser resurfacing can lead to improvements in rhytides such as those in the periorbital, cheek, and periocular areas, deep nasolabial creases, marionette lines, and severe skin laxity are often best managed with interventions such as injectable cosmetic fillers and surgery. Dynamic rhytides (wrinkles exacerbated by facial muscle movement) may recur within months after successful ablative laser therapy. Patients with dynamic rhytides may benefit from the use of botulinum toxin before and after laser resurfacing to delay the recurrence of rhytides [3]. (See "Overview of botulinum toxin for cosmetic indications", section on 'Use as adjunctive therapy'.)

Choice of laser — The paucity of high quality data on the efficacy of both traditional and fractional ablative lasers in facial rejuvenation makes evidence-based practice challenging. The available data are primarily limited to uncontrolled studies and a few small randomized trials. In addition, systematic interpretation of the published literature is compromised by wide variation in criteria used to assess treatment responses and clinically significant differences among devices within the same laser class. The differences among brands of ablative lasers also make standardization of treatment regimens impossible.

The relative efficacy of traditional and fractional ablative lasers remains uncertain, and the choice of procedure is heavily influenced by patient-specific factors, laser availability, and clinician expertise. The traditional CO₂ laser appears to have a greater effect on dermal collagen remodeling than traditional Er:YAG lasers; this effect clinically manifests as favorable tightening of lax skin [3,6]. However, due to a relatively high risk of adverse effects (eg, scarring, dyspigmentation, and prolonged erythema) and a recovery period that exceeds that associated with fractional lasers, use of the CO₂ laser has become less popular with the advent of new therapies [7].

The traditional Er:YAG laser requires more laser passes (retreatment of the same area during a single treatment session) than traditional CO₂ lasers to achieve a similar depth of ablation. The more precise skin ablation feasible with the Er:YAG laser is desired in some clinical settings, but may also contribute to reduced thermal damage to underlying collagen resulting in a lesser skin tightening effect [3,8]. The traditional Er:YAG has been favored by some clinicians for the treatment of dyschromia and fine wrinkling associated with photodamage rather than for the treatment of coarse, deep rhytides [3]. The Er:YAG also appears to have a lower risk for scarring than the CO₂ laser and may be beneficial for the treatment of areas at greater risk for laser-induced scar formation, such as delicate periorbital skin [8].

Like traditional ablative lasers, fractional ablative lasers improve dyschromia and rhytides associated with cutaneous photodamage [9]. Although comparative trials are lacking, some authors have suggested that the efficacy of fractional ablative lasers for skin tightening may exceed that of traditional ablative lasers [7]. This assertion plus the relatively short recovery period and reduced risk for adverse effects associated with fractional ablative lasers have contributed to a near total shift away from traditional lasers to fractional lasers as the preferred devices for ablative laser resurfacing [7]. Additional high quality studies are necessary to clarify the role of fractional ablative lasers in skin rejuvenation.

Skin phototype — Although photodamage often is less severe in individuals with dark skin compared with fair-skinned people, patients with skin phototypes IV and higher also present for the treatment of photoaging. Laser induced dyspigmentation is a major concern in this population, as the risk for this adverse effect rises with increasing baseline skin pigmentation. (See 'Adverse effects and complications' below and 'Adverse effects and complications' below.)

Hyperpigmentation and hypopigmentation may occur with all forms of ablative laser resurfacing, but is most likely to occur after treatment with traditional CO₂ lasers [3,10-12]. Thus, we generally avoid the use of traditional CO₂ lasers for the treatment of photodamage in patients with skin phototype IV or higher. Fractional ablative lasers may be a preferable alternative in this population [11,13]. Additional studies are necessary to determine the most appropriate treatments and laser settings for ablative laser therapy for skin rejuvenation in patients with dark skin.

Nonfacial sites — Ablative laser resurfacing for photodamage primarily is used for the treatment of the face; however, patients frequently present with photodamage on other photoexposed areas such as the neck and hands. Due to an unacceptably high risk for scarring, treatment with traditional CO₂ lasers is contraindicated in these locations [14]. The risk for scarring appears to be lower with fractional ablative lasers and traditional Er:YAG lasers, and successful treatment of the neck and hands with these devices has been documented in small, uncontrolled studies [15-21]. Yet, treatment must be approached with caution, as the development of severe scarring after treatment has been reported in some patients [14].

