The authors conducted rheographic and opthalmoretinal studies of 85 patients with cerebral venous dystonias and of 20 control patients using functional loads (-30 degrees head-down tilt). In the control subjects the diastolic pressure in the central retinal vein (CRV) in head-down tilt test was 10.1 +/- 0.3 mm Hg, showing no significant difference from the initial level (9.0 +/- 0.4 mm Hg), p greater than 0.05. The patients with cerebral venous dystonias presented a significant increase in the diastolic pressure in the CRV by 4.9 +/- 0.2 mm Hg, p less than 0.001, which is indicative of a compromised intracranial venous pressure.