Laser-based Treatment of the Aging Face for Skin Resurfacing: Ablative and Non-ablative Lasers

Chapter Summary

Many aspects of dermatoheliosis are amenable to treatment with a variety of ablative and non-ablative lasers and light sources.
Ablative laser skin resurfacing offers the most substantial clinical improvement, but is associated with greater postoperative recovery.
Non-ablative laser skin remodeling is a good alternative for patients who desire modest improvement of dermatoheliosis with a limited post-treatment recovery period.
Fractionated laser systems provide the benefits of higher energy treatments with fewer side-effects and faster recovery than traditional lasers.
Continued developments in laser technology will lead to greater efficacy with an improved safety profile.

Introduction

Dermatoheliosis, a term coined by the late Thomas B. Fitzpatrick, is the appearance of roughened surface texture, and variable degrees of dyspigmentation, telangiectasias, wrinkling, and skin laxity. Clinically, dermatoheliosis is equivalent to photoaging and histopathologically is usually limited to the epidermis and upper papillary dermis. It is, therefore, amenable to treatment with a variety of ablative and non-ablative lasers and light sources.

The armamentarium of laser technology available to treat dermatoheliosis is ever-expanding ( Table 34.1 ) and other types of energy-based devices (see Chapter 41 ) are also capable of improving photoaging. The most appropriate technique will depend upon the severity of photodamage and rhytides, the expertise of the laser surgeon, and the expectations and lifestyle of the individual patient.

Table 34.1

Lasers and light sources for skin rejuvenation

	Laser type	Wavelength (nm)
Ablative resurfacing	Carbon dioxide (pulsed)	10 600
	Erbium:YAG (pulsed)	2940
	YSGG (pulsed)	2790
	Fractionated	10 600, 2790 and 2940
Non-ablative remodeling	Pulsed-dye	585–595
	Nd:YAG (Q-switched; normal mode)	1064
	Nd:YAG, long-pulsed	1320
	Diode, long-pulsed	1450
	Erbium:glass	1540
	Intense pulsed light source	515–1200
Non-ablative	Fractional resurfacing	1550, 1540, 1320, 1440, 1927

Nd, neodymium; Q-switched, quality-switched; YAG, yttrium-aluminum-garnet; YSGG, yttrium-scandium-gallium-garnet.

Ablative Laser Skin Resurfacing

Laser resurfacing of photodamaged skin has been the gold standard for rejuvenation of photoaging facial skin for over 30 years. The early 1990s marked the start of this trend with the arrival of optimized CO ₂ lasers, and in the past several years has shifted towards fractional resurfacing (both ablative and non-ablative) as described by Manstein and colleagues, due to its faster recovery time and safer side-effect profile. Nonetheless, it provides an important historical framework for understanding cutaneous resurfacing and in a few instances, may be preferable over fractional resurfacing for certain dermatological conditions.

Proper patient selection

A focused history should be obtained prior to any resurfacing procedure. In particular, it is important to document if the patient has had any previous procedures or any contraindications to resurfacing. Ablative laser resurfacing may unmask hypopigmentation or fibrosis produced by prior dermabrasion, cryosurgery, or phenol peels. In addition, the presence of fibrosis may limit the vaporization potential of ablative lasers, thereby decreasing clinical efficacy. Patients who have had prior lower blepharoplasties (using an external approach) are at greater risk of ectropion formation after infraorbital ablative skin resurfacing. Likewise, patients with a history of lifting procedures may have non-facial skin present on the face, and the aggressiveness of any resurfacing procedure needs to be tempered. Any past history of herpes labialis puts the patient at risk for disseminated herpes infection with laser resurfacing. A history of delayed wound healing, autoimmune disease or other immunologic deficiency may complicate the postoperative healing course. Additionally, patients with scleroderma, lupus erythematosus, and vitiligo may also exhibit worsening of their conditions after ablative skin resurfacing. Other dermatologic conditions such as psoriasis, verrucae, and molluscum contagiosum that may undergo koebnerization after ablative laser skin resurfacing should be identified on history. Medications that may impact resurfacing should be elicited during the initial consultation. Isotretinoin may potentially lead to an increased risk of postoperative hypertrophic scar formation due to its detrimental effect on wound healing and collagenesis. Because the alteration in healing is idiosyncratic, a safe interval between the use of oral retinoids and ablative laser skin resurfacing is difficult to calculate; however, most practitioners delay the treatment for at least 6–12 months after cessation of the drug. Patients with a propensity to scar or keloid will be at greater risk of scar formation after laser resurfacing, independent of the laser's selectivity and the operator's expertise. Patients with active acne or a history of acne may experience a flare with postprocedural occlusive wound care.

