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TA Ciulla, MH Criswell, RP Danis, WJ Snyder, W Small; Evaluation of a Novel Photosensitizer MV6401 as a Photodynamic Therapy Agent using a Primate Choroidal Neovasularization Model . Invest. Ophthalmol. Vis. Sci. 2002;43(13):614.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Photodynamic therapy (PDT) is an evolving technology for treating choroidal neovascularization (CNV) in maculopathies, particularly age-related macular degeneration (AMD). The effectiveness of novel PDT photosensitizer MV6401 (Miravant Pharmaceuticals, Inc.) to limit CNV was evaluated in the squirrel monkey CNV model. Methods: To induce experimental CNV, an IRIS diode laser (532 nm, 0.05 sec duration, 650 mW, 75 µm) established a 3x3 macular grid of photocoagulation sites (PS) in 8 squirrel monkey eyes. On post-laser day 28, animals were IV injected with MV6401 (0.15 µmols/kg) which exhibits an absorption peak at 659 nm. At post-injection times (from 20-120 minutes) the nasal and central PS columns were selectively treated with laser light at the drug's activation wavelength (664 nm, 500 mW/cm2 irradiance, 800 µm spot dia), delivered at duration-dependent light doses of 10 and 20 J/cm2 respectively. Results: On day 35, moderate to complete closure of CNV and choriocapillaris vessels (accompanied by negligible to low tissue damage) was apparent around PS receiving PDT treatments 60-80 minutes post-injection, including sites where extensive neovascularization had developed. Greater retinal damage was observed at sites treated prior to 60 minutes post-injection, whereas decreased vessel closure corresponded to post-injection treatment times longer than 80 minutes. Paradoxically, less damage was noted at central macular sites receiving 20 J/cm2 light dosages, compared to nasal sites receiving only 10 J/cm2, possibly reflecting variations in vascular density across the macula. Control sites exhibited non-obstructed CNV with RBC's. Conclusion: Photosensitizer MV6401 demonstrates effective CNV closure; a post-injection delay is necessary to achieve optimal treatment results. Refinement of light dosage parameters within different portions of the macula deserves further study.
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