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S.-J. Sheu, Y.-S. Bee, S.-C. Lin; Comparison of Multiple Reduced-dose and Standard Light Application in Photodynamic Therapy (PDT) of Animal Model Choroidal Neovacularization (CNV). Invest. Ophthalmol. Vis. Sci. 2007;48(13):1466. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Current photodynamic therapy (PDT) for choroidal neovascularization (CNV) uses a standard radiant exposure of 50J/cm2 at an irradiance of 600mW/cm2. However, low-intensity PDT with verteporfin for neovacular tissue has been shown to be more effective than regular high-intensity PDT in animal model of corneal neovascularization. Low-intensity PDT was also supposed to induce less retinal damage. In this study, we try to compare the effect of reduced-dose and standard light application PDT in animal model CNV.
A laser injury model was used to induce CNV three 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 five activating doses of light energy (43, 53, 63, 73, and 83 seconds). Closure of CNV was assessed by fundus fluorescein angiography (FAG). Retinal damage was assessed histologically.
PDT with verteporfin significantly reduced the CNV area compared with eyes of control non-treated groups at 1st, 2nd, 3rd and 4th week after PDT (P < 0.05). All the five activating doses of light energy (43, 53, 63, 73, and 83 seconds) showed significant effect on the closure of CNV. There was no significant difference between the inhibition effects induced by those low-intensity light application (43, 53, 63, 73 seconds) compared to the standard radiant exposure (83 seconds). The consistency persists at all time points (1st, 2nd, 3rd and 4th week after PDT).
Low-intensity PDT with verteporfin for animal model CNV seems to be as effective as standard dose. Considering the possible retinal damage following standard PDT, dose of PDT might be adjusted to reduce to side effect. Future pre-clinical study will give us more idea about the appropriate dosimetry for effective and safe PDT in CNV.
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