A physical exam of the area to be resurfaced must also be done prior to treatment. While a variety of dermatologic conditions are amenable to laser skin resurfacing, clinically suspicious growths, especially pigmented lesions, should be properly evaluated with a thorough physical exam and possibly clinicopathologic correlation prior to any cosmetic procedure. The patient's Fitzpatrick skin phototype should be noted as fairer skin type patients have a lower incidence of undesirable postoperative hyperpigmentation compared to patients with darker Fitzpatrick skin types.

Finally, it is critical that the patient have a realistic expectation of the procedure and the potential risks, benefits and side effects. Patients who believe that every wrinkle will be abolished with the ablative laser resurfacing procedure are not good treatment candidates. Furthermore, those who cannot physically or emotionally handle the prolonged postoperative course should also be dissuaded from pursuing ablative laser skin resurfacing procedures.

Preoperative preparation

Lasers, such as carbon dioxide (10 600 nm), the erbium:yttrium-scandium-gallium-garnet (Er:YSGG) and erbium:yttrium-aluminum-garnet (Er:YAG, 2940 nm), are selectively absorbed by water and act to ablate skin in a highly precise fashion. Vaporization of the epidermis and upper part of the dermis stimulates healing with de novo collagen and elastin formation, collagen contraction and resultant tighter and rejuvenated skin. While fully ablative resurfacing produces impressive results, the healing process normally takes weeks to months and is accompanied by a risk of scarring and pigmentary alteration. Thus, more so than for any other type of laser procedure, proper patient selection and consultation is paramount. The ideal patient for ablative cutaneous laser resurfacing is one with a Fitzpatrick skin phototype I or II, conditions that are amenable to ablative resurfacing, and realistic expectations of the resurfacing procedure and accompanying risks. For patients that are not ideal candidates or are unable to tolerate extended postoperative healing, the fractional ablative and non-ablative lasers offer a more facile recovery course, with the caveat of the possible need for multiple procedures.

There is no strong consensus regarding the topical preoperative agents for ablative laser skin resurfacing. The use of topical retinoic acid compounds, hydroquinone bleaching agents, or α-hydroxy acids for several weeks before ablative cutaneous resurfacing have been anecdotally advocated as a means of hastening recovery and decreasing the incidence of postinflammatory hyperpigmentation. Investigators demonstrated that the preoperative use of topical tretinoin, hydroquinone, or glycolic acid had no effect on the incidence of postablative laser hyperpigmentation. Likewise, due to the de-epithelialized and compromised skin barrier following ablative laser skin resurfacing, the concern for infection has led to many laser surgeons advocating the use of oral antibiotic prophylaxis. However, a controlled study demonstrated no significant change in the postlaser resurfacing infection rate in patients treated with prophylactic antibiotics. Moreover, because laser resurfacing can trigger a herpes labialis outbreak, some believe that all patients, should receive prophylactic oral antivirals such as acyclovir, famciclovir, or valacyclovir starting 1 day prior to resurfacing and continuing for 6–10 days postoperatively.

