The effect of laser unit on photodynamic therapy spot size

  • Siamak Ansari-ShahrezaeiEmail author
  • Susanne Binder
  • Michael Stur
Retinal Disorders



To determine the effect of the laser unit on photodynamic therapy (PDT) spot size.


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).


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).


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.


Photodynamic therapy Laser Age-related macular degeneration Choroidal neovascularization 



The authors thank Werner Infanger from Zeiss Vienna for his support.

Conflicts of interest

The authors have no conflicts of interest to declare.

Financial support

No financial support was provided for this study.


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Copyright information

© Springer-Verlag 2010

Authors and Affiliations

  • Siamak Ansari-Shahrezaei
    • 1
    • 2
    • 3
    Email author
  • Susanne Binder
    • 1
    • 2
  • Michael Stur
    • 4
  1. 1.Department of OphthalmologyRudolf Foundation ClinicViennaAustria
  2. 2.The Ludwig Boltzmann Institute for Retinology and Biomicroscopic Laser SurgeryViennaAustria
  3. 3.Department of OphthalmologyMedical University of GrazGrazAustria
  4. 4.Department of OphthalmologyMedical University of ViennaViennaAustria

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