History

Laser skin resurfacing represents one of the least invasive methods with the highest efficacy and safety profile for rejuvenating the aging face. Traditional ablative skin resurfacing rapidly gained early acceptance since the first introduction of the CO₂ laser in 1964. Ablative skin resurfacing methods (CO₂ or the Erbium:YAG lasers), specifically target intracellular water in the skin based on the theory of selective photothermolysis. The CO₂ laser heats the target within cells instantaneously to greater than 100°C leading to vaporization of tissue on the surface layer of the skin; coagulation necrosis of cells and denaturation of extracellular proteins in the next layer; and finally non-fatal cellular damage in the deeper zones of the skin. Ablative lasers remove 100% of the epidermis and varying thickness of underlying dermis that results clinically in a smoother appearance to the skin and skin tightening due to heat induced collagen shrinkage. While ablative lasers have long been the gold standard for the treatment of photodamage, the applicability of the treatment has been limited by the potential for unfavorable side effects and by the prolonged healing period and downtime patients require before returning to their routine. Frequently, patients have post-treatment erythema, edema, burning and crusting. The erythema may last on average 4.5 months and pigmentary alteration, acne flares, herpes infection/reactivation, scars, milia, and dermatitis also occur. Single pass CO₂ laser resurfacing can reduce the severity of these side effects, however.

Non-ablative fractional photothermolysis was first introduced in 2005 with the introduction of the 1550-nm erbium-doped fiber laser (Reliant Technologies, Mountain View, CA). Initially the laser was approved for the soft tissue coagulation application, based largely on early studies of forearm tissue. In 2005 Khan et al. reported on the use of the first fractional resurfacing device, a 1550-nm erbium-doped fiber prototype laser system that produced microscopic columns of thermal injury surrounded by intact tissue using a handpiece that scanned across the skin up to 8 cm/second while delivering the microarray pattern to the skin. These microscopic treatment zones (MTZs) range in diameter from 70 to 100 micrometer in diameter and 250 to 800 micrometer in depth and are produced by varying the depth of the focused beam. Tissue in these coagulated zones is not vaporized and the epidermis and stratum corneum are left intact leaving the skin erythematous, edematous, but without evidence of wounding. The device is FDA cleared for the treatment of periorbital rhytids, pigmentary alteration, melasma, skin resurfacing, and surgical scars.

The handpiece of the fractionated laser makes direct contact with the skin’s surface and uses an intelligent optical tracking system to deliver an even array of MTZs. These are columns of tissue coagulation that show no loss in the integrity of the overlying stratum corneum (Fig. 77.1). The incipient wound healing cascade and inflammatory response in which heat shock protein-70 is a central player, initiates a number of incompletely understood events that leads to increase in collagen synthesis and collagen reorganization. Healing also involves the extrusion of damaged epidermal components, termed microepidermal necrotic debris (MEND), which clinically could be observed as a superficial exfoliation following treatment that imparts a fine rough sand paper-like feel to the skin and is associated with a mild bronzing color of the skin in the areas of treatment. This clinically translates into the observed improvement in photodamage, including softening of rhytids, tightening of pore ostia, improvement in dyschromia, and a general textural smoothening of the skin.

Fig. 77.1 H & E section of human skin 1 day after fractional resurfacing showing microscopic treatment zones (large arrows) and MENDS (arrowheads).

Though non-ablative fractional photothermolysis is a well-tolerated and effective modality for an expanding variety of conditions such as photoaging, periorbital wrinkling, mild to moderate acne scarring, melasma, pigmented lesions, and poikiloderma of Civatte, patients generally require multiple treatments to achieve significant results; however even with multiple treatments, severe acne scarring is only minimally improved with non-ablative energies. Additionally, the results for severe photodamage is modest in comparison to fully ablative CO₂ resurfacing. Ablative fractional photothermolysis was developed more recently to achieve an improved treatment outcome requiring fewer treatments than non-ablative fractional photothermolysis with shorter downtime and improved side-effect profile than ablative resurfacing.

