Effect of beta-irradiation by a 106 ruthenium plaque on the rabbit eye choroid

Abstract

Fourteen Chinchilla gray rabbit eyes were treated with a ruthenium plaque, receiving 200, 400, or 800 Gy, to assess the effect of beta-irradiation on the normal rabbit choroid. Radiation effects were evaluated using fundus photography, fluorescein angiography, fluorophotometry, and histology. Fluorophotometry showed a fluorescein leakage into the vitreous 1 day after irradiation. Leakage values returned to normal within 1 month after irradiation. Fluorescein angiography showed nonperfusion of the choroid after beta-irradiation; the time between irradiation and the onset of nonperfusion was found to be dose dependent. Five months after 200 Gy irradiation, choroidal atrophy had developed but some vessels still stained with fluorescein; 400 Gy irradiation induced subtotal choroidal nonperfusion within 3 months and 800 Gy within 1 week.

Etude comparative de l’irradiation bêta (¹⁰⁶Ru/¹⁰⁶Rh) et de l’irradiation gamma (¹²⁵I) sur l’œil du lapin

“…Dans notre étude nous avons utilisé un débit de 4,36 Gy/h au contact de la sclère, ce qui nous rapproche des bas débits. Schaling et al [17] ont spécialement étudié les effects du ruthénium-106 sur les vaisseaux de la choroïde du lapin, en angiographie et fluorophotométrie. Après traitement apparaît une non-perfusion de ce tissu dans des délais qui dépen-dent de la dose: 5 mois pour 200 Gy, 3 mois pour 400 Gy et 8 jours pour 800 Gy.…”

“…L'oeil humain est plus volumineux et ses membranes plus épaisses. Les doses reçues par la choroïde, la macula et le nerf optique seraient moindres [17,19] et la probabilité de complications radiques diminuée. Lors du traitement d'un mélanome choroïdien, d'autre part, les rapports anatomiques de la rétine avec les autres tissus oculaires peuvent être modifiés par la tumeur et la dose reçue être très différente.…”

Long-term Choroidal Vascular Changes after Iodine Brachytherapy versus Transpupillary Thermotherapy for Choroidal Melanoma

“…These authors reported that some wall ICG staining choroidal vessels eventually became nonperfused. Histopathologic studies (20,27) never reported signs of vasculitis within the irradiation field that could justify choroidal wall staining with ICG. But to our knowledge, histopathologic analysis has never been performed in eyes treated with IBT and with documented segments of choroidal vascular wall staining detected by ICG.…”

Transpupillary Thermotherapy

“…[29][30][31][33][34][35][36] FluoresceinangiographyafterTTTshowsarathersharp demarcation between the nonfluorescent heat-treated area and the surrounding normal fluorescence, as also found on histological examination, 5 because the choroid adjacent to the field of thermotherapy, which has a high blood perfusion rate, acts as a heat sink. 2,37 Conversely, after brachytherapy the treated area is surrounded by zones of nonperfusion of the choriocapillary layer and atrophy of the retinal pigment epithelium 38,39 (Figure 3).…”