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: (1) high IOP; (2) low blood pressure in the ciliary arterial circulation; (3) insufficiency of autoregulation, and (4) changes of the local conditions of diffusion of oxygen and nutrients.

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Pattern-reversal visual evoked cortical potentials (VECP) taken from 25 healthy volunteers before, during and after short-lasting elevation of intraocular pressure proved to be dependent on ciliary perfusion pressure (pp_cil) in a characteristic way. Reductions of pp_cil to ca. 30 mm Hg did not result in VECP changes. These results point to efficient autoregulation in the retinal circulation and in the circulatory region of the anterior part of the optic nerve. When ppcil was reduced to below 30 mm Hg a marked reduction of VECP amplitudes and prolongation of latencies were observed. An autoregulatory capacity of about 15 mm Hg was found.

This paper attempts to obtain a better understanding of the oxygen supply to tissue cells of the optic nerve head by describing all phases of the release, diffusion and consumption process by means of a mathematical model. As a result the oxygen partial pressure reduction induced by intraocular pressure elevation--as it occurs in glaucoma--seems to be mainly influenced by a pressure-induced lowering of the average blood velocity in the retinal capillaries. A reduction of this velocity to a fourth of its normal value even makes the oxygen partial pressure at the venous capillary wall drop below the critical level necessary for maintaining cell activity. Furthermore our calculations allow us to conclude that an involvement of the retinal capillary network supplied by the central retinal artery should not be neglected in glaucoma.

Procedures such a8 principal component analysis, autocorrelation and cross-correlation, Fourier analysis, Wiener filtering, which have been ueed 60 far for the mathematical analysis of VECP mainly serve purpose of quantization and frequency analysis of eignals and the evaluation of their intraindividual and interindividual variability. Although some of the above methods are also employed for the differentiation of VECPs, i t aeems that m e t h h of primarily comparative chararter are better suited for the claeeificcrtion of different signal forms. This paper reports on results obtained by multivariate analysis of variance.