TRADITIONAL ABLATIVE LASERS — The traditional ablative lasers used for skin rejuvenation include the 10,600 nm pulsed and rapidly scanning carbon dioxide (CO₂) lasers and the 2940 nm pulsed erbium:yttrium aluminum garnet (Er:YAG) laser.

Mechanism of action — The theory of selective photothermolysis is the basis for the efficacy of traditional ablative lasers in skin rejuvenation. The theory is based upon the following principles [22] (see "Principles of laser and intense pulsed light for cutaneous lesions", section on 'Selective photothermolysis'):

●The wavelength of light utilized should be absorbed preferentially by light absorbing molecules (chromophores) in the target and must penetrate the skin sufficiently to reach its depth.

●The light must be delivered in a period of time that is short enough to prevent the transfer of excessive heat to adjacent structures.

●The energy delivered per unit area (fluence) must be sufficient to exert the desired therapeutic effect, but should also be at a level that minimizes undesirable collateral tissue damage.

The depth of light absorption into the skin generally rises with increasing light wavelengths. According to this principle, one would expect infrared light emitted from CO₂ and Er:YAG lasers to penetrate more deeply into the skin than light emitted from the 585 to 600 nm pulsed dye lasers that are often used for the treatment of vascular lesions in the dermis (figure 2). However, because light emitted by CO₂ and Er:YAG lasers is highly absorbed by water in the epidermis, little light reaches deeper levels of the skin. At a setting of 5 J/cm² and a pulse duration of less than 1 ms, light from the CO₂ laser penetrates to a depth of approximately 20 to 30 micrometers [23]. Water molecules have an even greater affinity for light emitted from Er:YAG lasers, which reaches depths of only 1 to 3 micrometers per J/cm².

The absorption of light energy by water in the epidermis leads to the rapid accumulation of heat and consequent vaporization of the epidermis. Thermal damage extends beyond the penetration of light; residual thermal damage reaches depths of 100 to 150 micrometers with traditional CO₂ lasers and 10 to 40 micrometers with traditional Er:YAG lasers [23]. The heat transferred to underlying dermal collagen is believed to contribute to collagen contraction and remodeling as well as clinically evident skin tightening [6,24-26].

Excessive transfer of heat to the dermis can lead to adverse effects such as scarring and permanent hypopigmentation. To minimize this risk, the time the laser beam is in contact with the skin (pulse duration) should be shorter than the time it takes the treated area of skin to return to ambient temperature (tissue thermal relaxation time) (figure 3). CO₂ laser resurfacing was initially performed with continuous wave CO₂ lasers, which offered relatively poor control over the duration of time that the laser beam was in contact with the skin. The development of the high energy pulsed CO₂ laser (pulse duration less than 1 ms) and short pulsed Er:YAG laser (pulse duration 250 to 350 mcs) allowed the delivery of sufficient amounts of energy to induce ablation, while maintaining tight control over the duration of light delivery and reducing the risk for inadvertent damage. Rapidly scanning CO₂ lasers utilize a computerized scanning mechanism to limit the duration of contact of the laser beam with any given site on the skin and are an alternative to pulsed devices

The principles of laser therapy in the skin are discussed in greater detail separately. (See "Principles of laser and intense pulsed light for cutaneous lesions".)

Efficacy — It is generally accepted that skin resurfacing with traditional ablative lasers is effective for cutaneous rejuvenation. However, data on efficacy are primarily limited to uncontrolled studies and a few small randomized comparison trials. In addition, the methods used to assess treatment responses have been inconsistent and often poorly defined.

Carbon dioxide lasers — Examples of studies that have investigated the value of traditional carbon dioxide (CO₂) lasers in skin rejuvenation include:

●In an uncontrolled study, 259 patients with facial rhytides were treated with a high energy pulsed CO₂ laser [27]. All patients responded to treatment; the average improvement in rhytides compared with surrounding untreated skin was reported as 90 percent.

●In an uncontrolled study that investigated the efficacy of CO₂ laser resurfacing for perioral (n = 73) or periorbital wrinkles (n = 38), multiple pass treatment with a high energy pulsed CO₂ laser led to reduced severity of wrinkling as assessed with a nine-point clinical scoring system [28]. The average wrinkling score reduction was 2.25 in the periorbital region and 2.34 in the perioral area. A subjective improvement in skin laxity also was reported. Patient skin phototypes ranged from I to IV (table 1).

