PHOTODYNAMIC THERAPY AND DIGITAL ANGIOGRAPHY OF EXPERIMENTAL IRIS NEOVASCULARIZATION USING LIPOSOMAL BENZOPORPHYRIN DERIVATIVE

Purpose: To study the efficacy of liposomal benzoporphyrin derivative (BPD) (Verteporfin) for the angiographic visualization and photodynami c therapy (PDT) of experimental iris neovascularization. Methods: Expe rimental iris neovascularization was induced in eight cynomolgus monke y eyes by occluding all the branch retinal veins with a dye-yellow (57 7-nm) laser, Iris angiography was done with sodium fluorescein, indocy anine green (ICG), and liposomal BPD to compare the visualization of n ormal and neovascular vessels by these three dyes. PDT was performed u sing an intravenous infusion of liposomal BPD (0.375-0.75 mg/kg), foll owed by irradiation with 689-nm light from a diode laser/slit-lamp del ivery system using 600 mW/cm(2) irradiance and 150 J/cm(2) fluence. Th e effect of treatment was followed by iris photography and angiography , and the findings were confirmed by histopathology using light and el ectron microscopy. Results: Iris fluorescein angiography (FA) showed s uperficial tortuous and leaky new vessels. Liposomal BPD and ICG angio graphy of the same eye demonstrated deeper dilated and tortuous iris v essels, with minimal dye leakage. PDT of the iris with irradiation, pe rformed within 20 minutes of the start of dye infusion (0.75 mg/kg), r esulted in angiographic and histologic occlusion of iris vessels exami ned at 24 hours. Three to nine days after PDT, histopathologic examina tion showed regression of the iris neovascular membrane, with some ope n vessels, Conclusions: Liposomal BPD and ICG provided angiographic vi sualization of deeper normal and neovascular iris vessels. PDT using l iposomal BPD leads to effective early closure to experimental iris neo vascularization.