title: Excimer laser for psoriasis: a review of theories regarding enhanced efficacy over traditional UVB phototherapy.
abstract: BACKGROUND
  Fiber-optically targeted ultraviolet B (UVB) therapy has been shown to clear plaques of psoriasis in a significantly fewer number of treatments and reduce overall cumulative UVB dose than traditional UVB phototherapy.
  
  
  OBJECTIVE
  This article reviews existing theories in the literature attempting to explain the superior efficacy of targeted UVB.
  
  
  METHODS
  Medline was used to perform a comprehensive review of the literature from 1965 to present. Only information from the English language journals are reported in this study.
  
  
  RESULTS
  The theories proposed to explain the higher efficacy of the excimer (XeCl) laser relative to traditional UVB include the ability to use higher intensities of ultraviolet (UV) light and a more efficient induction of T cell apoptosis.
  
  
  CONCLUSIONS
  The possible explanations for the superior efficacy of the excimer laser over traditional UVB therapy for psoriasis include: 1) a higher intensity UV light to plaques, which is more effective in clearing psoriasis; 2) penetration into the dermis where it may induce T cell apoptosis, potentially to a greater extent than the wavelength or given energy level predicts; and 3) the difference in the delivery of UVB light may result in cell death and skin immune system suppression more effectively than traditional UVB.
authors.affiliation: Department of Pediatrics, University of California, Irvine, CA, USA. kzakaria@uci.edu
authors.forename: Karine
authors.initials: K
authors.lastname: Zakarian
authors.forename: Alain
authors.initials: A
authors.lastname: Nguyen
authors.forename: Julie
authors.initials: J
authors.lastname: Letsinger
authors.forename: John
authors.initials: J
authors.lastname: Koo
mesh_terms: D017209:Apoptosis / Q000528:radiation effects; D003131:Combined Modality Therapy; D006801:Humans; D053685:Laser Therapy; D011565:Psoriasis / Q000532:radiotherapy*; D013601:T-Lymphocytes / Q000276:immunology / Q000528:radiation effects; D013997:Time Factors; D016896:Treatment Outcome; D014467:Ultraviolet Therapy / Q000295:instrumentation*