title: Deep coagulation of dermal collagen with repetitive Er:YAG laser irradiation.
abstract: OBJECTIVE
  Er:YAG lasers are known to effectively ablate human skin with minimal thermal damage to subjacent dermal tissue. We have investigated whether deep coagulation of dermal collagen, similar to that observed with the CO(2) laser, could be achieved with repetitive Er:YAG laser exposures.
  
  
  METHODS
  Skin on the back of a Sprague-Dawley rat in vivo was irradiated with sequences of 1-10 Er:YAG laser pulses at a repetition rate of 10 or 33 Hz and single-pulse fluences from 0.8 to 1.4 J/cm(2). The resulting lesions were biopsied within 1 hour after laser exposure, and the histologic sections were examined by using optical microscopy.
  
  
  RESULTS
  The depth of dermal collagen denaturation increases dramatically when 3-10 low-fluence Er:YAG laser pulses are stacked at a repetition rate of 10 or 33 Hz.
  
  
  CONCLUSIONS
  Coagulation of dermal collagen deeper than 200 microm below the epidermal-dermal junction is feasible by using the appropriate settings of a repetitive Er:YAG laser.
authors.affiliation: Beckman Laser Institute and Medical Clinic, University of California, Irvine, California 92612, USA. majaron@bli.uci.edu
authors.forename: B
authors.initials: B
authors.lastname: Majaron
authors.forename: S M
authors.initials: SM
authors.lastname: Srinivas
authors.forename: H e
authors.initials: He
authors.lastname: Huang
authors.forename: J S
authors.initials: JS
authors.lastname: Nelson
mesh_terms: D000818:Animals; D003094:Collagen / Q000378:metabolism*; D062109:Dermatologic Surgical Procedures; D004817:Epidermis / Q000378:metabolism*; D004871:Erbium; D005260:Female; D006801:Humans; D017075:Laser Coagulation / Q000379:methods*; D051381:Rats; D017207:Rats, Sprague-Dawley; D012867:Skin / Q000378:metabolism / Q000473:pathology
chemical_list: D004871:Erbium; D003094:Collagen