Review of Non-Ablative Laser Resurfacing Modalities Corresponding author for Coauthor: Proofs and reprints:
Review of Non-Ablative Laser Resurfacing Modalities Corresponding author for Coauthor: Proofs and reprints:
Edwin F. Williams III, MD, FACS Ravi Dahiya, MD
Williams Center for Facial Plastic Surgery Suite 1517
1072 Troy-Schenectady Road 410 Queens Quay W.
Latham, New York 12110 Toronto, ON MV53T1
(518) 786-7000 Canada
(518) 786-1160 (fax) dahiyarav@yahoo.com
edwilliamsmd @ pol.net
Assistant Clinical Professor of Surgery
Chief, Section of Facial Plastic and Reconstructive Surgery
Division of Otolaryngology Head and Neck Surgery
at Albany Medical College
Non-Ablative Laser Resurfacing
One of the cornerstones of a successful facial plastic surgery practice is skin rejuvenation. Chemical exfoliation, dermabrasion, and ablative laser resurfacing have been the modalities of choice in skin resurfacing. Both the CO2 and Erbium: YAG laser have been the gold standard of laser resurfacing. Though these lasers provide excellent results in rejuvenation they are associated with significant potential morbidity and a prolonged recovery period. Patients are counseled to expect at least two to three weeks of erythema and edema. The risks also include infection, hypopigmentation, milia, and permanent scarring. Ablative lasers, dermabrasion, and chemical exfoliation all result in epidermal effacement in addition to stimulating collagen synthesis in the dermis. This open wound not only has the potential morbidities listed but also requires extensive wound care.
The ideal modality of resurfacing will stimulate collagen synthesis in the dermis and spare the epidermis, eliminating the prolonged recovery period and limiting potential complications. Potential nonablative resurfacing techniques are essentially limited to laser technologies. Unlike mechanical abrasion and chemical exfoliation, light energy can be directed to only targeted levels of tissue. This concept, known as selective photothermolysis is based on the presence of chromophores. Blood vessels, water, and melanin are among several chromophores in the skin. Chromophores preferentially absorb light of a particular wavelength. By determining the absorption spectra of target dermal structures a laser of the appropriate wavelength can be selected. The other important concept in selective photothermolysis is thermal relaxation time (TRT). TRT is defined as the amount of time required for an object to dissipate one-half of its heat. Theoretically, a laser would only be selective if the pulsewidth is less than the thermal relaxation time, otherwise the thermal injury to surrounding tissue could eliminate the selective application of the laser. Thus the combination of targeting a specific component of tissue and limiting collateral damage by respecting the thermal relaxation time can result in an effective nonablative laser.
Several lasers have had multiple studies documenting efficacy in skin rejuvenation, including the 1320 nm Nd:YAG, Er:Glass, and pulse dye lasers. Though not a true laser, intense pulsed light has also been reported to improve rhytidosis.
Q -Switched 1064-nm Nd:YAG Laser
The first reported attempt at nonablative resurfacing was with the Q switched Nd:YAG laser. Goldberg and Whitworth, using a fluence of 5.5 J/cm2 and spot size of 3mm, found modest improvement in periorbital and perioral rhytids in 6 of 11 patients and excellent results in 3 of 11patients.1 Goldberg and Silapunt note in another study histologic changes in the dermis similar to ablative therapy.2 However, in the first study they describe pinpoint bleeding and protracted erythema (three months) in several patients. Another study using a lower fluence, by Newman et al., demonstrated less epidermal effacement but only mild to modest improvement of rhytids.3 Due to the substantial epidermal injury associated with the Q switched Nd:YAG laser at fluences that yield significant improvement, it has largely been abandoned as a nonablative resurfacing modality.
1320-nm Nd:YAG laser
More success has been reported with the 1320 nm Nd:YAG laser. To understand why, another aspect of laser-tissue interaction must be understood. Laser energy can be transmitted through, absorbed, scattered, or reflected by tissue. Tissue injury (both desired and undesired) occurs with absorption of laser photon energy. Absorption occurs secondary to the presence of chromophores and as a function of the wavelength of the laser used. The penetration depth is determined by the reciprocal of the absorption coefficient at a given optical wavelength. To target the dermis, a depth of 100 to 400 um below the skin surface is the goal. This desired depth corresponds to a wavelength of 1.3 to 1.8 um, a requirement met by the 1320nm Nd:YAG and Er:Glass lasers.
