Long-term effectiveness of photodynamic therapy by using a hydrophilic photosensitizer ATX-S10(Na) against experimental choroidal neovascularization in rats

Background and Objective: We previously demonstrated that a hydrophilic pho tosensitizer ATX-S10 had a potent photodynamic effect. This study was desig ned to reveal the long-term effectiveness of photodynamic therapy (PDT) wit h this agent in occluding choroidal neovascularization (CNV) and its select ivity in the neovascular tissue. Study Design/Materials and Methods: Experimental CNV was induced by intense photocoagulation in rat eyes. Immediately or 2 hours after intravenous inj ection of 8 mg/kg body weight of ATX-S10(Na), a cis isomer ofATX-S10, eyes were irradiated by a diode laser at the radiance of 3.25-65.3 J/cm(2) Vascu lar occlusion was identified by fundus photography, fluorescein angiography , and histology at 1, 3, 7, 14, and 28 days after PDT. As controls, non-neo vascular eyes were subjected to PDT and similarly analyzed. Results: By using the following treatment parameters, PDT with ATX-S10(Na) successfully occluded CNV without causing occlusion of retinal capillaries for 28 days; 7.4 and 19.6 J/cm(2) immediately after dye injection and 36.7 and 65.3 J/cm2 2 hours after injection. Although these conditions also caus ed occlusion of normal choriocapillaries and mild injuries of retinal vesse ls, retinal pigment epithelium, and photoreceptors at I day, retinal vessel s and pigment epithelial cells recovered from damages by 28 days. No injuri es were found in the inner retina. Conclusion: In optimal treatment conditions, PDT with ATX-S10(Na) can induc e long-term, selective occlusion of CNV without causing irreversible damage s in the inner retina. (C) 2000 Wiley-Liss, Inc.