In early 2008, ablative fractional photothermolysis was introduced in the form of a novel ablative 30W CO₂ laser (Reliant Technologies, Inc., Mountain View, CA). Ablative fractional photothermolysis is a technique similar to non-ablative fractional photothermolysis in that a pixilated pattern of microscopic ablative wounds surrounded by healthy tissue is deposited on the skin in a manner similar to that of non-ablative fractional photothermolysis. Ablative fractional photothermolysis combines the increased efficacy of fully ablative techniques with the safety and reduced downtime associated with non-ablative fractional photothermolysis. As the literature on ablative fractional resurfacing is in its infancy and is rapidly evolving at the time of preparation of this chapter, the discussion presented here focuses on non-ablative fractional photothermolysis, and we refer the reader to recent (Chapas et al. 2008) and future publications on this topic.

Physical evaluation

Assessment of patients’ expectations of the procedure needs to be done during the cosmetic consultation. Realistic expectations need to be clearly stated prior to embarking on a series of non-ablative fractional resurfacing treatments. Patients should be advised that only modest results are achieved early in the series, and that more significant improvement will be observed as the series of treatments progress. For the application to photorejuvenation, the optimal candidate would have mild to moderate photodamage. While severe photodamage may be improved as well with fractional resurfacing, the clinical improvement at the endpoint of treatment is expected to be only modest.

The cosmetic consultation visit should focus on the following:

Anatomy for procedure

Fractional photothermolysis, unlike ablative systems used for skin rejuvenation, can be safely used both on facial and non-facial locations. While the most common application is photorejuvenation of the face, photodamage on the neck, chest, and external arms, are the next most common applications. Abdominal stretch marks, scars on the back, scalp, and extremities can all be treated safely with fractional resurfacing. Similar to facial treatments, there is no wounding of the skin following fractional photothermolysis treatments on non-facial areas. Post-treatment scarring is generally rare, if ever encountered.

The period of time to resolution of erythema in non-facial areas is prolonged compared to facial skin. As such, the treatment density and treatment energy may need to be altered to achieve equivalent healing times for the individual patient in whom this may be a concern.

Both upper and lower eyelids can also be safely treated to achieve an overall rejuvenation and, in some cases, tightening of eyelid laxity. The method involves retraction of the eyelid skin over the supraorbital and infraorbital rim and limiting treatment to the retracted area. Eye shields should be employed if treatment is extended beyond the orbital rims to the lid margin to avoid the risk of corneal damage. One series shows impressive tightening of the eyelids and improvement in eye aperture following a series of treatments using this method.

Technical steps

Preparation for fractional resurfacing involves thorough cleansing of the skin, followed by a degreasing step where 70% alcohol is used to prepare the area. Topical anesthesia is then applied. We tend to use 30% lidocaine in a gel base applied for 1 hour prior to the treatment. Although for the overwhelming majority of patients pain during the procedure is well-tolerated, select patients will require analgesics, local anesthesia, and/or nerve blocks for the procedure.

Just prior to treatment the topical anesthetic is removed. We have observed that all anesthetic ointment must be completely removed from the skin before treating so as to avoid backsplash that may cloud the windows of the roller tip reducing the fidelity of the beam. Each “track” of the roller tip is easily visualized as each pass leaves a treatment imprint on the skin that ensures proper placement of the subsequent track.

The handpiece of the laser device makes direct contact with the skin and is rolled along the area in linear fashion. The treatment energy and treatment density can be varied depending on the application. Treatment density can be increased by performing a greater number of passes and/or overlapping subsequent tracks of the laser with the previous one. Typically the direction of each pass is alternated between a superior–inferior direction and a horizontal left to right one. Forced cool air should always be used in combination with fractional resurfacing to improve patient discomfort during treatments and to protect the epidermis from the risk of overheating. Bulk heating can occur if treatments are performed too vigorously without a cooling source for epidermal protection.

It is important that the operator be attentive to the amount of total energy delivered to one area of the face in order to administer equal treatments on both sides of the face. Typically, we divide the face into cosmetic subunits. Treatment of one side of a particular subunit is completed followed by the subunit before moving on to another subunit. This allows careful delivery of equal energies to both sides of any given subunit. It is also important to deliver equal numbers of total MTZ density which is done by equalizing the numbers of passes on each side of the face.

Hand speed for the device has an upper threshold above which the density of the delivered MTZs falls off. The maximum speed is inversely related to the treatment energy selected and with the selected MTZ density. For example, the maximum speed at a 40 mJ treatment energy and density 264 MTZ/cm² is 5.5 cm/sec compared to 3.2 cm/sec at 70 mJ and 258 MTZ/cm², or 8.0 cm/sec at 40 mJ and 162 MTZ/cm². It is therefore important to maintain a constant subthreshold hand speed to deliver the desired MTZ density evenly to both sides of the face.

