[Accumulation of a photosensitizer ATX-S 10 Na (II) to experimental corneal neovascularization].

In order to determine the most appropriate time point for laser irradiation in photodynamic therapy with a new photosensitizer, ATX-S 10 Na (II), which produces selective occlusion of new vessels, we investigated the time course of plasma levels of ATX-S 10 Na (II) after intravenous administration and degree of dye accumulation in the corneal neovascularization in rabbit eyes. Plasma ATX-S 10 Na (II) concentration decreased rapidly after injection and become virtually undetectable at 24 h, indicating rapid excretion from the body. Nitrogen-pulsed laser spectrofluorometry demonstrated that the amount of ATX-S 10 Na (II) in new corneal vessels increased and reached a maximal level 2 to 4 hours after dye injection. Under a fluorescence microscope, ATX-S 10 Na (II) was localized in the wall new corneal vessels and in extravascular tissue 2 to 4 hours after dye injection. These results indicate that the appropriate time for laser irradiation in selective PDT is between 2 and 4 hours after dye injection, when a larger amount of dye is accumulated in neovasculature tissue compared to normal tissue.