title: Comparing 18- versus 12-mm spot size in hair removal using a gentlease 755-nm alexandrite laser.
abstract: BACKGROUND
  Laser epilation is based on the principle of selective photothermolysis, absorption of laser energy by the target chromophore melanin. It is claimed that larger spot sizes may be more effective for hair removal at identical fluences.
  
  
  OBJECTIVE
  To compare the efficacy of 18- vs. 12-mm spot size in hair removal using a Gentlelase Alexandrite laser from Candela Corporation (Boston, MA).
  
  
  METHODS
  In this double-blind, randomized control trial, patients underwent laser-assisted hair removal on the axillary region. Regions were randomly selected and treated with either an 18- or a 12-mm spot size. Three treatments at 6-week intervals with a 755-nm Gentlelase Alexandrite laser (Candela Corp., Canton, MA) at a fluence of 16 J/cm(2) with cooling and delay times of 60 ms. Hair counts were taken before each treatment session and compared. The mean percentage hair reduction and student's paired t-test were used to compare 18 versus 12 mm versus control sites at each visit and compared it with the baseline hair count.
  
  
  RESULTS
  There was a 10.3% difference in mean reduction favoring the 18-mm spot size treated area at the 6-month follow-up.
  
  
  CONCLUSIONS
  Our results indicate that a larger spot size appears to be more effective for laser assisted hair removal.
authors.affiliation: Department of Dermatology and Cutaneous Surgery, University of Miami School of Medicine, 1475 NW 12th Avenue, Suite 2175, Miami, FL 33136, USA. knouri@med.miami.edu
authors.forename: Keyvan
authors.initials: K
authors.lastname: Nouri
authors.forename: Halland
authors.initials: H
authors.lastname: Chen
authors.forename: Sogol
authors.initials: S
authors.lastname: Saghari
authors.forename: Carlos A
authors.initials: CA
authors.lastname: Ricotti
mesh_terms: D000328:Adult; D001365:Axilla / Q000601:surgery; D004311:Double-Blind Method; D005260:Female; D006204:Hair Removal / Q000295:instrumentation*; D006801:Humans; D053685:Laser Therapy / Q000295:instrumentation*; D016896:Treatment Outcome