PhotoDerm® therapy uses a laser-like pulse of light to destroy veins. But while lasers utilize a single wavelength, or color, of light, the PhotoDerm device produces a wide spectrum of colored light, which can be adjusted to treat different types of veins. The light seeks out the pigment in the vein, generating heat and causing the vein's eventual collapse and re-absorption. The process works best on those with fair skin, due to a greater contrast with vein color. As the technique is more expensive than injections, some experts recommend trying sclerotherapy first on the larger varicose veins. Those which remain after sclerotherapy or are too tiny to be injected may then be suitable for PhotoDerm treatment. Concentrated areas of spider veins, a condition called matting, may also respond to PhotoDerm therapy. The procedure is performed with a hand- held device that's passed over the skin. Anesthesia isn't usually required and the sensation has been compared to the snap of a rubber band. After treatment, the skin may redden or swell for a few days. Skin discoloration may also occur and can persist for several months. An uncommon but possible complication is blistering or burning of the skin. Typically, three to six treatments are needed for optimal results.