Vascular anatomy of the optic nerve head.

Although intraocular pressure remains the main modifiable risk factor for open-angle glaucoma, other factors such as vascular perfusion likely play a significant role. It is not clear how mechanical deformation, axonal damage, glial responses, and ischemia interact to lead to the tissue remodeling seen clinically as glaucomatous cupping. To understand the potential role of vascular risk factors in glaucoma, it is important to understand the vascular anatomy of the optic nerve head (ONH). The focus of this review is to provide a description of the vascular anatomy of the ONH and to describe recent work in the central nervous system that suggests that astrocytes play a key role in vascular regulation. Finally, the evidence for vascular regulation in the ONH and retina is reviewed.