Abstract
Abstract: :
Purpose:To assess a novel Photodynamic Therapy (PDT) agent, Talaporfin Sodium, for the cessation or reduction of leakage in the choroidal neovascular membranes (CNVM) of late stage age related macular degeneration (ARMD). Method:A pilot, non–comparative, prospective clinical study. Patients with persistent leakage from ARMD and a central disciform scar were included in this study. Talaporfin Sodium (0.5mg/kg), a chemically synthesized photosensitizer, was used in conjunction with a low power 664nm laser. The light energy dose used was determined by earlier animal experimentation. In the primate model, 300mW/cm2 resulted in closure of vessels predominantly in the choroid with minimal photoreceptor damage. A drug light interval of 15 minutes was used. Visual acuity and adverse effects were recorded at each visit. Fluorescein angiographic image analysis was performed during the PDT treatment and at follow up visits to demonstrate changes in the amount of leakage from the CNVM. Results:Fluorescein angiography at 2 weeks, post PDT with Talaporfin Sodium, showed evidence of choroidal vessel closure of the CNVM’s. Visual acuity remained stable in all treated patients at 2 week and 8 week follow up visits. None of the patients had adverse effects or reported any photosensitivity reactions. The retinal vasculature remained intact even when treated directly over a major retinal vessel in 1 patient Conclusion:Talaporfin PDT treatment can reduce CNVM leakage in late ARMD, with evidence of choroidal vessel closure on fluorescein angiography. Although the patients selected had very poor central visual acuity, persistent CNVM leakage can threaten the residual vision they have. Treatment may conserve navigational vision in this patient group. The primate data showed some retinal damage, which was dose dependant and also affected by the drug light interval. The treatment effect in monkeys ranged from no effect to retinal haemorrhage. In our experience of treatment in human eyes, there has been no evidence of retinal damage emphasizing the differences between primates and humans in the realm of ARMD.
Keywords: age–related macular degeneration • photodynamic therapy • retina