Excimer Laser for Psoriasis: A Review of Theories Regarding Enhanced Efficacy Over Traditional UVB Phototherapy
August 2007 | Volume 6 | Issue 8 | 794 | Copyright © August 2007
Karine Zakarian MD, Alain Nguyen MD, Julie Letsinger MD, John Koo MD
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.
Conclusion: 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. 
