title: Low Fluence Q-Switched Nd: YAG Laser Toning and Q-Switched Ruby Laser in the Treatment of Melasma:A Comparative Split-Face Ultrastructural Study.
abstract: BACKGROUND
  Melasma still presents as a difficult entity to treat, especially in the Asian skin phe-notype. Recently laser toning with the Q-switched Nd:YAG has attracted attention. The present study investigated the efficacy of Q-switched Nd:YAG laser toning for melasma, with a histopathological comparison with the Q-switched ruby laser.
  
  
  METHODS
  Eight Japanese females (41-57 yr, mean 52.5 yr) with Fitzpatrick skin type III and bilateral melasma participated in the study. One half of each subject's face (randomly chosen) was treated with Q-switched 1064 nm Nd:YAG laser toning (pulse width 5-20 ns; spot size, 6 mm diameter; fluence, 3.0 J/cm(2), 5-7 passes, once/week, 4 weeks: QS:YAG group), and the contralateral half with a single treatment using a Q-switched ruby laser (694.5 nm, pulse width 20 ns, spot size 4 mm diameter; fluence 4.0 J/cm2, 1 pass with approximately 20% overlap: QS:Ruby group). Skin biopsies were taken immediately after the 4(th) Nd:YAG session and the single ruby session, and histopathological comparison was performed with light- and transmission electron microscopy (TEM).
  
  
  RESULTS
  Improvement in melasma pigmentation was seen in both the QS:YAG- and QS:Ruby-treat-ed sides, and this was well-maintained in the QS:YAG group. Ultrastructurally, melanin granules were destroyed in both groups, but there was considerably more morphological epidermal and dermal damage in the QS:Ruby specimens compared with minimal epidermal disruption and cellular damage in the QS:YAG specimens.
  
  
  CONCLUSIONS
  Q-switched 1064 nm Nd:YAG laser toning offered superior results in the treatment of melasma in the Japanese skin type compared with the Q-switched ruby laser, both ultrastructurally with less immediately post-treatment cellular damage and macroscopically, and a longer recurrence-free interval.
authors.affiliation: Department of Dermatology, Queen's Square Medical Center, Yokohama, Japan ; Department of Dermatology, Nippon Medical School, Tokyo, Japan.
authors.forename: Tokuya
authors.initials: T
authors.lastname: Omi
authors.affiliation: Department of Plastic & Reconstructive Surgery, Shonan Kamakura General Hospital, Kamakura, Japan.
authors.forename: Rie
authors.initials: R
authors.lastname: Yamashita
authors.affiliation: Department of Dermatology, Nippon Medical School, Tokyo, Japan.
authors.forename: Seiji
authors.initials: S
authors.lastname: Kawana
authors.affiliation: Central Institute for Electron Microscopic Research, Nippon Medical School, Tokyo, Japan.
authors.forename: Shigeru
authors.initials: S
authors.lastname: Sato
authors.affiliation: Central Institute for Electron Microscopic Research, Nippon Medical School, Tokyo, Japan ; Department of Pathology, Nippon Medical School, Tokyo, Japan.
authors.forename: Zenya
authors.initials: Z
authors.lastname: Naito
keywords: Q-switched laser; laser toning; selective photothermolysis; subcellular selective photothermolysis; transmission electron microscopy