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Accumulation of photosensitizer ATX-S10 (Na) in experimental corneal neovascularization
1Departments of Ophthalmology, Osaka City University School of Medicine, Osaka, Japan.
Purpose:
To determine the most appropriate time for laser irradiation to produce selective occlusion of new corneal vessels by photodynamic therapy (PDT) 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 administration was determined in rabbit eyes. 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 spectrofluorometry. Frozen sections of neovascularized cornea and iris were observed by fluorescence microscopy.
Results:
Plasma ATX-S10(Na) concentration was highest 5 minutes after dye injection and rapidly decreased and reached almost zero at 24 hours, indicating its prompt excretion from the body. The amount of ATX-S10(Na) in the new corneal vessels as measured by nitrogen-pulsed laser spectrofluorometry increased and reached maximal level at 2 to 4 hours. Under fluorescence microscopy, the dye was more abundantly localized in the wall of new corneal vessels than in the normal tissue at 2 to 4 hours.
Conclusion:
These results indicate that laser irradiation between 2 and 4 hours after dye injection is appropriate for selective PDT with ATX-S10(Na) for the occlusion of new corneal vessels.