Ablative Laser Skin Resurfacing

Summary and Key Features

• Ablative laser resurfacing has long been a very popular cosmetic procedure.

• A variety of carbon dioxide, erbium:yttrium-aluminum-garnet, and yttrium-scandium-gallium-garnet lasers are included in the category of ablative lasers.

• “Full-field” means 100% of the treated area is removed to the selected depth.

• Fractional means discontinuous portions of the treated area are removed in columns.

• Hybrid fractional lasers are a combination of ablative and nonablative fractional resurfacing.

• Recovery time is linked to depth of treatment and percentage of surface damaged.

• Fractional treatments have less downtime than full-field treatments.

• Experience with these lasers is important to achieving optimal results.

• Posttreatment care is very important, especially infection precautions.

• Complications can arise with these laser modalities.

Introduction

Ablative laser resurfacing encompasses a group of popular procedures in the United States and worldwide. These treatments can be broadly divided into two categories: “full-field” ablative resurfacing and “fractional” ablative resurfacing. Full-field ablative resurfacing is defined by confluent vaporization of treated epidermis and superficial dermis, allowing for impressive outcomes but significant associated downtime following treatment. In contrast, ablative fractional resurfacing results in vertical columns of vaporized tissue called microscopic thermal zones, but leaves the skin adjacent to these zones intact. These areas of intact skin expedite wound healing and reduce the associated downtime relative to full-field ablative resurfacing.

In the mid-1990s, full-field ablative procedures with (CO ₂ ) lasers were extremely popular. Cases of postoperative infections, delayed hypopigmentation and of scarring led to a rapid decline in the use of CO ₂ lasers in the early 2000s. The introduction of nonablative technology at the turn of the 20th century then caused full-field ablative resurfacing to largely fall out of favor. Ablative resurfacing resurged after 2004 with the introduction of fractional ablative lasers, which for many patients allowed a more acceptable compromise between downtime, the risk of complications, and clinical improvement with the skin only being treated in microthermal zones.

Recent trends in the number of resurfacing procedures performed reflect growing public interest in these treatments. From 1997–2016, the American Society for Aesthetic Plastic Surgery reported cosmetic procedure data from core specialties including dermatology, plastic surgery, and otorhinolaryngology. Overall, ablative resurfacing was the eighth most common nonsurgical procedure performed in 2016, with over 525,000 procedures performed ( Table 9.1 ).

History

Continuous wave lasers were first introduced into the dermatology and plastic surgery world in the 1970s for the treatment of vascular lesions and for treatment of a variety of benign cutaneous lesions. The introduction of the pulsed CO ₂ laser for skin resurfacing in the mid-1990s rapidly became popular, and largely replaced chemical peels and dermabrasion in many practices. The CO ₂ laser has a wavelength of 10,600 nm, has an absorbing chromophore of water, and is used to vaporize tissue. Continuous wave lasers were initially used but often resulted in excessive depths of ablation and unwanted collateral thermal damage. To limit both, competing technologies were developed to either deliver short pulses, each of which contained enough energy to cause tissue ablation (Ultrapulse laser, Lumenis lasers, Yokneam, Israel) or an optomechanical flash scanner used to scan a continuous laser beam in a spiral pattern (Silk-touch and Feather-touch lasers, (ESC) Lumenis lasers, Yokneam, Israel). Both methods created a tissue exposure time of less than 1 millisecond, which allowed tissue ablation with limited residual thermal damage of approximately 75–100 µm. Short-term results of eradicating wrinkles and tightening lax tissue were excellent, but hypopigmentation was seen at longer-term follow-up in some cases. These pigmentary complications and the considerable downtime created for the patient led to the demise of “full-field” CO ₂ laser resurfacing around the turn of the last millennium.

Erbium:yttrium-aluminum-garnet (Er:YAG) lasers (2940 nm) were introduced around 2000 and marketed for superficial resurfacing. Erbium lasers have a higher water absorption coefficient than CO ₂ lasers (approximately 10–15 times) and ablate tissue with much less residual thermal damage (5–10 µm). Initial machines were low-powered, lacked pattern generators, and needed a considerable number of passes and treatment time to achieve deeper depths of ablation. Subsequent systems had more significant power and thus could be used for efficient deeper resurfacing. There is a linear relationship between the energy delivered and depth of ablation, with approximately 3–4 µm ablated per joule of Er:YAG laser fluence delivered. Complications were fewer, yet the healing and downtime appeared to be similar to that of CO ₂ systems. Conclusions of comparative studies were that the combined depth of ablation and coagulation was the determining factor in length of recovery. Combination systems of CO ₂ and Er:YAG lasers were popular for a short time (Derma-K, Lumenis lasers, Yokneam, Israel) with the beams being delivered either sequentially or at the same time.