●In a retrospective study of 47 patients with perioral, periorbital, and glabellar rhytides (skin phototype I to IV) who were treated with a rapidly scanning CO₂ laser, good to excellent cosmetic results were attained in all anatomic areas [29].

Er:YAG lasers — Examples of studies of traditional erbium:yttrium aluminum garnet (Er:YAG) lasers in skin rejuvenation include:

●In an uncontrolled study of 15 patients with facial rhytides (skin phototype I to III), full face resurfacing with a short pulse Er:YAG laser was associated with marked improvement (50 to 75 percent improvement in fine to moderate wrinkles) in eight patients (53 percent) and moderate improvement (25 to 50 percent improvement in fine to moderate wrinkles) in six patients (40 percent) [4].

●In an uncontrolled study of 20 patients with perioral, periorbital, or forehead rhytides (skin phototype I to III), treatment with a short pulse Er:YAG laser led to clinical improvement in all patients [5].

Fluence levels of 5 to 15 J/cm² are commonly used for ablative resurfacing with Er:YAG lasers. Microablative procedures that utilize lower fluences and a single laser pass may also have some benefit for the treatment of photoaging [30,31].

Comparative studies — On a per laser pass basis, traditional CO₂ laser resurfacing is associated with more dramatic clinical improvement than traditional Er:YAG laser resurfacing [32]. The use of higher numbers of passes with the Er:YAG laser may augment the treatment effect.

The following studies compared the efficacy of traditional CO₂ and Er:YAG lasers:

●A single pass with pulsed CO₂ laser was compared with four passes with a short pulse Er:YAG laser in a split-face randomized trial of 13 patients (skin phototype I to III) with facial rhytides [33]. No significant difference was noted between the two therapies in regards to improvement in hyperpigmentation and reduction of rhytides. Overall, improvement was modest.

●In a split-face randomized trial of 21 patients (skin phototype I to III), one side of the face was treated two to three passes with a pulsed CO₂ laser and the other side treated with at least two passes with a short pulse Er:YAG laser. Treatment with the CO₂ laser led to greater improvement in rhytides [32]. However, patients who received five or more passes with the Er:YAG device exhibited similar results as those who received two to three passes with the CO₂ laser. Patients treated with the Er:YAG device showed faster resolution of post-treatment erythema and a lower incidence of laser-induced hypopigmentation.

The Er:YAG laser has a lesser coagulative effect than the CO₂ laser. In practice, bleeding can be a limiting factor for the performance of multiple passes [34].

Long pulse Er:YAG lasers have been used in an attempt to improve the efficacy of Er:YAG devices for deep rhytides through increasing the depth of thermal damage. However, CO₂ lasers remain more effective for this indication. In a bilateral comparison study of 12 patients with perioral and periorbital rhytides, both a 10 ms pulsed Er:YAG laser and high energy pulsed CO₂ laser resulted in good improvement, yet the CO₂ laser was more efficacious for deep rhytides [35]. A split-face randomized trial that compared the response of perioral rhytides to two nonoverlapping passes with a pulsed CO₂ laser or six passes with a variable pulse Er:YAG laser (including one pass with a 10 ms pulse duration) found similar results [36].

Combination therapy with CO₂ and Er:YAG lasers also has been reported [37,38]. In a randomized trial of 20 patients with facial rhytides, sequential treatment with a pulsed CO₂ laser and short pulse Er:YAG laser resulted in similar treatment efficacy as CO₂ laser treatment alone and a reduced incidence of adverse effects [37].

Adverse effects and complications — Adverse effects of traditional ablative laser resurfacing include persistent erythema, dyspigmentation, infections, and scarring. Erythema usually resolves approximately one month after Er:YAG resurfacing [4,5] and two months following CO₂ resurfacing, but can persist for up to one year in patients treated with CO₂ lasers [2,29].

Transient postinflammatory hyperpigmentation occurs in approximately 30 percent of patients and is more likely to occur in patients with skin phototypes III or higher (table 1) [1,10,27]. Hypopigmentation, which is more common in light skinned individuals, may not be evident until several months after the procedure [39,40]. CO₂ laser resurfacing is more likely to induce dyschromia than other forms of laser resurfacing. (See 'Skin phototype' above.)

