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Fok et al. Plast Aesthet Res 2017;4:1-8 Plastic and
DOI: 10.20517/2347-9264.2016.85
Aesthetic Research

www.parjournal.net
Original Article Open Access

Thermal distribution and response in

Q-switched ruby laser treatment for

oculodermal melanosis (Nevus of Ota)

David Cheong Chon Fok , Cheng-Jen Chang , Yun-Liang Su , Shu-Ying Chang , Yen-Chang Hsiao , Kuen Ting ,
1
4
3
1
1
1,2
Wen-Shiung Lin , Kuen-Tasnn Chen , Shih-Feng Chen 4
3
4
1 Department of Plastic Surgery, Chang Gung Memorial Hospital, Chang Gung University, Taoyuan 333, Taipei, China.
2 Department of Plastic Surgery, Taipei Medical University Hospital, Taipei 110, Taipei, China.
3 Department of Applied Mathematics, National Chung Hsing University, Taichung 402, Taipei, China.
4 Department of Mechanical Engineering, Lunghwa University of Science and Technology, Taoyuan 333, Taipei, China.
Correspondence to: Prof. Cheng-Jen Chang, Department of Plastic Surgery, Taipei Medical University Hospital, Taipei 110, Taipei, China. E-mail:
chengjen@h.tmu.edu.tw
How to cite this article: Fok DCC, Chang CJ, Su YL, Chang SY, Hsiao YC, Ting K, Lin WS, Chen KT, Chen SF. Thermal distribution and response
in Q-switched ruby laser treatment for oculodermal melanosis (Nevus of Ota). Plast Aesthet Res 2017;4:1-8.
Dr. Cheng-Jen Chang is currently the vice Superintendent of Taipei Medical University Hospital, Taipei, China. He
is also the Editor of Laser Therapy and Aesthetic Surgery Journal. Dr. Chang is an outstanding member of Fellow of
American College of Surgeon (FACS) as well as Fellow of International College of Surgeon (FICS) and is honored to
be the Fellow of American Society of Laser Medicine and Surgery (ASLMS). In addition, Dr. Chang has worked on
publication review for the Monthly Journal Archives of Dermatology and for the US Surgical Dermatology Magazine.

ABSTRACT

Article history: Aim: A clinically useful treatment laser must generate stable and precise energy of low
Received: 11-10-2016 diffusivity. This study assessed the photothermal response of a Q-switched ruby laser (QSRL)
Accepted: 13-10-2016 in the treatment of oculodermal melanosis (Nevus of Ota). Methods: A two-year retrospective
Published: 19-01-2017 review of 40 patients with oculodermal melanosis treated with a QSRL (λ = 694 nm, pulse
duration = 25 ns, 3 mm spot size, energy density 6-10 J/cm ) was performed. Demographics
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Key words: included an age range of 18-54 years (mean 28) and a gender distribution of 25 females and
Infrared thermal imaging, 15 males. The values recorded from real-time infrared thermal imaging of the lasered skin
thermal wave equation, were inserted into standard thermal wave equations. This permitted analysis of the resultant
Q-switched ruby laser, temperature distributions related to the energy change. Results: Skin temperature was
Nevus of Ota unchanged during the initial heating stage. This was followed by a very rapid temperature
rise. A thermal burn injury manifested by dermal-epidermal disruption, resulted when the
energy density of the QSRL exceeded 8 J/cm (> 44 ℃). Conclusion: The use of infrared
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thermal imaging with a standard thermal wave equation allows prediction of skin temperature
distribution when QSRL is used for the treatment of oculodermal melanosis. With the use of
appropriate settings, complications may be minimized.

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