One of the earlier studies of the 1320 nm Nd:Yag laser, by Menaker et al., provided discouraging results.4 The laser parameters included a spot size of 5 mm, 20 msec macropulse duration, and fluence of 32 J/cm2. Cryogen spray was applied to protect the epidermis. In this study, of the 10 treated patients, only 4 patients demonstrated minimal improvement in their rhytids. The statistically insignificant improvement was associated with notable morbidity. Both hyperpigmentation and pitted scarring were observed in 4 and 3 patients respectively. With their observed complications and limited benefit they withheld recommending the 1320nm Nd:YAG laser for nonablative resurfacing. A larger study (n= 35) by Kelly et al., using similar laser parameters for three treatments, found fewer complications than in the Menaker study. However, the study also demonstrated minimal benefit.5 At 24 weeks, only patients with severe rhytids demonstrated a statistically but clinically limited improvement (less than one point improvement on a one to nine scoring scale).
Levy et al. included more objective outcomes in their study of 13 patients, including not only independent observer evaluations but also histologic and prolifometric assessment.6 Cryogen spray cooling and previously described parameter were used over two treatments. The subjective assessment methodology was poorly described and we are told that 4 patients had “good improvement.” The objective measures were better described and suggest that the dermis did undergo significant remodeling, with more and better-organized collagen present. The epidermis, analyzed with the another objective measure, based on silicon imprints, suggested limited improvement. Because of the limited epidermal improvement, the authors of this study also had reservation in recommending the 1320nm Nd:YAG laser alone as a resurfacing tool. More recent studies also demonstrate substantial improvement in collagen deposition and overall organization in the dermis with marginal clinical improvement in the epidermis. 7 Goldberg reported the best clinical outcomes, in a study in which patients received 4 treatment sessions.8 The increased number of treatments may certainly have played a role in the improved outcomes in the Goldberg study and it remains to be seen what the ideal number of treatments will be to achieve our resurfacing goals.
Erbium:Glass laser
In an attempt to penetrate appropriate dermal depths and minimize melanin absorption, the Er:Glass laser with a wavelength of 1.54 um has been used as a nonablative modality. Ross et al. were among the first to describe their results with the 1540nm Er:Glass laser.9 They found significant increases in collagen deposition in the dermis of post-treatment punch biopsies. The positive dermal response was outweighed though by significant epidermal damage with both short-term erythema and edema and longer term scarring. Using a different pulse mode, Fournier et al were able to reduce the epidermal injury reported by Ross. The laser was set at 8J/cm2/pulse and 2 Hz with a 4 mm spot handpiece in this study, with 4 treatments given over 6 week intervals. Fournier et al. used a “pulse-train” mode whereas Ross had employed a single pulse.10 Multiple studies have illustrated the advantage of multiple short pulses over longer single pulses. This finding is based on the concept of thermal relaxation time, as described earlier. Not only can surrounding thermal injury be limited by an appropriately short pulse but also by insuring adequate time between pulses (usually 3-5 times the thermal relaxation time). Subjectively, 62% of Fournier’s patients reported being “satisfied” with the results, and observers of the pre and post -treatment photographs described a “global mild improvement.” Prolifometric analysis with silicon imprints of 16 patients showed a 36 % reduction of anisotropy, an optical measure of rhytids. Though an impressive statistic, the silicon imprints were only obtained in 16 of 52 patients with no explanation of the selection criteria for the imprinted patients. Ultrasound and histologic data demonstrated dermal thickening but were also only available for a minority of the patients. A more recent study by Lupton et al. using 10 J/cm2 also provided modest results.11 Patients were treated for three sessions at one month intervals and photo documentation and patient improvement scores were obtained at 1, 3 and 6 months after the last treatment. Both patients and independent evaluator used a quartile scoring system (i.e. “1” represents an improvement of <25%, 2 – 25-50%, etc). In the periorbital regions the mean improvement score was 1.6 for patients and 2.1 given by the observers. Only descriptive results are provided of the histologic analysis, with “a mild but noticeable increase in dermal fibroplasias.”
