CUSTOM DERMATOLOGY SEARCH:
ADVANCES IN DERMATOLOGIC SURGERY - Editors: Jeffrey S. Dover, MD and Murad Alam, MD
Nonablative Laser and Light Therapy: An Approach to Patient and Device SelectionM. Alam, MD1 and J. S. Dover, MD, FRCPC2,3,4
11Section of Cutaneous and Aesthetic Surgery, Department of Dermatology, Northwestern University, Chicago, IL
2SkinCare Physicians, Chestnut Hill, MA
3Department of Medicine (Dermatology), Dartmouth Medical School, Hanover, NH
4Section of Dermatologic Surgery and Cutaneous Oncology, Department of Dermatology, Yale University School of Medicine, New Haven, CT
What is Nonablative Laser and Light Therapy?
Nonablative laser and light treatments (other equivalent terms include subsurface resurfacing, photorejuvenation, and laser toning) have been used for several years for the aesthetic improvement of photoaged skin, particularly of the face. These treatments provide an alternative to traditional full-face laser resurfacing, an ablative modality in which carbon dioxide and/or erbium:YAG lasers are used to remove the entire epidermis and portions of the dermis. Ablative resurfacing improves skin roughness, fine and moderately deep facial wrinkles, and dyspigmentation by replacing the damaged epidermis and superficial dermis with a new papillary dermis and overlying epidermis. While results in expert hands are impressive, patients undergo an unpleasant healing period of 1-2 weeks during which time there is swelling, oozing and crusting, as well as discomfort. All nonablative treatments improve skin texture and tone, some improve wrinkles or surface irregularities including scarring, and some additionally address dyspigmentation and/or erythema and telangiectasia. The epidermis is not visibly disrupted in nonablative treatment. Nonablative resurfacing is attractive to physicians and patients alike because, contrary to ablative resurfacing, there is little if any downtime.
What are the Available Nonablative Devices?
Based on the work of Zelickson and Kilmer1 the pulsed dye laser was initially found to induce dermal fibroblasts to produce a zone of new collagen within the papillary dermis after one or two purpuric treatments to photoaged periocular skin. Since then it has been determined that a significant number of wavelengths of both visible and infrared radiation applied to the skin have the ability to induce this very same change. It remains to be determined which of the different wavelengths is most effective at inducing this change.
Numerous laser and light devices,2 including the KTP laser (532nm), pulsed dye laser (585nm, 595nm), intense pulsed light (IPL) devices (515-1200nm), Nd:YAG lasers (1064nm Q-switched, 1064nm long-pulse, 1319nm, 1320nm), diode lasers (980nm, 1450nm), Er:Glass laser (1540nm) and light emitting diodes have been adapted to be effective in, or specifically developed for, nonablative resurfacing. The mid-infrared devices, including 1320, 1450, and 1540nm devices, appear most effective for wrinkle and acne scar reduction. Red color and vascular lesions are best addressed by vascular-selective devices, such as the KTP, pulsed-dye, and long pulsed Nd:YAG lasers. The KTP also has efficacy for pigmentation as does the Q-switched Nd:YAG laser, but IPL devices, by virtue of their broad emission spectrum, appear the most effective for simultaneous treatment of both red and brown patches.
Clinical Efficacy: Does Nonablative Therapy Work
Clinical evaluations of this therapeutic intervention have routinely relied on patient and treating physician evaluations and before and after photographs. To assure some degree of standardization in the evaluation process, images have been rated by double-blinded observers, and these ratings supplemented by more objective noninvasive texture measurement such as profilometry, ultrasound, and the PRIMOS (Phaseshift Rapid In-Vivo Measurement of Skin, GF Mestechnik, Teltow, Germany) 3-dimensional in vivo skin imaging system.3 Differences between before and after results can be subtle and not always seen easily, even in side-by-side photographic comparisons. However, the popularity of these treatments among patients and physicians strongly suggests that differences, while not always easy to quantify, are likely real.
Tissue Effects: How and Where Does Nonablative Therapy Work?
For nonablative therapy, an epidermal surface temperature of 40-48º C is ideal since this correlates with a dermal temperature of 55 to 65º C, which is required for collagen denaturation. Recently, there has been some attempt to define the mechanisms underlying the clinical results observed with nonablative resurfacing. Most invasive investigations of nonablative resurfacing have compared the histology of preoperative and postoperative biopsies. A very few investigators have employed in situ hybridization to dissect what is occurring at the mRNA level; however, this work has been limited in scope. In histologic analyses, dermal thickening interpreted as “increased” and “organized” horizontally arrayed bundles of normal collagen fibers in the papillary dermis may in fact be a vestige of trauma and inflammation caused during remodeling after thermal or light injury to the dermis.4 Whether the alterations produced by nonablative laser are as persistent as typical photodamage, and the extent to which they are comparable to photodamage, is not known. However, the lasers used for nonablative resurfacing do not emit at ultraviolet wavelengths, and at present there is no evidence to indicate that nonablative laser treatments are deleterious.