Technical aspects

Carbon dioxide laser

The Ultrapulse 5000 (Lumenis Corp, Yokneam, Israel), was one of the first high-energy pulsed-laser systems, and emits individual carbon dioxide pulses (ranging from 600 µs to 1 ms) with peak energy densities of 500 mJ. The SilkTouch (Lumenis Corp), another high-energy pulsed-laser system, is a continuous-wave carbon dioxide system with a microprocessor scanner that continuously moves the laser beam so that light does not dwell on any one area for more than 1 ms. The peak fluences delivered per pulse or scan range from 4 to 5 J/cm ² , which are the energy densities necessary for complete tissue vaporization. Studies with these and other pulsed and scanned carbon dioxide laser systems have shown that after a typical skin resurfacing procedure, water-containing tissue is vaporized to a depth of approximately 20–60 µm, with an underlying zone of thermal damage ranging from 20 to 150 µm.

The depth of tissue ablation is directly correlated with the number of passes performed and ideally is restricted to the epidermis and upper papillary dermis. Stacking of laser pulses by treating an area with multiple passes in rapid succession or by using a high overlap setting on a scanning device leads to deeper thermal injury with subsequent increased risk of scarring. An ablative plateau is reached, with less effective tissue ablation and accumulation of thermal injury. This effect is most likely caused by reduced tissue water content after initial desiccation, resulting in less selective absorption of energy. Removal of partially desiccated tissue by wiping and avoidance of pulse stacking is paramount to prevention of excessive thermal accumulation.

Ideally, the goal of ablative laser skin resurfacing is to vaporize tissue to the papillary dermis. Containing ablation to this level decreases the risk for scarring and permanent pigmentary alteration. In selecting treatment parameters, the surgeon must consider factors such as the anatomic location to be resurfaced, the skin phototype of the patient, and previous treatments delivered to the area. Areas with thinner skin (e.g., periorbital) require fewer laser passes, and laser resurfacing of non-facial areas (e.g., neck, chest) should be cautiously approached due to the relative paucity of pilosebaceous units in these areas. However, safe resurfacing of the neck has been reported. To reduce the risk of excessive thermal injury, partially desiccated tissue should be removed manually with wet gauze after each laser pass to expose the underlying dermis.

The benefits of cutaneous ablative laser resurfacing are numerous. With the carbon dioxide laser, most studies have shown at least a 50% improvement over baseline in overall skin tone and wrinkle severity. The biggest advantages associated with carbon dioxide laser skin resurfacing are the excellent tissue contraction, hemostasis, prolonged neocollagenesis, and collagen remodeling that it provides. Histologic examination of laser-treated skin demonstrates replacement of epidermal cellular atypia and dysplasia with normal, healthy epidermal cells from adjacent follicular adnexal structures. The most profound effects occur in the papillary dermis, where coagulation of disorganized masses of actinically induced elastotic material are replaced with normal compact collagen bundles arranged in parallel to the skin's surface. Immediately after carbon dioxide laser treatment, an inflammatory wound healing response begins, with granulation tissue formation, neovascularization, and increased production of macrophages and fibroblasts.

Absolute contraindications to carbon dioxide laser skin resurfacing include active bacterial, viral, or fungal infection or an inflammatory skin condition involving the skin areas to be treated. Isotretinoin use within the preceding 6–12-month period or history of keloids are also considered contraindications to carbon dioxide laser treatment because of the unpredictable tissue healing response and increased risk for scarring.

Erbium:yttrium-aluminum-garnet laser

The 2940-nm Er:YAG laser can more precisely ablate water than the carbon dioxide laser due to its wavelength corresponding to the 3000-nm absorption peak of water. The absorption coefficient of the Er:YAG is 12 800 cm ⁻¹ (compared with 800 cm ⁻¹ for the carbon dioxide laser), making it 12–18 times more efficiently absorbed by water-containing tissue than is the carbon dioxide laser. The pulse duration (mean 250 ms) is also much shorter than the carbon dioxide laser, resulting in decreased thermal diffusion, less hemostasis, and increased intraoperative bleeding which often hampers deeper dermal treatment. Because of the limited ability of the Er:YAG laser to result in thermal injury, the amount of collagen contraction is also significantly lower (1–4%) compared with that observed with carbon dioxide laser irradiation. Taken together, these characteristics lead to a direct linear relationship between fluence delivered and amount of tissue ablated of approximately 2–4 µm of tissue vaporization per J/cm ² and much smaller collateral zones of thermal necrosis (~20–50 µm) are therefore produced. Laser-induced ejection of desiccated tissue from the target site produces a distinctive popping sound. Manual removal of desiccated tissue is often unnecessary due to the limited thermal damage.

