Nonablative devices examined

October 1, 2006

Boston - Understanding the basic science behind new and evolving laser surgery devices provides a basis for safe, effective clinical use, according to an expert.

Boston - Understanding the basic science behind new and evolving laser surgery devices provides a basis for safe, effective clinical use, according to an expert.

For starters, plasma skin resurfacing (Portrait PSR3, Rhytec) doesn't use light, but instead millisecond pulses of nitrogen plasma to create zones of thermal damage to the skin and is used for skin tightening and wrinkle treatments, says Kristen M. Kelly, M.D., associate clinical professor of dermatology and surgery at the University of California, Irvine.

Treatments aim in new directions

Additionally, she says that more recent studies evaluating indications that are not yet Food and Drug Administration (FDA)-approved have shown that plasma resurfacing may achieve skin contraction of 10 to 15 percent when used for tightening (Tremblay JF, et al. Publication pending) and improve acne scarring by 20 percent to 40 percent (Gault D et al. Publication pending).

In contrast, Dr. Kelly says that another relatively new technology, fractional photothermolysis (Fraxel, Reliant Technologies), falls somewhere between the spectrum of ablative and nonablative laser treatments because it creates microscopic zones of thermal injury and denatured collagen. With this technology, she explains, "One is only really treating about 10 to 20 percent of the skin's surface area," leaving zones of skin intact between microthermal zones (MTZs).

This process achieves complete re-epithelialization within 24 hours, along with new collagen formation, within the MTZs, according to Dr. Kelly.

In using this technology, Dr. Kelly says it's important to understand that one must set both the pulse energy (in mJ) and treatment density (in MTZ) to achieve the desired result. Presently, she notes, settings used by individual practitioners vary. However, she adds that studies currently under way and soon to be published may provide information about optimal parameters.

Vascular treatments, theories

For vascular treatments, physicians can choose a new laser that combines the 595 and 1,064 wavelengths (Cynergy, Cynosure). Dr. Kelly says, "The theory is that one uses the 595 nm wavelength to heat up the blood, and that causes a change from hemoglobin to methemoglobin."

She explains that because methemoglobin has three to five times greater absorption of the 1,064 nm wavelength than does hemoglobin, one can achieve clinical improvement with lower energies on the 1,064 nm laser than one ordinarily would use. Likewise, she says Cynosure has shown that the combined lasers can reach perhaps twice the depth of either laser alone.

Synergism of combined modalities

Somewhat like the combination laser, devices such as the Polaris WR (Syneron) combine radiofrequency (RF) and light. Such devices operate on the principle that pairing these two modalities allows one to use lower amounts of each, perhaps increasing treatments' safety profile while still achieving clinical improvement, Dr. Kelly says.

"Syneron has stated that one can use these kinds of devices in many skin types, even patients with darker skin types," she reports. Applications for combined laser/RF devices include hair removal, skin rejuvenation and acne scarring, she adds.

It was also proposed that such devices might be able to remove blond and gray hairs, which have been resistant to removal by other light-based devices, Dr. Kelly says.