Patient Selection and Education
Deciding which patients are best suited for nonablative rejuvenation depends in part on understanding what they want so that it can be determined if nonablative therapy is likely to provide these results. Good candidates for nonablative resurfacing tend to be relatively young, usually 25-65 years of age, and have minimal sagging of the face. Patients should understand that skin texture will improve and fine lines in particular will be softened, not eradicated. Cumulative aesthetic benefits from nonablative resurfacing are similar in type though less in magnitude than the results of ablative resurfacing. Additionally, since changes will occur gradually, typically after three to six or more treatments, those receiving nonablative treatments should not expect dramatic results immediately.
Patients who want to minimize treatment discomfort and downtime tend to appreciate nonablative treatments. These treatments are variably painful. The infrared sources are the most painful of these non-ablative procedures and usually require topical anesthesia for the procedures to be tolerable. Mild erythema and edema do occur following each treatment, but these sequelae remit within minutes to a few hours or may be concealed with cosmetics. Intense treatments can elicit moderate erythema and edema, which may peak 1-2 days after treatment and tend to subside a day or two later. In general, it is important to distinguish between the infrared nonablative devices (1320nm, 1450nm, 1540nm) on the one hand, and pulsed dye lasers, IPLs, and 532 and 1064nm Nd:YAG lasers on the other. Infrared lasers, while uncomfortable, are associated with only a few hours of redness and swelling, while side-effects and longer duration tissue effects are routine with the other devices.
Dark-skinned patients or those with a tendency to develop hyperpigmentation after skin injury can often safely undergo nonablative infrared therapy. These lasers are less prone to pigmentary complications, and patient skin color is less important when using these. With the non-infrared devices, treating tan patients is more risky, and skin color problems after treatment, more likely. Although recent evidence indicates that, in most cases, dark-skinned and Asian patients seldom develop pigmentary abnormalities after nonablative treatment, the risk of hyperpigmentation and hypopigmentation in such patients is still greater than in lighter-skinned patients.
After nonablative treatment, little if any post treatment care is required. Unusually stringent sun protection is not necessary after nonablative therapy although patients should refrain from active sun-seeking behaviors for a few days thereafter. Patients who prefer to continue to receive maintenance therapy for the texture and color of their facial skin will often be satisfied with nonablative resurfacing. After the standard course of three to six nonablative facial treatments separated by 3-4 week intervals, treatments can be continued indefinitely on a 3 to 4 times/year basis. Some patients may choose to receive subsequent treatment courses on different devices to obtain cumulative benefits.
Lasers and light sources should be chosen so that the features most bothersome to the patient are best addressed. Most devices are relatively specific, in that they are better for some purposes.
In general, the less specific the patient objective, the greater the likelihood of satisfaction with nonablative therapy. Thus, patients who want removal of a particular feature, like redness or brown spots, or a particular wrinkle, tend to be less pleased after treatment than those interested in overall facial skin rejuvenation. Specific complaints are better treated with a laser device and setting specific for that indication (e.g., a Q-switched laser for lentigines, or a pulsed-dye laser with purpura for a spider angioma).
Specific Features of Nonablative Devices
KTP or frequency-doubled Nd:YAG laser (532nm)
Pulsed-dye laser (585nm, 595nm)
Intense-pulsed light device (500-1200nm)
Nd:YAG laser (1064nm)
Mid-infared lasers (1320nm Nd:YAG, 1450nm diode, 1540nm Er:Glass)
Future Directions for Nonablative Therapy
New machines may provide more specific improvements of greater absolute magnitude. As the mechanisms underlying nonablative therapy are better understood, these treatments may be adapted to exploit these biochemical and physical changes.9
Also, combined rejuvenation regimens that incorporate nonablative resurfacing will likely be further perfected. Botulinum toxin and soft-tissue augmentation materials are already being used on the upper and lower face, respectively, to improve lines of negative facial expression and hence augment the wrinkle reduction achievable by nonablative therapy. Glycolic acid peels, and other superficial abrasion techniques such as microdermabrasion can buff and exfoliate the epidermis in association with nonablative therapies that thicken the dermal collagen. The overall result, a rosier glow of the skin and a smoother skin texture, will likely be enhanced as materials technology continues to improve.
All content ©2004-2014 SkinTherapyLetter® |
Last modified: Wednesday, 20-Jan-2016 15:39:04 MST