Variable or long-pulse Er:YAG lasers (Sciton Inc., Palo Alto, CA) allow control over the amount of residual thermal injury produced for a given amount of tissue removal. These variable pulse Er:YAG systems seem to produce etched-wrinkle reduction and some skin tightening similar to CO ₂ lasers, with a much shorter period of erythema and much lower risk of hypopigmentation. These devices have remained very popular since their introduction in 1998.

Other wavelengths for skin resurfacing have been introduced (2780 and 2790 nm) (Cutera Lasers, Palomar Lasers), which allow variable degrees of thermal damage and ablation settings, but have not had significant commercial success. Plasma skin resurfacing uses nitrogen plasma energy to coagulate a very controlled depth of skin. Healing times and results appear to be similar to Er:YAG lasers. These devices were popular for some time but were removed from the marketplace due to financial problems of the manufacturer. They were recently reintroduced into the market.

In 2004, Manstein and Anderson introduced the concept of fractional photothermolysis. Full-field or traditional laser resurfacing as described previously removes the entire skin surface in the area being treated, with depth of injury depending upon energy level. Fractional laser resurfacing, on the other hand, treats a small “fraction” of the skin at each session, leaving skip areas between each exposed area ( Fig. 9.1 ). This was first performed commercially using nonablative fluences at 1550 nm ([Reliant] Solta Medical, Mountain View, CA). These nonablative fractional lasers created a column of thermal damage with intact epidermis. Healing occurred from deeper structures, as well as from adjacent structures. This differs from full-field resurfacing in which healing occurred from only deeper structures. Deeper treatments (i.e., to the reticular dermis) can safely be performed using this approach than would be tolerated using a full-field treatment. Advantages of this approach include avoidance of an open wound and very low risk of pigment disturbance or scarring. Disadvantages have included the need for multiple treatments and somewhat less clinical response than with full-field ablative resurfacing. Since the introduction of the original system, there have been many manufacturers that have introduced similar nonablative fractional devices with wavelengths of 1440, 1540, and 1550 nm. These devices differ in power output, spot size, density, etc., and comparisons of clinical efficacy are difficult, yet similar degrees of tissue injury should produce similar clinical results.

Fractional ablative resurfacing with CO ₂ , Er:YAG, and yttrium-scandium-gallium-garnet (YSGG) systems was introduced with the intent of providing more significant results than nonablative fractional systems, while achieving shorter healing times and complications when compared with full-field ablative systems. During fractional ablative resurfacing, vertical columns of vaporized tissue termed microscopic thermal zones are created. Importantly, the epidermis between the microscopic thermal zones remains intact, allowing for more rapid healing relative to full-field ablative treatments (see Fig. 9.1 ).

These devices differ not only in wavelength but in system power, spot size, and amount of thermal damage created adjacent to and deep to the ablated hole. One popular Er:YAG system, the Sciton ProFractional, allows one to vary the amount of thermal damage similarly to their full-field system. Other newer CO ₂ fractional lasers allow variation of the thermal damage zones (Deka Medical), whereas others allow superficial and deeper penetration with a single scan (Syneron, Yokneam, Israel). As with the nonablative fractional systems, direct comparison between devices is difficult because devices differ in power output, spot size, density, and degree of thermal damage, but conceptually similar degrees of injury should produce similar clinical results.

The newest wavelength to be introduced into the fractional arena is the Thulium (1927 nm) by Solta Medical. This nonablative fractional device is especially effective in removing superficial pigment and treating actinic keratosis. Given the nonablative, minimal downtime and minimal discomfort aspects of thulium 1927 nm, other companies have now entered this space including Lutronic (Ultra) and Sciton (MOXI).

The newest fractional laser on the market is a hybrid fractional laser made by Sciton called the Halo. This is a very interesting device because it allows coincident delivery of first their Er:YAG fractional laser then a nonablative 1470-nm pulse in the same hole. This device is very efficacious and creates minimal healing times.

