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The effect of laser unit on photodynamic therapy spot size

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

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.

Keywords

Photodynamic therapy Laser Age-related macular degeneration Choroidal neovascularization 

Notes

Acknowledgments

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.

References

  1. 1.
    Treatment of Age-Related Macular Degeneration with Photodynamic Therapy (TAP) Study Group (2001) Photodynamic therapy of subfoveal choroidal neovascularization in age-related macular degeneration with verteporfin: two-year results of 2 randomized clinical trials—TAP Report 2. Arch Ophthalmol 119:198–207Google Scholar
  2. 2.
    Verteporfin in Photodynamic Therapy (VIP) Study Group (2003) Verteporfin therapy of subfoveal choroidal neovascularization in pathologic myopia: 2-year results of a randomized clinical trial—VIP report no. 3. Ophthalmology 110:667–673CrossRefGoogle Scholar
  3. 3.
    Kramer M, Miller JW, Michaud N, Moulton RS, Hasan T, Flotte TJ, Gragoudas ES (1996) Liposomal benzoporphyrin derivative verteporfin photodynamic therapy: selective treatment of choroidal neovascularization in monkeys. Ophthalmology 103:427–438PubMedGoogle Scholar
  4. 4.
    Postelmans L, Pasteels B, Coquelet P, El Ouardighi H, Verougstraete C, Schmidt-Erfurth U (2004) Severe pigment epithelial alterations in the treatment area following photodynamic therapy for classic choroidal neovascularization in young females. Am J Ophthalmol 138:803–808CrossRefPubMedGoogle Scholar
  5. 5.
    Husain D, Kramer M, Kenny AG, Michaud N, Flotte TJ, Gragoudas ES, Miller JW (1999) Effects of photodynamic therapy using verteporfin on experimental choroidal neovascularization and normal retina and choroid up to 7 weeks after treatment. Invest Ophthalmol Vis Sci 40:2322–2331PubMedGoogle Scholar
  6. 6.
    Reinke MH, Canakis C, Husain D, Michaud N, Flotte TJ, Gragoudas ES, Miller JW (1999) Verteporfin photodynamic therapy retreatment of normal retina and choroid in the Cynomolgus Monkey. Ophthalmology 106:1915–1923CrossRefPubMedGoogle Scholar
  7. 7.
    Ranchod TM, Brucker AJ, Liu C, Cukras CA, Hopkins TB, Ying GS (2009) Evaluation of actual vs expected photodynamic therapy spot size. Am J Ophthalmol 147:859–864CrossRefPubMedGoogle Scholar
  8. 8.
    Kondo M, Ito Y, Miyata K, Kondo N, Ishikawa K, Terasaki H (2006) Effect of axial length on laser spot size during photodynamic therapy: an experimental study in monkeys. Am J Ophthalmol 141:214–215CrossRefPubMedGoogle Scholar
  9. 9.
    Ansari-Shahrezaei S, Ergun E, Stur M (2006) The effect of axial length on photodynamic therapy. Am J Ophthalmol 141:699–702CrossRefPubMedGoogle Scholar
  10. 10.
    Rassow B (1972) A model of Gullstrand’s normal eye (in German). Ophthalmologica 164:143–148CrossRefPubMedGoogle Scholar
  11. 11.
    Altman DG, Bland JM (1983) Measurement in medicine: the analysis of method comparison studies. Statistician 32:307–317CrossRefGoogle Scholar
  12. 12.
    Antoszyk AN, Tuomi L, Chung CY, Singh A, Focus Study Group (2008) Ranibizumab combined with verteporfin photodynamic therapy in neovascular age-related macular degeneration (Focus): year 2 results. Am J Ophthalmol 145:862–874CrossRefPubMedGoogle Scholar
  13. 13.
    Arias L, Garcia-Arumi J, Ramon JM, Badia M, Rubio M, Pujol O (2006) Photodynamic therapy with intravitreal triamcinolone in predominantly classic choroidal neovascularization: one-year results of a randomized study. Ophthalmology 113:2243–2250CrossRefPubMedGoogle Scholar
  14. 14.
    Tao Y, Jonas JB (2010) Refractive error and smoking habits in exudative age-related macular degeneration in a hospital-based setting. Eye 24:648–652CrossRefPubMedGoogle Scholar
  15. 15.
    Ulvik SO, Seland JH, Wentzel-Larsen T (2005) Refraction, axial length and age-related maculopathy. Acta Ophthalmol Scand 83:419–423Google Scholar
  16. 16.
    Ansari-Shahrezaei S, Ergun E, Stur M (2006) The effect of digital measurement software on photodynamic therapy. Graefes Arch Clin Exp Ophthalmol 244:137–142CrossRefPubMedGoogle Scholar
  17. 17.
    Stur M, Ansari-Shahrezaei S (2001) The effect of axial length on laser spot size and laser irradiance. Arch Ophthalmol 119:1323–1328PubMedGoogle Scholar
  18. 18.
    Ansari-Shahrezaei S, Ergun E, Stur M (2006) Digital area measurement of fundus landmarks. Graefes Arch Clin Exp Ophthalmol 244:649–653CrossRefPubMedGoogle Scholar
  19. 19.
    Ansari-Shahrezaei S, Ergun E, Chong R, Tufail A, Wedrich A, Stur M (2007) Magnification-corrected photodynamic therapy. Graefes Arch Clin Exp Ophthalmol 245:333–337CrossRefPubMedGoogle Scholar
  20. 20.
    Bennett AG, Rudnicka AR, Edgar DF (1994) Improvements on Littmann’s method of determining the size of retinal features by fundus photography. Graefes Arch Clin Exp Ophthalmol 232:361–367CrossRefPubMedGoogle Scholar

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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