title: The effect of digital measurement software on photodynamic therapy.
abstract: BACKGROUND
  To investigate the effect of refraction-corrected digital measurement software on photodynamic therapy (PDT) treatment spot size.
  
  
  METHODS
  Experimental study using a calibrated Gullstrand-type model eye. The axial length of the model eye was set to different values, ranging from 20 to 31 mm, and the PDT treatment spot sizes obtained from refraction-corrected digital measurement software and manual measurement with a fixed-magnification factor, as well as four different indirect contact laser lenses, were calculated and compared for a treatment spot with a diameter of 4 mm.
  
  
  RESULTS
  The maximum deviation from the treating laser spot was +39.6% under myopic and +17.4% under hyperopic conditions when the refraction-corrected digital measurement software was used. The maximum deviation was +14.2% under myopic and +13.3% under hyperopic conditions when the manual measurement with the fixed-magnification factor was used.
  
  
  CONCLUSIONS
  The use of refraction-corrected digital measurement software produces a larger deviation from treating laser spot than the use of manual measurement with a fixed-magnification factor. Therefore, refraction-corrected digital measurement software might not be suitable for calculating the recommended PDT treatment spot size in eyes with high refractive errors.
authors.affiliation: Department of Ophthalmology and Optometry, Medical University of Vienna, Vienna, Austria. siamak.ansari-shahrezaei@meduniwien.ac.at
authors.forename: Siamak
authors.initials: S
authors.lastname: Ansari-Shahrezaei
authors.forename: Erdem
authors.initials: E
authors.lastname: Ergun
authors.forename: Michael
authors.initials: M
authors.lastname: Stur
mesh_terms: D020256:Choroidal Neovascularization / Q000601:surgery*; D005123:Eye / Q000473:pathology*; D005451:Fluorescein Angiography; D006801:Humans; D006956:Hyperopia / Q000150:complications*; D007090:Image Interpretation, Computer-Assisted; D008954:Models, Biological; D009216:Myopia / Q000150:complications*; D010778:Photochemotherapy; D010781:Photography / Q000295:instrumentation; D017319:Photosensitizing Agents / Q000627:therapeutic use; D011166:Porphyrins / Q000627:therapeutic use; D012029:Refraction, Ocular; D012984:Software; D000077362:Verteporfin
chemical_list: D017319:Photosensitizing Agents; D011166:Porphyrins; D000077362:Verteporfin