A rough guide for parameter selection has been published. One should take into consideration the application for which one is treating, as well as the skin phototype of the patient within the individual patient’s social context in the selection of treatment parameters. For scarring processes, we tend to use a higher treatment energy with lower total density. For textural improvement such are rhytids and other photoaging applications, a medium treatment energy is selected with higher density. Dyschromias are best treated with more superficial penetration of the laser; thus, a lower treatment energy at higher density is our choice.

Darker skin types can be treated effectively by cutting back on total treatment density while maintaining the treatment energy for the particular application. Although fractional photothermolysis has a very favorable side effect profile in all skin types, darker skin types are best approached cautiously in experienced hands. Even though the downtime associated with fractional photothermolysis treatments is negligible, busy patients whose work and/or social obligations requires absolutely no erythema are common in many urban practices. The patient’s social context should always be considered when choosing parameters for any one treatment. Lighter treatments with a lower density at the same treatment energies can improve healing time dramatically and allow patients with busy social schedules to have little or no erythema for upcoming social engagements, while maintaining some treatment efficacy. The need for additional treatment should be discussed with the patient ahead of time to properly gauge expectations in such a setting.

For photorejuvenation of the skin, 3–5 treatments are the usual recommendations for optimal improvement. Scars and dyschromia, including melasma, may improve further with additional treatments.

Postoperative care

Following treatment, the skin is erythematous and mildly edematous. Wounding is generally not observed, although reports of superficial linear erosions that heal without scarring exist. Patients are advised to use band cleansers and a heavy moisturizer (e.g. Aquaphor Healing Ointment®) for the next few days for the duration of the healing process. As erythema wanes, a superficial exfoliation that imparts a rough sandpaper-like texture to the treated area ensues and may be accompanied by an itching sensation. Moisturization of the skin at this point hastens the exfoliation and recovery to smooth, healthy appearing skin surface.

We routinely use prophylactic oral antivirals beginning the day of treatment for three days, with the goal of preventing reactivation of herpes virus. This is done even in the absence of a history of herpes infection as a significant percentage of the population shed herpes simplex virus asymptomatically. Topical and oral antibiotics are usually unnecessary, unless a severe acneiform eruption occurs following treatment. Acneiform eruptions following therapy are best addressed with the use of a topical antibacterial acne agent and/or an oral tetracycline depending on the severity of the eruption. Short courses of oral steroids have been used to reduce post-treatment edema. It has been suggested that steroids may limit the efficacy of treatment by altering the wound healing process. The use of steroids should therefore be chosen on a case-by-case basis and individualized to a patient’s needs. Short course low to medium potency topical steroids may be useful in treating eczematous eruptions that can occur in the treatment area during and shortly following the healing period.

Complications

Adverse effects of fractional photothermolysis range from the most common, pain, erythema, edema and xerosis a few days following treatment, to the less common findings of acneiform eruptions, and rarely pruritus and scarring. Downtime is minimal as most patients can return to social activities in 2 days. Fisher and Geronemus examined the frequency of 14 different adverse effects using patient surveys following treatments and on subsequent treatments. They noted all subjects had erythema resolving within 3 days. Edema was present in 82% of cases and also resolved rapidly. Xerosis also was commonly observed starting 2 days following treatments and resolved in 3 to 4 days with moisturization of the skin. 75% of patients were able to return to full social activity in 2 days. Pain scores were found to average 4.6 (1 to 10 scale) with 8–12 mJ treatment energy at a density of 2000 MTZ/cm².

Additionally, fairly common acneiform eruptions may accompany the healing process and persist after it, in some cases. These are easily controlled with topical benzoyl peroxide-based or antibiotic-based acne products and with short courses of oral antibiotics (usually tetracycline-type antibiotics) for more severe or persistent cases. Eczematous eruptions can also follow treatment. Short courses of low to mid potency topical steroids easily control these eruptions.

Some concern for lidocaine toxicity from topically applied anesthesia due to a “compromised” skin barrier during fractional photothermolysis has been expressed in the literature, though alternative explanations for the few reported cases have been recently presented. This has not been observed thus far in our experience.

