Laser Resurfacing

Although laser physics was first described by Albert Einstein in 1917, laser technology did not appear until the 1960s. Only in recent times have the CO2 and erbium lasers found their way into the cosmetic surgeon's armamentarium as skin resurfacing tools. These high-energy lasers have revolutionized the treatment of photoaged skin. In contrast to other forms of skin resurfacing, laser resurfacing has captured the attention of many people worldwide. When referring to laser resurfacing, the media conjure up the image of someone using a magical wand to transform a severely photoaged face into a youthful-appearing one. This fictional belief has led patients who were once fearful of undergoing chemical peeling to flock to the cosmetic surgeon's office for laser skin resurfacing. These patients have been mistakenly told that recovery from laser resurfacing will be markedly reduced and that complications are less likely. As these beliefs are not true, patients must be better informed as to the true advantages and disadvantages of laser resurfacing. The main advantage to laser resurfacing is the ability to treat certain patients who might not otherwise be candidates for other methods of skin resurfacing. This is particularly true for patients with Fitzpatrick type IV-VI skin types, who may be at greater risk of developing pigmentary problems after deep phenol chemical peeling.

HISTOLOGIC CHANGES

The histologic changes observed after treatment with high-energy pulsed CO2 lasers are similar to those found in patients undergoing resurfacing with phenol chemical peeling. Lasers produce a controlled thermal injury that extends to the upper reticular dermis. As the wound heals, angiogenesis and fibroplasia are stimulated as new collagen is laid down. Improvement in epidermal morphology, including the reversal of epidermal atypia and a return of cellular maturation and vertical polarity, are consistent features found after laser resurfacing. Epidermal healing is usually complete by 2 weeks after the procedure, whereas dermal healing continued for 4 to 6 months. Histo-logically, the major difference between laser resurfacing and phenol resurfacing is the impact to the melanocyte. After phenol chemical peeling, epidermal melanocytes lose their ability to synthesize melanin. By contrast, after treatment with the CO2 laser, melanocytes retain their ability to produce melanin. This has been demonstrated in the biopsies from black skin, in which melanocytic activity returned 3 months after laser resurfacing. For this reason, patients with darker skin types who are otherwise poor candidates for phenol peeling, may be successfully treated by CO2 laser resurfacing. Although the laser is less detrimental to melanocyte function, there is still a risk of hypopig-mentation as the depth of penetration increases. This is true of all skin resurfacing agents and should not be overlooked.

Indications

CO2 laser resurfacing may be used for many types of clinical problems; however, we find it most useful in patients seeking treatment for dermatologic conditions affecting the reticular dermis. We have found that patients with acne scarring benefit more from CO2 laser resurfacing than from any type of chemical peeling. In our practice, it has supplanted dermabrasion as the procedure of choice for the treatment of acne scarring. For patients with deep ice-pick type scars, the best treatment is punch excision and grafting, followed by laser resurfacing. This has produced improved results.

Laser skin resurfacing may also be used for patients seeking improvement of both fine and coarse facial rhytids. Overall, rejuvenation of photoaged skin is produced by the regeneration of elastic fibers and dermal collagen. Improvement in skin tightening and overall skin texture is comparable to results obtained with other chemical peeling agents. For the treatment of fine facial rhytids, we prefer TCA chemical peeling, as it is safer, faster, and less costly. Patients seeking treatment for epidermal dysplasias, including those with actinic keratoses, may also benefit from laser skin resurfacing. The laser's high energy results in the thermal ablation of these dysplasias. The epidermis regenerates with normal healing and, as it does, significantly improves the quality of the skin's appearance. Laser resurfacing is also useful for treating facial dyschromias. Dyschromias appear as a result of pigment that is unevenly distributed along the basement membrane. As with other resurfacing techniques, laser resurfacing improves this condition by reducing this clumping of pigment and distributing it more evenly.

Evaluation

When evaluating a patient who is considering laser skin resurfacing, several factors need to be evaluated regardless of the type of laser being used. The patient's skin type, skin thickness, degree of oil content, and the area to be resurfaced are among the most important variables to be considered. Thinner, drier skin in the lower eyelid region of an elderly patient will generally require fewer passes as compared with the thicker, oily skin in the forehead region of a younger patient. Laser treatment should therefore be individualized and the pulse energy selected appropriately. A higher pulse energy will produce more complete ablation and vaporization of the tissue, whereas a lower pulse energy will result in less tissue vaporization. However, lower energies also elicit increased dermal damage secondary to increased conductive thermal injury. For this reason, higher pulse energies are preferred, as greater precision is obtained with fewer passes.

