• [Issue] Understanding picosecond laser IV


    Are vacuoles a positive phenomenon?

     Manufacturers of the picosecond laser claim that photoacoustic effect occurs on the basis that vacuoles as part of the laser-induced optical breakdown (LIOB) are seen upon histological examination. Vacuoles only prove that there is a tissue defect and cannot be considered as evidence of a rejuvenating effect. It is true that the LIOB caused by photoacoustic effect promotes fibroblasts to cause regeneration of collagen, elastin, For vacuoles to be a proof of rejuvenation, they should develop over the entire treated area. However, they are seen only in limited areas and more active collagenesis is seen even in areas without any vacuoles. Therefore, I believe it is wiser to lower the fluence once vacuoles develop.  



    Treating melasma with the picosecond laser

    The current medical treatment for melasma is symptomatic and does not address the causes. With laser, lesions with increased epidermal melanocytes or dermal melanocytes can be cleared but if cellular hyperactivity is involved, laser is ineffective. For these reasons, it is advisable to combine laser with medication when laser alone is not bringing positive results.



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    The fractional tip

    Many doctors think that the fractional tip enhances the benefits of the picosecond laser but I beg to differ. The term “fractional” means that the laser beam is fractionated or that the area of irradiation is fractionated. This lowers the energy delivered and may reduce the risk of side effects but it can also mean lower efficacy.  

    There are claims that the 532nm picosecond laser used with a fractional tip is effective in Ota’s nevus or ABNOM, but I disagree. The 532nm wavelength has a short scattering depth and the fractional tip lowers the energy further, which would compromise the depth even more.

    Some claim to have treated nevus of Ota and Ito or ABNOM with the picosecond laser. These conditions present proliferation of dermal melanocytes but are also accompanied by epidermal accumulation of melanin. This patient was such a case and the 532nm picosecond laser with a fractional tip was effective in removing the epidermal component. This may have been confused with successful inhibition of dermal melanocyte proliferation. However, I believe only the epidermal melanin was removed and the dermal component was not addressed. Many doctors tend to be too optimistic with the efficacy of the picosecond laser, however, the reality is that the new treatment has much to improve. 


    -To be continued