You are in: eMedicine Specialties > Ophthalmology > LID Laser Tissue ResurfacingArticle Last Updated: Jun 19, 2006AUTHOR AND EDITOR INFORMATIONSection 1 of 11
  Author: Adam J Cohen, MD, Assistant Professor, Department of Ophthalmology, Northwestern University Feinberg School of Medicine; Consulting Surgeon, Myers Wyse Center for the Eye; Director, Center for Facial Rejuvenation; Founding Partner, HC Consulting, Inc Adam J Cohen is a member of the following medical societies: American Academy of Ophthalmology and American College of Surgeons Coauthor(s): Samer Alaiti, MD, Clinical Assistant Professor, Departments of Dermatology and Internal Medicine, University of California at Los Angeles School of Medicine; Michael B Stevens, MD, PhD, Consulting Staff, Department of Plastic Surgery, Kaweah Delta Hospital Editors: Stephen D Plager, MD, FACS, Chief, Department of Ophthalmology, Dominican Hospital; Assistant Clinical Professor, Department of Ophthalmology, Stanford University Hospital; Simon K Law, MD, PharmD, Assistant Professor of Ophthalmology, Jules Stein Eye Institute; Chief of Section of Ophthalmology Surgical Services, Department of Veterans Affairs Healthcare Center, West Los Angeles; Mark T Duffy, MD, PhD, Consulting Staff, Division of Oculoplastic, Orbito-facial, Lacrimal, and Reconstructive Surgery, Green Bay Eye Clinic, BayCare Clinic; Lance L Brown, OD, MD, Ophthalmologist, Affiliated With Freeman Hospital and St John's Hospital, Regional Eye Center, Joplin, Missouri; Hampton Roy Sr, MD, Associate Clinical Professor, Department of Ophthalmology, University of Arkansas for Medical Sciences Author and Editor Disclosure Synonyms and related keywords: CO2 laser resurfacing, carbon dioxide laser resurfacing, cutaneous laser resurfacing, mechanical abrasion, chemical peeling INTRODUCTIONSection 2 of 11
  Until the advent of cutaneous laser resurfacing in the late 1980s, physicians had long utilized mechanical abrasion and a variety of chemical peeling agents to restore a youthful look to the aged face. Some authors reported satisfactory resurfacing results with the use of continuous wave carbon dioxide lasers. This technique was not widely employed because of the significant thermal damage that accompanied the use of continuous wave lasers, which meant a high likelihood of potential scarring. The application of short-pulsed, high-energy, scanned carbon dioxide lasers and other laser systems that limit skin heating have revolutionized laser resurfacing. INDICATIONSSection 3 of 11
Recognition of suitable candidates for carbon dioxide laser resurfacing is of paramount importance to avoid undesired outcomes. Generally, middle-aged patients (40-65 y) with fair skin and fine-to-moderate static (nondynamic) wrinkles are ideal candidates. Selecting patients with realistic expectations (those who seek improvement, not complete eradication of wrinkles or scars) is important. Rhytids Carbon dioxide laser resurfacing (as the sole treatment) can achieve excellent results in patients with mild-to-moderate surface texture changes and fine superficial or moderate static wrinkles (not deep furrows or severe dermatoheliosis, see Image 1). Carbon dioxide laser resurfacing combined with botulinum toxin A (BOTOX®, Allergan) for dynamic rhytids, or with cervicofacial rhytidectomy and/or blepharoplasty or eyebrow lifting, can also result in excellent aesthetic improvement. Scars Acne scars can be classified into 3 basic types: shallow depressed scars, wide-base atrophic scars, and ice-pick scars. The first 2 types of acne scars are generally amenable to carbon dioxide laser resurfacing. Fibrotic or ice-pick scars often require punch excision, punch grafts, or punch elevation. Scar-base lifting and injection of filling substances for atrophic acne scars (completed as a separate procedure at a different time) can be combined with laser resurfacing for optimal results. Varicella and smallpox scars may also be improved with carbon dioxide laser resurfacing. Dermatoheliosis Carbon dioxide laser resurfacing is a valuable tool for facial rejuvenation of photodamaged skin. Improvement of fine lines and wrinkles, dyspigmentation, rough skin texture, and solar lentigines, along with eradication of premalignant tumefactions, such as actinic keratoses, can be achieved. Prevention of actinic keratosis development has not been substantiated with carbon dioxide resurfacing. Other indications Other indications for carbon dioxide laser skin resurfacing include the following:
