The Laser Landscape

Ranella Hirsch, M.D., a cosmetic dermatologist and laser surgeon in Cambridge, Massachusetts, who writes the "Laser Technology" column in the journal Cosmetic Dermatology, helped me navigate this vast and fast-moving world. Medical lasers are named for the material that is "pumped" with energy and made to lase, or emit some kind of single-wavelength radiation, explains Dr. Hirsch. The lasing material might be a gas (such as carbon dioxide), a crystal (ruby or alexandrite), or a chemical (usually rhodamine dye). It's the lasing material that determines the wavelength, or "color," of the laser light, and the color of the light determines the laser's effect on human tissue and thus its medical uses. For instance, infrared-light lasers work best for skin resurfacing because the light is absorbed primarily by water, while visible- and ultraviolet-light lasers are adept at zapping age spots because they're absorbed mainly by hemoglobin and melanin.

That said, it's also true that you can't really request or specify a particular type of laser. Other complex factors influence the decision of which laser is best for a particular problem. "They're absorbed differently and are used for different kinds of lesions," says Dr. Hirsch. "It's apples and oranges."

The laser used also determines the amount of downtime necessary after the treatment. A carbon-dioxide laser is the most aggressive and requires the longest recovery time but offers a potentially dramatic outcome. At the other end of the scale, a nonlaser light treatment is likely to yield more subtle results with a minimum of discomfort or recuperation. The following list breaks down the equipment you're likely to see on medi-spa menus by the function for which it is most suited. Keep in mind that product names (in parentheses) change as new models are introduced.