Picosecond laser

Author(s): Dr Faisal R. Ali and Dr Firas Al-Niaimi, Consultant Dermatologists, Dermatological Surgery & Laser Unit, St John’s Institute of Dermatology, Guy’s and St Thomas’ NHS Foundation Trust, London, United Kingdom. DermNet NZ Editor in Chief: Adjunct A/Prof Amanda Oakley, Dermatologist, Hamilton, New Zealand. Copy edited by Gus Mitchell. September 2018. 


What is a picosecond laser?

A picosecond laser is a laser device that uses very short pulse durations to target endogenous pigmentation and exogenous ink particles (tattoos). The medium varies accordingly to the wavelength being used: neodymium-doped yttrium aluminum garnet (Nd:YAG) crystal (532nm, 1064nm), Alexandrite crystal (755nm).

Tattoo

What are the indications for a picosecond laser?

The main indication for use of a picosecond laser is tattoo removal [1]. Depending on the wavelength, they are particularly useful for clearing blue and green pigments, which are difficult to eliminate using other lasers, and tattoos that are refractory to treatment with the traditional Q-switched lasers.

The use of picosecond lasers has also been reported for treatment of melasma, naevus of Ota, naevus of Ito, minocycline-induced pigmentation and solar lentigines [2].

Some picosecond lasers have fractionated hand pieces that facilitate tissue remodelling and are used to treat acne scarring, photoageing and rhytides (wrinkles) [2]­­.

What are the contraindications to picosecond lasers?

As with other laser devices, picosecond lasers are relatively contraindicated in patients with darker skin tones (Fitzpatrick skin types 4–6), who are more susceptible to side effects.

Tell me more about picosecond lasers

Picosecond lasers use pulse durations of less than one nanosecond, which causes predominantly photoacoustic damage (ie, mechanical reverberation) rather than photothermal destruction of pigment or ink particles. This results in effective clearance of abnormal pigment, whilst minimising photothermal damage to the surrounding tissue.

Why choose a picosecond laser?

A picosecond laser selectively destroys the target pigment without damaging healthy, normal tissue. This allows rapid clearing of the abnormal pigmentation with minimal collateral damage to surrounding tissue.

Picosecond lasers used for tattoo removal require fewer treatments, cause fewer side effects, and result in reduced post-procedural downtime compared to nanosecond Q-switched lasers. They can clear some tattoos that are refractory to other forms of laser therapy and there is a reduced risk of causing scarring and hypopigmentation.

The additional cost and reduced availability of picosecond lasers compared to Q-switched lasers currently restricts their widespread use.

What are the side effects and risks of picosecond lasers?

Picosecond laser treatment is mostly well tolerated. Potential side effects include pain, erythema, oedema, pinpoint bleeding, crusting, blistering, scarring, post-inflammatory hyperpigmentation and post-inflammatory hypopigmentation. Side effects are more severe if excessive fluences are used.

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References

  1. Hsu VM, Aldahan AS, Mlacker S, Shah VV, Nouri K. The picosecond laser for tattoo removal. Lasers Med Sci 2016; 31:1733-1737. DOI: 10.1007/s10103-016-1924-9. Available at: https://link.springer.com/article/10.1007%2Fs10103-016-1924-9 (accessed 14 August 2018)
  2. Forbat E, Al-Niaimi F. The use of picosecond lasers beyond tattoos. J Cosmet Laser Ther. 2016; 18: 345-7. DOI: 10.1080/14764172.2016.1188209. Available at: https://www.tandfonline.com/doi/abs/10.1080/14764172.2016.1188209?journalCode=ijcl20 (accessed 14 August 2018)

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