Selective occlusion of choroidal neovascularization by photodynamic therapy with a water-soluble photosensitizer, ATX-S10

Background and Objective: To determine the optimal treatment parameters for selective occlusion of choroidal neovascularization (CNV) by photodynamic therapy (PDT) by using the photosensitizer ATX-S10 and a diode laser (wavel ength = 670 nm). Materials and Methods: Experimental CNV was induced in rat fundi by argon l aser photocoagulation. The distribution of ATX-S10 in the chorioretina was analyzed by fluorescence microscopy, and the optimal treatment parameters f or selective occlusion of CNV were investigated by changing the dosage and timing of laser irradiation. CNV closure and resulting damage of the surrou nding tissue were documented by fluorescein angiography and light and elect ron microscopies. Results: Fluorescence of ATX-S10 was observed to be localized in the vascul ar lumen of the retina and choroid within 5 min after dye injection and inc reased in intensity in CNV up to 2-6 h and decreased rapidly in normal tiss ue. Laser irradiation with radiant exposures of 7.4 J/cm(2) applied immedia tely after dye injection or with 22.0 J/cm(2) at 2-4 h later effectively oc cluded the induced CNV without causing significant damage to normal retinal capillaries and large choroidal vessels. Conclusions: PDT using ATX-S10 can selectively occlude CNV. ATX-S10 is a po tentially useful photosensitizer for the treatment of CNV. (C) 1999 Wiley-L iss, Inc.