Fluences used for the short-pulsed Er:YAG laser commonly range from 5 to 15 J/cm ² , depending on the degree of photodamage and anatomic location. When lower fluences are used, it is often necessary to perform multiple passes to ablate the entire epidermis and three to four times as many passes are needed with the short-pulsed Er:YAG laser to achieve similar depths of penetration as with a single pass of the carbon dioxide laser. The need for multiple passes increases the likelihood of uneven tissue penetration in a treatment area. Deeper dermal lesions or areas of the face with extreme photodamage and extensive dermal elastosis may require upwards of nine or ten passes of the short-pulsed Er:YAG laser.

Pinpoint bleeding caused by inadequate hemostasis and tissue color change with multiple Er:YAG passes can hinder adequate clinical assessment of wound depth. Treated areas whiten immediately after treatment and then the white color quickly fades. These factors render it far more difficult for the surgeon to determine treatment end-points and thus extensive knowledge of laser–tissue interaction is required.

Conditions amenable to Er:YAG laser resurfacing include superficial epidermal or dermal lesions, mild photodamage, and subtle dyspigmentation. The major advantage of short-pulsed Er:YAG laser treatment is its rapid recovery period. Re-epithelialization is completed within an average of 5.5 days, compared with 8.5 days for multiple-pass carbon dioxide laser procedures. Postoperative pain and duration of erythema are reduced after short-pulsed Er:YAG laser resurfacing, with postoperative erythema resolving within 3–4 weeks. Because there is less thermal injury and trauma to the skin, the risk of pigmentary disturbance is also decreased, making the short-pulsed Er:YAG laser a good alternative in patients with darker skin phototypes. The major disadvantages of the short-pulsed Er:YAG laser are its limited ability to effect significant collagen shrinkage and its failure to induce new and continued collagen formation postoperatively. The final clinical result is typically less impressive than that produced by carbon dioxide laser skin resurfacing for deeper rhytides. However, for mild photodamage, improvement of approximately 50% is typical.

Erbium:yttrium-scandium-gallium-garnet (Er:YSGG) laser

The Er:YSGG laser emits at 2790 nm and lies between the CO ₂ and Er:YAG laser water absorption spectra, and was thus hypothesized to harvest the benefits of both CO ₂ and Er:YAG laser ablative resurfacing (i.e., milder thermal damage with faster recovery) with fewer of the drawbacks of each individual laser. Small studies have demonstrated these claims but a direct head to head comparison of the Er:YSGG to the CO ₂ or Er:YAG laser has yet to be performed. In our opinion, it remains a viable option for those seeking improvement of their dermatoheliosis without the prolonged downtime of ablative CO ₂ resurfacing.

Ablative fractional resurfacing (see )

While ablative resurfacing lasers remove tissue in a horizontal fashion, ablative fractional resurfacing devices drill vertically oriented columns into the skin and have the ability to achieve comparable clinical results while still keeping portions of epidermis intact, thereby allowing for quicker recovery and an improved safety profile. Fractional energy is delivered through microscopic zones of thermal injury, leading to coagulation necrosis and resultant new collagen formation (see ). An annular pattern of coagulation occurs, with increasing fluences resulting in increasing treatment depths. This annular coagulation leads to collagen contraction and tissue shrinkage, which translates to improvement in laxity, appearance of pores, and scars. Improvement in textural abnormalities, dyschromias, and mild skin laxity can be achieved in as little as a single treatment ( Fig. 34.1 ).