RELEVANT ANATOMYSection 4 of 11
Extensive knowledge of skin microanatomy, histology, physiology, and function is essential before proceeding with resurfacing procedures. Familiarity with relative facial skin thickness (ie, thin, medium, thick) is salutary to avoid overtreatment and potential complications. CONTRAINDICATIONSSection 5 of 11
Contraindications to carbon dioxide laser skin resurfacing include the following:
TREATMENTSection 6 of 11
Preoperative details
Intraoperative detailsLaser tissue interaction Carbon dioxide laser emits light at a wavelength of 10,600 nm, which is strongly absorbed by water (the primary chromophore for carbon dioxide light that is abundant in the skin). Although approximately 90% of the carbon dioxide laser energy is absorbed by the initial 20-30 µm of skin, traditional continuous wave lasers leave behind a thick zone of thermal damage measuring 0.2-1 mm in thickness. The theory of selective photothermolysis states that selective heating of the target chromophore can be achieved when using laser pulses shorter than the thermal relaxation time (TRT) of the chromophore (the time that it takes the chromophore to loose 50% of its heat to the surrounding tissue). The TRT for 20-30 µm of skin tissue is about 1 millisecond. By using the theory of selective photothermolysis, carbon dioxide lasers with a pulse duration of less than 1 millisecond are capable of selectively vaporizing tissue with only a very thin zone of residual thermal necrosis measuring about 100 µm. To have a clinical effect in the skin, laser energy must be absorbed by the target chromophore. It was determined that the energy fluence (density) necessary to vaporize tissue is approximately 5 joules/cm2 (ablation threshold). Overall, delivering a 1-millisecond carbon dioxide laser pulse with an energy fluence of approximately 5 joules/cm2 leads to tissue vaporization measuring 20-30 µm and residual thermal injury measuring 40-120 µm. This zone of thermal necrosis is sufficient to seal small dermal blood vessels and lymphatics, yet narrow enough to reduce the incidence of scarring. Laser technology and systems Basically, 2 different types of carbon dioxide lasers are promoted for the purpose of skin resurfacing. The first is a high-power, pulsed carbon dioxide laser that can deliver approximately 500 millijoules of energy in each submillisecond pulse resulting in energy fluence measuring 5-7 joules/cm2. Some of these systems have a computerized pattern generator (CPG) that can rapidly and precisely place individual laser pulses in several different patterns. The other type uses an optomechanical flash scanner connected to a conventional continuous wave carbon dioxide laser. This scanner can efficiently distribute the laser energy into a train of pulses with a dwell time shorter than the skin TRT, thus mimicking truly pulsed carbon dioxide lasers. Recently, carbon dioxide resurfacing lasers with very short pulse duration (60 microseconds) have emerged. They ablate less tissue per pass and leave behind a narrower zone of thermal necrosis compared with the original carbon dioxide resurfacing lasers. All of the above laser systems appear to be equally effective in skin resurfacing when they achieve similar depths of skin injury. Follow-up
COMPLICATIONSSection 7 of 11
Similar to all other resurfacing modalities, the incidence of complications following carbon dioxide laser resurfacing primarily is related to the depth attained. Expected sequelae commonly encountered after carbon dioxide laser resurfacing must be clearly differentiated from true complications. Sequelae include the following:
Complications include the following:
OUTCOME AND PROGNOSISSection 8 of 11
The results of laser resurfacing are good to excellent, depending on the indication for which the procedure was performed. Patient satisfaction is based on the delivery of natural results with minimal downtime and a low incidence of complications. Actinic changes are improved to the greatest degree. Typically, wrinkles are improved by 60-80%, while scars are improved to a lesser degree. Improvement can be seen in deeper skin folds of the cheeks, forehead and neck, malar bags, and even in the excess skin of the upper eyelid (pseudoblepharoplasty effect), but their improvement are less predictable. Static lines are improved to a greater degree than dynamic lines. Treatment of these dynamic lines with botulinum toxin A provides significant improvement. To best estimate the degree of improvement after healing is complete, results should be assessed at 6 months after resurfacing. Usually, some loss of early improvement and some recurrence of wrinkles can be seen as postoperative edema resolves. Repeat treatments are possible but should be spaced approximately 6 months apart. Laser skin resurfacing is relatively a new procedure, and long-term skin effects are largely unknown. Overall success in laser skin resurfacing is related to the following: proper patient and skin type selection; attention to preoperative, intraoperative, and postoperative details; aggressive management of emerging complications; and good patient-physician relationship. FUTURE AND CONTROVERSIESSection 9 of 11
