What is Pico Laser?
Pico Laser VS Nano Second Laser: The Difference
Q switched treatments are lasers that are known for their short pulse duration. Picosecond lasers and nanosecond lasers are both” Q switched lasers”. The difference between picosecond or nanosecond Q switched laser is this: Nanosecond pulse (or pulse duration) is one billionth of a second, whereas Picosecond pulse (or pulse durations) is one-trillionth of a second. What that means is the duration of the picosecond laser pulse is way faster or shorter than a nanosecond.
There was an initial impression that PICO lasers are 1000 times faster than a nanosecond laser. That is not accurate. Picosecond laser pulses have a duration of 300-750 ps, which is only 10-20 times shorter or faster than nanosecond lasers (ranges 5-20 ns or 5000ps to 20000ps). There are no “true” picosecond lasers that have “true” picosecond pulses (or pulse duration of 100 or less ps).
As you can analyse from the diagram, the spike in peak power for picosecond treatments is distinctly higher than what nanosecond laser treatments can produce. What does that mean?
It means a higher explosive power but in a very brief duration. However, the energy levels delivered might not be comparable to their nanosecond counterpart. (look at the areas under the red and blue lines in the graph)
To understand better the unique properties of a picosecond laser, here’s one way of looking at it:
Is Pico laser treatment better for skin hyperpigmentation?
Let’s compare the skin pigmentation removal effects between pico second laser and nanosecond laser. Pico laser treatment produces a more photo-acoustic effect (mechanical) than photothermal(heating) effect compared to nanosecond laser. As the laser light energy is delivered so rapidly, it creates swift vibrations of the pigmentation it targets. The heat dissipates also rapidly which means that the skin only experiences very little heating effect (the laser feeling is like tiny warm pricks on the skin). (see diagram below)
Pico (picosecond) laser, therefore, has a more photo-mechanical effect than photothermal effect.
Q switched (nanosecond) laser, on the other hands, has both photothermal (heat) and photo-mechanical (acoustic) effect.
There is a difference of opinions as to whether a photoacoustic effect or photothermal effect is more suitable for skin pigmentation treatment. Till recently, no published article shows that pico laser treatments are more superior to nanosecond laser in treating skin hyper pigmentation except in tattoo removal. Neither is there any article that suggests pico laser is better than nanolaser for skin rejuvenation.
However, one recent split-face study (one side treatment with 755 picosecond Alexandrite laser and the other side treated with Q switch Nd YAG laser Medlite) showed that the side treated with picosecond laser showed better results and clearance of melasma. (1) Both patients and the accessors (doctors that are “blinded” as to which side received which treatment) consistently pointed that the side treated with picosecond laser yields better results. There is, of course, limitations to this study: the sample size is small, and not all nanosecond laser has the same efficiency and output power. The med lite laser was launched more than ten years ago and might not represent the most recent nanosecond lasers that are launched.
(1 ) https://pubmed.ncbi.nlm.nih.gov/29732522/
In another review article, however, the findings are different. It mentions that in the treatment of superficial pigmentation such as age spots and sun spots, long-pulsed laser procedures and IPLs are the best treatment options, as they have fewer side effects and complications such as risks of hyper pigmentation when compared to the treatments with more photoacoustic effect. (2) This article cites studies that show better clinical outcomes with long pulse lasers compared to shorter pulse type of laser with a lesser risk of complications. The conclusion is that photomechanical effects are unpredictable (due to sudden rise in peak power) and photothermal effects are better as long as it is controlled.
In Ozhean Zoey Singapore, we use both picosecond laser and nanosecond laser to better improve our patient’s pigmentation removal results with lesser sessions. Pico laser’s strength lies in removing superficial pigments, while for deeper larger pigmentation, using a long pulse pigmentation will result in a safer and more effective pigmentation removal.
What is truly unique to a picolaser treatment in Singapore – the focus lens
This is a unique handpiece to pico treatments (although the newest nanosecond lasers also have similar handpieces), and each brand of pico laser has its different versions of a focus lens handpiece, i.e. picosure (Cynosure) called it the focus lens array, picocare (Wontech) called it the microlens array (MLA); picoplus (Lutronic) has two focus lens handpiece called the MLA and DOE.
What does the focus lens handpiece do? It focuses or concentrates the laser energy passing through into several smaller spots, pretty much like how a magnifying lens can focus the sun’s beam and cause a fire.
This is how the focus lens’ laser beams profile will look like:
(The spikes represent the points of focused laser)
As a result of this focusing, the power of the pico laser is magnified several times up to 20 times stronger than the usual energy at these focused points. This creates laser-induced optical breakdowns (LIOB) or small micro areas of injuries which shows up as small microcavities in the skin under a microscope. The diagrams below explain in technical detail how these LIOB are formed and how collagen is subsequently formed at these LIOB sites.
Pico laser in treating skin issues like acne scars, skin and rejuvenation
Conventional acne scar laser treatments in Singapore involves ablation (or burning) of the scar tissue for its removal, and as the skin heals, new skin takes the place of the acne scars. There are also non-ablative lasers, but results are usually subtle.
Skin ablation with ablative lasers such as CO2 or erbium YAG treatments work from the surface to deep. The limitations of these acne laser scar treatments are that because of the relative high energies of laser that are administered to the skin and with a disruption of the skin surface ( basal membrane of the epidermis), there is often very long recoveries need (with redness, swelling, scabbing and browning lasting to weeks), and also a significant risk of complications such as post-inflammatory Hyperpigmentation (PIH) and increased skin sensitivity.
This is an example of PIH post fractional CO2 laser:
What makes PICO lasers really unique in acne scar treatment in Singapore is this: the focus lens handpiece creates LIOBs without disrupting the skin surface (or the epidermis). That means that pico laser can deliver acne scar improvements with better recovery, fewer treatment sessions, and lower risks of complications than conventional ablative lasers. Studies show pico laser’s acne scar results comparable with ablative laser with a lower risk of hyperpigmentation—one study shows pico laser to be safe in treating scar in darker skin types.
Pico second laser in Singapore has also shown to be as effective as Erbium: YAG in reducing acne scarring. (https://www.ncbi.nlm.nih.gov/pubmed/31646393)