$FIGURE 34.1, Resurfacing with a fractionated CO 2 laser (A) before and (B) several months after a single treatment.$

Several devices perform ablative fractional resurfacing. The Fraxel repair (Reliant Technologies Inc, Mountain View, CA) system is the “first in class” fractionated carbon dioxide laser with a rolling handpiece that allows for treatment energies up to 70 mJ/cm ² . The ActiveFX (Lumenis Ltd, Yokneam, Israel) is another fractionated carbon dioxide device using a computerized pattern generator (UltraScan Encore CPG) with a 1.3 mm spot for moderate effects on tone, texture, and tightening with low downtime. DeepFX, another computerized pattern generator used with UltraPulse Encore (Lumenis Ltd) carbon dioxide laser, delivers 0.1 mm diameter spots; therefore, it enables tightening of skin with deep wrinkles and scars more effectively than other methods of skin resurfacing. The ablation depth and the residual thermal damage depend on the energy density (micropulse laser energy up to 50 mJ) and the number of stacked pulses (up to five) used. With increasing parameters, the postoperative bleeding increases and the patient's downtime will be prolonged. The Lutronic® eCO ₂ ™ (Lutronic Corporation, Goyang, S. Korea) dual mode CO ₂ laser system enables users to ablate tissue with 0.12 mm or 0.3 mm diameter microbeams. Fully ablative resurfacing can be performed with a 1.0 mm tip. The scanned microbeams are delivered using Controlled Chaos Technology™ (CCT™), which is an algorithm to pseudo-randomly deliver each laser microbeam as far apart as possible from the previous one, in an effort to minimize thermal diffusion between ablative columns. Other devices include a fractionated 10 600-nm CO ₂ RE (Syneron-Candela, Wayland, MA), a 2790-nm fractionated Pearl laser (Cutera, Brisbane, CA), and a Lux 2940-nm fractional handpiece (Palomar Medical Technologies Inc, Burlington, MA), which can be attached to a pulsed light laser system utilizing erbium laser energy to deliver deep dermal ablative columns.

While ablative fractional devices allow for quicker recovery than traditional fully ablative devices, when compared with their non-ablative counterparts, downtime can be considerably longer, lasting on average 5–7 days. The procedure is generally tolerated after topical anesthesia has been applied for 1 h and local nerve blocks are administered. If the patient is accompanied by a capable escort, an anxiolytic may be given. A forced air cooling system can be utilized to further minimize procedural pain. Most patients experience erythema, edema, and crusting which usually resolves within 7 days. Some patients experience hyperpigmentation, acneiform eruptions, or milia formation. Some laser surgeons advocate giving patients oral corticosteroids in the perioperative period to minimize associated edema. Antiviral and antibiotic prophylaxis should also be considered as part of the pre- and post-procedure care.

Results from a single treatment take 3–6 months to be fully realized. Most patients receive only one or two treatments, but selected patients with significant photodamage or acne scarring may require more. Several features of ablative fractional resurfacing represent true advances over traditional ablative lasers. While ablative fractional resurfacing can be performed safely on the neck and chest, hypertrophic scarring of the neck has been reported. Unlike ablative resurfacing, hypopigmentation following ablative fractional resurfacing has not yet been reported and appears to be very rare.

Optimizing outcomes

Side-effects associated with ablative skin resurfacing vary and are related to the expertise of the laser surgeon, the body area treated, and the skin phototype of the patient ( Table 34.2 ). Certain tissue reactions, such as erythema and edema, are expected in the immediate postoperative period and are not considered adverse events. Erythema can be intense and may persist for several months after traditional ablative procedures. The degree of erythema correlates directly with the depth of ablation and the number of laser passes performed. It may also be aggravated by underlying rosacea or dermatitis. Postoperative erythema resolves spontaneously but may be reduced with the application of topical ascorbic acid which may serve to decrease the degree of inflammation. Its use should be reserved until at least 4 weeks after the procedure in order to avoid irritation. Similarly, other topical agents such as retinoic acid derivatives, glycolic acid, and fragrance-containing or chemical-containing cosmetics and sunscreens should be strictly avoided in the early postoperative period until substantial healing has occurred. Adequate preoperative patient evaluation and education are absolute essentials to avoid the pitfalls discussed below and optimize the clinical outcome.