Reactivation and local spread of herpes simplex virus (HSV) infection can occur after laser ablation. Because of the relatively high prevalence of HSV infection, all patients undergoing full face ablative resurfacing should be treated with prophylactic antivirals. Bacterial and candidal infections may also follow laser resurfacing. Clinical signs suggestive of infection include worsening pain, drainage, erosions, or crusting. (See 'Prophylaxis' below.)

Acneiform eruptions and milia can develop in the postoperative period and may be exacerbated by the occlusive ointments utilized for the maintenance of skin moisture during healing [2,3,29]. In addition, compromise of the skin barrier in the treated area contributes to an increased susceptibility to contact dermatitis.

The risk for scarring is greatest with traditional CO₂ laser resurfacing, but scarring can also occur after treatment with the traditional Er:YAG laser. Use of appropriate laser settings and careful preoperative screening may reduce the risk for this adverse event. (See 'Patient selection' below.)

Administration — A variety of measures are necessary for the safe utilization of traditional ablative lasers. Safe practices begin with preoperative interventions and continue into the postoperative period.

Preoperative

Patient selection — Prior to the initiation of treatment, patients must be fully informed of treatment risks and expectations. Patients also should be assessed for contraindications to therapy. Laser resurfacing is contraindicated in the following settings [3]:

●History of keloidal scarring – The exclusion of patients with a history of keloids is based upon concern for an elevated risk for severe scarring after ablative laser treatment. However, this has not been specifically studied.

●Oral isotretinoin therapy within one year – The recommendation to avoid laser resurfacing in patients recently treated with oral isotretinoin is generally accepted; however, data on the risk of scarring after laser resurfacing are lacking [2,41]. Atypical scarring has been reported after dermabrasion in patients treated with isotretinoin [42,43], but the validity of this risk has been questioned [44].

●Sites of morphea, scleroderma, or prior radiation therapy – Treatment should be avoided in these sites. In affected areas, a diminished supply of the adnexal stem cells necessary to repopulate the epidermis may contribute to impaired wound healing [2,23].

●Ectropion – Infraorbital resurfacing is contraindicated in patients with ectropion, and in patients with lax infraorbital skin, care must be taken to treat the infraorbital skin less aggressively than other facial areas [3]. Skin tightening after laser resurfacing may exacerbate or induce ectropion.

Underlying cutaneous diseases that can appear in sites of cutaneous injury, such as vitiligo, lichen planus, and psoriasis, are relative contraindications for laser resurfacing due to the potential for the appearance or worsening of lesions in treated areas (Koebner phenomenon) [2]. The risks and benefits of treatment should also be considered carefully in patients with a history of facial surgery (eg, face-lifts or blepharoplasty). Surgical procedures may result in an altered blood supply and a higher risk for necrosis and scarring [45].

In addition, the patient's skin color influences the decision to proceed with therapy. The risk of dyspigmentation rises with increasing skin pigmentation [10], making patients with skin phototypes I to IV the preferred candidates for ablative laser resurfacing (table 1). Because the risks for temporary and permanent dyspigmentation are greatest with the CO₂ laser, we generally avoid CO₂ laser resurfacing for skin rejuvenation in patients with skin phototypes IV or higher and prefer to use fractional ablative or traditional Er:YAG lasers in this subgroup of patients. (See 'Skin phototype' above.)

Prophylaxis — Oral antiviral prophylaxis is recommended to prevent reactivation of facial herpes simplex virus infections [46,47]. We typically administer acyclovir 200 mg twice daily, valacyclovir 500 mg twice daily, or famciclovir 500 mg twice daily, one day before treatment and continue until reepithelialization is complete (usually two weeks for patients receiving CO₂ laser ablation).

Opinions vary on the use of prophylactic therapy for bacterial infections [48,49]. The routine administration of antibiotics with gram positive coverage has been recommended by some authors [48], while others have suggested that prophylactic antibiotics may not be necessary in all patients [49,50]. We typically do not use antibiotic prophylaxis, and limit its use for patients who we perceive to be at high risk for infection, such as immunosuppressed individuals.