Other smaller series using the Erbium Glass laser have reported similar outcomes, with no study being able to claim results approaching those of the CO2 laser. Nonetheless, refinement of the parameters used for nonablative resurfacing has accomplished the goal of minimizing epidermal injury with this laser.
Pulsed-Dye Laser
The pulsed-dye laser holds promise as an effective nonablative resurfacing modality. At a wavelength of 585 nm the laser is predominately absorbed by oxyhemoglobin. As the vascular plexus lies in the dermis and not the epidermis, the epidermis is spared. More importantly the fibroblasts surrounding the vessels in the dermis are stimulated which results in collagen deposition.
An extensive prospective-randomized study conducted at our institution using a porcine model with multiple parameters of the pulsed-dye laser demonstrated, with statistical significance, the abundant collagen deposition that results after even one treatment.12 The amount of collagen deposition was statistically no different than in CO2 laser treated spots. This promising histologic outcome would suggest the likelihood of significant clinical improvement. Our study also elucidated the effects that changing each parameter produced. Not surprisingly increasing fluence, spot size, and pulse duration all resulted in more collagen deposition. No epidermal injury occurred at any of our pulsed-dye laser settings. No other study has provided comparable objective histologic analysis of the effects of the pulsed-dye laser.
Unfortunately though, few large, well-designed studies of the clinical benefits of resurfacing with the pulsed-dye laser are described in the literature. Zelickson et al. were among the first to describe their results with the pulsed-dye laser in 20 patients.13 After one treatment, 90% of their treated patients with mild to moderate rhytids experienced clinical improvement. 13 Forty percent of patients with moderate to severe rhytids showed clinical improvement. However, the parameters employed included a spot size of 7 to 10 mm and fluence from 3.o to 7.6 J/cm2. This relatively high power resulted in significant edema and purpura, which lasted for up to 2 weeks, negating the nonablative nature of the treatment. Bjerring et al. treated 30 patients with a lower fluence, 2.4 J/cm2, thereby avoiding epidermal injury.14 Moreover, they were still able to demonstrate significant rhytids reduction in a majority of their patients. Fitzpatrick treated 15 patients with moderate to severe rhytidosis on one hemiface with the pulsed-dye laser and with the cryogen cooling spray alone on the other hemiface.15 Blinded photographic analysis demonstrated 11 of 15 patients to have improvement on the treated hemiface, with no significant morbidity. Though these latter studies are compelling there remains a lack of a large, well controlled study with long term follow up with the use of the pulsed-dye laser.
Intense Pulsed Light
Intense pulsed light (IPL) is by definition not a laser, rather the product of flashlamp devices that emit noncoherent light at wavelengths between 550 and 1,100 nm. With the use of absorbing filters, longer wavelengths can be selected out which then target vessels of the dermis. As with the pulsed-dye laser, the surrounding fibroblasts are thought to be stimulated and this is the proposed explanation for the rhytid reduction reported by several authors. One study of only 5 patients showed “moderate to very good” improvement.16 The study, however, was without controls, highly subjective, and described burns that lasted up to 7 days. Weiss et al. offer their experience with 80 patients.17 They treated the face, neck and chest and looked at “skin texture” and actinic changes as their outcome measures. Though long term (4 years) improvement in 83% patients is described, there are no controls and texture can be interpreted to include some actinic changes not exclusively rhytidosis. Also, multiple different treatment sites are compared to one another, which limits interpreting the results. Goldberg and Cutler treated 30 patients over 4 sessions.18 Two observers graded 6-month post-treatment photographs and determined 16 patients to have some improvement and 9 patients to have substantial improvement. As with other studies described, no controls were used. Blistering was reported in 10% of patients. This certainly represents a high complication rate for a treatment touted as “nonablative.” Interestingly, in our porcine model study, we used IPL as a comparison to the pulsed-dye laser. Despite having a company representative present to demonstrate proper use of the IPL device, we observed significant epidermal injury at post-treatment day number 3.
