Electro-encephalo-dynamographic investigations taken from 36 glaucoma patients showed that the autoregulative mechanism in the region of the anterior part of the optic nerve (apon) is disturbed and the ciliary perfusion pressure is altered in a characteristic manner. The results lead to the conclusion that glaucomatous ischemia occurring in the apon may mainly be due to the following causes and their combinations: high IOP; low blood pressure in the ciliary arterial circulation; insufficiency of autoregulation, and changes of the local conditions of diffusion of oxygen and nutrients.