Pretreatment with topical tretinoin is often recommended as a measure to improve healing time; however, there are insufficient data on the efficacy of this practice [51-57]. One randomized trial in which topical tretinoin 0.05% or a placebo cream was applied to the forearm for three weeks prior to CO₂ laser resurfacing found no evidence that topical tretinoin enhanced collagen formation, accelerated reepithelialization, or stimulated more rapid resolution of postoperative erythema [52]. Additional studies are necessary to determine whether these findings are applicable to the treatment of facial skin.

The efficacy of another common practice, the use of preoperative topical skin-lightening agents, was brought into question by a randomized trial of 100 patients. No significant difference in the incidence of post-laser hyperpigmentation was detected among patients given no pretreatment, pretreatment with 10% glycolic acid cream, or pretreatment with hydroquinone 4% cream plus tretinoin 0.025% cream [58]. However, patients in the trial were limited to skin phototypes I to III, and it is unclear whether these results apply to patients with darker skin tones, in whom the risk of hyperpigmentation is much higher (table 1). We typically do not use skin lightening products before treatment, but utilize these agents in the post-treatment setting. (See 'Postoperative' below.)

Oral glucocorticoids are used by some clinicians to reduce post-treatment edema. The value and safety of oral glucocorticoids in this setting has not been formally studied, and we generally do not use oral glucocorticoids in the management of our patients.

Intraoperative — Ablative laser therapy is painful. Topical anesthetics often are sufficient for focal procedures utilizing the Er:YAG laser. Local infiltrative anesthesia or nerve blocks can be used when additional anesthesia is required. Local anesthesia plus systemic anxiolytics, oral narcotics, or intramuscular sedation are usually needed for full face procedures or localized CO₂ laser resurfacing [23]. Intravenous anesthesia is often utilized during full face CO₂ laser resurfacing. (See "General anesthesia: Intravenous induction agents".)

More than one laser pass (retreatment of a site during the same treatment session) is often performed in ablative laser resurfacing. The effacement of wrinkles indicates the treatment endpoint [2]. A yellow or brown color noted after wiping away desiccated tissue after a pass with a CO₂ laser suggests tissue necrosis; additional laser passes should not be performed if this is detected. Two passes are often performed during treatment of rhytides with the CO₂ laser, and between four and ten passes typically are required to achieve desired results with Er:YAG devices. The direction of treatment should be altered with subsequent passes to prevent the development of a striped pattern after healing [3].

Treatment of focal areas can result in an unfavorable color contrast between treated and untreated skin. If the entire face is not treated, the treatment should at least incorporate an entire cosmetic unit to minimize this effect (figure 4).

Postoperative — Edema and exudate are expected within the first few days after ablative resurfacing. The initial appearance after treatment may be disturbing for some patients, which underlies the importance of careful preoperative counseling [59]. Postoperative management includes the use of cool compresses, head elevation, and saline or water soaks applied as often as is necessary to keep the skin moist. Moisture promotes wound healing, and both open and closed wound care techniques have been advocated [3]. We favor the open technique and instruct patients to apply petrolatum ointment to the treatment area after each soak until reepithelialization is complete. Advocates of the closed technique tend to utilize wound dressings for the first 24 to 72 hours [2,3,60]. Pain can be managed with acetaminophen or stronger oral analgesic agents when necessary.

Erythema may persist for months, particularly after CO₂ laser resurfacing. Makeup with a green tint is useful for masking erythema. Throughout this period, patients should engage in daily sun protective practices and daily sunscreen use to reduce the development of postinflammatory hyperpigmentation. When it occurs, postinflammatory hyperpigmentation improves slowly over time; daily application of topical hydroquinone cream, retinoids, and/or peeling agents such as glycolic acid can be prescribed to accelerate resolution [3,27]. We typically use topical hydroquinone and low potency glycolic acids. Topical retinoids are added if tolerated. (See "Postinflammatory hyperpigmentation".)

If scarring occurs, treatments such as topical or intralesional steroids, silicone gel, pulsed dye laser therapy, or nonablative fractional laser resurfacing can be utilized to minimize the cosmetic impact.

Most patients can return to work two to three weeks after full face CO₂ laser resurfacing. After Er:YAG laser resurfacing, the recovery period is between three and eight days.

ABLATIVE FRACTIONAL LASERS — The relatively long recovery period required for carbon dioxide (CO₂) laser resurfacing and its associated adverse effects stimulated the search for alternative methods for laser skin rejuvenation. Ablative fractional photothermolysis is a newer form of laser therapy that has some advantages over traditional ablative laser resurfacing.