Pretreatment Care

As with other types of skin resurfacing procedures, we prefer to pretreat our patients with a combination of 8% hydroquinone, 1% hydrocortisone, and 0.05% retinoic acid. This regimen offers several advantages, including a shorter healing period and a lower risk of postoperative pigmentary disturbances. In addition, we use an antiviral agent and antibiotic prophylaxis in all our patients. This consists of oral acyclovir 400 mg three times per day, and Keflex 250 mg four times per day, starting 2 days before laser resurfacing and continuing for 5 days postopera-tively. We have found that this significantly reduces the risk of developing herpes infections, which may occur in 10% of the population despite a negative herpes simplex history. Prophylactic antibiotics reduce the risk of problems related to bacterial infections. Although rare, we have had instances in which a partial-thickness wound was converted into a full-thickness injury attributable to a bacterial infection that led to scar formation. Meticulous postoperative wound care has helped minimize these potentially devastating complications.

Patient Preparation

In the operating suite, the patient is placed in an upright sitting position and the regions to be resurfaced are marked. Special attention is paid to the natural shadow beneath the mandibular border, where the line of demarcation can be camouflaged. We do not advocate laser resurfacing of the cervical region, as the cervical skin heals more slowly and may display scarring secondary to its reduced number of adnexal structures.

Many types of anesthesia may be used for patients undergoing laser skin resurfacing. When resurfacing the entire face, we prefer IV sedation along with nerve blocks and infiltration of 1% lidocaine as needed. When individual facial subunits or other small regions are resurfaced, local infiltration of 1% lidocaine is preferred. We have not been especially satisfied with the use of EMLA cream, although other physicians advocate its use. Instead, we prefer to use sodium bicarbonate 8.4% mixed with lidocaine, to reduce the pain associated with injection. After local infiltration is completed, tetracaine eyedrops are instilled into the patient's eyes, before protective corneal shields are inserted. Protection of the eye is extremely important when using the laser and should not be disregarded. Other safety precautions must also be employed to avoid intraoperative complications. The patient's hair and surrounding inflammable drapes must be protected with wet towels; the flow of supplemental oxygen must be stopped, as these represent potential fire hazards. To avoid injury to the dental enamel, a moist gauze sponge should be placed over the patient's teeth when resurfacing the perioral region. In addition, all operating room personnel must wear protective eye gear, and a smoke evacuator should be activated to remove laser plume, which may harbor infective agents. Finally, after all necessary precautions have been taken, the laser is tested by firing it at a moistened wooden tongue blade. This ensures that the appropriate settings have been selected and that the laser is functioning properly before laser delivery to the facial skin.

USING THE LASER

As with other skin resurfacing techniques, laser resurfacing of the face is done in a regional fashion. The deepest individual rhytids are generally treated first, using a single pass of the laser. After this localized resurfacing, the remainder of the subunit is treated. When resurfacing the periorbital region, we avoid treating the pretarsal orbicularis region of the upper eyelid. Although it does little for the overall result, it increases postlaser edema and the risk of scarring and webbing significantly, particularly in the medial aspect of the eyelid. The remaining portions of the periorbital region, including the skin of the preseptal area and lateral crow's feet, are then resurfaced with two or three passes as required. The glabella, forehead, nasal, and cheek regions are then treated in a systematic fashion. The skin in these regions is thicker and may therefore be treated with multiple passes with a reduced risk of scarring. The perioral region is treated last. In older patients, this area may exibit significant deep rhytids requiring multiple passes to eradicate. It is not unusual for these patients to require three passes for effective treatment of this area.

Understanding Laser Injury

Understanding the endpoint of laser resurfacing is critical to achieving a safe and effective result. Judging the depth of penetration is a visual art that cannot be determined solely on the basis of the number of passes made with the laser. Treatment must be individualized and should not be performed using a "cookbook" approach. When laser resurfacing, several key visual clues can be observed as the treatment proceeds. The first pass of the CO2 laser removes the epidermis and penetrates the papillary dermis. The skin color will appear pink, corresponding to the level of the dermal-epidermal blood vessels. The next pass of the laser will generally penetrate the upper reticular dermis, as the skin appears whitish brown. As additional passes are performed, the skin will turn a chamois color. When this color appears, the midreticular dermis has been reached, and resur facing should not be carried further. Even if residual rhytids remain, resurfacing beyond this point should not be performed, as this will lead to scarring.

Laser Safety and Predictability

The predictability of laser skin resurfacing may be improved by following several guidelines. When laser resurfacing, a certain degree of spot overlap is required to ensure that the result will be satisfactory. However, if the overlap is too great, char builds up and begins to act as a heat sink. When this occurs, increased conductive thermal injury causes additional unpredictable tissue injury, which can lead to postoperative scarring. For this reason, char should always be removed after every pass of the laser. We use a saline-soaked 4 x 4-in. gauze sponge to remove the char before proceeding to the next pass. This allows the necrotic tissue to be removed in a simple manner. After removing the tissue, the skin should be dried before additional resurfacing. If the tissue is wet, the laser will not penetrate the skin in a predictable manner.

