The vascular concept of glaucoma.

The regulation of ocular perfusion is different for different parts of the eye. Observations on the retina can, therefore, not be extrapolated to the optic nerve head. Extraocular vessels, especially the short posterior ciliary arteries, might play a major role in regulation of ocular circulation, but additional regulation takes place in the eye itself. Dysregulation might be transient and, thus, not necessarily present and detectable at any one examination. Older patients with arteriosclerotic vessels may behave differently in this regard than do young, healthy animals. Not only the arterial but also the venous side of the circulation may be disturbed. Disk hemorrhages can not only be a sign of damage; they can also provoke ischemia. Besides hypoxia, diseased vessel walls might play a direct role in the pathogenesis of optic nerve head cupping. Finally, a relation between vascular dysregulation and aqueous-humor dynamics is conceivable.