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In this light, dual laser toning was widely used in the past decade. Generally, dual laser toning also uses 1064nm nanosecond Q-switched Nd:YAGlaser but simultaneously combines milisecondlong-pulsed laser.

 

The so-called Genesis laser toning delivers continuous thermal energy using quasi-long pulse duration to induce thermal stimulation of dermal tissues and collagenesis. In practice, a few minutes of irradiation is insufficient to cause the desired thermal change using the long-pulsed laser. Laser should be irradiated for a long time until severe redness is seen to achieve the desired thermal stimulation. As this is not feasible due to excessive pain and downtime, Genesis laser toning was performed much more gently until only light redness is seen.

 

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Principles and problems of long-pulsed laser and picosecond laser

 

Milisecond long-pulsed laser has avery long pulse duration and cannot induce selective photomechanical effect on skin tissues butinduces photothermal effect. Considering laser-tissue interactions, it is desirable to maximize photomechanical effect and minimizephotothermal effect to lower the risk ofPIH and scarring. Not being aware of the delayed tissue reaction of the long-pulsed laser can lead to unwanted side effects.

 

It has already been over a decade since picosecond and femtosecond lasers were developed. These new lasers were not widely commercialized because they require high-performance power supply and also because the photomechanical effects of these lasers were not correctly used in pigment, vascular and hair removal treatments. Most commerciall yavailable picosecond lasers are not at the true picosecond range (350ps or shorter) and have pulse duration of 750ps or shorter. This interferes with delivering quality photomechanical effects and may be another key reason why the picosecond laser is not yet widely used. Also, there were technical limitations in the early days such the medium being limited to alexandrite.

 

However, the picosecond laser is closer to selectivephotothermolysis (SPTL) compared to long-pulsed laser and is relatively safer as it is highly selective and does not cause photothermalside effects.

 

The 1064nm picosecond laser is good for removing deep pigmentsand the 755nm picosecond laser is good for shallow pigments, pores, texture and fine wrinkles. The 755nm and 1064nm picosecond laser is markedly superior to the nanosecond laser in terms of pigment removal. Q-switchedalexandrite or Q-switches Nd:YAGlaserrequires repeated treatments for lower risk of PIH and better efficacy.

 

-To be continued