Concerning the pathogenesis of retinal detachment 4 groups of each 10 eyes have been examined by fluorescein angiography: the periphery of normal eyes (Table 2), ophthalmoscopically inconspicuous sectors of patients with detachment (Table 3), the area of lattice degeneration, radial perivascular degeneration and round holes without detachment (Table 4) and the area of tears and holes, when detachment has taken place (Table 5). The time passing between the injection of dye into the cubital vein and the first arterial filling in the retinal periphery is practically equal in all groups. The prolongation of retinal circulation time II from the first arterial to the complete venous filling in areas of lattice degeneration etc. without detachment seems to be in connection with small vessel closures. The striking short retinal circulation time I from the first arterial to the first venous filling in the cases of detachment is apparently caused by capillary dilatations central of the tears and holes; the dilated capillaries seem to have the function of a arteriovenous anastomosis. Own measurements of circulation times in the area of optic disc (Table 1), performed for comparisments, are accordant to literature.