Fractional Laser Treatment for Pigmentation and Texture Improvement

/Home/Cosmetic Laser Treatments/Anti Aging Laser Treatment/Anti Aging Treatment

Fractional Laser Treatment for Pigmentation and Texture Improvement
November 2006
Z. Rahman, MD; M. Alam, MD, MSCI; J. S. Dover, MD, FRCPC, FRCP
Skin Therapy Letter.com

ABSTRACT

Fractional laser treatment with the 1,550nm erbium fiber laser (Fraxel? Laser, Reliant Technologies) has bridged the gap between the ablative and nonablative laser modalities used to treat the epidermal and dermal signs of skin aging. By targeting water as its chromophore, the laser induces a dense array of microscopic, columnar thermal zones of tissue injury that do not perforate or impair the function of the epidermis. The significant skin remodeling that ensues can be used to treat, with limited downtime, epidermal pigmentation, melasma, and rhytides, as well as textural abnormalities that include acne-related and surgical scars.

Key Words: ablative laser, pigmentation, textural abnormalities, photoaging, acne scars, surgical scars

Although ablative laser modalities remain the gold standard for the treatment of photoaging, most patients cannot tolerate the 1Ò2 weeks of downtime required with these procedures. Additionally, ablative skin treatment carries the risks of pigmentary alteration, infection, and scarring. At the other end of the spectrum, nonablative modalities induce collagen remodeling through deep dermal heating, yet have no epidermal resurfacing effect.

The Fraxel? Laser is a 30watt, diode pumped, 1,550nm erbium fiber laser that targets water as its chromophore. Utilizing the concept of fractional treatment 70Ò100um wide and 250Ò800um deep, microthermal zones (MTZs) of tissue coagulation are produced. Tissue is not vaporized and the stratum corneum remains intact. The epidermal coagulated tissue is expelled and replaced by keratinocyte migration. When there is significant damage to the basement membrane zone, dermal contents are also expelled as microscopic epidermal and dermal necrotic debris (MENDs). In this way, epidermal and dermal pigmentation can be treated without specifically targeting melanin as the chromophore. Zones of collagen denaturation in the dermis cause upregulation of the inflammatory cascade, which leads to collagen remodeling and new collagen formation.

In the first study of the fractional laser, 15 subjects received treatments of varying densities at test sites on the distal forearm. Biopsies were taken from the treated tissue at intervals of 48 hours, 1 week, 1 month, and 3 months in order to identify MTZs and to characterize the wound healing process.1 This data supported the use of the device for coagulation of soft tissue and, in November 2003, the US FDA approved it for that purpose. Since then, the fractional laser device has received additional FDA clearance for the treatment of periorbital rhytides, pigmented lesions, melasma, skin resurfacing, acne scars, and surgical scars.

The fractional laser contains an intelligent optical tracking system that utilizes OptiGuide BlueÙ tint, a water soluble FDC dye. The optical mouse in the laser handpiece recognizes subtle differences in the density of blue dye on the skinÌs dermatogliphs. The mouse communicates with the laser to lay down an even MTZ spot pattern independent of handpiece velocity. This system allows for a more even placement of MTZs, which is important in fractional tissue treatment where the optimal spacing between lesions allows for rapid re-epithelialization and prevents negative sequelae associated with fully ablative treatment at depths of 300Ò800um. The dye can be challenging to remove in patients with enlarged pores or with hyperkeratotic lesions, such as actinic keratoses. The use of a dimethicone-based sealant prior to blue dye application can assist in removal of the dye. Blue dye is best removed with a foam-based skin cleanser that increases the surface area of the surfactant in contact with the skin.
Pain Management

Pain management is one of the most significant hurdles of the procedure. Discomfort from the laser treatment is managed by use of topical anesthetics, e.g., LMX-5?, EMLA? (AstraZeneca), and other lidocaine/tetracaine formulations, such as 7% lidocaine/ 7% tetracaine (S-CaineÙ, ZARS), prior to procedure.

Forced air cooling (Zimmer Cryo 5?, Zimmer Medizin Sytems), which is often used concurrently with fractional laser treatment,2 increases patient comfort significantly. Histologic analysis reveals a slight reduction in thermal damage zone width, but no statistically significant change in lesion depth. Forced cooled air should be used at the lowest possible setting to minimize alteration in the MTZs. When treating for superficial indications such as pigmentation and melasma, Zimmer settings should be 1Ò2. When treating deeper indications such as deep rhytides or scars, higher forced air settings, in combination with higher laser settings, may be used.

Oral anxiolytics and analgesics may be required in a small minority of patients who cannot tolerate the procedure with topical anesthetic alone.
Treatment Protocols by Indication

The current recommended treatment protocols are listed in Table 1. Important concepts to consider when using the fractional laser device are treatment energy, density, coverage, volume of tissue treated, and treatment intervals. The first three concepts, energy, density, and coverage, are closely related. The depth and width of the MTZs are proportional to energy. These are displayed in Figures 1 and 2. In order to achieve the desired coverage, densities should be lowered for higher energy treatments. For example, a 10mJ, 2,000MTZ/cm2 treatment and a 20mJ, 1000MTZ/cm2 treatment both have 20% coverage.

However, the 20mJ treatment results in twice the volume of tissue treated. This is important when treating deeper indications such as scars or deep rhytides. Treatments can be spaced as close as 1 week and as far apart as 6 weeks. Higher energy treatments should be spaced every 2Ò4 weeks.

NOTE: Please visit the website to view the entire article, with photos and tables.