Patient Selection

Patient selection and a clear understanding of potential complications are important to achieving consistent results. The most common indications for both full-field and fractional laser resurfacing are superficial dyschromias, dermatoheliosis, textural anomalies, superficial to deep rhytides, acne scars, and surgical scars. Other conditions that may respond favorably to ablative lasers (either full-field or fractional) include rhinophyma, sebaceous hyperplasia, xanthelasma, syringomas, actinic cheilitis, and diffuse actinic keratoses. Dyschromias, such as melasma, have been successfully treated with fractional resurfacing, but results are not consistent. It seems that the thulium wavelength lasers do better with melasma over a series of treatment sessions. The most commonly treated area is the face, but body and neck skin may be resurfaced with variations of the technique. Non-facial areas lack the appendages necessary for skin rejuvenation, and treatment must be performed non-aggressively to avoid complications. These devices are generally used with patients with Fitzpatrick skin types I to IV but can be used in skin types V and VI, with modification of technique.

Patient assessment starts at the consultation with observation of the patient's Fitzpatrick skin type, ethnicity, and pathology to be treated. For example, deep acne scarring will not be successfully treated with a single treatment of nonablative fractional treatment, but mild textural issues may respond to superficial treatment. The next assessment is of the patient's tolerance of healing period “downtime.” A busy executive with no urgency for end point of clinical results may be able to be treated only with a series of no-downtime nonablative fractional therapy, whereas the bride's mother looking for maximum improvement in a short time to look her best for her daughter's wedding may need a single session with more aggressive treatment. The last parameter is one not usually discussed in medical journals or book chapters: patient finances. A deep full-field resurfacing performed under general anesthesia will be more expensive for the patient than a superficial treatment performed with topical anesthesia. However, in patients with deep rhytides a more aggressive procedure under general anesthesia may be more cost-effective than multiple more superficial treatments. Another consideration is same-session laser resurfacing while patients are undergoing other procedures, such as facelift, abdominoplasty, or esthetic breast surgery. These patients often have built-in downtime from other procedures and have the recovery time available for deep resurfacing.

Many of us with various devices in our offices can offer patients a plethora of treatment options, and this can be very confusing to the patient. An effective consultation will encompass a thorough evaluation of the pathology and provide options to the patients in terms of downtime, efficacy, risks, and cost.

Expected Benefits and Alternatives

The potential for improvement depends upon the device used, as well as the depth and degree of injury produced. There are many options for superficial treatment of texture issues, dyschromias, and superficial rhytides, including nonaggressive full-field resurfacing with Er:YAG, CO ₂ , YSGG, or plasma devices or with nonablative or ablative fractional treatment. Many practitioners are using combination therapy with superficial full-field treatment combined with fractional treatment, whereas others are combining fractional ablative and nonablative therapy and others again are using intense-pulsed light (IPL) therapy combined with resurfacing. Other treatments that may yield similar results for superficial lines and photodamage include light chemical peels, such as 15%–30% trichloroacetic acid, IPL devices, and Q-switched lasers (532 nm for dyschromias). We prefer lasers to chemical peels, owing to the uniformity and predictability of treatment because the device produces consistent tissue effects with minimal variability from pulse to pulse or patient to patient. The learning curve with lasers is less than with chemical peels, due to the predictability of the treatment. Expert chemical peelers may get similar results to laser treatment at a fraction of the laser cost, but years of experience are necessary to achieve consistency of results. IPL devices may be used to treat dyschromias and superficial vasculature—but these are rather non-specific devices with “filters” to target chromophores and require multiple sessions and do not address textural issues or rhytides. Q-switched lasers (532, 694, 755, 1064 nm) are excellent at removing dyschromias in one session but have resultant erythema that lasts for up to 10 days.

More significant pathology requires deep treatment to achieve results in a single session. Full-field resurfacing can produce impressive outcomes in a single treatment session, with a low rate of complications when appropriate treatment guidelines are followed. There is still a question of whether repeated superficial therapies with ablative fractional devices will achieve similar results to one more aggressive full-field session, although in the authors’ opinion this is not the case. Deep ablative full-field resurfacing may be performed with either Er:YAG or CO ₂ systems. YSGG in full-field mode and plasma devices do not ablate deep enough to treat more significant pathology. Acne scars appear to respond better to fractional therapy than to full-field therapy, although these treatments are not mutually exclusive and may be complementary. For instance, full-field single shot erbium may be applied to the shoulders surrounding acne scars prior to fractional therapy during the same treatment session. Alternative treatments may be deeper chemical peels, such as phenol, or dermabrasion. The authors think that lasers provide more consistent and reproducible results than chemical peels or dermabrasion.

Lasers and Technical Overview

As discussed previously, current devices used for ablative laser resurfacing include CO ₂ , Er:YAG, and YSGG lasers, in both full-field and fractional modes, and nonablative devices in a variety of wavelengths, including 1440, 1540, 1550, and 1927 nm ( Table 9.2 ). Some machines offer upgradeable expandable platforms in which full-field devices and fractional devices are available in one machine, whereas other companies offer only isolated full-field or fractional devices.

