Fig. 2.

The brain-eye-vascular triad. This triad illustrates the interdependency of the three organ systems and their role in vision loss. The retina, which transforms light rays to electrical cell signals weighs only about 1 gram. But the estimated weight of the brain areas needed to support normal vision is on the order of several hundred grams. To understand the causes and consequences of vision loss, and to find new treatment options, the eye and the visual system cannot be viewed in isolation but rather need to be considered within the holistic context of different systems throughout the brain and vascular system. The arrows indicate the direction of interaction between brain (b), vascular system (v) and eye (e). The eye-brain influence is denoted as E2B (eye-to-brain) and B2E (brain-to-eye or brain-to-central visual structures). Such interactions can be direct or indirect. Note: blood flow is not only important for delivering nutrition / oxygen and removal of metabolic by-products, but it is also important for thermo-regulation when the eye is exposed to extreme heat or cold. IOP is at least in part regulated by the brain.