Geun Soo Lee
Secretary-General
Korean Society for Aesthetic and
Dermatologic Surgery
Korea
francise2@hanmail.net
Background
Dr. Lee is board-certified dermatologist in Korea. He is a member of Korean
Dermatological Association (KDA) and the Association of Korean Dermatologists (AKD).
He has received M.D. and Ph.D. degree from Hanyang University, Seoul, Korea.
Currently, he is the Director of Dr. Woo & Hann's Skin and Laser Clinic.
Dr. Lee have given many lectures regarding various lasers, light source, energy-based
devices, and other topics related on aesthetic dermatology in domestic, regional, and
international conferences. Recently, he had participated in organizing committee of
Koreaderma 2019 as chief course director and, Koreaderma 2020 as co-chief course
director. He had written scientific papers in Dermatologic surgery, Laser Therapy,
Annals of Dermatology, and Journal of Dermatological Treatment. He had presented
laser treatments related topics in American Society for Laser Medicine and Surgery
annual meetings. In addition, he had also participated as a co-author Textbook of
Dermatologic Surgery written in Korean and had written a book named "Principle and
clinical application of fractional lasers" in Korean as one of the representative writers.
He is serving as chairperson in the scientific committee of the AKD. He is councilor of
KDA and auditor of Korean Society of Dermatologic Laser Surgery and Korean Medical
Laser Society.
His major concerns are acne treatments, pigmented skin disease treatments including
melasma, dermal melanosis, lentigines, or photodamages, and skin rejuvenation
treatment by use of fractional technology, non-ablative skin rejuvenation lasers,
ultrasound, radiofrequency, and light sources. Recently he is exploring the benefit and
versatility of picosecond laser.
Topic: Laser Tissue Interaction Review for Pigmented Lesion Treatments
Abstract:
Laser surgery for melanin pigment lesion treatment requires understanding of the biophysics of
laser-tissue interactions, main three chromophore absorption curves and tissue selectivity. In melanin
containing pigmented lesions, the concentration of melanin, as well as its depth distribution, is strongly
affected by amount of previous ultraviolet radiation. Due to the wide absorption spectrum of melanin,
many kinds of cutaneous lasers are introduced for the treatment of pigment lesions which producing
various wavelength laser beam. Before selecting proper device, we think the melanin distribution depth,
thickness, pattern and amount of the pigmented skin lesions. Pulse duration is an important factor that
should not ignored when selecting treatment method. Depends on pulse duration, coagulation and
vaporization appears in milliseconds or microseconds pulse width. If the pulse width is much shorter like
nanoseconds or picoseconds level, photoablation and photodisruption appears.
Theory of selective thermolysis which is proposed by Rox Anderson and John Parrish in 1983, made new
horizon in cutaneous laser surgery. A lot of cutaneous lasers applied this principle are developed and
clinically used, consequently resulted in better therapeutic results and low risk of adverse effects. Under
the influence of this theory, progress of ultrashort pulse duration producing lasers has been made rapidly
with the advancement of ultrashort laser technology. Starting from nanosecond laser to picosecond
laser, both has been created a variety of novel laser therapeutic applications in dermatology. Nanosecond
lasers are generated by Q switching or gain switching. On the other hands, under the basis of extended
theory of selective photothermolysis which is explained in 2001, longer pulse duration beyond thermal
relaxation time was shown effective also on main chromophores by heat diffusion.
Picosecond lasers produce mainly photomechanical effect on the targeted tissue with minimal
photothermal effect. Picosecond laser laser-tissue interaction shows photodisruption. The
photodisruption is induced by plasma formation and LIOB (laser induced optical breakdown). The injury
induced by LIOB stimulates the production of cytokines and, which dermal remodeling is followed by.
When picosecond laser pulse duration become more shortened, the photomechanical effect become
more prominent. The photomechanical stress generated within the particle in very short time has not
enough time to diffuse stress. In this case, stress is locked-in so, fracture of the particle does not occur.
As if temperature-based threshold condition for saving surround tissue from photothermal damage in
selective photothermolysis theory, time-based threshold condition that preserve particle integrity from
photomechanical damage is called the stress relaxation time (SRT). Picosecond domain lasers hold a
lead compare to Q-switch nanosecond domain lasers in terms of SRT.
Long pulse lasers or IPL, which produce photothermal response mainly, destroy melanosomes by
condensation response. Nanosecond lasers or picosecond lasers are producing spattering response to
melanosomes. Proper combination or selection of various lasers or light source can lead effective
pigment lesion treatment.
