Photodynamic therapy in ocular vascular disease

Photodynamic therapy (PDT) is a novel therapeutical approach which is noninvasive and potentially selective for neoplastic pathologies. Association of photosensitizers with low density lipoprotein (LDL) leads to direct targeting of the treated lesions with enhanced efficiency and selectivity. LDL-mediated PDT is particularly useful in the treatment of neo-vascular structures since LDL receptors are abundantly expressed on vascular endothelial cells. To evaluate the potential of selective photodynamic vasoocclusion in ocular neo-vascular disease a sequence of experiments was designed: Efficiency of the LDL-carrier was tested in vitro, the system was then transferred to an in vivo model demonstrating a vascularized neoplasm. Occlusion was successfully performed in experimentally induced neovascularization in the cornea, while selective photothrombosis of subretinal vasculature revealed lack of collateral damage. The experimental results were used to establish a first clinical trial for the use of PDT in age-related macular degeneration, one of the leading causes for blindness.