Post-inflammatory hyperpigmentation (PIH) in Fitzpatrick skin types IV and V is the most common post-operative complication seen in this patient group. However, PIH can be avoided if appropriate modalities and settings are used.
Signs of photoaging in ethnic skin types include wrinkles and mottled pigmen-tation. In light-complexioned Chinese, Korean and Japanese patients at the age of 50 years old, solar lentigines, seborrheic keratosis and deep wrinkles are the most common signs of photoaging observed. However, these signs can appear even earlier in light-complexioned Asians living closer to the equator (Cambodia, Thailand and Singapore).
In our study, published in 20151, we evaluated the use of the MiXto laser from Lasering USA (San Ramon, Calif.) in a group of six Vietnamese-American patients between the ages of 26 and 45 who, at the time, resided in the Silicon Valley (Calif.)
In this study, a single-depth fractionated CO2 laser resurfacing treatment was performed with no overlap, using a pulse width of 2.5 ms, energy of 21 J/cm2, a 300 µm spot size and the 8 x 8 mm square shaped scan pattern.
Results showed improvement in the overall texture and tone for all patients. In addition, photograph evaluation by an experienced oculofacial plastic surgeon serving as an independent observer found no PIH.
Bulk tissue heating during ablative laser resurfacing is the leading cause of PIH. Fractionated resurfacing leaves untreated areas surrounding the laser spot, thereby minimizing the inflammatory response associated with ablative laser resurfacing.
Furthermore, the patented mathematical algorithm of the scan is designed to deliver a non-sequential Z-shaped pattern, allowing the skin to cool off with negligible heat buildup. It is this patented technology that helps further reduce the inflammatory response and prevent PIH.
In the same study, a histologic arm was performed with a seventh patient whose upper eyelid skin was incised using the cutting handpiece of the MiXto laser. The laser was set in continuous wave mode with an energy level of 5 W. Areas within the incised skin were resurfaced with the MiXto laser using the same settings as the primary arm of the study.
Results showed uniform diathermy at a depth of 0.05 mm for the resurfaced areas and 0.15 mm for the area next to the edge of the incised skin. Histologic findings confirmed the depth precision of the MiXto laser and showed that, despite being a CO2 laser, MiXto was able to achieve a shallow depth of resurfacing comparable to that of an Erbium YAG laser.
However, it was the uniform depth of penetration, as shown by the uniform diathermy noted in our histologic study, that helped the MiXto laser achieve consistent and reproducible results in skin resurfacing.
The proprietary features of the MiXto laser, the patented scanning pattern and the uniform energy delivery system for both cutting and resurfacing applications, make this laser a versatile tool that I can use in most of my ethnic skin patients.
1. Pham, R.T.H., Mattoch, I., Baker, S.S. (2015) Hyperpigmentation after Fractionated CO2 Laser Resurfacing in Asians. Modern Plastic Surgery, 5, 9-13.