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Clinical Papers

Topical anesthesia for laser hair removal: comparison of spot sizes and 755 nm versus 800 nm wavelengths


PubMed Reference: Eremia S, Newman N. Dermatol Surg. 2000 July. 

Study Details:

  • 12 females (18–34 years old) with skin type I–IV 
  • Each axilla was split into 2 halves and treated on superior/inferior area: 
    • Right axilla: 755nm alexandrite (3 msec pulses, 8 mm round spot size, cryogen cooling device) at maximum tolerated fluence up to 40J/cm2
    • Other half of right axilla: 755nm alexandrite (3 msec pulses, 12 mm round spot size, cryogen cooling device)
    • Half of left axilla: 800nm diode laser (9 mm square spot size and built in sapphire window contact cooling device) at maximum tolerated fluence up to 40J/cm2
    • Other half of left axilla: 755nm alexandrite (3 msec pulses, 12 mm round spot size, cryogen cooling device)
  • 3-4 treatment sessions at 4 to 6-week intervals.

Study Results:

  • Pain level significantly greater with diode laser with the same fluence for both lasers (with or without topical anesthetic) and for both spot sizes
  • Cryogen spray (DCD) protects the epidermis by: 
    • Physically impeding the laser beam by the spray
    • Cooling the skin surface. 
  • Cryogen spray cooling of the skin allows higher fluence to be used on all skin types.