Mechanism — Similar to traditional ablative lasers, the target chromophore for fractional lasers is water. The ablative fractional lasers include the 2940 nm fractional erbium:yttrium aluminum garnet (Er:YAG) laser, the 2790 nm fractional yttrium scandium gallium garnet (YSGG) laser, and the 10,600 nm fractional CO₂ laser. Nonablative fractional lasers emit wavelengths of light that are less strongly absorbed by water molecules in the skin. Nonablative fractional lasers have also been used for skin rejuvenation, but are less effective for this indication [9].

Fractional lasers deliver a multitude of narrow columns of laser light to the skin, resulting in the creation of numerous microscopic vertical zones of thermal damage called microscopic thermal zones (MTZs) (figure 1). MTZs are usually less than 400 micrometers in diameter and up to 1300 micrometers deep; the type of fractional laser and specific laser settings determine the size of the MTZ [61].

The undamaged surrounding skin immediately adjacent to an MTZ serves as a reservoir of viable tissue, permitting the rapid repopulation of the epidermis observed after fractional laser therapy [62]. Reepithelialization typically occurs within a few days. In contrast, reepithelialization after traditional laser ablation is dependent on migration of epidermal cells from adnexal structures [7]. A skin tightening effect also occurs after treatment with ablative fractional lasers; both immediate and delayed collagen contraction and collagen remodeling may contribute to improvements in skin laxity [7,63].

Efficacy — Evidence in support of the efficacy of ablative fractional lasers for the treatment of photoaged skin is increasing [9]. However, published studies of this form of therapy for photodamaged skin are primarily limited to uncontrolled studies. Examples of studies investigating the use of ablative fractional lasers include the following:

●An uncontrolled study that evaluated the effects of three treatments with a fractional CO₂ laser on cutaneous photodamage on the face in 25 women found that treatment significantly reduced wrinkle size and depth in all facial areas, with the best results evident on the cheeks and periorbital skin [64]. Pigmentary irregularities and skin roughness also improved after fractional CO₂ laser therapy.

●In an uncontrolled study of 30 adults with cutaneous photodamage (skin phototype I to IV), facial and neck skin were treated with a fractional CO₂ laser for one or two treatment sessions [15]. Based upon the investigators' assessment of clinical photographs, 23 out of 30 patients (83 percent) exhibited at least 50 percent improvement in the overall appearance of photodamaged skin three months after the completion of therapy.

●Another uncontrolled study (n = 55) evaluated the efficacy of a fractional CO₂ laser device in patients with severe photodamage (skin phototype II or III) [65]. Patients were given one treatment session. Statistically significant improvement in fine lines, mottled pigmentation, sallow complexion, and skin texture were evident one month after treatment. Scores for coarse wrinkles and telangiectasias exhibited a nonsignificant trend towards improvement. Additional statistically significant improvement was noted for fine lines, sallowness, and skin texture three months after the completion of therapy.

●The efficacy of a fractional Er:YAG laser was investigated in an uncontrolled study of 28 patients with mild to moderate photodamage (skin phototype II to IV) [66]. Patients were treated for one to four treatment sessions with a treatment interval of four weeks. Two months after the completion of therapy, clinical outcomes for photodamage and wrinkling were rated by the investigators as excellent in 75 percent of patients and good in 25 percent of patients.

Several other studies have also documented improvement in signs of photoaging following treatment with fractional CO₂, Er:YAG, or YSGG lasers [67-69].

Comparative trials of fractional lasers are limited. In a randomized split-face trial of 28 patients with facial rhytides that compared a single treatment with a fractional CO₂ laser to one treatment with a fractional Er:YAG laser, no significant difference in clinical effect was detected [70]. The investigators found that 64 percent and 57 percent of sites treated with the fractional CO₂ laser or fractional Er:YAG laser, respectively, showed clinical signs of improvement. Wrinkle depth was modestly, but significantly, improved in sites treated with both lasers. Wrinkle depth decreased from 1.97±2.05 mm to 1.64±2.04 mm and from 1.97±1.29 to 1.63±1.20 mm, respectively.

