Micro-Fractional Ablative Skin Resurfacing with Two Novel Erbium Laser Systems

By Christine C. Dierickx, M.D., Khatri A. Khatri, M.D., Zeina S. Tannous, M.D., James J. Childs, PhD, Richard H. Cohen, PhD, Andrei Erofeev, PhD, David Tabatadze, PhD, Ilya V. Yaroslavsky, PhD, & Gregory B. Altshuler, DrSc
Published in Lasers Surg Med 2008, 40;2:113–23

Introduction

Treatment of photoaged skin with ablative lasers has been shown to produce clinically efficacious results in a number of studies. However, these procedures are painful, have significant downtime and adverse side effects such as infection, pigment alterations, long-lasting erythema, and scarring. Fractional non-ablative treatments have been useful in treating conditions such as mild to moderate rhytides (wrinkles), photo damaged skin, acne scarring, leucodermic scars, melasma, and non-facial skin rejuvenation. Investigators have reported re-epithelization in 24 hours with fractional treatments thereby reducing downtime for the patient. The effect of Er:YAG (2940 nm) and Er:YSGG (2790 nm) lasers were compared in order to optimize ablative fractional device parameters for new treatment regimens.

Materials and Methods

Two fractional lasers were used including an Er.YAG (2940 nm) and Er:YSGG (2790 nm). Six millimeter punch biopsies from ex vivo Yucatan pig and human abdomen skin as well as a series of 2 mm punch biopsies were collected from the periauricular area of the face at various points to demonstrate the healing responses. All the face biopsies were performed on patients scheduled for a facelift procedure. There were 108 treated areas across 13 patients with mild to moderate photo damage and aged facial skin. Fitzpatrick skin types ranged from I to III and the participants ages ranged from 33 to 62. The subjects were treated with the 2940 nm erbium fractional laser using parameters ranging from 1 to 9 mJ/ub and a pulse width varying from 250 microseconds to 5 milliseconds. Subjects were also treated with the 2790 nm handpiece using parameters ranging from 4 to 12 mJ/ub and a pulse width varying from 2 to 5 milliseconds. Areas were treated with multiple passes and stacked pulses. A total of 108 treatment areas were evaluated for wound healing and side effects immediately post-treatment and at 3 follow-up visits: 3-4 days, 1 week, and 1-3 months post-treatment. Wrinkle appearance 3 months after the single treatment was evaluated on a 0-9 scale in a randomized, blinded side-by-side fashion by three dermatologists. Photographic documentation was performed with a facial photo fixture that ensured a fixed distance and fixed angles between the camera and the patient.

Results

The porcine histology demonstrated micro-beam ablation and coagulation after single-pulse treatments with a center ablation zone surrounded by a thick coagulation zone. This was supported by human histology. Histology findings for the 2940 nm wavelength treatment indicated that within 12 hours there was a very rapid re-epithelization. Re-epithelization was noted at 24 hours with the 2790 nm treatment. Skin reactions and discomfort were mild, transient, and short lasting when compared to ablative resurfacing. Immediately after treatment nearly all subjects developed mild or moderate erythema, which was markedly reduced by week 1. All treatment areas showed the presence of necrotic debris that sloughed off by day 4 revealing pinkish healthy skin. By the end of one week natural skin texture was restored. There were no incidents of hyper- or hypopigmentaion at 1 month.

The overall average reduction in the periorbital wrinkle score was statistically significant at p<0.0001. The improvement in perioral wrinkles was also significant (p<0.05) although aggressive treatments were required (4 or more passes and double stacking pulses).

Skin treatments with fractional laser ablative skin resurfacing is shown to be safe with rapid healing. Histologic evaluation confirms that the epidermis undergoes re-epithelization within 24 hours. The depth and width of the ablated micro columns and the extent of surrounding coagulation can be varied and used to target specific indications and areas. For the periorbital and perioral tested areas, wrinkle reduction tended to improve with increasing number of passes and stacking of pulses. Stacked pulses provide deeper columns into the dermis as compared to single pulses treatment and therefore may be used in more resistant areas (e.g. perioral). Multiple passes have an accumulating effect on the skin and an increasing probability that micro-columns will merge or overlap, enlarging the zones of thermal injury and ultimately extending the healing time. For some subjects the reduction in wrinkles was substantial and significant and similar to the improvement seen in full-ablative procedures. The 2790 nm wavelength generated greater thermal damage than the 2940 nm; therefore the article focused on defining treatment parameters for the 2940 nm laser.

Conclusion

Micro-fractional ablative treatment with 2790 and 2940 nm erbium lasers resulted in the safe and effective reduction in mild to moderate rhytides. In comparison to full-surface ablative skin resurfacing there is very rapid re-epithelization, limited adverse side effects and reduced downtime to 4 days or less.

Reprint requests: Dr. Christine C. Dierickx, Skin and Laser Center, Beukenlaan 52, 2850 Boom, Belgium.