title: The effect of laser unit on photodynamic therapy spot size.
abstract: BACKGROUND
  To determine the effect of the laser unit on photodynamic therapy (PDT) spot size.
  
  
  METHODS
  A calibrated Gullstrand-type model eye was used for this study. The axial length of the model eye was set to different values ranging from 22.2 to 27.0 mm, and the actual spot size from the laser console was recorded for treating a spot of 4 mm in the center of the artificial fundus using two different laser units (Coherent Opal laser; Coherent Inc, Santa Clara, California, USA and Zeiss Visulas laser; Carl Zeiss Meditec Inc, Dublin, California, USA) and two indirect contact laser lenses (Volk PDT laser lens and Volk Area Centralis lens; Volk Optical Inc, Mentor, Ohio, USA).
  
  
  RESULTS
  From myopia to hyperopia, the total deviation from the intended spot size was -22.5% to -7.5% (Opal laser and PDT laser lens), and -17.5% to +2.5% (Visulas laser and PDT laser lens), -12.5% to +7.5% (Opal laser and Area Centralis lens), and -7.5% to +10% (Visulas laser and Area Centralis lens).
  
  
  CONCLUSIONS
  The used laser unit has a significant effect on PDT spot size in this model. These findings may be important for optimizing PDT of choroidal neovascular lesions.
authors.affiliation: Department of Ophthalmology, Rudolf Foundation Clinic, Vienna, Austria. siamak.ansari-shahrezaei@wienkav.at
authors.forename: Siamak
authors.initials: S
authors.lastname: Ansari-Shahrezaei
authors.forename: Susanne
authors.initials: S
authors.lastname: Binder
authors.forename: Michael
authors.initials: M
authors.lastname: Stur
mesh_terms: D020256:Choroidal Neovascularization / Q000188:drug therapy; D006801:Humans; D053685:Laser Therapy; D008268:Macular Degeneration / Q000188:drug therapy; D008954:Models, Biological; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000627:therapeutic use; D011166:Porphyrins / Q000627:therapeutic use; D000077362:Verteporfin
chemical_list: D017319:Photosensitizing Agents; D011166:Porphyrins; D000077362:Verteporfin