Ablative fractional CO₂ lasers have also been used in conjunction with photodynamic therapy for the treatment of premalignant and malignant cutaneous lesions associated with photodamage [71-73]. (See "Treatment of actinic keratosis", section on 'Laser resurfacing' and "Treatment of actinic keratosis", section on 'Laser-assisted photodynamic therapy' and "Treatment and prognosis of low-risk cutaneous squamous cell carcinoma (cSCC)", section on 'Photodynamic therapy'.)

Adverse effects and complications — Compared with traditional ablative laser resurfacing, complications of ablative fractional laser resurfacing appear to be less severe and less frequent. Treatment-induced erythema is expected and usually resolves within a few days. Prolonged erythema (lasting more than one month) occurs in approximately 12 percent of patients [47] and usually resolves within three months. In one small, randomized, split-face trial, use of a 590 nm light-emitting diode array reduced the severity and duration of post-treatment erythema by one to two days [74].

Viral, bacterial, or fungal infections can follow treatment. The risk for herpes simplex virus (HSV) infection after fractional laser resurfacing is lower than for traditional laser resurfacing (0.3 to 2 percent versus 2 to 7 percent) [47]. However, all patients undergoing fractional resurfacing of the entire face or who have a history of facial HSV infection should be treated with antiviral prophylaxis [47]. We typically administer either acyclovir 200 mg twice daily, valacyclovir 500 mg twice daily, or famciclovir 500 mg twice daily. Treatment should begin one day prior to treatment and should be continued for five to seven days after treatment. Patients with HSV infection may present only with nonspecific superficial erosions in the treated area.

Bacterial infection is uncommon, and as with traditional ablative laser resurfacing, the routine use of antibiotic prophylaxis is controversial. We generally reserve antibiotic prophylaxis for people who we perceive to be at high risk for infection, such as immunosuppressed patients [47]. Signs of infection include worsening pain, drainage, erosions, or crusting within the first few days after treatment. In our experience, patients who develop candidal infections frequently complain of intense pruritus.

When infection is suspected, the involved sites should be cultured and broad-spectrum antibiotic therapy should be administered while awaiting culture results. Candidal infections are managed with oral antifungal agents.

Similar to traditional ablative laser resurfacing, the risk of postinflammatory hyperpigmentation rises with increasing baseline skin pigmentation. However, the duration and severity of hyperpigmentation tends to be less in patients treated with fractional lasers [47]. We instruct patients to avoid sun exposure for two weeks prior to treatment and for two weeks after therapy to reduce this risk. Longer treatment intervals and adjustments to the energy and density settings may be beneficial for reducing the incidence of hyperpigmentation [11,47]. Hypopigmentation is rare after fractional laser resurfacing.

Scarring also is uncommon, but can be devastating when it occurs [75,76]. Initial signs of scarring include a focal, persistent area of erythema or induration that appears a few weeks after therapy. Most cases of scarring after fractional laser resurfacing have involved treatment of the neck [47].

Other complications of fractional ablative laser resurfacing include transient acneiform eruptions, milia, and ectropion. Ectropion may be most likely to occur in patients with a history of eyelid surgery or reduced skin elasticity in this area at baseline [47].

Administration

Preoperative — Preoperative measures are similar to those for traditional ablative laser resurfacing. (See 'Preoperative' above.)

Intraoperative — In preparation for treatment, the skin should be cleansed thoroughly with a gentle cleanser. A topical anesthetic is applied one hour prior to treatment and cold air is used to further improve patient comfort during the treatment session. The use of cold air is supported by a nonrandomized prospective split-face study that found that treatment with a fractional C0₂ laser was less painful when given with both cold air anesthesia and topical anesthesia than when given with topical anesthesia alone [77]. For more aggressive procedures, local nerve blocks, oral sedatives, or intravenous anesthesia may be necessary [23].

Laser settings are not transferable between different ablative fractional laser devices, and clinician familiarity with the device utilized is essential. In general, the use of higher energies with small spot sizes increases the depth of laser injury. Increasing the pulse duration widens the diameter of the MTZ and may increase the depth of ablation [78]. The density setting, which determines the amount of space between the MTZs, can also be altered. It is advisable to reduce density settings in areas at greater risk for complications such as the neck and periocular skin; higher densities may be appropriate for deep rhytides, such as those in the perioral area [7].

