title: Efficacy and Safety of Hair Removal with a Long-Pulsed Diode Laser Depending on the Spot Size: A Randomized, Evaluators-Blinded, Left-Right Study.
abstract: BACKGROUND
  The efficacy of the long-pulsed diode laser (LPDL) in hair removal is determined with various physical parameters. Recently, LPDLs with a larger spot size are commercially available; however, the independent effect of spot size on hair removal has not been studied.
  
  
  OBJECTIVE
  This study aimed to compare the efficacy of the LPDL in hair removal depending on the spot size.
  
  
  METHODS
  A randomized, evaluators-blind, intrapatient comparison (left vs. right) trial was designed. Ten healthy Korean women received three hair removal treatment sessions on both armpits with the 805-nm LPDL and followed for 3 months. A 10×10 mm handpiece (D1) or a 10×30 mm handpiece (D3) was randomly assigned to the right or left axilla. The fluence, pulse duration, and epidermal cooling temperature were identical for both armpits. Hair clearance was quantified with high-resolution photos taken at each visit. Postprocedural pain was quantified on a visual analogue scale. Adverse events were evaluated by physical examination and the patients' self-report.
  
  
  RESULTS
  The mean hair clearance at 3 months after three treatment sessions was 38.7% and 50.1% on the armpits treated with D1 and D3, respectively (p=0.028). Procedural pain was significantly greater in the side treated with D3 (p=0.009). Serious adverse events were not observed.
  
  
  CONCLUSIONS
  Given that the pulse duration, fluence, and epidermal cooling were identical, the 805-nm LPDL at the three times larger spot size showed an efficacy improvement of 29.5% in axillary hair removal without serious adverse events.
authors.affiliation: Department of Dermatology, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Seong Jin
authors.initials: SJ
authors.lastname: Jo
authors.affiliation: Department of Dermatology, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Jin Yong
authors.initials: JY
authors.lastname: Kim
authors.affiliation: JMO Dermatology, Seoul, Korea.
authors.forename: Juhee
authors.initials: J
authors.lastname: Ban
authors.affiliation: JMO Dermatology, Seoul, Korea.
authors.forename: Youngjoo
authors.initials: Y
authors.lastname: Lee
authors.affiliation: Department of Dermatology, Seoul National University College of Medicine, Seoul, Korea.
authors.forename: Ohsang
authors.initials: O
authors.lastname: Kwon
authors.affiliation: JMO Dermatology, Seoul, Korea.
authors.forename: Wooseok
authors.initials: W
authors.lastname: Koh
keywords: Hair; Hair removal; Laser spot size; Long pulsed diode laser