Conclusions
Several trends become apparent in reviewing the studies of the multiple modalities being used for nonablative skin resurfacing. First, none of the proposed modalities have been proven to approach the efficacy of ablative laser resurfacing. Nonetheless, there certainly is a role for a modality that can address mild to moderate rhytidosis in patients who cannot afford any “down time”. With appropriate selection of parameters we have seen that all of the lasers described can be nonablative. The question remains as to how effective they can be with the lower fluences, spot sizes and pulse durations that are being used to avoid epidermal injury. The histologic data clearly illustrates that a dermal response results, more specifically that collagen deposition occurs. This dermal improvement has been well documented with all of the modalities reviewed.
Less conclusive statements can be made in regard to the clinical outcomes. Though there are studies that provide, at a glance, impressive results, their validity is limited by lack of appropriate controls and efforts to maximize objectivity. This flaw can somewhat be attributed to the subjective nature of the outcomes, reduction in rhytids. Fitzpatrick was able to overcome this by treating one hemiface alone and using the other side as the control. Obviously replicating this type of study on a large scale is difficult both because it is difficult to find patients who would consent to such a study and to get approval by most IRBs. The design of most of the current studies is for observers to grade the degree of improvement in post treatment photographs as compared to pretreatment photographs. This method has an inherent bias in that the observer is told that a patient has been treated. With the mild improvement that is often described, a more challenging process to an observer would be to have to determine the order of photographs from pretreatment, between treatment sessions and finally at the end of all treatments. After properly sequencing the photographs, the observer could then grade the degree of improvement. This would insure that the improvement was not secondary to changes in lighting, distance, differences in resolution/focus, or the desire to show some change simply to validate the study. Nonetheless, most of the clinical studies indicate that mild to moderate improvement in fine rhytids, particularly periorbital rhytids, can be achieved with many of the tested modalities.
Multiple treatments over several months appear to help improve outcomes especially with the pulsed-dye and Er:Glass lasers. The need for multiple treatments can certainly be seen as a disadvantage of these resurfacing techniques as compared to ablative modalities. However, the ability to return to work or other normal activities the same day may prove to outweigh this consideration for many patients.
In summary, the 1320nm Nd:Yag, Er:Glass, and pulsed-dye lasers have been shown through both histologic and clinical studies to show promise as nonablative resurfacing modalities. Intense pulsed light and the Q-switched 1064 Nd:YAG laser have fewer scientifically rigorous and consistent studies to support their use as effective modalities. However, the former mentioned lasers should not be purported to be equivalent tools to the CO2 or Er:YAG lasers. They do not and are not intended to address photo damage. Nonetheless, these modalities do seem to improve fine rhytids through their effects on the dermis. Further clinical trials with varying settings will be required to determine the ideal method for reducing rhytids without the cost of epidermal injury.
References
1. Goldberg DJ, Whitworth J. Laser skin resurfacing with the Q-switched Nd:YAG laser. Dermatol Surg. 1997;23:121-127.
2. Goldberg DJ, Silapunt S. Histologic evaluation of a q-switched Nd:YAG laser in the nonablative treatment of wrinkles. Dermatol Surg. 2001;27:744-746.
3. Newman J, Lord J, McDaniel DH. Non-ablative laser therapy in skin types I-VI: clinical evaluation of facial treatment using QS 1064 nm Nd:YAG laser combined with carbon suspension lotion. Lasers Surg Med. 2000; suppl 12:17.
4. Menaker GM, Wrone DA, Williams RM, Moy RL. Treatment of facial rhytids with a nonablative laser: A clinical and histologic study. Dermatol Surg. 1999;25:440-444.
5. Kelly KM, Nelson S, Lask GP, Geronemus RG, Bernstein LJ. Cryogen spray cooling in combination with nonablative laser treatment of facial rhytids. Arch Dermatol. 1999;135:691-4.
6. Levy JL, Trelles M, Lagarde JM Borrel MT, Mordon S. Treatment of wrinkles with the nonablative 1,320-nm Nd:YAG laser. Ann Plast Surg. 2001;47:482-488.
7. Trelles MA, Allones I, Luna R. Facial rejuvenation with a nonablative 1320 nm Nd:YAG laser: A preliminary clinical and histologic evaluation. Dermatol Surg. 2001;27:111-116.
