Physicians and laser manufacturers alike have been working for several years to develop a viable, cost-effective laser-based leg-vein treatment that can compete with conventional therapies. As a result, researchers believe they have now identified the optimal treatment parameters to eliminate both the smaller, superficial and larger, deeper leg veins without long-term side effects.

In fact, more options are available now than ever before for physicians to achieve good outcomes and high patient satisfaction, according to Robert Weiss, M.D., assistant professor of dermatology at Johns Hopkins University (Baltimore, MD) and director of the Maryland Skin and Laser Institute. Weiss gave an overview of developments in this field at the '98 Summer Meeting of the American Academy of Dermatology in Chicago last month. "We have learned a great deal in the past few years," Weiss says.

"We compared the various vein lasers, from the green, yellow, and near-infrared wavelengths to the diode array, and found them all lacking. On the up side, we learned that the versatility of the treatment parameters are key to the effectiveness of light energy on vascular structures."

For example, researchers now know that larger leg vessels require treatment with a longer wavelength, longer pulse duration, and a large spot size (up to 3mm), according to Weiss. "The more flexibility the operator has to adjust the pulse duration, pulse sequencing and spacing, and fluence of the light source relative to vessel size and vessel depth, the better the results will be," he says.

Although investigators know that a relatively large amount of energy is necessary, it must be delivered at a wavelength that does not injure the epidermis so that all skin colors can be treated.

"This capability opens the market to people of South America and Asia; previously we could not treat them," he added.

Vessel size is another important parameter. Small vessels include those up to 0.3mm; medium sizes are 0.3 to 0.7mm; large vessels are 0.7 to 1.5mm; and, on the legs, larger spider veins can be 1.5 and 2.5mm. The deeper, blue veins are 3mm and larger. Epidermal cooling has made a big difference in the ability of the laser to safely treat leg veins of 3 to 4mm.

"Cooling systems have really helped all of the available devices to more safely treat bigger vessels on the leg," Weiss says. "The next step is to explore epidermal cooling even with the 1064nm."

A Spectrum of Wavelengths

Weiss' presentation also included an overview of the various types of lasers used in leg-vein treatments and a comparison of their efficacy. He noted that neither the argon not KTP lasers are appropriate for treating leg veins due to their small spot size (2mm). In addition, the 532nm wavelength of the KTP is absorbed to a great degree by melanin. Thus, these devices work well on the face due to the superficial nature of facial vessels but are inappropriate for the deeper, larger vasculature of the legs.

Recent technological developments have made the 532nm wavelength more appropriate for larger vessels however. Coherent (Santa Clara, CA) has developed a sapphire crystal epidermal cooling device (water circulates at 4 degrees Celsius) that can be used with a 532nm laser whose spot size has been enlarged to 5mm.

"This is a continuous-wave contact device that is placed directly on the skin," Weiss explains. "The beam is shot through it and the water is circulated through the solid-state device that keeps the water temperature exactly at 4 degrees Celsius." This cools the epidermal melanin within the first 1.5mm of the treatment area.

While the idea is a good one, Weiss says there are some technical difficulties. For example, if the physician presses too hard and chills the blood vessels too much, they will not respond as well. The vessels must at least heat up to over 100 degrees Celsius to contract and close.

"Some physicians are getting good results with this device, but I do not," Weiss says. "Even with the epidermal cooling, about 50% of the type II and above patients who have tans will get hypopigmentation. I find that I can reproducibly use this device primarily in the winter when most people are not tan. We use it as a secondary device when others have failed."

Dye-Laser Barriers

One of the biggest advances in laser leg-vein treatment was the flashlamp-pumped dye laser (585nm) pioneered by Candela (Wayland, MA). However, while this laser is effective, it also has certain limitations, according to Weiss. For example, the laser eliminates superficial vessels by heating them to 300 degrees Celsius and causing them to burst. But such explosions cause red blood cells to splatter the tissue, resulting in purpura (bruising) and hyperpigmentation. This hyperpigmentation, which lasts from 8 to 12 months, is the reason the dye laser has never been widely accepted fro leg-vein treatment, according to Weiss.

"Candela has tried to tweak their system for the legs...and slightly bigger vessels," he says. These improvements include adding a cooling device and elongating the pulse from 0.50 to 1.50ms. The wavelength was also increased from 585 to 600 and 605nm. Despite these improvements, however, hyperpigmentation still occurs and lasts about 6 months, according to Weiss.

Solid-State Lasers

Ultimately Weiss says that the visible-wavelength lasers do not penetrate enough to effectively treat leg veins.

"Much of their energy gets dissipated after the beam strikes the front wall of the vessel and the first layer of hemoglobin," he says. "The energy is dissipated laterally and does not do a thorough job of heating." Thus, many researchers have turned to lasers in the infrared range. These include 649nm ruby lasers and the 735nm alexandrite lasers - neither of which are truly viable options for leg veins, according to Weiss.

"I don't think anyone has made a ruby laser with the right wavelength for blood vessels," he says. "Cynosure (Bedford, MA) is developing an alexandrite laser that the company says works well on veins, and I think it is reasonable to assume that we are getting closer to the right wavelength for larger vessels with that laser."

Another solid-state infrared laser development is the arsenide diode, which emits at about 810nm. There are two competing diode-laser technologies for leg veins, according to Weiss: a single diode that delivers energy through a fiber and a diode-laser array that is characterized by a grid of diodes.

"These lasers are primarily being developed for hair removal, not for treatment of blood vessels," he said. "Presentations at the American Society for Lasers in Medicine and Surgery meeting showed some improvement with blood vessels, but there is really no large-scale study that I know of."

The Right Wavelength

Finding the correct pulse duration of the 1064nm Nd:YAG laser has been an important development because it enables the treatment of larger vessels, Weiss says. "Years ago, the Nd:YAG laser was thought to be too penetrating, too powerful," he says. "But the 1064nm wavelength penetrates 3 to 4mm into the skin. With the lower wavelengths, there is maybe 1 to 2mm of penetration."

HGM (Salt Lake City, UT) is one company that has developed a 1064nm laser for this application. However, because the HGM laser has only a 2mm spot size, Weiss says it is not as effective for larger veins.

"Even though it is the right wavelength, the physician really needs a spot size at least twice the diameter for leg veins beacuse of the scattering of light photons," he says. "Treating a 3mm vein almost requires a 6mm spot size." ESC (Yokneam, Israel) also recently introduced a 1064nm laser, the VascuLight, for leg-vein removal. Weiss, who has been using the VascuLight since April and has no financial interest in ESC (or any other company mentioned in this article), is pleased with the results and says it is the only laser that can treat larger leg veins. In a clinical study of 30 patients, Weiss reported very good results with an average of 50% to 90% improvement after one treatment at 60 days. There was complete closure (100%) in approximately 75% of vessels with diameters up to 3mm and depths as great as 4mm. The overlying skin was not affected, and no side effects were observed.

"The VascuLight is the only device that actually shrinks the big purple vessels on the leg," he says. "It's like using an eraser." In addition, there is no interaction with melanin, even in type IV skin. Weiss is impressed because the epidermis is untouched. In fact, up to this point he and his colleagues have not seen any epidermal injury following treatment with the VascuLight.

"We are very excited, because we may finally have a safe and successful option to sclerotherapy, which is especially good news for patients who are reluctant to undergo needle therapy," Weiss concludes.