Pearls & pitfalls

Pearls

• Acne and other scars should be treated as early as possible following an inciting insult. We have observed improved responses in more recent scars as compared to older ones. Surgical scars can be safely treated as early as one month following an uneventful surgery and postop recovery (Figs 77.2–77.4).

• Eyelids can be treated safely and rapidly by retraction of the eyelid skin over the orbital rim and limiting treatment to the portion of the lid that can be retracted, or in the case where eyeshields are used, to the lid margin. Rejuvenation and, in some cases, tightening may be achieved (Figs 77.5–77.7).

• When treating scarring, patients should be advised that more treatments give more results. It should be clearly stated, however, that scars cannot be erased.

• In contrast to ablative laser systems, off the face fractional resurfacing is safe and effective and has a negligible risk of scarring.

• Both hyperpigmentation and hypopigmentation can be improved with fractional resurfacing. This conundrum has yet to be explored (Figs 77.8, 77.9).

Fig. 77.2 Pre- (A) and post-treatment (B) photographs of a patient with a depressed surgical scar on the forehead treated with a series of fractional photothermolysis treatments. Improvement in pigmentation, depression and overall quality of the scar is evident.

Fig. 77.3 Pre- (A) and post-treatment (B) photographs of a patient with a graft scar on the nose following repair of a Mohs surgery defect following a series of fractional photothermolysis treatments. Improvement in the pigmentation and texture of the scar can be observed.

Fig. 77.4 Dramatic improvement in acne scarring is evident following a series of fractional photothermolysis treatments.

Adapted from Geronemus RG. Fractional photothermolysis: current and future applications. Lasers Surg Med 2006;38:169–176. Reprinted with permission of John Wiley & Sons, Inc.

Figs 77.5, 77.6 and 77.7 Upper eyelid tightening and improvement in eyelid aperture is observed in these patients following a series of fractional photothermolysis treatments.

Fig. 77.7 Adapted from Geronemus RG. Fractional photothermolysis: current and future applications. Lasers Surg Med 2006;38:169–176. Reprinted with permission of John Wiley & Sons, Inc.

Figs 77.5, 77.6 and 77.7 Upper eyelid tightening and improvement in eyelid aperture is observed in these patients following a series of fractional photothermolysis treatments.

Figs 77.5, 77.6 and 77.7 Upper eyelid tightening and improvement in eyelid aperture is observed in these patients following a series of fractional photothermolysis treatments.

Fig. 77.8 Pre- (A) and post-treatment (B) photographs of a patient with melasma treated with a series of fractional resurfacing treatments. Improvement in melasma and hypopigmentation is also noted.

Adapted from Geronemus RG. Fractional photothermolysis: current and future applications. Lasers Surg Med 2006;38:169–176. Reprinted with permission of John Wiley & Sons, Inc.

Fig. 77.9 Pre- (A) and post-treatment (B) photographs of a patient with post-inflammatory hypopigmentation treated with a single fractional photothermolysis treatment. Improvement in color is already evident.

Pitfalls

• Inadequate cooling of the epidermis and too many repetitive passes may lead to bulk heating of the epidermis and lower layers of the skin that can result in blistering, wounding and scar formation.

• Reactivation of zoster virus and herpes simplex virus can be incited by any resurfacing method, including fractional resurfacing. As a significant portion of the general patient population sheds herpes simplex virus asymptomatically, it is imperative to prophylax with oral antiviral medication against reactivation of viral infection. Failure to do so could potentially be a serious pitfall.

• Aggressive treatment of melasma, especially in darker skin phototypes, could lead to worsening of the pigmentary alteration. It is best advised to approach such cases with caution, with lighter treatments perhaps in a “test” area to gauge a particular patient’s response to therapy.

• Unrealistic patient expectations may result in premature termination of the treatment course before full benefit is realized. Realistic patient expectations should be established during the initial consultation, and care should be taken to avoid “over-selling” the benefits of therapy. Full disclosure to a patient fully educated about the potential benefits, risks, expectations, and limitations of therapy are essential to avoid this pitfall.

• Patients with severe photodamage are not optimal candidates for fractional resurfacing. Improvement is expected to be only modest in this group. It is best to offer other methods of rejuvenation, including surgical methods and appropriate referrals, in the best interest of the patient to avoid the pitfall of a disappointed patient at the endpoint of therapy.