Erbium:Yttrium-Aluminum-Garnet Full-Field

The Er:YAG laser (2940 nm) has an absorption coefficient 10–16 times greater than the CO ₂ laser and ablates tissue more efficiently and leaves less residual thermal damage (5–10 µm). There is a linear relationship between energy density (fluence) delivered and tissue ablated with 3–4 µm of tissue removed per J/cm ² , and multiple passes can be used to produce deeper tissue removal without additive residual thermal injury. This leads to recovery time of deep full-field Er:YAG laser resurfacing of 7–14 days to full epithelialization followed by 4–8 weeks of erythema. Superficial and deep resurfacing can be performed with these devices with increasing results and increasing recovery times with deeper treatments ( Figs. 9.2 and 9.3 ). Complications, including hypopigmentation, are much less than with CO ₂ laser full-field resurfacing. In the opinion of one author (JLC) this is related to the fact that full-field erbium treatment is done to a recognized endpoint of pinpoint dermal bleeding.

Variable pulse Er:YAG systems allow a shorter ablative pulse followed by longer sub-ablative pulses to create increasing thermal damage. These devices are typically used to achieve CO ₂ laser-like results, but without the long healing times and complications, such as hypopigmentation.

Fractional Ablative Technology

Ablative fractional resurfacing can be performed with CO ₂ , Er:YAG, and YSGG devices. There are many devices available from many well-known laser manufacturers. Differences in devices are the mode of spot placement—scanning versus stamping, size of holes (width and depth) created, and power output of devices. Differences between fractional CO ₂ systems, fractional Er:YAG systems, and YSGG systems are similar to their full-field counterparts in that the CO ₂ systems cause more residual thermal damage. Newer Er:YAG systems have variable pulse widths, which cause CO ₂ -like thermal damage. Reepithelialization is quicker than with full-field ablation, and recovery time varies from hours to a few days, depending upon depth and density of treatment.

Both ablative fractional and nonablative fractional devices are used to treat acne and other scars ( Fig. 9.4 ). Multiple treatments are needed, and there is no current consensus as to the best technology for this at present. It was very common in our offices to perform combination treatment with superficial full-field Er:YAG resurfacing followed by Er:YAG fractional treatment. The superficial Er:YAG treatment improves skin texture and minor irregularities, whereas the fractional treatment is useful for collagen remodeling. This treatment regimen was replaced by treatment with a hybrid fractional laser with or without simultaneous IPL treatment.

As fractional CO ₂ laser treatments have been pushed to higher and higher coverages in an attempt to maximize efficacy, healing times predictably have increased. More importantly, complications, such as scarring and hypopigmentation, have been observed at coverages in excess of 45%. CO ₂ resurfacing histology consistently shows a significant component of tissue ablation and coagulation. Efficacious resurfacing is believed to require a significant component of both. One strategy that has been explored to increase coverage percentage and maximize efficacy involves a combination treatment with ablative Er:YAG fractional and nonablative fractional exposures in a single treatment session. This provides a component of largely ablative exposure with the fractional Er:YAG treatment and a component of coagulation with the nonablative fractional treatment. Rather than being spatially overlapped as in a fractional CO ₂ MTZ, the coagulation and ablation are separated. Coverages up to 65% are routinely applied with only a modest increase in healing time and erythema compared with fractional Er:YAG treatment alone and somewhat less than that reported for fractional CO ₂ . Advantages of this approach include preservation of the short recovery and low incidence of complications seen with fractional Er:YAG treatments and the potential for significant improvement even in perioral rhytides. Disadvantages include the need for two lasers or a single laser platform that offers both options and the time-consuming nature of the treatments ( Fig. 9.5 ).

This combined treatment regimen led to the introduction of the Sciton Halo hybrid laser. This device allows either nonablative fractional resurfacing with a 1470-nm laser or coincident treatment with both a fractional ablative wavelength (2940 nm) and a fractional nonablative wavelength 1470 nm. Treatment with this device has very little downtime, and the results of coincident ablative/nonablative resurfacing on pigment, texture, and pores appear to surpass that achieved with either nonablative or ablative fractional resurfacing alone ( Fig. 9.6 ). Fewer treatments are needed then with other fractional devices to achieve similar results. Newer protocols with this device are for combined treatment with an IPL device (Broad Band Light) and initial results we have seen appear to be better than non-combined treatments.