Postoperative Wound Care

Although some physicians prefer to use closed-wound dressings after laser skin resurfacing, we currently prefer open-wound dressings. We have used Flexan for regional and full-face laser skin resurfacing in the past but have had some difficulty keeping the dressing in place. Although easier for the patient, closed dressings limit postoperative wound inspection and may increase the incidence of postoperative infections. More recently, we have preferred to use open-wound care consisting of Elta or Eucerin cream for the first 5 to 7 days. This requires more patient compliance as the dressing is reapplied 4 to 5 times per day, but we find that reepithelialization occurs rapidly, with a lower risk of developing postoperative infections. At 7 to 10 days, once reepithelialization has occurred, the Eucerin cream is replaced with Eucerin lotion, which is continued for up to 6 weeks until the sebaceous glands begin to resume their normal functioning. After reepithelialization has occurred, pa-tients may begin using camouflage makeup. Patients are instructed to avoid direct exposure to sun for 6 weeks and are instructed to use a SPF 25 sunscreen during this period.

Complications

Hyperpigmentation Although postinflammatory hyperpig-mentation may occur in any patient undergoing skin resurfacing procedures, the risk may be lessened by pretreating the skin with a bleaching agent. We pretreat our patients, especially those with type III skin or greater, with a combination of 8% hydro-quinone, 1% hydrocortisone, and 0.05% retinoic acid for up to 4 weeks before they undergo laser resurfacing. By following this preoperative protocol, patients with Fitzpatrick type III or IV skin can undergo laser resurfacing with a reduced risk of postoperative hyperpigmentation. We have also treated patients with type V and VI skin with some success. These patients, however, usually develop transient hyperpigmentation and require prolonged skin care with bleaching agents. Rarely, hyperpigmentation may persist for longer than 6 months. Superficial TCA peels will correct this condition.

Herpes Simplex Infection The most common infection resulting after laser resurfacing is herpes simplex. Similar to other forms of skin resurfacing, herpes simplex infection poses a risk for all patients. We prefer to pretreat all our patients with acyclovir or valacyclovir 400 mg 3 times per day. Despite prophylaxis, some patients will still develop herpes infections during the postoperative period. When this occurs, valacyclovir 500 mg 4 times per day is recommended. These patients need to be followed very closely, as they are at increased risk of postoperative scarring. When treatment is instituted early and aggressively, herpes infection generally will respond well without subsequent complications.

Scarring Hypertrophic scarring after laser resurfacing is most likely to be the result of improper laser techniques, postoperative infections, or poor wound care. Although most experienced surgeons rarely experience this complication, its occurrence is very disconcerting. By following the proper techniques and understanding how to read the laser, postoperative scarring will infrequently occur. If scarring begins to develop, it should be treated aggressively with low-dose intralesional Kenalog injections, starting approximately 4 weeks postoperatively. Patients should be followed up every 2 weeks and additional injections given as needed. Most scars can be treated effectively with this approach. Rarely, a formal scar revision is necessary.

Prolonged Erythema Prolonged erythema is an expected outcome after laser resurfacing. It is related to new collagen formation and angiogenesis and usually lasts several months. In general, the deeper the laser treatment, the greater the degree and duration of erythema. When erythema lasts more than 3 months, we prefer to use 1 to 2.5% hydrocortisone lotion. We have not experienced erythema lasting longer than 6 months.

Hypopigmentation Hypopigmentation after laser resurfacing occurs more often in patients with Fitzpatrick type I or II skin. It becomes more apparent in these patients because they have less pigment in their skin to camouflage the dermal changes that occur after laser therapy. Hypopigmentation may also be noted more readily by the patient who undergoes regional resurfacing because of the contrast in the untreated areas. In general, the deeper the laser penetrates the dermis, the greater the chance of developing hypopigmentation. Unlike hyperpig-

mentation that can be successfully treated with bleaching agents, this problem is generally more problematic because the only treatment for the patient is camouflage makeup.

Other Potential Laser Complications Lasers are powerful instruments that can potentially be hazardous if proper precautions are not followed. Because the CO2 laser absorbs water, proper ocular protection must be worn by all personnel and patients in the operating room to avoid serious ocular damage. Reflection hazards, electrical hazards, pollution hazards, and fire hazards also need to be prevented. Only experienced personnel should be allowed to use this equipment.

SUMMARY

Laser resurfacing has already proved a good alternative to other skin resurfacing methods. However, the benefits of laser resurfacing will not be known until long-term results are obtained. Unfortunately, because of the public's high demand and the media's ever-increasing intrigue for laser resurfacing, many physicians now routinely use laser techniques. As a result, patients are victimized by overzealous operators who do not have the proper training with this technology. In well-trained hands, laser skin resurfacing has been an extremely successful tool used to treat photoaged skin.

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