Accumulation of photosensitizer ATX-S10 (Na) in experimental corneal neovascularization

Purpose: To determine the most appropriate time for laser irradiation to pr oduce selective occlusion of new corneal vessels by photodynamic therapy (P DT) with a new photosensitizer, ATX-S10(Na). Methods: The time course of the plasma levels of ATX-S10(Na) and the degree of dye accumulation in the corneal neovascularization after intravenous ad ministration was determined in rabbit eves. Plasma concentration of ATX-S10 (Na) was analyzed by a spectrophotometer. The amount of ATX-S10(Na) in the new corneal vessels was measured by nitrogen-pulsed laser spectrofluorometr y. Frozen sections of neovascularized cornea and iris were observed by fluo rescence microscopy. Results: Plasma ATX-S10(Na) concentration was highest 5 minutes after dye i njection and rapidly decreased and reached almost zero at 24 hours, indicat ing its prompt excretion from the body. The amount of ATX-S10(Na) in the ne w corneal vessels as measured by nitrogenpulsed laser spectrofluorometry in creased and reached maximal level at 2 to 4 hours. Under fluorescence micro scopy, the dye was more abundantly localized in the wall of new corneal ves sels than in the normal tissue at 2 to 4 hours. Conclusion: These results indicate that laser irradiation between 2 and 4 h ours after dye injection is appropriate for selective PDT with ATX-S10(Na) for the occlusion of new corneal vessels. (C) 2000 Japanese Ophthalmologica l Society.