Early fractional lasers required the application of a blue dye to the skin to optimize functioning, but this is no longer necessary with most devices. A thick layer of gel is applied before the start of treatment, and the number of laser passes needed is determined by the specific laser system and laser settings. Similar to nonfractional ablative lasers, treatment of an entire cosmetic unit is preferred if full-face treatment is not being performed (figure 4) (see 'Intraoperative' above). Immediate edema and bleeding and crusting can occur during treatment [23].

Postoperative — Immediately after treatment, we apply ice-cold wet compresses followed by a bland occlusive ointment. Home care after less intense treatments involves gentle skin cleansing and repeated application of the ointment to maintain constant skin moisture until crusting ceases (usually by day three) [23]. In more aggressively treated individuals (bleeding associated with treatment), we apply a biologic dressing that is removed 24 hours later and is followed by soaking and gentle cleansing of the skin every three to four hours for five to seven days. After each soak the ointment should be reapplied to maintain skin moisture. Subsequently, a nongreasy moisturizing cream can be utilized.

For patients who develop pruritus during the healing period, we prescribe a mid-potency topical corticosteroid for application twice daily for a few days. Itching most commonly begins on the third postoperative day.

Desquamation for several days after treatment is normal. Scratching or rubbing of the skin should be avoided. As with ablative laser resurfacing, photoprotection is important to reduce risk for hyperpigmentation. Hyperpigmentation is managed similarly to hyperpigmentation associated with traditional ablative lasers.

Most patients can return to work 4 to 10 days after fractional CO₂ laser resurfacing depending on the extent and intensity of treatment. After fractional Er:YAG laser resurfacing, the recovery period is between one and three days. We find that most patients require one to three treatments to achieve desired results (picture 1).

SUMMARY AND RECOMMENDATIONS

●Ablative laser resurfacing procedures can lead to improvement in the clinical signs of photoaging. The ablative lasers used for skin resurfacing include pulsed and rapidly scanning carbon dioxide (CO₂) lasers, pulsed erbium:yttrium aluminum garnet (Er:YAG) lasers, and fractional ablative lasers. (See 'Introduction' above and 'Overview' above.)

●Patients should be thoroughly informed of the expected treatment outcome, anticipated recovery period, and treatment risks prior to proceeding with ablative laser resurfacing. A variety of factors influence the selection of the appropriate laser resurfacing technique, including the severity and location of photodamage, the patient's skin color, and patient preference regarding the length of time required for healing. (See 'Approach to therapy' above.)

●Both traditional CO₂ lasers and traditional Er:YAG lasers are effective for the treatment of photoaging. CO₂ lasers appear to have a greater effect on skin tightening, which may be related to greater transfer of heat to underlying dermal collagen during irradiation with the CO₂ laser. However, CO₂ laser resurfacing is associated with a relatively longer recovery period, higher risk for scarring and dyspigmentation, and a longer period of persistent erythema after treatment. Due to an elevated risk for dyspigmentation in patients with dark skin, we typically limit CO₂ laser resurfacing to patients with skin phototypes I to III. (See 'Approach to therapy' above and 'Traditional ablative lasers' above.)

●Traditional ablative laser resurfacing is contraindicated in patients with a history of keloidal scarring, recent history oral isotretinoin therapy, and sclerotic disorders involving the site to be treated. Infraorbital resurfacing should not be performed in patients with ectropion. Relative contraindications include cutaneous disorders that may Koebnerize and a history of facial surgery. (See 'Patient selection' above.)

●Prophylactic antiviral therapy should be provided to all patients undergoing full facial traditional or fractional ablative laser resurfacing due to a risk for herpes simplex virus reactivation. The need for antibiotic prophylaxis is controversial. If bacterial infection is suspected, the affected area should be cultured and systemic antibiotic therapy should be initiated. (See 'Prophylaxis' above and 'Adverse effects and complications' above.)

●Pain management is often necessary during laser resurfacing. Depending on the type of procedure, patients may require only topical anesthetics or the addition of systemic agents. (See 'Intraoperative' above and 'Intraoperative' above.)

●Fractional ablative lasers operate through the creation of numerous microscopic columns of thermal damage involving the epidermis and dermis (figure 1). Due to a relatively short recovery period, and a relatively low risk of adverse effects, fractional ablative lasers are increasingly becoming the preferred devices for ablative laser resurfacing. Additional studies are necessary to explore the efficacy and safety of fractional ablative lasers for rejuvenation. (See 'Ablative fractional lasers' above.)