Selective photodynamic effects of the new photosensitizer ATX-S10(Na) on choroidal neovascularization in monkeys

Objective: To determine the optimal treatment variables for photodynamic th erapy (PDT) with new photosensitizer ATX-S10(Na) (13,17-bis[1-carboxypropio nyl] carbamoylethyl-8-etheny-2-hydroxy-3-hydroxyimino- ethylidene-2,7,12,18 -tetranethyl 6 porphyrin sodium) to induce selective occlusion of choroidal neovascularization (CNV) in nonhuman primate eyes. Methods: Experimental CNV was induced in monkey eyes by laser photocoagulat ion, and PDT was performed in neovascularized and healthy eyes with differe nt treatment variables. At 0 to 150 minutes after 4-, 8-, and 12-mg/kg of b ody weight intravenous injections of ATX-S10(Na), a diode laser was irradia ted at the dose of 1 to 127 J/cm(2) (wavelength, 670 nm). Vascular occlusio n induced by PDT was evaluated using fluorescein angiography, indocyanine g reen angiography, and histological examination at 1 day to 4 weeks after ir radiation. Results: Selective occlusion of CNV without damage to healthy retinal and c horoidal capillaries was achieved in the following conditions: 30 to 74 J/c m(2) irradiation at 30 to 74 minutes after the 8-mg/kg injection, and 1 to 29 J/cm(2) irradiation at 30 to 74 minutes or 30 to 74 J/cm(2) irradiation at 75 to 150 minutes after the 12-mg/kg dye injection. Regrowth of CNV ofte n occurred when the retina was heavily injured by excessive PDT. Conclusion: Dy using optimal treatment variables, PDT using ATX-S10(Na) ind uces selective occlusion of CNV in nonhuman primate Eyes, providing the pos sibility of therapeutic application to the clinical practice. Clinical Relevance: Occlusion of CNV without direct damage to the sensory r etina is useful to preserve visual acuity in patients with exudative age-re lated macular degeneration. A clinical trial of PDT using ATX-S10(Na) is de sirable.