8. Goldberg DJ. Full-face nonablative dermal remodeling with a 1320 nm Nd:YAG laser Dermatol Surg. 2000;26:915-918.
9. Ross EV, Miller C, Meehan K, McKinlay J, Sajben P, Trafeli JP, Barnette DJ. One-pass CO2 versus multiple-pass Er:YAG laser resurfacing in the treatment of rhytids: A comparison side-by-side study of pulsed CO2 and Er:YAG lasers. Dermatol Surg. 2001;27:709-715..
10. Fournier N, Dahan S, Barneon G, Diridollou S, Lagarde JM, Gall Y, Mordon S. Nonablative remodeling: Clinical, histologic, ultrasound imaging, and profilometric .
11. Lupton JR, Williams CM, Alster TS. Nonablative laser skin resurfacing using a 1540 nm Erbium Glass laser: a clinical and histologic analysis. Dermatol Surg 2002; 28:9:833-835
12. Dahiya R, Lam S, Williams EF. A systematic histologic analysis of nonablative laser therapy in a porcine model using the pulse-dye laser. Arch Facial Plast Surg 2003; 3: 518-23.
13. Zelickson BD, Kilmer SL, Bernstein E, et al. Pulsed dye laser therapy for sun damaged skin. Lasers Surg Med. 1999;25:229-236.
14. Bjerring P, Clement M, Heickendorff L, Egevist H, Kiernan M. Selective non-ablative wrinkle reduction by laser. J Cutan Laser Ther 2000;2:9-15.
15. Roston E, Bowes LE, Iyer S, Fitzpatrick RE. A double-blind, side-by-side comparison study of low fluence long pulse dye laser to coolant treatment for wrinkling of the cheeks. J Cosmetic & Laser Ther. 2001;3:129-36.
16. Hernandez-Perez E, Ibiett EV. Gross and microscopic findings in patients submitted to nonablative full-face resurfacing using intense pulsed light: a preliminary study. Dermatol Surg 2002;28:8:651-655.
17. Weiss RA, Weiss MA, Beasley KL. Rejuvenation of photoaged skin: 5 years results with intense pulsed light of the face, neck, and chest. Dermatol Surg. 2002;28:12:1115-1119.
18. Goldberg DJ, Cutler KB. Nonablative treatment of rhytids with intense pulsed light. Lasers Surg Med. 2000; 26:196-200.
19. Stuzin JM, Baker TJ, Baker TM, Kligman AM. Histologic effects of high-energy pulsed CO2 laser on photoaged facial skin. Plast Reconstr Surg. 1997;99:2036-2050.
20. Trelles MA, Mordon S, Benitez V, Levy JL. Er:YAG laser resurfacing using combined ablation and coagulation modes. Dermatol Surg. 2001;27:727-34.
21. Kelly KM, Majaron B, Nelson S. Nonablative laser and light rejuvenation. The newest approach to photodamaged skin. Arch Facial Plast Surg 2001;3:230-35.
22. Khatri KA. The effects of variable pulse width of Er:YAG laser on facial skin. Dermatol Surg. 2001;27:332-334.
Figure Legends.
Figures 1A and 1B and demonstrate the significant reduction in rhytids that the CO2 laser can achieve even in the setting of relatively deep rhytids. (A- left, pre-treatment, B- right, post-treatment).
Figures 2A and 2B. Many of the nonablative therapies have demonstrated increased collagen deposition in the dermis. Note the increased width of the fibroblasts and the overall decreased cellularity in the treated dermis (B- right, treated)
Figure 3. A patient being treated with the pulse-dye laser. The left peri-ocular region has been treated without any notable purpura or other signs of laser treatment.
Figures 4A and 4B provide a closeup view of the periocular region, demonstrating the typical moderate reduction in fine rhytids we have observed with pulse-dye laser resurfacing. (A- left, pre-treatment; B- right, post-treatment).
Synopsis
Due to the considerable morbidities and recovery time associated with CO2 laser resurfacing, many efforts are being made to discover a less ablative resurfacing modality. A thorough review of the literature demonstrates promising but less than ideal results for all of the currently employed lasers. The clinical efficacy does not appear to be as significant as the histologic results that have been documented. Our review of the literature also demonstrates that not all of the modalities to be equal.