In general, given the overall success and safety of carbon dioxide laser resurfacing, the demand for this procedure will continue to increase at a relatively notable speed. Every resurfacing procedure (eg, lasers, peels, dermabrasion) has specific indications for which it is the procedure of choice. Each procedure has inherent advantages and disadvantages; therefore, making the choice of whether to use one resurfacing procedure or another procedure is sometimes difficult. Choice of resurfacing modality certainly depends on the physician's skills in regards to that procedure and the patient's needs. Furthermore, it is unknown if the long-term results of various resurfacing procedures differ if the depth achieved was equal. Certainly, what gives carbon dioxide laser resurfacing an advantage over other resurfacing procedures is the precise control over the depth of tissue ablated. Combined resurfacing modalities Realizing that different regions of the face display various degrees of skin damage, there is often a need to combine more than one resurfacing modality to achieve the best result possible. A common example is a patient with deeper rhytids around the eyes and mouth but without many wrinkles on the rest of the face. To achieve good improvement in these wrinkles, a papillary or reticular dermis level of resurfacing is needed. However, there is no need to subject the rest of the face to this same depth of resurfacing; an upper papillary dermis-level procedure or even epidermal exfoliation may be all that is needed in these areas. In this case, periorbital and perioral carbon dioxide laser resurfacing can be combined with a more superficial TCA peel such as the Blue Peel (15-20% TCA) over the rest of the face. This helps to blend the results better and to prevent any lines of demarcation. While carbon dioxide laser resurfacing of undermined skin such as a rhytidectomy flap is controversial, carbon dioxide laser resurfacing can be performed safely on nonundermined skin and combined with a superficial TCA peel such as the Blue Peel (15-20% TCA) over the undermined skin flap if the depth of the peel is kept superficial (see Images 4-5). Newer resurfacing modalities Three resurfacing modalities recently have emerged with claims of achieving faster healing and less potential for complications than carbon dioxide laser resurfacing. The erbium:Yttrium-aluminum-garnet (Er:YAG) laser has a wavelength of 2940 nm and a pulse duration of 250-500 microseconds. Because of greater water absorption, the Er:YAG laser ablates less tissue per pass (approximately 4-5 µm) with a narrower zone of thermal necrosis (approximately 20-30 µm) than the carbon dioxide laser. The Er:YAG laser can neither induce the same collagen tightening nor impart the hemostasis commonly seen with carbon dioxide laser. It is most suitable for exfoliation (epidermis level) or papillary dermis-level resurfacing (pinpoint bleeding as an endpoint), and it may not be as effective when used to correct deeper wrinkles or scars. The neodynium:YAG laser (Nd:YAG) has a wavelength of 1320 nm. It can induce a certain degree of thermal collagen coagulation in the papillary dermis, while generally sparing the epidermis (nonablative resurfacing). The coagulation necrosis in the papillary dermis leads to collagen contracture and subsequent neo-collagenesis. This procedure is suited best for mild wrinkles. Multiple treatments are required over many weeks to achieve an optimal result. Nonablative skin resurfacing modalities, such as the Fraxel SR laser (Reliant Technologies, Inc, Mountain View, Calif) and intense pulsed light (IPL), are newer technologies offering few adverse effects. MULTIMEDIASection 10 of 11
REFERENCESSection 11 of 11
Laser Tissue Resurfacing excerpt Article Last Updated: Jun 19, 2006 | ||||||||||||||||||||||||||||||||||||||||