Table 34.2

Side-effects and complications of ablative laser skin resurfacing

Expected side-effects	Complications
	Mild	Moderate	Severe
Erythema Edema Pruritus	Extended erythema Milia Acne Contact dermatitis	Infection (bacterial, viral, fungal) Hyperpigmentation	Hypopigmentation Hypertrophic scarring Ectropion

Minor side-effects of laser resurfacing include milia formation and acne exacerbation, which may be caused by the use of occlusive dressings and ointments during the postoperative period, particularly in patients who are prone to acne. Milia and acne usually resolve spontaneously as healing progresses and the application of thick emollient creams and occlusive dressings ceases. Oral antibiotics may be prescribed for acne flares that do not respond to topical preparations. Allergic and irritant dermatitis can also develop from various topical medications, soaps, and moisturizers used postoperatively. Most of these reactions are irritant in nature due to decreased barrier function of the newly resurfaced skin.

Wound infections associated with ablative laser resurfacing include Staphylococcus, Pseudomonas, or cutaneous candidiasis and should be treated aggressively with an appropriate systemic antibiotic or antifungal agent. However, the use of prophylactic antibiotics remains controversial. The most common infectious complication is a reactivation of labial herpes simplex virus (HSV), which is most likely caused by the thermal tissue injury and epidermal disruption produced by the laser. After carbon dioxide resurfacing, approximately 7% of patients develop a localized or disseminated form of HSV. These infections develop within the first postoperative week and can present as erosions without intact vesicles because of the denuded condition of newly lased skin. Even with appropriate prophylaxis, a herpetic outbreak still can occur in up to 10% of patients and must be treated aggressively. Oral antiviral agents, such as acyclovir, famciclovir, and valacyclovir are effective agents against HSV infection, although severe (disseminated) cases may require intravenous therapy. Patients should begin prophylaxis by the day of surgery and continue for 7–10 days postoperatively.

The most severe complications associated with ablative cutaneous laser resurfacing include hypertrophic scar and ectropion formation. Although the risk of scarring has been significantly reduced with the newer pulsed systems (compared with the continuous wave lasers), inadvertent pulse stacking or scan overlapping, poor technique, as well as incomplete removal of desiccated tissue between laser passes, can cause excessive thermal injury that could increase the development of fibrosis. Focal areas of bright erythema, with pruritus, particularly along the mandible, may signal impending scar formation. Ultrapotent (class I) topical corticosteroid preparations should be applied to decrease the inflammatory response. A pulsed-dye laser (PDL) also can be used to improve the appearance and symptoms of laser-induced burn scars.

Ectropion of the lower eyelid after periorbital laser skin resurfacing is rarely seen, but if encountered it usually requires surgical correction. It is more likely to occur in patients who have had previous lower blepharoplasty or other surgical manipulation of the periorbital region. Preoperative examination is essential to determine eyelid laxity and skin elasticity. If the infraorbital skin does not return briskly to its normal resting position after a manual downward pull (snap test), then ablative laser resurfacing near the lower eyelid margin should be avoided. In general, lower fluences and fewer laser passes should be applied in the periorbital area to decrease the risk of lid eversion.

Hyperpigmentation is one of the more common side effects of cutaneous laser resurfacing and may be expected to some degree in all patients with darker skin tones. The reaction is transient, but its resolution may be hastened with the postoperative use of a variety of topical agents, including hydroquinone, retinoic, azelaic, and glycolic acid. Regular sunscreen use is also important during the healing process to prevent further skin darkening. The prophylactic use of these products preoperatively, however, has not been shown to decrease the incidence of post-treatment hyperpigmentation. Postoperative hypopigmentation is often not observed for several months and is particularly difficult because of its tendency to be intractable to treatment. The use of an excimer laser or topical photochemotherapy to stimulate repigmentation has proven successful in some patients.

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