Effect of spot size and fluence on Q-switched alexandrite laser treatment for pigmentation in Asians: a randomized, double-blinded, split-face comparative trial

J Dermatolog Treat. 2012 Oct;23(5):333-8. doi: 10.3109/09546634.2011.560929. Epub 2011 Jul 14.


Background: Q-switched laser treatment for pigment disorders commonly leads to postinflammatory hyperpigmentation (PIH) in Asians.

Objectives: 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.

Publication types

  • Comparative Study
  • Randomized Controlled Trial

MeSH terms

  • Adult
  • Asian Continental Ancestry Group
  • Double-Blind Method
  • Female
  • Humans
  • Hyperpigmentation / etiology*
  • Inflammation / complications
  • Lasers, Solid-State / adverse effects
  • Lasers, Solid-State / therapeutic use*
  • Lentigo / pathology
  • Lentigo / radiotherapy
  • Melanosis / pathology
  • Melanosis / radiotherapy*
  • Middle Aged
  • Nevus of Ota / pathology
  • Nevus of Ota / radiotherapy*
  • Patient Satisfaction
  • Skin Neoplasms / pathology
  • Skin Neoplasms / radiotherapy*