Journal of the Chinese Medical Association
Volume 71, Issue 3 , Pages 135-142, March 2008

Comparison of Multiple Reduced-dose and Standard Light Application in Photodynamic Therapy in an Animal Model of Choroidal Neovascularization

  • Shwu-Jiuan Sheu

      Affiliations

    • Department of Ophthalmology, National Yang-Ming University School of Medicine, Taipei, Taiwan, R.O.C.
    • Department of Ophthalmology, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan, R.O.C.
    • Corresponding Author InformationCorrespondence to: Dr Shwu-Jiuan Sheu, Department of Ophthalmology, Kaohsiung Veterans General Hospital, 386, Ta-Chung 1st Road, Kaohsiung 813, Taiwan, R.O.C.
    • ,
  • Youn-Shen Bee

      Affiliations

    • Department of Ophthalmology, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan, R.O.C.
    • ,
  • Hsiu-Chen Lin

      Affiliations

    • Department of Ophthalmology, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan, R.O.C.
    • ,
  • Wan-Ling Ho

      Affiliations

    • Department of Ophthalmology, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan, R.O.C.
    • ,
  • Tsung-Tien Wu

      Affiliations

    • Department of Ophthalmology, National Yang-Ming University School of Medicine, Taipei, Taiwan, R.O.C.
    • Department of Ophthalmology, Kaohsiung Veterans General Hospital, Kaohsiung, Taiwan, R.O.C.

Received 4 May 2007; accepted 13 February 2008.

Background

Current photodynamic therapy (PDT) for choroidal neovascularization (CNV) uses a standard radiant exposure of 50 J/cm2 at an irradiance of 600 mW/cm2. However, low-intensity PDT with verteporfin for neovascular tissue has been shown to be more effective than regular high-intensity PDT in an animal model of healthy choroids and corneal neovascularization. Low-intensity PDT also supposedly induces less retinal damage. In this study, we compared the effect of reduced-dose and standard light application PDT in an animal model of CNV.

Methods

A laser injury model was used to induce CNV 3 weeks prior to PDT in brown Norway rats. The CNV lesions were then treated with verteporfin PDT with a dose of verteporfin 6.0 mg/m2 and 5 activating doses of light energy (43, 53, 63, 73 and 83 seconds). Closure of CNV was assessed by fundus fluorescein angiography (FAG). Histopathologic study was done after the last FAG.

Results

PDT with verteporfin significantly reduced the CNV area compared with control non-treated groups 1 week after PDT (p < 0.05). Only those lesions treated for 63 seconds or longer retained their significantly attenuating effect on CNV up to 3 weeks after PDT. There was no significant difference between the inhibition effects induced by reduced-intensity light application for 63 or 73 seconds compared to the standard radiant exposure (83 seconds). Histopathologic study showed that eyes treated with PDT showed significantly less extent and vascularity of CNV lesion than control lesions.

Conclusion

Reduced-intensity PDT with 63-second duration seemed to be as effective as standard dose for CNV suppression. Considering the possible retinal damage following standard PDT, the PDT dose might be adjusted to reduce side effects. Further preclinical study will provide more data on what constitutes appropriate dosimetry for effective and safe PDT in CNV.

Key Words:  age-related macular degeneration , choroidal neovascularization , dose , photodynamic therapy

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PII: S1726-4901(08)70005-4

doi:10.1016/S1726-4901(08)70005-4

Journal of the Chinese Medical Association
Volume 71, Issue 3 , Pages 135-142, March 2008

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