title: Effect of spot size and fluence on Q-switched alexandrite laser treatment for pigmentation in Asians: a randomized, double-blinded, split-face comparative trial.
abstract: BACKGROUND
  Q-switched laser treatment for pigment disorders commonly leads to postinflammatory hyperpigmentation (PIH) in Asians.
  
  
  OBJECTIVE
  To evaluate the effect of spot size and fluence on Q-switched alexandrite laser (QSAL) treatment for pigmentation in Asians.
  
  
  METHODS
  Ten patients with freckles, 18 with lentigines, and 8 with acquired bilateral nevus of Ota-like macules (ABNOM) received 1 session of QSAL treatment for a 3-mm spot on one cheek and a 4-mm spot on the other cheek. The lowest fluences to achieve a visible biologic effect were chosen.
  
  
  RESULTS
  The patients with freckles experienced the highest improvement rate (83-84%), followed by those with lentigines (52%) and ABNOM (35%). Similar efficacy was observed for both cheeks (p > 0.05). PIH developed in 10% (1/10), 44% (8/18), and 75% (6/8) of the patients with freckles, lentigines, and ABNOM, respectively. The severity of PIH was lower in the 4-mm spot with a lower fluence than in the 3-mm spot with a higher fluence in patients with lentigines (p = 0.03), but not in those with freckles or ABNOM.
  
  
  CONCLUSIONS
  Using a larger spot to achieve the same biologic effect at a lower fluence is associated with equal efficacy and less-severe PIH in patients with lentigines.
authors.affiliation: Department of Dermatology, Cardinal Tien Hospital, Hsin Tien, New Taipei, Taiwan. jamiewang@tma.tw
authors.forename: Chia-Chen
authors.initials: CC
authors.lastname: Wang
authors.forename: Chih-Kang
authors.initials: CK
authors.lastname: Chen
mesh_terms: D000328:Adult; D044466:Asian People; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D017495:Hyperpigmentation / Q000209:etiology*; D007249:Inflammation / Q000150:complications; D053844:Lasers, Solid-State / Q000009:adverse effects / Q000627:therapeutic use*; D007911:Lentigo / Q000473:pathology / Q000532:radiotherapy; D008548:Melanosis / Q000473:pathology / Q000532:radiotherapy*; D008875:Middle Aged; D009507:Nevus of Ota / Q000473:pathology / Q000532:radiotherapy*; D017060:Patient Satisfaction; D012878:Skin Neoplasms / Q000473:pathology / Q000532:radiotherapy*