PHOTODYNAMIC THERAPY FOR CHOROIDAL NEOVASCULARIZATION

Abstract

To review the biophysical basis and current state of therapy for photodynamic closure of subfoveal choroidal neovascularization in the eye. A review of the literature is included, which encompasses the chemical structure, biophysical mechanism of action, range of available agents, status of clinical trials, clinical indications, results of treatments, complications, and future directions. Photodynamic therapy has been shown to be effective in closing both experimental choroidal neovascularization in animal models as well as subfoveal choroidal neovascularization in humans. The therapy results in temporary closure of choroidal new vessels for a period of approximately 1 to 4 weeks. By 12 weeks, most patients have reperfusion or reproliferation of choroidal new vessels resulting in the need for retreatment to achieve continued closure and visual stabilization. Differences exist in the quantum yield, clinical efficiency, and light and sensitizer dose requirements between different classes of agents. Further clinical trials will be required to determine the optimal form of therapy, with verteporfin (Visudyne) as the only currently approved agent. Other agents, including tin etiopurpurin (Purlytin) and motexafin lutetium (Optrin), are currently undergoing phase III, and phase II trials, respectively. Photodynamic therapy is a promising treatment modality shown to be effective in achieving closure and stabilization of vision loss compared with placebo control in eyes with subfoveal choroidal neovascularization.