What is picosecond technology?

With new technologies minimising downtime, at the same time as widening the scope and broadening the parameters of indications and skin types that can be safely treated, lasers are now one of the most versatile tools at a salon or clinic’s disposal. The latest development to fit this mould is picosecond lasers. These devices emit super-fast pulse widths of less than one nanosecond and as such they have been described as the “next generation” in ultra-short pulse laser technology.

Although picosecond technology has been available outside of the aesthetic setting for decades, the use of picosecond lasers on skin is still in its infancy. Its potential was first discussed in the late 1990s in clinical journals, centring around whether experimental picosecond lasers demonstrated greater efficacy over their nanosecond predecessors in the context of targeted destruction of tattoo ink.

But it would be almost two decades after those initial hypotheses before the first FDA-approved picosecond laser became available for aesthetic clinics, with the launch of the PicoSure from Cynosure in 2012. Since then, three other laser companies have brought picosecond devices to market – Syneron Candela with its PicoWay machine, Lynton with Discovery Pico and Cutera with its Enlighten device.

Cost factor
Jon Exley, managing director of Lynton Lasers, who has a PhD in laser physics, explains, “In the world of physics picosecond is definitely not new. However, what is a step forward is the fact that the industry has managed to commercialise picosecond lasers now and make them affordable. “One of the issues with the old pico lasers was that the average powers weren’t as good so the spot sizes were very small. Advances in technology and improvement in optics have allowed higher average powers, giving bigger spot sizes in pico-pulse, making it more viable in clinical applications.”

So what is the advantage of these picosecond pulses for clinics and salons? It is claimed that because these devices have the ability to deliver energy to tissue in a shorter time than preceding technologies, this enables higher energy density, more specific targeting of smaller particles, more efficient delivery of energy, and lower thermal diffusion to surrounding tissues. For salons and clients this means more precise and faster treatment with less damage to the surrounding areas.

Picosecond for tattoos
Tattoo removal is becoming increasingly popular. Some 20% of women and 8% of men in the UK have already undergone a tattoo-removal procedure, according to research carried out by Syneron Candela to support the launch of its PicoWay device. This means the potential market for tattoo removal is huge and this is the space in which picosecond technology is thriving. Tattoo removal using lasers really came into its own with the evolution of the Q-Switched or “quality switched” lasers, which reduced the pulse duration to nanoseconds. Picosecond technology goes even further by reducing it to sub-nanosecond.

Jo Martin, clinical director at Mapperley Park Clinic in Nottingham, has been doing tattoo removal for more than 22 years. She explains, “The introduction of picosecond lasers is really the first exciting thing that has happened in tattoo removal for a long time. They are about 10 times faster than Q-Switched lasers. The pulses are so fast that the pigment-shattering effect is so much more efficient and the heat we are generating in the skin is so much less. “It means we can reduce the number of treatments, which is really useful because removing a tattoo can take a long time. It also means we can perform the treatments closer together if we want to. This means pico technology is going to give us a much more efficient, and therefore faster, removal than anything that has come before, which is exciting.”

However, Exley is more cautious about singing the praises of pico as a game changer in tattoo removal. He says, “There is definitely a clinical benefit to picosecond lasers. I believe you can achieve clearance in fewer treatments, for example, than normal nanosecond lasers. I also believe you can probably remove some ink that is further into the tissue, but I do think there are some downsides. Picosecond is a very aggressive laser. The problem, in my opinion, is with darker skin types as you do run the potential risk of hypopigmentation, more so than with Q-Switched lasers.”

Winning combination

Exley believes that the most effective way to treat tattoos is to combine different laser technologies, which Lynton has done with its Discovery Pico device. He adds, “In my view picosecond is a very good tool alongside all of the other tools you have got to treat tattoos. It definitely offers some great advantages; fading tattoos faster than the traditional lasers is probably one of them. “If you walk in with light coloured skin and a black tattoo then the picosecond laser is a great choice. However, if you have only got a picosecond laser, you are going to limit yourself as to who you can treat. If you want to get clearance of tattoos with multiple colours, still the most important characteristic in your laser is wavelength. We also have the Q-Plus C that is a nanosecond laser, not picosecond, but it has three wavelengths: Nd:YAG 1064nm and 532nm and ruby 694nm. If you want the best treatment for colours I would still advise those different wavelengths.”

One device that recently achieved FDA clearance for all tattoo colours – red, yellow and orange for the 532nm wavelength and black, brown, green, blue and purple for the 1064nm wavelength – is the PicoWay from Syneron Candela. Its performance was evaluated in a study in which 86% of subjects achieved at least 50% tattoo clearance after only three treatments. The treatment also presented a favourable safety profile with no device-related serious adverse events, and low levels of pain or discomfort.

The PicoSure also claims to be able to treat the full colour spectrum of tattoo inks by combining 755nm and 532nm wavelengths, the latter being designed to more effectively treat red, orange, and yellow ink. Cynosure says that while traditional nanosecond lasers predominately rely on photothermal action, delivering heat to the pigment and surrounding tissue, PicoSure uses “PressureWave” technology to shatter the target ink into tiny particles that are easily eliminated by the body. It claims this allows the device to provide better clearance with fewer treatments and without injury to the surrounding skin.

Picosecond for rejuvenation
Although picosecond lasers have been largely reported in terms of their application in tattoo removal, new modalities for their use in other areas, such as skin rejuvenation, scar revision and removal of pigmentation, are now being explored. Both Syneron Candela and Cynosure have now extended the use of their pico devices to include rejuvenation. Cynosure’s PicoSure Focus can be used for skin revitalisation, toning and texture, acne scars, wrinkles and fine lines, and pigmented lesions.

Roy Geronemus, director of the Laser and Skin Surgery Center of New York and clinical professor of dermatology at NYU Medical Centre, explains, “Our histologic analysis following PicoSure treatments revealed a remarkable ‘lengthening’ of the elastin fibres in the skin. This has been previously seen with ablative CO2 resurfacing lasers, which required extended patient recovery periods. The PicoSure technology is unique as we are seeing a global improvement in the overall 2016quality of the skin from a non-ablative laser that leaves patients with virtually no recovery time.”

Syneron Candela’s Picoway Resolve handpiece was launched in late 2015. Resolve claims to be the only picosecond device on the market to employ a holographic fractionator to deliver precisely consistent energy to the entire treatment area. Its two wavelengths mean it can treat shallow lesions with the 532nm wavelength, while the 1064nm one is used for deeper lesions and to treat all skin types, with no downtime. David Friedman, a board-certified dermatologist, says, “We recently began to use the PicoWay fractional hand-pieces for skin rejuvenation, acne scars and wrinkles, with improvement in skin tone, brightness and texture after one or two treatments.”

Pigmentation potential
Exley is sceptical and believes more evidence is needed. He adds, “We are not actually pushing the skin rejuvenation application at this stage with the pico. I’m not saying it doesn’t work, just that we haven’t got any evidence to suggest whether it is any better or any worse than existing options. “With acne scarring or skin rejuvenation, if you can get any disruption in the dermis to collagen that causes reversible damage, so your skin can repair itself, then there is some element of photorejuvenation or collagen remodelling. Certainly picosecond has the potential to be able to do that but I don’t think we have enough evidence for it.”

Instead, he believes that a more interesting application for pico is pigmented lesions. “Picosecond lasers are very well suited to targeting melanin so they might be a very good option for treating some pigmented lesions that couldn’t be treated well before – melasma for example. We haven’t done any work on that yet so I wouldn’t say you can use this for melasma but I would say this is an interesting area that needs further research and one in which picosecond might give some new advantages.”