Dynamic observation of selective accumulation of a photosensitizer and itsphotodynamic effects in rat experimental choroidal neovascularization

Purpose: The authors investigated the selective accumulation of a photosens itizer, ATX-S10(Na), in experimental choroidal neovascularization (CNV) in rats using a highly sensitive colorchromatic charge coupled device (CCD) ca mera. Methods: To detect the development of experimental CNV in 30 rats, the anim als were followed weekly with simultaneous fluorescein and indocyanine gree n angiography. After injecting ATX-S10(Na), the authors detected fluorescen ce from the photosensitizer using a highly sensitive color CCD camera. The camera was connected to a surgical microscope, under which rat fundi were o bserved through a coverglass in contact with the cornea. The retinas were e xcited with 405-435 nm light, and the light emitted from the photosensitize r passed through a 680-nm bandpass filter before being detected by the CCD camera. Results: Immediately after injection, fluorescence appeared in the retinal vessels and then the entire retina. Thirty minutes postinjection, the inten sity of the fluorescence was still strong from the whole retina, and the CN V was not detected. One hour after injection, retinal fluorescence was weak but still observable; 1.5 hours postinjection, retinal fluorescence was un detectable but fluorescence was strong from the CNV, Under the optimum ther apeutic conditions, CNV was effectively occluded. Conclusion: ATX-S10(Na) selectively accumulates in the CNV in rats. The opt imum therapeutic timing is approximately 1.5 hours postinjection of the dye in this CNV model.