We present a patient with isolated angiomatosis retinae, in whom ruthenium irradiation was administered for treatment of a secondary serous retinal detachment. Prior to therapy, we measured an increased vessel diameter. Following treatment, decreasing venous vessel diameter was documented three-dimensionally utilizing laser scanning tomography. The changes in vessel height (87%) exceeded the changes in width (49%). This is most probably because the vessels are embedded in the nerve fiber layer, stabilized by the surrounding tissues more in a horizontal than in a vertical direction. In addition, spontaneous venous pulsation located in the optic disc and in the retina was documented.