Neuroprotective Role of VEGF Induced in Response to Photodynamic Therapy

Age-related macular degeneration (AMD) is a vision-threatening disease, and its prevalence is increasing worldwide. Two approaches are commonly used to suppress the pathological choroidal neovascularization (CNV) that characterizes “wet” AMD. One is photodynamic therapy (PDT), which involves using a systemic photosensitizer in combination with low-power laser irradiation of CNV through the neural retina and retinal pigment epithelium (RPE); the other involves the intravitreous injection of drugs targeting vascular endothelial growth factor (VEGF). In some cases, both methods are used simultaneously. However, recent results from animal experiments indicate that transient increase in VEGF in the tissue following PDT is required for retinal cell survival in overcoming the cellular stress caused by PDT. To maximize the visual outcome and retinal protection, it will be necessary to optimize the combination therapy, which requires the elucidation of the molecular and cellular changes that occur in the retinal tissue during the course of treatment.